Patient interface

Abstract

A patient interface for delivering positive pressure respiratory therapy to a patient is disclosed. The patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of the patient. The patient interface comprises a first chamber and a second chamber. The first and second chamber are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface. The patient interface further comprises a respiratory gas inlet in fluid communication with the first chamber and a flow valve in fluid communication with the second chamber. Respiratory gas is exhaustible through the flow valve from the second chamber to external of the patient interface. The flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across a range of respiratory therapy pressures.

Description

PATIENT INTERFACETECHNICAL FIELD

[0001] The present invention relates to a patient interface for delivering respiratory therapy to a patient. In particular, the present invention relates to a non-invasive patient interface for delivering pressurised respiratory gasses to a patient.BACKGROUND

[0002] One current treatment for respiratory diseases, such as thoracic restrictive diseases, acute respiratory failure, advanced neuromuscular diseases, chronic obstructive pulmonary disease (COPD - which includes emphysema, refractory asthma and chronic bronchitis), is non-invasive ventilation (NIV) therapy. There is some evidence to suggest that NIV therapy may be useful for assisting respiration before and / or after intubation, including reducing the chances of re-intubation. The NIV therapy applies a positive airway pressure to the lungs throughout the inhalation and exhalation cycles. This improves the flow of respiratory gas into and out of the lungs.

[0003] However, one side effect of the positive pressures applied in current NIV treatments is that the therapy pressures applied can make patients uncomfortable and, therefore, less willing to undergo the treatment. A follow-on effect of the positive pressure is that it requires the patient interface to be secured firmly to the patient to create a seal sufficient to minimize leakages and, thereby ensure that the pressure can be maintained in both the patient interface and the respiratory system. Such firm application of the patient interface to the patient’s face can cause pressure sores, particularly for patients that are semi-conscious or unconscious and, therefore, are unable to provide feedback on any soreness caused by the pressure of the patient interface on their skin.

[0004] For at least the reasons above, NIV therapy gives rise to two prominent challenges, namely compliance (the extent to which patients are willing to submit to the therapy) and pressure sores created from contact between the patient interface and the patients skin. In addition to these challenges, a further challenge for patients with obstructive respiration diseases or acute respiratory failure is flushing exhaled carbon dioxide from their anatomical dead space. Specifically, the end of the exhalation cycle is characterised by a reduction in pressure of the patient’s airway.This means that the carbon dioxide-loaded respiratory gas remains in the throat, nose, and mouth of the patient and is pulled back into the lungs at the commencement of the next inhalation cycle. Replacing the carbon dioxide-loaded respiratory gas in these regions with fresh respiratory gas that includes lower levels of carbon-dioxide (and higher levels of oxygen) than the carbon dioxide-loaded respiratory gas therefore assists patients in achieving improved respiration via improved ventilation efficiency.

[0005] It is believed that this improved ventilation efficiency may enable a reduction in therapy pressures which may lead to a reduction in pressure sores and an improvement in patient compliance. Alternatively, it may provide improved ventilation at the same therapy pressures and lead to improved patient outcomes and a reduction of time spent undergoing NIV therapy.

[0006] It is desirable to provide a patient interface that improves patient comfort and that reduces pressure sores by improving ventilation of the patient.

[0007] It is also desirable to provide a patient interface that assists with flushing anatomical dead space.SUMMARY OF DISCLOSURE

[0008] The present invention will now be described by way of a set of embodiments. However, it will be appreciated that the invention may be defined by combining the features of two or more of the embodiments.

[0009] In one aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprises:• a cushion module comprising a first chamber with one or more oral openings to communicate gas with a mouth of the patient, a second chamber with one or more nasal openings to communicate gas with one or more nares of the patient and a dividing wall that separates the first chamber from the second chamber;• an inlet through which the pressurized respiratory gas is receivable into the first chamber;• an outlet through which respiratory gas is exhaustible from the second chamber; andwherein the patient interface enables a respiratory gas pressure in the second chamber that is lower than a respiratory gas pressure in the first chamber, a respiratory gas pressure difference between the first chamber and the second chamber that is below a pressure difference upper limit across a range of different respiratory therapy pressures and a respiratory gas flow rate through the outlet that is substantially constant across the range of different respiratory therapy pressures.

[0010] In another aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprises:• a cushion module comprising a first chamber with one or more oral openings to communicate gas with a mouth of the patient, a second chamber with one or more nasal openings to communicate gas with one or more nares of the patient and a dividing wall that separates the first chamber from the second chamber;• an inlet through which the pressurized respiratory gas is receivable into the first chamber;• an outlet through which respiratory gas is exhaustible from the second chamber; and wherein the patient interface enables a respiratory gas pressure in the second chamber that is lower than a respiratory gas pressure in the first chamber, a respiratory gas pressure difference between the first chamber and the second chamber that is below a pressure difference upper limit across a range of different respiratory therapy pressures and a respiratory gas flow rate through the outlet that is below an upper limit across the range of different respiratory therapy pressures.

[0011] In another aspect, there is provided a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprises:• a cushion module comprising a first chamber with one or more oral openings to communicate gas with a mouth of the patient, a second chamber with one or more nasal openings to communicate gas with one or more nares of the patient and a dividing wall that separates the first chamber from the second chamber;• an inlet through which the pressurized respiratory gas is receivable into the first chamber;• an outlet through which respiratory gas is exhaustible from the second chamber; andwherein the patient interface enables a respiratory gas pressure in the second chamber that is lower than a respiratory gas pressure in the first chamber, a respiratory gas pressure difference between the first chamber and the second chamber that is below a pressure difference upper limit and above a pressure difference lower limit across a range of different respiratory therapy pressures.

[0012] A respiratory gas flow rate through the outlet may be substantially constant across the range of different respiratory therapy pressures.

[0013] A respiratory gas flow rate through the outlet may be below an upper limit across the range of different respiratory therapy pressures.

[0014] In another aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprises:• a cushion module comprising a first chamber with one or more oral openings to communicate gas with a mouth of the patient, a second chamber with one or more nasal openings to communicate gas with one or more nares of the patient and a dividing wall that separates the first chamber from the second chamber;• an inlet through which the pressurized respiratory gas is receivable into the first chamber;• an outlet through which respiratory gas is exhaustible from the second chamber; and wherein the patient interface enables a respiratory gas pressure in the second chamber that is lower than a respiratory gas pressure in the first chamber, and a respiratory gas pressure difference between the first chamber and the second chamber that is below a pressure difference upper limit across a range of different respiratory therapy pressures.

[0015] The range of different respiratory therapy pressures may be 4 cm H2O to 40 cm H2O, may be 4 cm H2O to 35 cm H2O, or may be 4 cm H2O to 30 cm H2O.

[0016] In each of the above aspects, the patient interface may enable a respiratory gas pressure difference between the first chamber and the second chamber that is between the pressure difference upper limit and a pressure difference lower limit across the range of different respiratory therapy pressures.

[0017] The pressure difference upper limit may be 4.0 cmH2O, 3.5 cmH2O, 3.0 cmH2O, 2.5 cmFhO, 2.0 cmFhO, 1 .5 cmFhO, 1 .4 cmFhO, 1 .3 cmFhO, 1 .2 cmFhO, 1 .1 cmH2O, 1 .0 cmH2O, 0.9 cmH2O, 0.8 cmH2O, 0.7 cmH2O, 0.6 cmH2O, 0.5 cmH2O, 0.4 cmH2O, 0.3 cmH2O or 0.2 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0018] The pressure difference lower limit may be greater than 0.0 cmH2O or may be 0.1 cmH2O, 0.2 cmH2O, 0.3 cmH2O, 0.4 cmH2O, 0.5 cmH2O, 0.6 cmH2O, 0.7 cmH2O, 0.8 cmH2O, 0.9 cmkhO, 1.0 cmkhO, 1.1 cmkhO, 1.2 cmkhO, 1.3 cmkhO,1 .4 cmH2O, 1 .5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0019] The patient interface may comprise a pressure valve.

[0020] The pressure valve may be operable to provide a substantially constant respiratory gas pressure decrease between the first chamber and the second chamber across the range of different respiratory therapy pressures.

[0021] The pressure valve may be operable to provide a respiratory gas pressure difference between the first chamber and the second chamber that is between an upper limit and a lower limit across the range of different respiratory therapy pressures.

[0022] The pressure valve upper limit may be 4.0 cm H2O, 3.5 cm H2O, 3.0 cm H2O,2.5 cm H2O, 2.0 cm H2O, 1 .5 cm H2O, 1 .4 cm H2O, 1 .3 cm H2O, 1 .2 cm H2O, 1 .1 cm H2O, 1 .0 cm H2O, 0.9 cm H2O, 0.8 cm H2O, 0.7 cm H2O, 0.6 cm H2O or 0.5 cm H2O lower than the respiratory gas pressure in the first chamber across a range of different respiratory therapy pressures.

[0023] The pressure valve lower limit may be greater than 0.0 cm H2O or may be 0.1 cm H2O, 0.2 cm H2O, 0.3 cm H2O, 0.4 cm H2O, 0.5 cm H2O, 0.6 cm H2O, 0.7 cm H2O, 0.8 cm H2O, 0.9 cm H2O, 1 .0 cm H2O, 1 .1 cm H2O, 1 .2 cm H2O, 1 .3 cm H2O, 1 .4 cm H2O, 1 .5 cm H2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0024] The pressure valve may control a respiratory gas pressure in the second chamber during use of the patient interface.

[0025] The pressure valve may regulate the gas pressure in the second chamber in response to the range of different respiratory therapy pressures delivered to first chamber of the patient interface.

[0026] In another aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising:• a cushion module comprising a first chamber with one or more oral openings to communicate gas with a mouth of the patient, a second chamber with one or more nasal openings to communicate gas with one or more nares of the patient, and a dividing wall that separates the first chamber from the second chamber;• an inlet through which the pressurized respiratory gas is receivable into the first chamber;• an outlet through which respiratory gas is exhaustible from the second chamber; and wherein the patient interface enables a respiratory gas flow rate through the outlet that is substantially constant across a range of different respiratory therapy pressures.

[0027] In another aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising:• a cushion module comprising a first chamber with one or more oral openings to communicate gas with a mouth of the patient, a second chamber with one or more nasal openings to communicate gas with one or more nares of the patient, and a dividing wall that separates the first chamber from the second chamber;• an inlet through which the pressurized respiratory gas is receivable into the first chamber;• an outlet through which respiratory gas is exhaustible from the second chamber; and wherein the patient interface enables a respiratory gas flow rate through the outlet that is below an upper limit across a range of different respiratory therapy pressures.

[0028] In all of the above aspects, the first chamber may be in fluid communication, within the cushion module, with the second chamber.

[0029] In all of the above aspects, the first chamber may be in fluid communication, external of the cushion module, with the second chamber.

[0030] In all of the above aspects, the dividing wall may comprise one or more flow directors that provide fluid communication between the first chamber and the second chamber.

[0031] In all of the above aspects, the first chamber may comprise a lower chamber and the second chamber may comprise an upper chamber.

[0032] The different respiratory therapy pressures may be in the range of 4 cm H2O to 40 cm H2O, 4 cm H2O to 35 cm H2O, or 4 cm H2O to 30 cm H2O.

[0033] The substantially constant flow rate of respiratory gas through the outlet may comprise a flow rate within the range of 10 to 50 L / m, 10 to 40 L / m, or 10 to 30 L / m across the range of different respiratory therapy pressures.

[0034] The patient interface may enable a respiratory gas flow rate through the outlet that is less than 50L / m, less than 45L / m, less than 40L / m, less than 35L / m, less than 30L / m, less than 25L / m, less than 20 L / m, less than 18 L / m, less than 17L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of different respiratory therapy pressures.

[0035] The upper limit of the respiratory gas flow rate through the outlet is 50L / m, 45L / m, 40L / m, 35L / m, 30L / m, 25L / m, 20 L / m, 17L / m, 16 L / m, 15 L / m, 14 L / m, 13 L / m or 12 L / m across the range of different respiratory therapy pressures

[0036] The patient interface may enable a respiratory gas flow rate through the outlet that is greater than 4 L / m, greater than 6 L / m, greater than 8 L / m, greater than 10 L / m, greater than 12 L / m, greater than 14 L / m, or greater than 16 L / m across the range of different respiratory therapy pressures.

[0037] The patient interface may enable a respiratory gas flow rate through the outlet that is above a lower limit across a range of different respiratory therapy pressures.

[0038] The lower limit may be 4 L / m, 6 L / m, 8 L / m, 10 L / m, 12 L / m, 14 L / m, 16 L / m or 18 L / m across the range of different respiratory therapy pressures.

[0039] The patient interface may comprise a flow valve that regulates the respiratory gas flow rate through the outlet during use of the patient interface.

[0040] The flow valve may regulate the respiratory gas flow rate through the outlet in response to variations in respiratory gas pressure.

[0041] The flow valve may be responsive to variations in respiratory gas pressure in the second chamber.

[0042] The flow valve may be operable to provide a respiratory gas flow rate through the outlet that is less than 50L / m, less than 45L / m, less than 40L / m, less than 35L / m, less than 30L / m, less than 25L / m, less than 20 L / m, less than 18 L / m, less than 17L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across a range of different respiratory therapy pressures.

[0043] The flow valve may be operable to provide a respiratory gas flow rate through the outlet that is greater than 4 L / m, greater than 6 L / m, greater than 8 L / m, greater than 10 L / m, greater than 12 L / m, greater than 14 L / m, or greater than 16 L / m across a range of different respiratory therapy pressures.

[0044] The flow valve may be in fluid communication with the outlet.

[0045] The flow valve may be coupled to the outlet.

[0046] The flow valve may be adjacent to the outlet.

[0047] The flow valve may be located within the outlet.

[0048] The flow valve may be downstream of the outlet.

[0049] The cushion module may comprise a housing to which a patient-contacting seal is connected.

[0050] The cushion module may comprise a housing formed of a rigid material.

[0051] The cushion module may further comprise a seal formed of an elastomeric material and supported by the housing.

[0052] The housing may be formed of a plastics material.

[0053] The seal may be formed of a silicone material.

[0054] The seal may be formed of a foam material.

[0055] The seal may be formed of a textile material.

[0056] The flow valve may be part of the housing.

[0057] At least part of the flow valve may be integrally formed with the housing.

[0058] The flow valve may be part of the seal.

[0059] At least part of the flow valve may be integrally formed with the seal.

[0060] The flow valve may comprise the outlet.

[0061] The flow valve may be connectable to the housing.

[0062] The flow valve may be connectable to the housing via a screw-fit, bayonet-fit, snap-fit, friction-fit or adhesive.

[0063] The outlet may comprise one or more openings in the housing.

[0064] The outlet may comprise one or more openings in the seal.

[0065] The outlet may comprise one or more openings in the frame.

[0066] The outlet may comprise one or more openings in the flow valve.

[0067] The flow valve may be connectable with the seal.

[0068] The patient interface may comprise a frame that is connectable with the cushion module.

[0069] The patient interface may comprise a frame that is connectable with the housing.

[0070] The patient interface may comprise a frame that is couplable with the seal.

[0071] The seal may comprise sealing formation configured for coupling to the frame.

[0072] The flow valve may be part of the frame.

[0073] At least part of the flow valve may be integrally formed with the frame.

[0074] The flow valve may be connectable to the frame.

[0075] The flow valve may be connectable to the frame via a screw-fit, bayonet-fit, snap-fit, friction-fit or adhesive.

[0076] The frame may be connectable with the cushion module such that the flow valve is in fluid communication with the outlet.

[0077] The frame may be connectable with the housing such that the flow valve is in fluid communication with the outlet.

[0078] The seal may circumscribe the outlet.

[0079] The frame may abut the seal circumscribing the outlet.

[0080] The flow valve may abut the seal circumscribing the outlet.

[0081] Connection of the frame to the cushion module may compress the seal circumscribing the outlet.

[0082] Connection of the frame to the housing may compress the seal circumscribing the outlet.

[0083] Compressing the seal may form a substantially airtight fluid communication path between the outlet and the flow valve.

[0084] Connection of the flow valve to the housing may compress the seal circumscribing the outlet.

[0085] The patient interface may comprise a gasket disposable between the frame and the cushion module.

[0086] The patient interface may comprise a gasket disposable between the frame and the housing.

[0087] The patient interface may comprise a gasket disposable between the flow valve and the housing.

[0088] The gasket may circumscribe the outlet.

[0089] The gasket may be compressible to form a substantially airtight fluid communication path between the outlet and the flow valve.

[0090] The gasket may be compressible to form a substantially airtight fluid communication path between the outlet and the frame.

[0091] Connection of the frame to the housing may compress the gasket between the frame and the housing.

[0092] The seal may be formed of a resilient material.

[0093] The flow valve may define a cavity.

[0094] The flow valve may comprise a feed opening to receive respiratory gas from the outlet.

[0095] The feed opening may be in fluid communication with the cavity.

[0096] The flow valve may comprise an exhaust vent.

[0097] The exhaust vent may be in fluid communication with the ambient atmosphere.

[0098] The exhaust vent may comprise one or more holes in fluid communication with the cavity.

[0099] The flow valve may be adjustable to select a flow rate of respiratory gas through the outlet.

[0100] The flow valve may automatically respond to different respiratory therapy pressures to substantially maintain a preferred flow rate of respiratory gas through the outlet.

[0101] The flow valve may be configured to allow a preferred flow rate through the outlet across the range of respiratory therapy pressures.

[0102] The flow valve may be adjustable by a user to select the preferred flow rate through the outlet.

[0103] The flow valve may be non-adjustable such that the preferred flow rate through the flow valve is predetermined.

[0104] The preferred flow rate may be between an upper limit and a lower limit across the range of respiratory therapy pressures.

[0105] The flow valve may comprise a pressure-displaceable diaphragm.

[0106] The pressure-displaceable diaphragm may be deformable in response to respiratory gas pressure to vary a flow rate of respiratory gas through the flow valve.

[0107] The pressure-displaceable diaphragm may be responsive to respiratory gas pressure in the second chamber.

[0108] The pressure-displaceable diaphragm may comprise a flow opening.

[0109] The flow valve may comprise a splint adjacent to the flow opening to define a throttle channel between the flow opening and the splint.

[0110] The splint may be tapered outwardly in a direction away from the pressure- displaceable diaphragm.

[0111] The cross-sectional area of the splint may increase in a direction away from the pressure-displaceable diaphragm.

[0112] The throttle channel may comprise a cross-sectional flow area through which respiratory gas can flow between the flow opening and the splint.

[0113] The cross-sectional flow area of the throttle channel may comprise the area between the closest parts of the diaphragm and the splint.

[0114] The flow opening and the splint may be configured to change the cross- sectional flow area in response to the pressure-displaceable diaphragm being displaced by respiratory therapy pressure.

[0115] The flow opening and the splint may be configured to reduce the cross- sectional flow area in response to an increase in respiratory therapy pressure.

[0116] The flow opening and the splint may be configured to increase the cross- sectional flow area in response to a decrease in respiratory therapy pressure.

[0117] The diaphragm may comprise an outer portion, a central portion, the flow opening and a spring portion linking the central portion to the outer portion.

[0118] The central portion may be between the flow opening and the spring portion.

[0119] The spring portion may enable displacement of the central portion relative to the outer portion.

[0120] A wall thickness of the flow opening may be greater than the wall thickness of the central portion.

[0121] A wall thickness of the outer portion may be greater than the wall thickness of the central portion.

[0122] A wall thickness of the spring portion may be less than the wall thickness of the central portion.

[0123] A wall thickness of the outer portion may be the same as the wall thickness of the central portion.

[0124] A wall thickness of the central portion may be greater than the wall thickness of the outer portion.

[0125] The spring portion may have a curved cross-section in a direction from the central portion to the outer portion.

[0126] The spring portion may be concave when viewed from the feed opening.

[0127] The spring portion may be convex when viewed from the feed opening.

[0128] The pressure-displaceable diaphragm and a side wall of the cavity may comprise co-operable positioning formations.

[0129] The pressure-displaceable diaphragm may include one or more recesses.

[0130] The one or more recesses may be in an outer perimeter of the pressure- displaceable diaphragm.

[0131] The flow valve may comprise one or more protrusions which projects into the cavity.

[0132] The or each protrusion may be receivable in the one or more recesses.

[0133] The one or more recesses and the one or more protrusions may have complimentary shapes.

[0134] The flow valve may comprise a removable end cap.

[0135] The end cap may comprise the exhaust vent.

[0136] The end cap may comprise finger grips.

[0137] The flow valve may comprise a filter or diffuser.

[0138] The filter or diffuser may be downstream of the splint.

[0139] The filter or diffuser may be downstream of the feed opening.

[0140] The filter or diffuser may be located on the end cap.

[0141] The filter or diffuser may be upstream of the pressure-displaceable diaphragm.

[0142] The splint may be supported on one or more positioning arms. The one or more positioning arms extend between the splint and a side wall of the cavity.

[0143] In one embodiment, the position of the splint relative to the feed opening may be adjustable.

[0144] The position of the splint relative to the feed opening may be adjustable to regulate respiratory gas flow through the flow valve.

[0145] The exhaust vent may be spaced laterally from the splint.

[0146] The exhaust vent may comprise rings of holes in the end cap.

[0147] The exhaust vent may comprise one or more holes in the end cap.

[0148] The holes may be arranged concentrically around the splint.

[0149] The flow valve may comprise at least one groove defining a throttle channel between the groove and the pressure-displaceable diaphragm.

[0150] The groove may be formed in an end wall or a side wall or in both the end wall and the side wall of the flow valve defining the cavity.

[0151] The pressure-displaceable diaphragm may rest on the end wall or the side wall or on both the end wall and the side wall.

[0152] The flow valve may comprise a ridge on each side of the at least one groove.

[0153] The pressure-displaceable diaphragm may rest on the ridges.

[0154] The pressure-displaceable diaphragm may be displaceable at least partly into the at least one groove to reduce the cross-sectional dimension of the throttle channel.

[0155] The ridges and the at least one groove may extend radially on the end wall.

[0156] The pressure-displaceable diaphragm may be rectangular.

[0157] The grooves may be substantially parallel to a longitudinal axis of the pressure-displaceable diaphragm.

[0158] The grooves may be substantially parallel to a transverse axis of the pressure-displaceable diaphragm.

[0159] The ridges and the at least one groove may extend along the side wall.

[0160] One end of the at least one groove may terminate at the exhaust vent.

[0161] The exhaust vent may be located centrally of the end wall.

[0162] The pressure-displaceable diaphragm may be coupled to the housing.

[0163] The exhaust vent may comprise an opening through the housing.

[0164] The exhaust vent may comprise an opening through the seal.

[0165] The ridges extend may beyond a perimeter of the pressure-displaceable diaphragm.

[0166] The grooves extend may beyond a perimeter of the pressure displaceable diaphragm.

[0167] The ridges may be formed as part of an interior surface of the housing exposed to the chamber of the patient interface that is in fluid communication with the outlet.

[0168] At least part of the perimeter of the pressure-displaceable diaphragm may be spaced from a side wall of the cavity.

[0169] The spacing may form an inlet to the throttle channel.

[0170] The pressure-displaceable diaphragm may comprise a central region and a perimeter region.

[0171] The pressure-displaceable diaphragm may be supported remotely from a perimeter region of the pressure-displaceable diaphragm.

[0172] The pressure-displaceable diaphragm may be mounted at its central region to a support frame.

[0173] The support frame may be arranged with the pressure-displaceable diaphragm adjacent to the at least one groove.

[0174] The support frame may comprise positioning arms.

[0175] The pressure-displaceable diaphragm may be supported by positioning arms.

[0176] The pressure-displaceable diaphragm may comprise an elastomeric material.

[0177] The elastomeric material of the pressure-displaceable diaphragm may deform into the groove under respiratory therapy pressures.

[0178] The extent of deformation may depend on the respiratory therapy pressure.

[0179] A radial width of the ridges may taper inwardly in a radially inward direction.

[0180] A radial width of the at least one groove may taper inwardly in a radially inward direction.

[0181] The flow valve may comprise a plurality of grooves and ridges.

[0182] The at least one groove may extend radially outwardly further than the ridges.

[0183] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the positioning arms.

[0184] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the support frame.

[0185] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the housing.

[0186] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the frame.

[0187] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the seal.

[0188] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the at least one ridge.

[0189] The support frame and the side wall or the end wall may comprise cooperable positioning formations.

[0190] The end wall may comprise the positioning arms.

[0191] The pressure-displaceable diaphragm may be mechanically fixed, adhered to or integrally formed with the end wall.

[0192] The support frame may comprise one or more recesses.

[0193] The one or more recesses may be in a perimeter portion of the support frame.

[0194] The flow valve may comprise one or more protrusions which projects into the cavity.

[0195] The or each protrusion may be receivable in the one or more recesses.

[0196] The one or more recesses and the one or more protrusions may have complimentary shapes.

[0197] The pressure-displaceable diaphragm may comprise an umbrella panel.

[0198] The umbrella panel may be resilient.

[0199] The umbrella panel may be in the cavity.

[0200] The umbrella panel may be concave when viewed from the feed opening.

[0201] The umbrella panel may comprise a convex side which faces the exhaust vent.

[0202] The umbrella panel may extend across and may be spaced from the exhaust vent to define a throttle channel between the umbrella panel and the exhaust vent.

[0203] The spacing between the umbrella panel and the exhaust vent may vary depending on the respiratory therapy pressure.

[0204] Deformation of the umbrella panel to reduce the spacing between the umbrella panel and the exhaust vent may reduce the cross-sectional flow area of the throttle channel.

[0205] The umbrella panel may comprise a first region that is more susceptible to deformation than a second region.

[0206] The first regions may deform under respiratory therapy pressures that are lower that the respiratory therapy pressures at which the second region deforms.

[0207] The first region may be a centre region and the second region is a perimeter region.

[0208] A wall thickness of the umbrella panel may increase in a direction from the centre region of the umbrella panel toward the perimeter region of the umbrella panel.

[0209] A wall thickness of the umbrella panel may be greater at the perimeter region than the wall thickness at the centre region.

[0210] The umbrella panel may be deformable initially at a central region.

[0211] The deformation may change the spacing between the umbrella panel and the exhaust vent.

[0212] The umbrella panel may be circular when viewed from the feed opening.

[0213] The umbrella panel may be joined to a body of the flow valve.

[0214] The body is couplable with the seal.

[0215] The body is couplable with the housing.

[0216] The body is couplable with the frame.

[0217] The body comprises the end cap.

[0218] The umbrella panel may be joined to an end wall of the flow valve.

[0219] The umbrella panel may be mechanically connected to or is over moulded to the end wall.

[0220] The pressure-displaceable diaphragm may be resilient.

[0221] The pressure-displaceable diaphragm may be in the cavity.

[0222] The pressure-displaceable diaphragm may be flat at rest.

[0223] The pressure-displaceable diaphragm may comprise a disc.

[0224] The pressure-displaceable diaphragm may be co-operable with one or more of exhaust vents.

[0225] The one or more exhaust vents may comprise inlet openings which are formed in a generally convex surface of the flow valve when viewed from the upper chamber.

[0226] The convex surface comprises part of the body of the flow valve.

[0227] The convex surface comprises an end wall of the flow valve.

[0228] The pressure-displaceable diaphragm may be spaced from the one or more exhaust vents to define a throttle channel between the pressure-displaceable diaphragm and the one or more exhaust vents.

[0229] The spacing between the pressure-displaceable diaphragm and the one or more exhaust vents may vary depending on the respiratory therapy pressure.

[0230] Deformation of the pressure-displaceable diaphragm to reduce the spacing between the pressure-displaceable diaphragm and the one or more exhaust vents may reduce the cross-sectional flow area of the throttle channel..

[0231] Deformation of the pressure-displaceable diaphragm under the influence of respiratory therapy pressure may close one or more of the exhaust vents.

[0232] One or more of the exhaust vents may be configured to retain an open throttle channel regardless of the respiratory therapy pressure.

[0233] The one or more exhaust vents may be configured to retain an open throttle channel by extending at least partly outside an umbra of the pressure-displaceable diaphragm when viewed from the upper chamber.

[0234] The one or more exhaust vents may be configured to retain an open throttle channel by extending at least partly outside an area of maximum contact between the pressure-displaceable diaphragm and the convex surface.

[0235] The flow valve may comprise a retaining structure in which the one or more exhaust vents are formed.

[0236] The exhaust vents may comprise through-holes formed in the retaining structure to enable respiratory gas to flow through the retaining structure.

[0237] The exhaust vents may be arranged in a regular array.

[0238] The exhaust vents may be equally spaced apart in two or more rows.

[0239] The exhaust vents may be arranged concentrically.

[0240] The exhaust vents may be arranged in an irregular array.

[0241] The pressure-displaceable diaphragm may be linked to the retaining structure.

[0242] The exhaust vents may be arranged at different radial distances from a point where the pressure-displaceable diaphragm links to the retaining structure.

[0243] The exhaust vents may comprise a radially inner array of exhaust vents and a radially outer array of exhaust vents.

[0244] The cross-sectional flow area of an exhaust vent which is part of the radially inner array of exhaust vents may be less than the cross-sectional flow area of an exhaust vent which is part of the radially outer array of exhaust vents.

[0245] The cross-sectional flow area of an exhaust vent which is part of the radially inner array of exhaust vents may be greater than the cross-sectional flow area of an exhaust vent which is part of the radially outer array of exhaust vents.

[0246] The exhaust vents and the pressure-displaceable diaphragm may be disposed within an area bound by a perimeter wall.

[0247] The perimeter wall may be spaced outwardly from an outer edge of the pressure-displaceable diaphragm.

[0248] The perimeter wall may comprise a leading edge and the pressure- displaceable diaphragm is downstream of the leading edge.

[0249] The pressure-displaceable diaphragm may be mechanically connected to or may be over-moulded to the retaining structure.

[0250] The generally convex surface may be integral with the end cap.

[0251] The generally convex surface may be integral with the housing of the patient interface.

[0252] The retaining structure may be attached to the housing of the patient interface.

[0253] The retaining structure may be integral with the housing of the patient interface.

[0254] The retaining structure may be attached to the seal of the patient interface.

[0255] The exhaust vents may comprise through-holes formed in the end cap to enable respiratory gas to flow through the retaining structure.

[0256] The pressure-displaceable diaphragm may be linked to the end cap.

[0257] The exhaust vents may be arranged at different radial distances from a point where the pressure-displaceable diaphragm is linked to the end cap.

[0258] The pressure-displaceable diaphragm may be mechanically connected to, adhered to or over-moulded to the end cap.

[0259] One or more of the exhaust vents may comprise a cross-sectional flow area that is different to a cross-sectional flow area of another exhaust vent.

[0260] One or more of the exhaust vents may comprise a shape of the cross- sectional flow area that is different to a shape of the cross-sectional flow area of another exhaust vent.

[0261] One or more of the exhaust vents may extend at least partly outside an umbra of the pressure-displaceable diaphragm when viewed from the second chamber.

[0262] One or more of the exhaust vents may, at least in part, increase in width in a radially outward direction from a point where the pressure-displaceable diaphragm links to the retaining structure.

[0263] A width of a radially inner end of one or more of the exhaust vents may be less than a width of a radially outer end of the one or more exhaust vents.

[0264] The size and the shape of cross-sectional flow area of the exhaust vents may be selected to enable a substantially constant respiratory gas flow rate through the flow valve over a range of different respiratory therapy pressures.

[0265] The pressure-displaceable diaphragm may comprise a frusto-pyramid shaped valve.

[0266] The valve may comprise one or more concave facets.

[0267] The valve may comprise a flow opening.

[0268] The flow opening may comprise a generally polygonal shape with one or more concave sides.

[0269] The flow opening may be shaped generally as a hyperbolic triangle.

[0270] The valve may comprise convex edges.

[0271] The facets have a wall thickness that may be less than a wall thickness of the convex edges.

[0272] The facets may be less resistant to deformation than the convex edges.

[0273] The flow opening may have a cross-sectional flow area that is variable.

[0274] The cross-sectional flow area may vary with deformation of the facets under different respiratory therapy pressures.

[0275] The facets may be configured to deform toward a centre of the flow opening to reduce the cross-sectional flow area of the flow opening under increasing respiratory therapy pressures.

[0276] The pressure-displaceable diaphragm may comprise a base.

[0277] The base may comprise a ring shape.

[0278] The base may be seated in a support frame.

[0279] The base may be integrally formed with the valve.

[0280] The pressure-displaceable diaphragm may comprise a unitary structure.

[0281] The pressure-displaceable diaphragm may be integrally formed.

[0282] The base may define an opening through which respiratory gas can flow from the flow opening.

[0283] The support frame may define an opening through which respiratory gas can flow from the pressure-displaceable diaphragm.

[0284] The exhaust vent may be aligned with the opening in the base.

[0285] The exhaust vent may be aligned with the opening in the support frame.

[0286] The diffuser may be disposed between the support frame and the exhaust vent.

[0287] The filter may be disposed between the support frame and the exhaust vent.

[0288] The diffuser may be downstream of the exhaust vent.

[0289] The filter may be downstream of the exhaust vent.

[0290] The base may be co-operable with the end wall.

[0291] The base may be seated in a groove formed in the end wall.

[0292] The end wall may comprise a groove in which the base is receivable.

[0293] The groove may circumscribe the exhaust vent.

[0294] The flow valve may control the extent to which the exhaust vent is occluded.

[0295] The flow valve may comprise a gate valve.

[0296] The flow valve may comprise an iris diaphragm valve.

[0297] The iris diaphragm valve may comprise multiple overlapping blades arranged in a circular pattern, the multiple overlapping blades can open or close concentrically, forming a variable-sized orifice.

[0298] The flow valve may be controlled manually.

[0299] The flow valve may be controlled automatically.

[0300] The flow valve may be controlled by a drive system.

[0301] The drive system may convert rotational movement into lateral movement.

[0302] The drive system may comprise a motor that generates rotational movement.

[0303] The flow valve may be controlled by an electric motor.

[0304] The flow valve may be controlled by a servo motor.

[0305] The flow valve may be controlled in response to any one or more of: a patient’s measured physiological condition, gas flow or gas pressure information from a flow source that supplies the respiratory gas to the patient interface or humidity, temperature, gas flow, gas pressure, carbon dioxide concentration, oxygen concentration and / or acoustic information from sensors in the patient interface.

[0306] The gate valve may comprise a cover panel which is mounted between guide rails.

[0307] The guide rails may extend on each side of the exhaust vent.

[0308] The cover panel may be slidable along the guide rails to partly occlude the outlet.

[0309] The exhaust vent may be configured to provide a non-linear relationship between changes in the extent to which the exhaust vent is occluded and changes in the gas flow through the exhaust vent.

[0310] The flow valve may be operable to enable a substantial constant flow of respiratory gas through the exhaust vent across a range of respiratory therapy pressures or a selected flow of respiratory gas through the exhaust vent.

[0311] The flow valve may be positionable in an unoccluded position whereby the valve is clear of the exhaust vent.

[0312] The flow valve may be positionable in an occluded position whereby the valve occludes the exhaust vent.

[0313] The flow valve may be positionable in an occluded position whereby the valve occludes a maximum extent, but not all, of the exhaust vent.

[0314] The flow valve may be positionable in a range of different partially occluded positions between the unoccluded position and the occluded position.

[0315] The flow valve may be positionable clear of the exhaust vent.

[0316] The flow valve may be positionable to occlude a maximum extent, but not all, of the exhaust vent.

[0317] The flow valve may be positionable to partially occlude the exhaust vent.

[0318] The flow valve may not fully occlude the exhaust vent in the occluded position.

[0319] In the occluded position, the flow valve may be configured to maintain a minimum gas flow through the exhaust vent.

[0320] The exhaust vent may be configured to provide a non-linear relationship between changes in the position of the flow valve between an un-occluded position of the exhaust vent and an occluded position of the exhaust vent.

[0321] The exhaust vent may be asymmetrical in a direction of travel of the flow valve from an un-occluded position of the exhaust vent to an occluded position of the exhaust vent.

[0322] The exhaust vent may be asymmetrical about a notional line that is parallel to the guide rails.

[0323] The exhaust vent may be generally triangular with one side of the triangle generally parallel with a leading edge of the gate valve.

[0324] A driver arm may link the flow valve to the motor.

[0325] The flow valve may comprise a support to receive the motor.

[0326] The support may be integrally formed with the flow valve.

[0327] The support may be couplable to the flow valve.

[0328] The exhaust vent may be formed in a curved surface of the flow valve.

[0329] At least part of the guide rails may be curved to follow the curvature of the curved surface.

[0330] The cover panel may be formed of a flexible material to follow the curve of the guide rails.

[0331] Part of the guide rails may be in a plane that is perpendicular to an axis of rotation of the motor.

[0332] In a further aspect, there is provided a valve assembly that is removably couplable to a patient interface, the valve assembly comprising; a body comprising a feed opening for receiving respiratory gas from a patient interface; a flow valve comprising an outlet for exhausting respiratory gas from the valve assembly, the flow valve is in fluid communication with the body and is configured to exhaust respiratory gas at a respiratory gas flow rate that is below an upper limit across a range of respiratory therapy pressures.

[0333] The valve assembly further comprises a valve mount formation to which the flow valve is coupled

[0334] The flow valve may be adapted for coupling to the valve mount.

[0335] The valve mount formation may be integral with the body.

[0336] The valve mount formation may comprise a stem.

[0337] The stem may be threaded.

[0338] The valve mount formation may comprise a thread.

[0339] The flow valve may be threaded for connection with a threaded valve mount formation.

[0340] The valve mount may comprise one part of a bayonet connection.

[0341] The flow valve may comprise a complementary part of a bayonet connection.

[0342] The body may further comprise a gasket circumscribing the feed opening.

[0343] The body may comprise an abutment formation about the feed opening and which abutment formation comprises one or more outlets for respiratory gas.

[0344] The abutment formation comprises two or more gasket strips that are spaced apart by two or more outlets for respiratory gas.

[0345] The abutment formation comprises a lip of the body or lip segments of the body about the feed opening.

[0346] The valve mount may be on an opposite side of the body to the feed opening.

[0347] The body may increase in cross-sectional flow area from the feed opening to the valve mount.

[0348] The valve assembly may comprise coupling formations that are couplable with a patient interface.

[0349] The coupling formations may interact with complementary formations on the patient interface to enable removable coupling.

[0350] The coupling formations of the valve assembly may comprise attachment arms.

[0351] The attaching arms may be resiliently deformable.

[0352] When coupled with a patient interface, the attachment arms may be displaced from an at-rest position.

[0353] The attachment arms may be configured to be biased into retaining the valve assembly to a patient interface when the valve assembly is coupled to the patient interface.

[0354] The attachment arms may be configured to be biased into interacting with the complementary formations of the patient interface when the valve assembly is coupled to the patient interface.

[0355] The coupling formations may comprise tabs.

[0356] The tabs may be at a proximal end of the attachment arms.

[0357] The tabs may be directed laterally inwardly from the attachment arms.

[0358] The coupling formations may be configured to interact with a frame of a patient interface.

[0359] The coupling formations may be configured to interact with a housing of a patient interface.

[0360] The complementary formations may be on a frame of a patient interface.

[0361] The complementary formations may be on a housing of a patient interface.

[0362] The attachment arms may further comprise finger grips.

[0363] The finger grips may be depressed to control the lateral position of the tabs relative to an at-rest position.

[0364] The flow valve may comprise a flow opening in a first panel.

[0365] The first panel may be within the cavity or is in fluid communication with the cavity.

[0366] The flow valve may comprise the exhaust vent in a second panel.

[0367] The first panel or the second panel may be rotatable or slidable relative to the other to align, partially aligned or misalign the exhaust vent with the flow opening.

[0368] The flow opening may comprise one or more holes through the first panel.

[0369] The exhaust vent may comprise one or more holes through the second panel.

[0370] A gas flow rate through the exhaust vent may depend on the extent to which the flow opening is aligned with the exhaust vent.

[0371] The first and second panels may be in contact.

[0372] The gas flow rate through the flow valve may be controllable by adjusting the extent to which the flow opening is aligned with the exhaust vent.

[0373] Each of the flow opening and the exhaust vent may have a respective cross- sectional flow area through which respiratory gas can flow.

[0374] The gas flow rate through the flow valve may be controllable by adjusting the extent to which the cross-sectional flow area of the flow opening is aligned with cross-sectional flow area of the exhaust vent.

[0375] The flow opening or the exhaust vent may comprise at least one first opening with a first cross-sectional flow area and the respective exhaust vent or the flow opening may comprise a plurality of second openings ranging in cross-sectional flow area up to the cross-sectional flow area of the first opening.

[0376] The gas flow rate through the flow valve may be controllable by changing which of the second openings is aligned with the at least one first opening.

[0377] The flow valve may comprise a rotatable cover.

[0378] The second panel may be part of the rotatable cover.

[0379] The flow valve may be controlled manually.

[0380] The flow valve may be controlled automatically.

[0381] The flow valve may be controlled in response to any one or more of: a patient’s measured physiological condition, gas flow or gas pressure information from a flow source that supplies the respiratory gas to the patient interface, or humidity, temperature, gas flow, gas pressure, carbon dioxide concentration, oxygen concentration and / or acoustics from sensors linked to the patient interface.

[0382] The patient interface may comprise a pressure valve.

[0383] The pressure valve may enable the flow of respiratory gas from the first chamber to the second chamber within the cushion module.

[0384] The pressure valve may control the flow of respiratory gas from the first chamber to the second chamber within the cushion module.

[0385] The pressure valve may control a pressure differential between the first chamber and the second chamber within the cushion module during use of the patient interface.

[0386] The pressure valve may be part of the dividing wall.

[0387] The dividing wall may comprise the pressure valve.

[0388] The pressure valve may be in fluid communication with the first chamber and the second chamber.

[0389] The dividing wall may comprise a preferential deformation region.

[0390] The dividing wall may comprise a first resilient region.

[0391] The first resilient region may be on the distal side of the deformation region.

[0392] The first resilient region may be between the deformation region and the housing.

[0393] A wall thickness of the first resilient region may be greater than a wall thickness of the deformation region.

[0394] The dividing wall may comprise a second resilient region that may be on the proximal side of the deformation region.

[0395] A wall thickness of the second resilient region may be greater than a wall thickness of the deformation region.

[0396] The pressure valve may be on a distal side of the dividing wall relative to the deformation region.

[0397] The pressure valve may be between the deformation region and the housing.

[0398] The pressure valve may be located in the first resilient region.

[0399] The pressure valve may comprise a pressure-displaceable diaphragm.

[0400] The pressure valve may be on a proximal side of the dividing wall relative to the deformation region.

[0401] The pressure valve may be located in the second resilient region.

[0402] The pressure valve may comprise a flow opening in the dividing wall which defines an aperture through which respiratory gas can flow from the first chamber to the second chamber.

[0403] The cushion module may comprise one or more nasal openings to communicate respiratory gas with the nares of a patient.

[0404] The flow opening may be aligned with or is substantially aligned with the one or more nasal openings.

[0405] The pressure valve may comprise a pressure-displaceable diaphragm that extends at least partly across the aperture of the flow opening.

[0406] The pressure-displaceable diaphragm may be connected to the dividing wall.

[0407] The pressure-displaceable diaphragm may be integral with the dividing wall.

[0408] The pressure-displaceable diaphragm may extend into the first chamber from the dividing wall.

[0409] The pressure-displaceable diaphragm may be located in the second chamber.

[0410] The pressure-displaceable diaphragm does not extend into the first chamber.

[0411] At rest, the pressure-displaceable diaphragm may be inclined away from the dividing wall.

[0412] At rest, the pressure-displaceable diaphragm may be inclined generally toward the first chamber from a notional line connecting the flow opening and the dividing wall.

[0413] At rest, the pressure-displaceable diaphragm may be inclined generally toward the second chamber from a notional line connecting the flow opening and the dividing wall.

[0414] At rest, the pressure-displaceable diaphragm may be generally level with a notional line connecting the flow opening with the dividing wall.

[0415] The inclination of the pressure-displaceable diaphragm may vary depending on the respiratory therapy pressure in the first chamber.

[0416] The pressure-displaceable diaphragm may be bound partly by a rim.

[0417] A throttle channel may be formed between the rim of the pressure- displaceable diaphragm and the flow opening.

[0418] A cross-sectional flow area of the throttle channel may change in response to the pressure-displaceable diaphragm being displaced by respiratory therapy pressure.

[0419] The flow opening and the pressure-displaceable diaphragm may be configured to increase the cross-sectional flow area in response to an increase in respiratory therapy pressure.

[0420] The extent to which the pressure-displaceable diaphragm may be deformed toward the second chamber from a notional line connecting the flow opening with the dividing wall may depend on the respiratory therapy pressure in the first chamber.

[0421] The flow opening may project into the first chamber.

[0422] Alignment with a patient’s nares refers to alignment with a direction of gas flow through the pressure valve and into the second chamber toward a patient’s nares, when the patient interface is fitted to a patient.

[0423] The rim may be contoured to provide a variable spacing between the rim and the flow opening.

[0424] The spacing may be greater at parts of the rim that align with a patient’s nares than at parts of the rim that aren’t aligned with a patient’s nares, when the patient interface is fitted to a patient

[0425] The pressure-displaceable diaphragm may be contoured to provide a variable spacing between the rim and the flow opening.

[0426] The spacing may be greater at parts of the rim that align with a patient’s nares than at parts of the rim that aren’t aligned with a patient’s nares, when the patient interface is fitted to a patient.

[0427] The contour of the rim may comprise two peaks and a trough between the peaks, having regard to an upright orientation of the patient interface.

[0428] The contour of the rim may comprise an M-shape.

[0429] The peaks may coincide with parts of the rim that align with a patient’s nares when the patient interface is fitted to a patient.

[0430] The peaks may be spaced apart by 1 .0 to 3.0 cm.

[0431] The trough may be aligned with a patient’s columella when the patient interface is fitted to a patient in use.

[0432] The pressure-displaceable diaphragm may comprise a flap.

[0433] The pressure-displaceable diaphragm may comprise a generally rectangular flap.

[0434] The pressure-displaceable diaphragm may be fixed to the flow opening along one side of the flap.

[0435] The rim may comprise the remaining side or sides of the flap.

[0436] A wall thickness of the flow opening where the pressure-displaceable diaphragm joins with the flow opening may be greater than a wall thickness of the dividing wall that is adjacent to where the pressure-displaceable diaphragm joins the flow opening.

[0437] A wall thickness of a region of the dividing wall that is adjacent to the flow opening may be greater than a wall thickness of the dividing wall that is outside of the region.

[0438] At least part of the dividing wall surrounding the flow opening may be a reinforced region of the dividing wall.

[0439] The reinforced region may comprise a wall thickness that is greater than a wall thickness of adjacent parts of the dividing wall.

[0440] The reinforced region may comprise a different material or different grade of material compared to adjacent parts of the dividing wall.

[0441] The pressure-displaceable diaphragm may comprise a wall thickness in the range of 0.20 to 0.50 mm.

[0442] The pressure-displaceable diaphragm may comprise a wall thickness selected to provide a pressure drop between the first chamber and the second chamber that is greater than 0.00 cm H2O, 0.20 cm H2O, 0.25 cm H2O, 0.30 cm H2O, 0.35 cmH2O, 0.40 cm H2O, 0.45 cm H2O, or 0.50 cm H2O across a range of different respiratory therapy pressures.

[0443] The pressure-displaceable diaphragm may comprise a wall thickness selected to provide a pressure drop between the first chamber and the second chamber that is less than 4.00 cm H2O, 3.50 cm H2O, 3.00 cm H2O, 2.50 cm H2O, 2.00 cm H2O, 1 .50 cm H2O or 1 .40 cm H2O or 1 .30 cm H2O or 1.20 cm H2O or 1 .10 cm H2O or 1 .00 cm H2O or 0.90 cm H2O or 0.80 cm H2O or 0.70 cm H2O or 0.60 cm H2O or 0.50 cm H2O across a range of different respiratory therapy pressures.

[0444] The pressure valve may comprise a baffle wall.

[0445] The baffle wall may project into the second chamber.

[0446] The baffle wall may project from the flow opening into the second chamber.

[0447] The baffle wall may be adjacent to the rim.

[0448] The baffle wall may be integrally formed with the dividing wall.

[0449] The baffle wall may reinforce the dividing wall about the flow opening.

[0450] The reinforced region may be resilient to deformation by forces imparted on the dividing wall from a patient-contacting portion of the patient interface.

[0451] The baffle wall may follow at least part of the shape of the flow opening.

[0452] The baffle wall has a wall thickness that may be greater than the wall thickness of the pressure-displaceable diaphragm.

[0453] The pressure-displaceable diaphragm generally may extend in a proximal direction from where the pressure-displaceable diaphragm joins with the dividing wall.

[0454] The cross-sectional dimension of the throttle channel may comprise a distance between the rim and the flow opening or the baffle wall.

[0455] The baffle wall may project from the dividing wall into the second chamber by 0.1 to 8 mm.

[0456] The baffle wall may project from the dividing wall into the second chamber by approximately 6 mm.

[0457] The throttle channel may comprise a gap between the pressure-displaceable diaphragm and the baffle wall for deflections of the pressure-displaceable diaphragm in the range of 10 to 30° from an at rest position of the pressure-displaceable diaphragm.

[0458] The patient interface may comprise two pressure valves.

[0459] The two pressure valves may be part of the dividing wall.

[0460] The two pressure valves may be aligned to direct respiratory gas toward the one or more nasal openings.

[0461] Each pressure valve may comprise a flow opening and a pressure- displaceable diaphragm.

[0462] Each pressure valve may comprise a baffle wall.

[0463] The dividing wall may comprise a flow insert.

[0464] The flow insert may be over-moulded with the dividing wall.

[0465] The flow insert may be attachable to the dividing wall.

[0466] The dividing wall may comprise an aperture.

[0467] The aperture may be shaped to receive the flow insert.

[0468] The aperture may comprise a rim that is co-operable with the flow insert to attach the flow insert to the dividing wall.

[0469] The flow insert may comprise a channel around the periphery of the flow insert which is configured to receive the rim of the flow aperture to removably attach the flow insert to the dividing wall.

[0470] The flow insert may comprise an elastomeric material.

[0471] The flow insert may comprise a plastics material.

[0472] The flow insert may have a wall thickness that is greater than a wall thickness of the dividing wall about the aperture.

[0473] The aperture may be on the proximal side of the dividing wall relative to the deformation region.

[0474] The flow insert may comprise a pressure valve.

[0475] The pressure valve may comprise a pressure-displaceable diaphragm.

[0476] The pressure-displaceable diaphragm may comprise an umbrella valve.

[0477] The umbrella valve may comprise a resilient valve panel.

[0478] The pressure-displaceable diaphragm may comprise a convex umbrella panel when viewed from the second chamber.

[0479] The umbrella panel may comprise a concave side.

[0480] The concave side may face the flow insert.

[0481] The flow insert may comprise one or more flow openings that may enable respiratory gas to flow from the first chamber to the second chamber.

[0482] At least one of the one or more flow openings may be part of the umbrella valve.

[0483] At least one of the one or more flow openings may be covered by the umbrella panel.

[0484] The umbrella panel may seal or may substantially seal each of the one or more flow openings that is part of the umbrella valve when the pressure differential between the first chamber and the second chamber is below a threshold.

[0485] The pressure valve may comprise one or more of flow openings that are not sealable by the pressure-displaceable diaphragm.

[0486] The umbrella panel may be displaceable to allow respiratory gas to flow through each of the one or more flow openings that are part of the umbrella valve when the pressure differential between the first chamber and the second chamber is at or above a threshold.

[0487] A wall thickness of the umbrella panel may be greater at a perimeter of the umbrella panel than at a central region of the umbrella panel.

[0488] The umbrella panel may be deformable initially at a central region.

[0489] The deformation may change the spacing between the umbrella panel and the flow openings.

[0490] The umbrella panel may be supported on positioning arms.

[0491] The positioning arms may be integral with the flow insert.

[0492] The one or more flow openings that are part of the umbrella valve may be in part defined by the positioning arms.

[0493] The umbrella panel may comprise a generally constant wall thickness.

[0494] The umbrella panel may comprise a variable wall thickness.

[0495] A wall thickness of the umbrella panel may increase in a direction from a centre toward a perimeter of the umbrella panel.

[0496] The flow insert may comprise one or more flow directors.

[0497] At least one of the one or more flow openings may comprise an inlet to a flow director.

[0498] The flow insert may comprise a plurality of flow openings and one flow opening is an inlet to a flow director and the remaining flow openings are part of the pressure valve.

[0499] The patient interface may comprise an elbow.

[0500] The elbow may be couplable to the cushion module.

[0501] The elbow may be couplable to the housing or to the frame.

[0502] The pressure valve may be part of the elbow.

[0503] The elbow may be couplable to a gas source to communicate pressurised respiratory gas to the patient interface.

[0504] The elbow may comprise an inlet and first and second cavities.

[0505] The first cavity may be in fluid communication with the first chamber.

[0506] The second cavity may be in fluid communication with the second chamber.

[0507] The pressure valve may control the distribution of respiratory gas from the inlet between the first and second cavities.

[0508] The pressure valve may control the flow of respiratory gas from the first chamber to the second chamber via the elbow.

[0509] The dividing wall may bifurcate the inlet of the cushion module.

[0510] The dividing wall may co-operate with the elbow to enable fluid communication between the first cavity and the first chamber and between the second cavity and the second chamber.

[0511] A dividing panel may separate the first cavity from the second cavity in the elbow.

[0512] The dividing wall may form a seal with the dividing panel to enable fluid communication between the first cavity and the first chamber and between the second cavity and the second chamber.

[0513] The elbow may comprise an exhaust vent in fluid communication with the second cavity and the second chamber.

[0514] The first cavity may be below the second cavity, having regard to an upright orientation of the patient interface.

[0515] The pressure valve may be part of the dividing panel.

[0516] The pressure valve may comprise a pressure-displaceable diaphragm.

[0517] The pressure valve may be outside of the cushion module.

[0518] The pressure valve may comprise a flap valve.

[0519] The pressure valve may comprise a flow aperture in the dividing panel to enable respiratory gas from the inlet channel or from the first cavity to flow into the second cavity.

[0520] The flow aperture may comprise one or more openings through the dividing panel.

[0521] The pressure-displaceable diaphragm may seal the flow aperture when a gas pressure differential between the first chamber and the second chamber is below a threshold.

[0522] The pressure-displaceable diaphragm may be displaceable to allow respiratory gas to flow from the inlet or from the first channel to the second cavity when a gas pressure differential between the first chamber and the second chamber is above a threshold.

[0523] The elbow may comprise:• first and second cavities separated by a dividing panel;• an inlet in fluid communication with the first cavity;• an exhaust vent in fluid communication with the second cavity; and• a flow valve in the dividing panel to enable flow of respiratory gas from the inlet or the first cavity to the second channel.

[0524] An elbow for a patient interface, the elbow comprising: a dividing panel that separates the elbow into a lower cavity and an upper cavity, the lower cavity comprising an inlet to receive respiratory gas, the upper cavity comprising an outlet to discharge respiratory gas from the elbow, wherein the dividing panel comprises a valve configured to open when the respiratory gas pressure differential between the upper cavity and the lower cavity is greater than a threshold limit.

[0525] The elbow may be releasably couplable to a dock of a cushion module.

[0526] The dock comprises the inlet of the patient interface.

[0527] The elbow may be couplable to a frame of a patient interface.

[0528] The elbow may be releasably couplable to a frame of the patient interface.

[0529] The elbow may be couplable to a housing of a patient interface.

[0530] The elbow may be releasably couplable to a housing of a patient interface.

[0531] The elbow may be couplable to a seal of the patient interface.

[0532] The elbow may be releasably couplable to a seal of the patient interface.

[0533] The patient interface may comprise an upper chamber and, when the elbow is coupled to the dock, the upper cavity of the elbow is in fluid communication with the upper chamber.

[0534] The patient interface may comprise a lower chamber and, when the elbow is coupled to the dock, the lower cavity of the elbow is in fluid communication with the lower chamber.

[0535] The elbow may comprise a seal that is co-operable with the patient interface to provide a substantially airtight seal between the elbow and the patient interface.

[0536] The elbow may comprise one or more catches that interact with the patient interface to retain the elbow coupled to the patient interface.

[0537] The or each catch may comprise a lever arm.

[0538] The lever arm may comprise a hinge.

[0539] The hinge may be a living hinge

[0540] The wall thickness of the living hinge may be less than the wall thickness of the remainder of the lever arm.

[0541] The catch may be proximal of the living hinge.

[0542] Each lever arm may further comprise a finger grip.

[0543] The finger grip may be distal of the living hinge.

[0544] The elbow may comprise two lever arms respectively disposed at lateral opposing sides of the elbow.

[0545] The catch may be configured to interact with a shoulder on the dock.

[0546] The elbow may be configured to provide a friction fit connection with the dock.

[0547] The dividing panel may be releasably couplable with the elbow.

[0548] The dividing panel may be integral with the elbow.

[0549] The dividing panel and the elbow may be configured to form a substantially airtight seal between the upper cavity and the lower cavity.

[0550] The elbow may comprise a retaining slot in which at least part of the dividing panel is receivable.

[0551] The dividing panel may comprise perimeter segments that may be received in the retaining slot.

[0552] The dividing panel may comprise a pad that contacts part of the inlet of the patient interface to form a substantially airtight seal between the dividing panel and the inlet of the patient interface.

[0553] The dividing panel may be adapted to contact a pad, which is part of the inlet of the patient interface, to form a substantially airtight seal between the dividing panel and the inlet of the patient interface.

[0554] The dividing panel may contact the dividing wall to form a substantially airtight seal.

[0555] The valve may be a flap valve.

[0556] The flap valve may comprise a hinge and a flap body.

[0557] The flap body may pivot about the hinge between an open position and a closed position.

[0558] The valve may be pre-tensioned to open when a respiratory gas pressure drop from the upper cavity to the lower cavity exceeds a threshold limit.

[0559] The hinge may be pre-tensioned to open when a respiratory gas pressure drop from the upper cavity to the lower cavity exceeds a threshold limit.

[0560] Pre-tensioning for a flap valve formed of resilient material may comprise assembling the flap valve in the elbow such that the body is resiliently biased by the hinge to the closed position.

[0561] The length and / or wall thickness of the hinge and / or the shape of the formed hinge may be configured to provide pre-tension that results in the threshold limit being within a selected range.

[0562] The selected range for the threshold limit may be 0.2 to 1.5 cmH2O.

[0563] The valve may be configured to maintain a pressure drop between the lower cavity and the upper cavity in the range of 0.2 to 1 .5 cmFhO, 0.5 to 1 .5 cmFLO, 0.8 to 1 .5 cmH2O, 0.5 to 1 .0 cmH2O, 0.2 to 0.8 cmH2O or 0.5 to 0.7 cmH2O.

[0564] The outlet may comprise one or more apertures with a fixed cross-sectional flow area.

[0565] The outlet may comprise a flow valve.

[0566] The outlet may exhaust respiratory gas at a respiratory gas flow rate that is below an upper limit across a range of respiratory therapy pressures.

[0567] In a further aspect, there is provided a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising: an upper chamber to communicate respiratory gas with the patient's nares, a lower chamber to communicate respiratory gas with a patient's oral cavity, a dividing wall which separates the upper and the lower chamber, an elbow configured for releasable coupling to a dock of the patient interface, the elbow comprises a dividing panel which separates an upper cavity in fluid communication with the upper chamber and comprising an outlet, and a lower cavity in fluid communication with the lower chamber and comprising an inlet to enable respiratory gas to be supplied to the lower chamber through the elbow, wherein the dividing panel is configured to form a substantially airtight seal with the dividing wall or with the dock when the elbow is coupled to the dock.

[0568] The dividing panel may comprise a valve configured to open when the respiratory gas pressure drop from the lower cavity to the upper cavity is greater than a threshold limit.

[0569] The valve may be pre-tensioned to open when the respiratory gas pressure drop from the lower cavity to the upper cavity is greater than the threshold limit.

[0570] The valve may be configured to maintain a pressure drop between the lower cavity and the upper cavity in the range of 0.2 to 1 .5 cmFhO, 0.5 to 1 .5 cmFLO, 0.8 to 1 .5 cmH2O, 0.5 to 1 .0 cmH2O, 0.2 to 0.8 cmH2O, 0.5 to 0.7 cmH2O, or.

[0571] The valve may be a flap valve.

[0572] The flap valve may comprise a hinge and a flap body.

[0573] The flap body may pivot about the hinge between an open position and a closed position.

[0574] The hinge may be pre-tensioned to open when the respiratory gas pressure drop from the lower cavity to the upper cavity is greater than the threshold limit.

[0575] Pre-tensioning for a flap valve formed of resilient material may comprise assembling the flap valve in the elbow such that the body is resiliently biased by the hinge to the closed position.

[0576] The length and / or wall thickness of the hinge and / or the shape of the formed hinge may be configured to provide pre-tension that results in the threshold limit being in the range within a selected range.

[0577] The selected range for the threshold limit may be in the range of 0.5 to 4.0 cmH2O or 0.5 to 3.5 cmH2O or 0.5 to 3.0 cmH2O or 0.5 to 2.5 cmH2O or 0.5 to 2.0 cmH2O or 0.5 to 1 .5 cmH2O or 0.5 to 1 .4 cmH2O or 0.5 to 1 .3 cmH2O or 0.5 to 1 .2 cmH2O or 0.5 to 1 .1 cmH2O or 0.5 to 1 .0 cmH2O or 0.5 to 0.9 cmH2O or 0.5 to 0.8 cmH2O or 0.5 to 0.7 cmH2O or 0.2 to 4.0 cmH2O or 0.2 to 3.5 cmH2O or 0.2 to 3.0 cmH2O or 0.2 to 2.5 cmH2O or 0.2 to 2.0 cmH2O or 0.2 to 1 .5 cmH2O or 0.2 to 1 .4 cmH2O or 0.2 to 1 .3 cmFhO or 0.2 to 1 .2 cmFhO or 0.2 to 1 .1 cmFhO or 0.2 to 1 .0 cmH2O or 0.2 to 0.9 cmH2O or 0.2 to 0.8 cmH2O.

[0578] The elbow may form a substantially airtight seal with the dock of the patient interface.

[0579] The elbow may comprise a sleeve seal that interacts with the dock to form a substantially airtight seal.

[0580] The elbow may comprise a bushing which interacts with the dock to provide fluid communication between the elbow and the cushion module.

[0581] The sleeve seal may be part of the collar.

[0582] The dock and the bushing may comprise complementary shapes.

[0583] The bushing may comprise a U-shape with a flat top, having regard to a generally upright orientation of the patient interface.

[0584] The elbow may comprise lever arms that releasably interact with the dock.

[0585] The lever arm may comprise a hinge.

[0586] The hinge may be a living hinge

[0587] The wall thickness of the living hinge may be less than the wall thickness of the remainder of the lever arm.

[0588] The lever arm may comprise a catch which releasably interacts with the dock.

[0589] The catch may be proximal of the living hinge.

[0590] The catch may be configured to interact with a shoulder on the dock.

[0591] The catch may be rotatable about the living hinge into and out of alignment with the shoulder.

[0592] Each lever arm may further comprise a finger grip.

[0593] The finger grip may be distal of the living hinge.

[0594] The elbow may comprise two lever arms respectively disposed at laterally opposed sides of the elbow, having regard to an upright orientation of the patient interface.

[0595] The patient interface may further comprise a frame.

[0596] The frame may comprise headgear connectors.

[0597] The frame may comprise formations that interact with the dock.

[0598] The frame may comprise formation that interact with the housing.

[0599] The formations may comprise locking tabs.

[0600] The elbow may comprise lever arms that releasably interact with the frame.

[0601] The dock may comprise one or more indents which interact with the lever arms of the elbow to releasably couple the elbow to the dock.

[0602] The formations of the frame may interact with the one or more indents to releasably couple the frame to the dock.

[0603] The patient interface may comprise a cushion module.

[0604] The cushion module may comprise a seal and a housing.

[0605] The cushion module may be configured with the upper and lower chambers.

[0606] The cushion module may comprise one or more nare openings that enable respiratory gas to communicate with the patient's nares.

[0607] The cushion module may comprise one or more oral openings that enable respiratory gas to communicate with the patient's oral cavity.

[0608] The outlet may comprise an exhaust vent.

[0609] The outlet may comprise a bias vent.

[0610] The bias vent may comprise one or more apertures with a fixed cross- sectional flow area.

[0611] The outlet may comprise a flow valve.

[0612] The elbow may further comprise a gas-permeable cover in fluid communication with the outlet.

[0613] The gas-permeable cover may comprise a filter or a diffuser.

[0614] The gas-permeable cover may be releasably couplable with the elbow.

[0615] The gas-permeable cover may comprise a body.

[0616] The body may support filter media or diffuser media in a flow path of respiratory gas that flows through the outlet.

[0617] The filter media or the diffuser media may be integrally formed with the body.

[0618] The filter media or the diffuser media may be adhered the body.

[0619] The body may be over-moulded to the filter media or the diffuser media.

[0620] The body may comprise finger grips.

[0621] The finger grips may be adapted to facilitate coupling and decoupling of the gas-permeable cover to the elbow.

[0622] The body may comprise one or more catches that enable releasably coupling of the gas-permeable cover to the elbow.

[0623] The elbow may comprise one or more shoulders that are configured to interact with the one or more catches of the gas-permeable cover.

[0624] The shoulders and the catches enable snap-fit coupling of the gas-permeable cover to the elbow.

[0625] The cushion module may comprise a seal.

[0626] The frame may comprise the inlet and the outlet.

[0627] The frame may further comprise a frame body and a retaining bracket.

[0628] The frame body and the retaining bracket may be co-operable to couple the frame to the seal.

[0629] The seal may comprise a frame coupling formation.

[0630] The frame coupling formation may comprise one or more apertures through the seal.

[0631] The frame body and the retaining bracket may be configured to capture the frame coupling formation.

[0632] The frame body or the retaining bracket may comprise a seal seat in which the frame coupling formation of the seal is receivable.

[0633] The frame body or the retaining bracket may be configured to push the frame coupling formation into the seal seat when the retaining bracket and the frame body are coupled.

[0634] The frame coupling formation may comprise a seal lip that is receivable within the seal seat.

[0635] The frame coupling formation may further comprise an abutment that is configured to interact with the frame body or the retaining bracket to push the seal lip into the seal seat when the retaining bracket and the frame body are coupled.

[0636] The abutment may comprise a chamfer.

[0637] The chamfer may be at an opposite side of the coupling formation to the seal lip.

[0638] The frame body or the retaining bracket may comprise a bevel that interacts with the abutment to push the seal lip into the seal seat when the retaining bracket and the frame body are coupled.

[0639] The frame body may comprise clip arms that are couplable with arm-coupling formations on the retaining bracket to enable coupling of the frame body to the retaining bracket.

[0640] The retaining bracket may comprise a plurality of spaced bushing segments.

[0641] The retaining bracket may comprise clip arms that are couplable with armcoupling formations on the frame body to enable coupling of the frame to the retaining bracket.

[0642] The frame body may comprise a plurality of spaced bushing segments.

[0643] The arm-coupling formations may be disposed between adjacent bushing segments.

[0644] The clip arms may interact with the arm-coupling formations through a snap-fit interaction.

[0645] The snap-fit interaction may be releasable to enable releasable coupling of the frame body and the retaining bracket.

[0646] The seal may be over-moulded to the frame.

[0647] The seal may be coupled to the frame by elastic deformation of the seal.

[0648] The seal may be coupled to the frame by mechanical fasteners.

[0649] The seal may be releasably couplable to the frame.

[0650] The seal may be adhered to the frame.

[0651] The outlet may comprise a flow valve.

[0652] The outlet may further comprise a vent wall defining an opening.

[0653] The flow valve may be couplable to the vent wall.

[0654] The outlet may further comprise a vent wall defining an opening in which the flow valve is receivable.

[0655] The outlet may be laterally off-set from the inlet.

[0656] The outlet may be laterally off-set from a pressure valve.

[0657] The outlet and the pressure valve may be laterally off-set to opposite sides of the inlet.

[0658] The outlet may be configured to couple with a flow valve.

[0659] A flow valve may be couplable with the outlet via threaded fitting, a bayonet fitting, snap-fitting, interference fit, or clipping.

[0660] A flow valve may be integrally formed with the frame body.

[0661] The frame may comprise headgear connectors.

[0662] The frame may comprise lateral sides that incorporate the headgear connectors.

[0663] Each lateral side may comprise an upper headgear connector and a lower headgear connector.

[0664] The patient interface may comprise a dividing panel.

[0665] The dividing panel may be integral with the frame.

[0666] The dividing panel may comprise a pressure valve.

[0667] The pressure valve may be integrally formed with the dividing panel.

[0668] The pressure valve may be adhered to the dividing panel.

[0669] The pressure valve may be removably attached to the dividing panel.

[0670] The pressure valve may be over-moulded to the dividing panel.

[0671] The pressure valve may comprise a flap valve.

[0672] The dividing panel may comprise an aperture through which respiratory gas can flow from the lower chamber to the upper chamber.

[0673] The aperture is laterally off-set from the inlet.

[0674] The pressure valve may be laterally off-set from the inlet to a side of the frame that is opposite to another side in which the outlet is located.

[0675] The dividing panel may be co-operable with the dividing wall to separate the upper chamber from the lower chamber.

[0676] The retaining bracket may comprise the dividing panel.

[0677] The dividing panel may be integrally formed with the retaining bracket.

[0678] The dividing panel may be couplable to the retaining bracket.

[0679] The frame body may be configured to interact with the dividing panel of the retaining bracket to form a substantially airtight seal with the dividing panel.

[0680] The frame body may comprise a retaining slot in which the dividing panel is receivable.

[0681] The frame body and the retaining bracket may be configured to capture the flap valve between them when the retaining bracket and the frame body are coupled together.

[0682] The retaining bracket may comprise a formation that receives at least part of the flap valve.

[0683] The formation on the retaining bracket may comprises notches that are complementarily shaped to part of the flap valve.

[0684] The frame body may comprise a formation that receives at least part of the flap valve.

[0685] The formation on the frame body may comprises a detent that is complementarily shaped to part of the flap valve.

[0686] The formation on the frame body may further comprise a protrusion that is receivable within part of the flap valve.

[0687] The dividing panel may be integrally formed with the frame body.

[0688] The dividing panel may be formed separately to the frame body and the retaining bracket and may be coupled to the frame body.

[0689] The dividing panel may be over-moulded to the frame body.

[0690] The dividing panel may be adhered to the frame body.

[0691] The retaining bracket may be configured to receive at least part of the dividing panel.

[0692] The retaining bracket may comprise one or more retaining slots in which the dividing panel is receivable.

[0693] The dividing wall of the seal may comprise a distal sealing edge which interacts with the dividing panel.

[0694] The sealing edge of the dividing wall may form a substantially airtight seal with the dividing panel.

[0695] The sealing edge of the dividing wall may be spaced from the dividing panel.

[0696] The dividing wall is configured to permit respiratory gas to flow from the upper chamber to the lower chamber.

[0697] The dividing wall forms a gap with the dividing panel to allow respiratory gas to flow from the upper chamber to the lower chamber when respiratory gas pressure in the upper chamber exceeds a threshold pressure.

[0698] At least part of the distal sealing edge of the dividing wall forms a gap with the dividing panel to allow respiratory gas to flow from the upper chamber to the lower chamber when respiratory gas pressure in the upper chamber exceeds a threshold pressure.

[0699] The threshold pressure is the respiratory gas pressure in the lower chamber at the same time.

[0700] The dividing wall forming a gap with the dividing panel allows respiratory gas to flow from the upper chamber to the lower chamber, but not from the lower chamber to the upper chamber.

[0701] In patient interfaces defined in any one of the preceding or following aspects which comprise a pressure valve, the only flow path for respiratory gas to flow from the first chamber to the second chamber may be through the pressure valve.

[0702] In patient interfaces defined in any one of the preceding or following aspects, the dividing wall may comprise one or more flow directors.

[0703] The one or more flow directors may enable respiratory gas to flow into the second chamber from the first chamber.

[0704] The one or more flow directors may be configured to direct the respiratory gas flow toward the one or more nasal openings.

[0705] The one or more flow directors may extend from the dividing wall into the first chamber or into the second chamber or into both the first and the second chambers.

[0706] Each flow director may comprise a first flow director inlet in fluid communication with the first chamber and a first flow director outlet in fluid communication with the second chamber.

[0707] Each flow director may be shaped differently to one another in at least one way.

[0708] The flow director outlet of a first flow director and the flow director outlet of a second flow director may comprise cross-sectional flow areas that are unequal.

[0709] The ratio of the cross-sectional flow area of the flow director outlet of the first flow director to the cross-sectional flow area of the flow director outlet of the second flow director may be in a range from 1 :1.1 to 1 :4 or from 1 :1 .2 to 1 :4 or from 1 :1 .3 to 1 :4 or from 1 :1 .1 to 1 :1 .3 or from 1 :1.1 to 1 :1 .2.

[0710] The dividing wall may be joined with the outer wall to separate the first chamber from the second chamber.

[0711] The dividing wall may join with the outer wall at a location spaced from the one or more nasal openings.

[0712] The dividing wall may join with the outer wall across the entire width of the cushion module.

[0713] The dividing wall may join with the outer wall between the at least one or more nasal openings and the at least one or more oral openings.

[0714] The dividing wall may include a preferential deformation region.

[0715] The preferential deformation region accommodates at least some deformation force imparted by patient contact with a patient-engagement surface in preference to deformation of the flow directors.

[0716] The flow directors may be spaced from the preferential deformation region.

[0717] The one or more preferential deformation regions may decouple one portion of the dividing wall from another portion of the dividing wall such that a force imparted to one portion is greater than the force experienced by the decoupled portion.

[0718] The preferential deformation region may decouple one portion of the dividing wall from another portion of the dividing wall such that the two portions can move relative to each other.

[0719] The two portions of the dividing wall may be shaped to resist deformation.

[0720] The dividing wall includes a first resilient region that is on a distal side of the preferential deformation region.

[0721] The dividing wall includes a second resilient region that is on a proximal side of the preferential deformation region.

[0722] The first and second resilient regions translate deformation forces into the preferential deformation regions such that deformation of the dividing wall is substantially confined to the preferential deformation regions.

[0723] The one or more flow directors may be incorporated into the second resilient region.

[0724] The one or more preferential deformation regions may be interposed between the flow directors and a resilient region.

[0725] The preferential deformation region may have a wall thickness that is less than a wall thickness of the first resilient region.

[0726] The preferential deformation region may comprise a first wall projecting from the first resilient region and a second wall connecting the first wall with the second resilient region.

[0727] The first and second walls may be configured to deform in a predetermined sequence.

[0728] The patient interface may further comprise a cavity pressure port configured to be in fluid communication with the cavity formed by the housing and the seal.

[0729] The patient interface may further comprise a first pressure port configured to be in fluid communication with the first chamber, and a second pressure port configured to be in fluid communication with the second chamber.

[0730] The patient interface may further comprise a differential pressure sensor in fluid communication with the first pressure port and the second pressure port.

[0731] The patient interface may comprise one or more of the following sensors: humidity sensor, temperature sensor, acoustic sensor, gas pressure sensor, gas flow sensor, carbon dioxide sensor and oxygen sensor.

[0732] The carbon dioxide sensor may be an NDIR carbon dioxide sensor.

[0733] The carbon dioxide sensor may be an electrochemical sensor.

[0734] The carbon dioxide sensor may be photoacoustic sensor.

[0735] The oxygen sensor may be an electrochemical sensor.

[0736] The oxygen sensor may be a zirconia oxygen sensor.

[0737] The flow sensor may be a mass flow sensor or a volumetric flow sensor.

[0738] The one or more sensors may be inside the first chamber.

[0739] The one or more sensors may be inside the second chamber.

[0740] The one or more sensors may be outside the cushion module and in fluid communication with the first chamber.

[0741] The one or more sensors may be outside the cushion module and in fluid communication with the second chamber.

[0742] The one or more sensors may be in the first chamber and adjacent to the inlet.

[0743] The one or more sensors may be inside the second chamber and adjacent to a flow director.

[0744] The one or more sensors may be inside the second chamber and adjacent to the exhaust vent.

[0745] The one or more sensors may be inside the first chamber on the first resilient region.

[0746] The one or more sensors may be inside the first chamber on the housing.

[0747] The one or more sensors may be inside the first chamber on the seal.

[0748] The one or more sensors may be inside the first chamber and adjacent to the patient-contacting surface.

[0749] The one or more sensors may be inside the first chamber and adjacent to the oral opening.

[0750] The one or more sensors may be inside the second chamber on the first resilient region.

[0751] The one or more sensors may be inside the second chamber on the housing.

[0752] The one or more sensors may be inside the second chamber on the seal.

[0753] The one or more sensors may be inside the second chamber adjacent to the patient-contacting surface.

[0754] The one or more sensors may be outside the cushion module and in fluid communication with the exhaust vent.

[0755] The one or more sensors may be outside the cushion module on the housing and in fluid communication with the exhaust vent.

[0756] The one or more sensors may be outside the cushion module on the frame and in fluid communication with the exhaust vent.

[0757] The one or more sensors may be outside the cushion module on the seal and in fluid communication with the exhaust vent.

[0758] The patient interface may comprise one or more sampling tubes.

[0759] The one or more sampling tubes may have an inlet end within the cushion module.

[0760] The one or more sampling tubes may have an inlet end within the first chamber.

[0761] The one or more sampling tubes may have an inlet end within the second chamber.

[0762] The one or more sampling tubes may enable fluid communication with one or more sensors that are external of the patient interface.

[0763] The one or more sensors may be remote from the patient interface.

[0764] The inlet of the one or more sampling tubes may be in any of the locations identified above in respect of the sensor locations.

[0765] The one or more sampling tubes may be retained within the cushion module by a bracket.

[0766] The bracket may be part of the seal, the housing or the frame.

[0767] The bracket may be adjacent to the inlet.

[0768] Data from the one or more sensors may be transmissible to a processor.

[0769] The patient interface may comprise a processor.

[0770] The processor may be connectable to a power source within the cushion module.

[0771] The processor may be connectable to a power source that is external to the cushion module.

[0772] The processor may be connectable to a power source that is remote from the cushion module.

[0773] The processor may be external of the cushion module.

[0774] The processor may be remote from the cushion module.

[0775] Data from the one or more sensors may be transmissible wirelessly to the processor.

[0776] Data from the one or more sensors may be transmissible to the processor by a wired connection.

[0777] The wired connection may comprise the processor and the one or more sensors being embedded to a printed circuit board.

[0778] The wired connection may comprise a data transmission line between the one or more sensors and the processor.

[0779] One or more of the sensors may be in a sensor module.

[0780] The sensor module may be at any one of the locations above in respect of the sensor locations.

[0781] The processor may be part of a ventilator, a mobile device, a computer or a server.

[0782] In a further aspect, a respiratory therapy system comprising:• a patient interface according to any one of the preceding aspects above;• a respiratory gas source to supply respiratory gas to the patient interface;• an inspiratory limb that enables fluid communication between the respiratory gas source and the patient interface.

[0783] The respiratory system further may comprise an expiratory limb that enables fluid communication between the patient interface and the respiratory gas source or distil from the patient interface.

[0784] The respiratory therapy system may comprise a humidifier as part of the inspiratory limb.

[0785] The respiratory therapy system may comprise one or more of the following sensors: humidity sensor, temperature sensor, acoustic sensor, gas pressure sensor, gas flow sensor, carbon dioxide sensor and oxygen sensor.

[0786] The respiratory therapy system may comprise a processor remote from the patient interface.

[0787] Data from the one or more sensors may be transmissible to the processor.

[0788] The patient interface may further comprise a conduit connector configured to be connected to the inlet of the cushion module, the conduit connector comprising an anti-asphyxiation valve and a pressure port and further being configured to be removably attached to a respiratory therapy conduit.

[0789] The patient interface may further comprise a conduit connector configured to be connected to the inlet of the cushion module, the conduit connector comprising one or more bias vents and a pressure port and further being configured to be removably attached to a respiratory therapy conduit.

[0790] The conduit connector may be configured to be connected to a single-limb respiratory circuit.

[0791] The conduit connector may be configured to be connected to a dual-limb respiratory circuit.

[0792] The conduit connector may be configured to be connected to a dual-limb respiratory circuit via a y-piece.

[0793] In a further aspect, there is provided a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of the patient, the patient interface comprising:• a first chamber and a second chamber, the first and second chamber are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across a range of respiratory therapy pressures.

[0794] The flow valve may be configured to control the flow of respiratory gas from the second chamber in response to variations in the respiratory therapy pressure.

[0795] The flow valve may comprise a flow path from the second chamber to a flow outlet and a pressure-displaceable diaphragm positioned at least partially within the flow path.

[0796] The pressure-displaceable diaphragm may be deformable in response to the respiratory therapy pressure so that a cross-sectional area of the flow path is less for higher respiratory therapy pressures than the cross-sectional area of the flow path is for lower respiratory pressures.

[0797] The flow valve may be manually adjustable to control the flow of respiratory gas from the second chamber.

[0798] The flow outlet may comprise a plurality of apertures.

[0799] One or more apertures of the plurality of apertures may have a cross- sectional flow area that is different to the cross-sectional flow area of the other apertures.

[0800] The preferred range may be 10 L / m to 20 L / m or 10 L / m to 30 L / m across the range of respiratory therapy pressures.

[0801] The flow valve may enable the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of intended respiratory therapy pressures.

[0802] The flow valve may enable the respiratory gas flow rate to be greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

[0803] The range of respiratory therapy pressures may be 4cmH20 to 35cmH20, or 5cmH20 to 30cmH20, or 6cmH20 to 25cmH20, or 7cmH20 to 20cmH20, or 8cmH20 to 25cmH20.

[0804] The flow valve may comprise a diffuser or a filter.

[0805] The first chamber may be configured to communicate respiratory gas with the mouth, and the second chamber is configured to communicate respiratory gas with the one or more nares.

[0806] The first chamber may be configured to communicate respiratory gas with the one or more nares, and the second chamber is configured to communicate respiratory gas with the mouth.

[0807] The patient interface may further comprise a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient.

[0808] The seal may be configured to enable fluid communication between the first and second chambers and the mouth and the one or more nares.

[0809] The patient interface may further comprise a housing that structurally supports the seal.

[0810] The housing and seal may together form a cushion module comprising the first chamber and second chamber.

[0811] The patient interface may further comprise a frame that is couplable to headgear and to either the housing or the seal.

[0812] At least part of the flow valve may be integrally formed with the housing.

[0813] At least part of the flow valve may be integrally formed with the frame.

[0814] At least part of the flow valve may be integrally formed with the seal.

[0815] At least part of the flow valve may be integrally formed with the cushion module.

[0816] The flow valve may be removably couplable to the housing or to the frame.

[0817] The flow valve may be removably couplable to the cushion module.

[0818] The patient interface may comprise a dividing wall that separates the first chamber from the second chamber.

[0819] The cushion module may comprise a dividing wall that separates the first chamber from the second chamber.

[0820] The dividing wall may comprise one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber.

[0821] Each flow director may have a cross-sectional flow area.

[0822] The dividing wall may comprise two or more flow directors and each flow director comprises the same cross-sectional flow area as the or each of the other flow directors.

[0823] The dividing wall may comprise two or more flow directors and at least one flow director may comprise a cross-sectional flow area that may be different to the cross-sectional flow area of the or each of the other flow directors.

[0824] The dividing wall may comprise a single flow director.

[0825] A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising:• a first chamber configured to communicate respiratory gas with the mouth of the patient;• a second chamber configured to communicate respiratory gas with one or both nares of the patient;• the first and second chambers are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber• a respiratory gas outlet in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface; and• a pressure valve that is configured to control the flow of respiratory gas between the first chamber and the second chamber to provide a respiratory gas pressure in the second chamber that is lower than a respiratory gas pressure in the first chamber across a range of respiratory therapy pressures.

[0826] The pressure valve may enable the respiratory gas pressure in the second chamber that may be in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first chamber across the range of respiratory therapy pressures.

[0827] The pressure valve may enable a respiratory gas pressure in the second chamber that may be less than 4.0 cmFhO, less than 3.5 cmFhO, less than 3.0 cmH2O, less than 2.5 cmFhO, less than 2.0 cmFLO, less than 1 .5 cmFLO, less than 1 .4 crnkhO, less than 1 .3 cmFhO, less than 1 .2 cmFhO, less than 1 .1 cmFhO, less than 1.0 crnkhO, less than 0.9 cmFhO, less than 0.8 cmFhO, less than 0.7 cmFhO, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of respiratory therapy pressures.

[0828] The pressure valve may enable a respiratory gas pressure in the second chamber that may be greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4 cmH2O, greater than 0.5 greater than cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1 .0 cmFhO, greater than 1.1 cmFLO or greater than 1 .2 cmFhO lower than the respiratory gas pressure in the first chamber across the range of respiratory therapy pressures.

[0829] The pressure valve may be configured to control the flow of respiratory gas from the first chamber to the second chamber in response to the respiratory gas pressure in the second chamber.

[0830] In a further aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising:• a first chamber configured to communicate respiratory gas with the mouth of the patient;• a second chamber configured to communicate respiratory gas with one or both nares of the patient;• the first chamber and the second chamber being in fluid communication within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a respiratory gas outlet in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface; and• a pressure valve that is configured to permit gas flow from the first chamber to the second chamber when the pressure in the second chamber is at least a first threshold amount lower than the pressure in the first chamber, the first threshold amount being maintained across a range of respiratory therapy pressures.

[0831] The first threshold amount may be in the range of 0.2 to 4.0 cmFhO, 0.3 to 3.5 cmH2O, 0.4 to 3 cmH2O, 0.5 to 2.5 cmH2O, or 0.6 to 2 cmH2O.

[0832] The first threshold amount may be greater than 0.2 cmFhO, greater than 0.3 cmH2O, greater than 0.4 cmH2O, greater than 0.5 cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmH2O, greater than 1 .0 cmFhO, greater than 1 .1 cmFhO or greater than 1 .2 cmH2O.

[0833] The pressure valve may comprise a pressure-displaceable diaphragm.

[0834] The pressure valve may comprise a flap valve.

[0835] The patient interface may comprise a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient and a housing that structurally supports the seal.

[0836] The seal may be configured to enable fluid communication between the first and second chambers and the mouth and the one or more nares.

[0837] The seal and housing may together define a cushion module.

[0838] The cushion module may comprise the first chamber and the second chamber.

[0839] The patient interface may comprise a frame that is couplable to headgear and to the cushion module.

[0840] The patient interface may comprise a dividing wall that separates the first chamber from the second chamber.

[0841] The cushion module may comprise a dividing wall that separates the first chamber from the second chamber.

[0842] The seal may comprise the dividing wall.

[0843] The housing may defines the dividing wall.

[0844] The patient interface defined in claim 51 , wherein the dividing wall may be formed in part by the seal and in part by the housing.

[0845] The pressure valve may be integral with the dividing wall.

[0846] The pressure valve may be couplable with the dividing wall.

[0847] The pressure valve may be part of an insert that is co-operable with the dividing wall to separate the first chamber from the second chamber.

[0848] The pressure valve may be part of an insert that is couplable with the frame, the housing or the seal.

[0849] The pressure valve may be located externally of the cushion module.

[0850] The pressure valve may be located within a conduit connector which is configured to connect to the cushion module.

[0851] The dividing wall may comprise one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber within the patient interface.

[0852] Each flow director may have a cross-sectional flow area.

[0853] The dividing wall may comprise two or more flow directors and each flow director comprises the same cross-sectional flow area as the or each of the other flow directors.

[0854] The dividing wall may comprise two or more flow directors and at least one flow director comprises a cross-sectional flow area that is different to the cross- sectional flow area of the or each of the other flow directors.

[0855] The dividing wall may comprise a single flow director.

[0856] A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of a patient, the patient interface comprising:• a first chamber and a second chamber, the second chamber being configured to communicate a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to control the flow of respiratory gas from the first chamber to the second chamber within the patient interface to provide a respiratory gas pressure in the second chamber that is lower than the respiratory gas pressure in the first chamber across a range of respiratory therapy pressures;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across the range of respiratory therapy pressures; and• a relief valve that is configured to communicate respiratory gas from the second chamber to the first chamber within the patient interface when the respiratory gas pressure in the second chamber is greater than the respiratory gas pressure in the first chamber.

[0857] The pressure valve enables a respiratory gas pressure in the second chamber that may be in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0858] The pressure valve may enable a respiratory gas pressure in the second chamber that is less than 4.0 cmFhO, less than 3.5 cmFhO, less than 3.0 cmFhO, less than 2.5 cmFhO, less than 2.0 cmFhO, less than 1.5 cmFhO, less than 1.4 cmH2O, less than 1 .3 cmFhO, less than 1 .2 cmFLO, less than 1 .1 cmFLO, less than 1.0 cmH2O, less than 0.9 cmH2O, less than 0.8 cmH2O, less than 0.7 cmH2O, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0859] The pressure valve may enable a respiratory gas pressure in the second chamber that is greater than 0.0 cmFLO, greater than 0.1 cmFhO, greater than 0.2 cmH2O, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5cmH2O, greater than 0.6 cmFhO, greater than 0.7 cmFLO, greater than 0.8 greater than cmH2O, greater than 0.9 cmH2O, greater than 1.0 cmFhO, greater than 1.1 cmFhO or greater than 1 .2 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0860] In a further aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface may be configured to communicate respiratory gas with the mouth and with one or both nares of a patient, the patient interface comprising:• a first chamber and a second chamber, the second chamber being in fluid communication with the first chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to permit gas flow from the first chamber to the second chamber when the pressure in the second chamber is at least a first threshold amount lower than the pressure in the first chamber, the firstthreshold amount being maintained across a range of respiratory therapy pressures;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across the range of respiratory therapy pressures; and• a relief valve that is configured to permit gas flow from the second chamber to the first chamber when the pressure in the second chamber is at least a second threshold amount greater than pressure in the first chamber.

[0861] The first threshold amount may be in the range of 0.2 to 4.0 cmH2O, 0.3 to 3.5 cmH2O, 0.4 to 3 cmH2O, 0.5 to 2.5 cmH2O, or 0.6 to 2 cmH2O.

[0862] The first threshold amount may be greater than 0.2 cmFhO, greater than 0.3 cmH2O, greater than 0.4 cmH2O, greater than 0.5 cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmH2O, greater than 1 .0 cmFhO, greater than 1 .1 cmFhO or greater than 1 .2 cmH2O.

[0863] The second threshold amount may be greater than 0.0cmH2O, greater than 0.05 cmH2O, greaten than 0.1 cmFhO, greater than 0.2 cmFhO, greater than 0.3 cmH2O, greater than 0.4cmH2O, or greater than 0.5 cmFhO.

[0864] The flow valve may be configured to control the flow of respiratory gas from the second chamber in response to variations in the respiratory therapy pressure.

[0865] The flow valve may be manually adjustable to control the flow of respiratory gas from the second chamber.

[0866] The flow valve may comprise a flow path from the second chamber to a flow outlet and comprises a pressure-displaceable diaphragm positioned at least partially within the flow path.

[0867] The pressure-displaceable diaphragm may be deformable in response to the respiratory therapy pressure so that a cross-sectional area of the flow path is less forhigher respiratory therapy pressures than the cross-sectional area of the flow path is for lower respiratory pressures.

[0868] The preferred range may be 10 L / m to 20 L / m across the range of respiratory therapy pressures.

[0869] The flow valve may enable the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m less than 13 L / m, or less than 12 L / m across the range of respiratory therapy pressures.

[0870] The flow valve may enable the respiratory gas flow rate to be greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

[0871] The range of respiratory therapy pressures may be 4 cmh^O to 35 cmhhO, or 5 cmhbO to 30 cmhbO, or 6 cmh^O to 25 cmh^O, or 7 cmh^O to 20 cmh^O, or 8 cmhbO to 25 cmhbO.

[0872] The flow valve may comprise a diffuser or a filter.

[0873] The pressure valve may be configured to control the flow of respiratory gas from the first chamber to the second chamber in response to the respiratory gas pressure in the second chamber.

[0874] The pressure valve may comprise a first pressure-displaceable diaphragm.

[0875] The pressure valve may comprise a flap valve.

[0876] The relief valve may comprise a second pressure-displaceable diaphragm.

[0877] The relief valve may comprise a flap valve.

[0878] The patient interface may comprise a dividing wall that separates the first chamber from the second chamber.

[0879] The relief valve may comprise a flap valve portion of the dividing wall.

[0880] The patient interface may comprise an insert that is co-operable with the dividing wall to separate the first chamber from the second chamber.

[0881] The flap valve portion may overlay part of one side of the insert that defines the first chamber.

[0882] The flap valve portion may be configured to be urged into contact with the insert when the respiratory gas pressure in the first chamber is greater than the respiratory gas pressure in the second chamber and is configured to form an gap with the insert which enables respiratory gas to flow from the second chamber to the first chamber when the respiratory gas pressure in the second chamber is greater than the respiratory gas pressure in the first chamber.

[0883] The patient interface may further comprise a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient.

[0884] The patient interface further may comprise a housing that structurally supports the seal.

[0885] The housing and seal may together form a cushion module comprising the first chamber and second chamber.

[0886] The cushion module may comprise a dividing wall that separates the first chamber from the second chamber.

[0887] The patient interface may comprise a frame that is couplable to headgear and to either the housing or the seal.

[0888] At least part of the flow valve may be integrally formed with the housing.

[0889] At least part of the flow valve may be integrally formed with the frame.

[0890] At least part of the flow valve may be integrally formed with the seal.

[0891] At least part of the flow valve may be integrally formed with the cushion module.

[0892] At flow valve may be removably couplable to the housing or to the frame.

[0893] The flow valve may be removably couplable to the cushion module.

[0894] The dividing wall may comprise one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber within the patient interface.

[0895] Each flow director has a cross-sectional flow area.

[0896] The dividing wall may comprise two or more flow directors and each flow director comprises the same cross-sectional flow area as the or each of the other flow directors.

[0897] The dividing wall may comprise two or more flow directors and at least one flow director comprises a cross-sectional flow area that is different to the cross- sectional flow area of the or each of the other flow directors.

[0898] The dividing wall may comprise a single flow director.

[0899] The dividing wall may be formed in part by the housing and in part by the seal.

[0900] Part of the dividing wall may be formed by the seal and which part comprises the relief valve.

[0901] In a further aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of the patient, the patient interface comprising:• a first chamber and a second chamber, the first and second chambers are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to control the fluid communication between the first chamber and the second chamber to provide a respiratory gas pressure in the second chamber that is lower than the respiratory gas pressure in the first chamber across a range of different respiratory therapy pressures;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be below an upper limit across the range of respiratory therapy pressures.

[0902] The pressure valve may enable a respiratory gas pressure in the second chamber that is in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0903] The pressure valve may enable a respiratory gas pressure in the second chamber that is less than 4.0 cmFhO, less than 3.5 cmFhO, less than 3.0 cmFhO, less than 2.5 cmFhO, less than 2.0 cmFhO, less than 1.5 cmFhO, less than 1.4 cmH2O, less than 1 .3 cmFhO, less than 1 .2 cmFLO, less than 1 .1 cmFLO, less than 1.0 cmH2O, less than 0.9 cmH2O, less than 0.8 cmH2O, less than 0.7 cmH2O, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0904] The pressure valve may enable a respiratory gas pressure in the second chamber that is greater than 0.0 cmFLO, greater than 0.1 cmFhO, greater than 0.2 cmH2O, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5cmH2O, greater than 0.6 cmFhO, greater than 0.7 cmFLO, greater than 0.8 greater than cmH2O, greater than 0.9 cmH2O, greater than 1.0 cmFhO, greater than 1.1 cmFhO or greater than 1 .2 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0905] In a further aspect, a patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of a patient, the patient interface comprising:• a first chamber and a second chamber, the second chamber being in fluid communication with the first chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to permit gas flow from the first chamber to the second chamber when the pressure in the second chamber is at least a first threshold amount lower than the pressure in the first chamber, the first threshold amount being maintained across a range of respiratory therapy pressures; and• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across the range of respiratory therapy pressures.

[0906] The first threshold amount may be in the range of 0.2 to 4.0 cmH2O, 0.3 to 3.5 cmH2O, 0.4 to 3 cmH2O, 0.5 to 2.5 cmH2O, or 0.6 to 2 cmH2O.

[0907] The first threshold amount may be greater than 0.2 cmFLO, greater than 0.3 cmH2O, greater than 0.4 cmH2O, greater than 0.5 cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmFLO, greater than 0.8 greater than cmFLO, greater than 0.9 cmH2O, greater than 1 .0 cmFLO, greater than 1 .1 cmFLO or greater than 1 .2 cmH2O.

[0908] The flow valve may be configured to control the flow of respiratory gas from the second chamber in response to variations in the respiratory therapy pressure.

[0909] The flow valve may comprise a flow path from the second chamber to a flow outlet and a pressure-displaceable diaphragm positioned at least partially within the flow path.

[0910] The flow outlet may comprise a plurality of apertures.

[0911] One or more of the plurality of apertures may have a cross-sectional flow area that is different to the cross-sectional flow area of the other apertures.

[0912] The pressure-displaceable diaphragm may be deformable in response to the respiratory therapy pressure so that a cross-sectional area of the flow path is less for higher respiratory therapy pressures than the cross-sectional area of the flow path is for lower respiratory pressures.

[0913] The flow valve may be manually adjustable control of the flow of respiratory gas from the second chamber.

[0914] The flow valve may enable a flow rate within the range of 10 L / m to 20 L / m across the range of respiratory therapy pressures.

[0915] The flow valve may enable the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, lessthan 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of respiratory therapy pressures.

[0916] The flow valve may enables the respiratory gas flow rate to be greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

[0917] The range of respiratory therapy pressures may be 4 cmh^O to 35 cmhhO, or 5 cmh O to 30 cmh O, or 6 cmh^O to 25 cmh^O, or 7 cmh^O to 20 cmh^O, or 8 cmh O to 25 cmh O.

[0918] The pressure valve may enable a respiratory gas pressure in the second chamber that is in the range of 0.2 to 4.0 cmh^O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

[0919] The pressure valve may be configured to control the flow of respiratory gas from the first chamber to the second chamber in response to the respiratory gas pressure in the second chamber.

[0920] The pressure valve may comprise a deformable diaphragm.

[0921] The pressure valve may comprise a flap valve.

[0922] The flow valve may comprise a diffuser or a filter.

[0923] The patient interface may comprise a dividing wall that separates the first chamber from the second chamber.

[0924] The patient interface may further comprise a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient.

[0925] The patient interface may further comprise a housing that structurally supports the seal.

[0926] The housing and seal may together form a cushion module comprising the first chamber and second chamber.

[0927] The cushion module may comprise a dividing wall that separates the first chamber from the second chamber.

[0928] The patient interface may comprise a frame that is couplable to headgear and to either the housing or the seal.

[0929] At least part of the flow valve may be integrally formed with the housing.

[0930] At least part of the flow valve may be integrally formed with the frame.

[0931] At least part of the flow valve may be integrally formed with the seal.

[0932] At least part of the flow valve may be integrally formed with the cushion module.

[0933] The flow valve may be removably couplable to the housing or to the frame.

[0934] The flow valve may be removably couplable to the cushion module.

[0935] The seal may comprise the dividing wall.

[0936] The housing may comprise the dividing wall.

[0937] The dividing wall may be formed in part by the seal and in part by the housing.

[0938] The dividing wall may comprise one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber.

[0939] Each flow director has a cross-sectional flow area.

[0940] The dividing wall may comprise two or more flow directors and each flow director comprises the same cross-sectional flow area as the or each of the other flow directors.

[0941] The dividing wall may comprise two or more flow directors and at least one flow director comprises a cross-sectional flow area that is different to the cross- sectional flow area of the or each of the other flow directors.

[0942] The dividing wall may comprise a single flow director.

[0943] In a further aspect, a conduit connector configured to provide fluid communication between a respiratory gas supply conduit and a patient interface, the conduit connector comprising:• a first outlet channel and a second outlet channel, the first and second outlet channel are in fluid communication to enable a flow of respiratory gas fromthe first outlet channel to the second outlet channel within the conduit connector;• a respiratory gas inlet in fluid communication with the first outlet channel;• a respiratory gas outlet in fluid communication with the second outlet channel and through which respiratory gas is exhaustible from the second outlet channel to external of the conduit connector; and• a pressure valve that is configured to control the flow of respiratory gas from the first outlet channel to the second outlet channel to provide a respiratory gas pressure in the second outlet channel that is lower than a respiratory gas pressure in the first outlet channel across a range of respiratory therapy pressures.

[0944] The conduit connector may be releasably couplable to a patient interface.

[0945] The conduit connector may be couplable to a seal or a housing or a frame or a cushion module of a patient interface.

[0946] The pressure valve may enable a respiratory gas pressure in the second outlet channel that is in the range of 0.2 to 4.0 cmFhO lower than the respiratory gas pressure in the first outlet channel across the range of respiratory therapy pressures.

[0947] The pressure valve may enable a respiratory gas pressure in the second outlet channel that is less than 4.0 cmFhO, less than 3.5 cmFhO, less than 3.0 cmH2O, less than 2.5 cmFhO, less than 2.0 cmFLO, less than 1 .5 cmFLO, less than 1 .4 crnkhO, less than 1 .3 cmFhO, less than 1 .2 cmFhO, less than 1 .1 cmFhO, less than 1.0 crnkhO, less than 0.9 cmFhO, less than 0.8 cmFhO, less than 0.7 cmFhO, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first outlet channel across the range of respiratory therapy pressures.

[0948] The pressure valve may enable a respiratory gas pressure in the second outlet channel that is greater than 0.0 cmFhO, greater than 0.1 cmFhO, greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5 greater than cmFhO, greater than 0.6 cmFhO, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmFLO, greater than 1.0 cmFhO, greaterthan 1 .1 cmH20 or greater than 1 .2 cmH20 lower than the respiratory gas pressure in the first outlet channel across the range of respiratory therapy pressures.

[0949] The pressure valve may be configured to control the flow of respiratory gas from the first outlet channel to the second outlet channel in response to the respiratory gas pressure in the second outlet channel.

[0950] The pressure valve may comprise a deformable diaphragm.

[0951] The pressure valve may comprise a flap valve.

[0952] The conduit connector may comprise a dividing panel that separates the first outlet channel from the second outlet channel.

[0953] The pressure valve may be integral with the dividing panel.

[0954] The pressure valve may be couplable with the dividing panel.

[0955] The dividing panel may be co-operable with a dividing wall of the patient interface.

[0956] In a patient interface comprising a first chamber and a second chamber and comprising a dividing wall separating the first chamber from the second chamber, the dividing panel may be co-operable with the dividing wall.

[0957] The dividing panel may be configured to be co-operable with the dividing wall to enable respiratory gas to flow from the first outlet channel of the conduit connector to the first chamber of the patient interface and to enable respiratory gas to flow from the second chamber of the patient interface to the second outlet channel of the conduit connector.

[0958] The respiratory gas outlet may comprise a flow valve in fluid communication with the second outlet channel and through which respiratory gas is exhaustible from the second outlet channel to external of the conduit connector and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be below an upper limit across a range of different respiratory therapy pressures.

[0959] The flow valve may enable a flow rate within the range of 10 L / min to 20 L / m across the range of different respiratory therapy pressures.

[0960] The flow valve may enable the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of respiratory therapy pressures.

[0961] The flow valve may enable the respiratory gas flow rate to be is greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

[0962] A respiratory therapy assembly comprising:• the patient interface of any one of the claims 1 to 150; and• headgear that is couplable with the patient interface and which is operable to maintain a seal with between a patient’s face and the patient interface across the range of respiratory therapy pressures.

[0963] The respiratory therapy assembly may further comprise a conduit connector.

[0964] The pressure valve may be within the conduit connector and is not within the patient interface.

[0965] The patient interface may comprise a dividing wall that separates the first and second chambers of the patient interface.

[0966] A dividing panel may separate the first and second outlet channels of the conduit connector.

[0967] The dividing panel may be co-operable with the dividing wall.

[0968] The dividing panel may be co-operable with the dividing wall to enable respiratory gas to flow from the first outlet channel of the conduit connector to the first chamber of the patient interface and to enable respiratory gas to flow from the second chamber of the patient interface to the second outlet channel of the conduit connector.

[0969] In another aspect, there is provided a positive pressure respiratory therapy system comprising: a patient interface comprising:• a cushion module comprising a chamber to communicate respiratory gas with the mouth and nares of a patient;• an inlet through which the pressurized respiratory gas is receivable into the chamber;• an outlet through which respiratory gas is exhaustible from the chamber;• a dual limb ventilator;• a y-piece connected to the inlet of the patient interface;• an inspiratory limb that enables fluid communication between the ventilator and the y-piece;• an expiratory limb that enables fluid communication between the y-piece and the ventilator; and• a supplementary inlet to receive respiratory gas into the system or to a patient from a secondary gas source.

[0970] The outlet may enable venting of respiratory gas from within the chamber to ambient atmosphere.

[0971] The cushion module may comprise a dividing wall that divides the chamber into a first chamber and a second chamber.

[0972] The first chamber may comprise one or more oral openings to communicate gas with the mouth.

[0973] The second chamber may comprise one or more nasal openings to communicate gas with the nares.

[0974] The inspiratory limb may comprise a humidifier.

[0975] The supplementary inlet may be in the inspiratory limb.

[0976] The supplementary inlet may be upstream or downstream of the humidifier.

[0977] The supplementary inlet may be in the expiratory limb.

[0978] The supplementary inlet may be in the patient interface.

[0979] The supplementary inlet may be in fluid communication with the first chamber.

[0980] The supplementary inlet may be in fluid communication with the first chamber via the inlet.

[0981] The supplementary inlet may be in fluid communication with the second chamber.

[0982] The supplementary inlet may be in fluid communication with the second chamber through the housing.

[0983] The outlet may be in fluid communication with the first chamber.

[0984] The outlet may be in fluid communication with the second chamber.

[0985] The supplementary inlet may comprise a tube to supply respiratory gas to the nose, mouth or larynx of a patient.

[0986] The tube may extend through the patient interface.

[0987] The supplementary inlet may be capable of supplying 25 to 90 L / m of respiratory gas.

[0988] Although various features are disclosed above in relation to one or more aspects, it will be appreciated that one or more features of one aspect may be combined with one or more features of other aspects to arrive at additional embodiments. It follows that disclosure of features in the preceding statements should not be interpreted as meaning that the features are limited in application to the aspects in respect of which they are disclosed. For example, any embodiment of the flow valve may be combined with any embodiment of the pressure valve.Similarly, any embodiment of the flow valve may be combined with any embodiment of the relief valve and any embodiment of the pressure valve may be combined with may be combined with any embodiment of the relief valve. Additionally, any of the flow valve, pressure valve, or relief valve may be combined with any embodiment of patient interfaces shown (for example, full-face under-nose and full-face over-nose patent interfaces).

[0989] Ordinal references (e.g. first, second, third) to aspects disclosed above serve to differentiate aspects from one another only. The ordinal references are not to be interpreted as the order of importance of the aspects.

[0990] Throughout the above disclosure, the following description and the claims, the terms “proximal” and “distal” and their grammatical variants are references to the respective proximal direction and the distal direction. Proximal direction referencesindicate a direction that is toward a patient as if the patient interface were fitted to a patient. Distal references indicate a direction that is away from the patient as if the patient interface were fitted to a patient. These directions are shown in Figure 28. The same directionality applies to all of the drawings and all of the embodiments disclosed in this specification. Use of the terms “proximal” and “distal” is not to be taken as indicating a state when the patient interface is fitted to a patient, unless the context indicates otherwise.

[0991] Throughout the above disclosure, the following description and the claims, the term “chamber” is taken to mean a structure of the patient interface that encloses a volume and which structure has one or more respiratory gas inlets and one or more respiratory gas outlets.

[0992] Throughout the above disclosure, the following description and the claims, the term “upright orientation” is taken to mean the orientation of the patient interface when a mid-plane between the lateral sides of the patient interface is oriented vertically and when the distal-most point of the wall portion on the mid-plane and a below-mouth point of the oral opening on the mid-plane are vertically aligned. The mid-plane is the plane of the cross-section line A-A’ in Figure 4 and is also the plane of the cross-section line U-U in Figure 24.

[0993] Throughout the above disclosure, the following description and the claims, the term “y-piece” refers to a component of a respiratory therapy circuit that is also known as a wye-piece. That is, references in this specification to “y-piece” should not be read as referring to a component that is different to a wye-piece.BRIEF DESCRIPTION OF THE DRAWINGS

[0994] The aspects of the patient interface disclosed above are described in detail below by reference to embodiments, which serve as examples only, and with reference to the accompanying drawings, in which:

[0995] Figure 1 is perspective view of a patient interface according to a first embodiment.

[0996] Figure 2 is an exploded perspective view of the patient interface of Figure 1 .

[0997] Figure 3 is an exploded side view of the patient interface of Figure 1 .

[0998] Figure 4 is a front view of the patient interface of Figure 1 .

[0999] Figure 5 is a side view of the patient interface of Figure 1 .

[1000] Figure 6 is a rear view of the patient interface of Figure 1 .

[1001] Figure 7 is a top view of the patient interface of Figure 1.

[1002] Figure 8 is a bottom view of the patient interface of Figure 1 .

[1003] Figure 9 is a cross-sectional side view of the patient interface of Figure 1 along line AA’ as shown in Figure 4.

[1004]

[1005] Figure 10 is a perspective view of a patient interface according to a further embodiment.

[1006] Figure 11 is a front view of the patient interface of Figure 10.

[1007] Figure 12 is a side view of the patient interface of Figure 10.

[1008] Figure 13 is a rear view of the patient interface of Figure 10.

[1009] Figure 14 is a top view of the patient interface of Figure 10.

[1010] Figure 15 is a bottom view of the patient interface of Figure 10.

[1011] Figure 16 is a cross-sectional side view of the patient interface of Figure 43 along line HH’ as shown in Figure 11.

[1012] Figure 17 is a cross-sectional perspective view of the patient interface of Figure 43 along line HH’ as shown in Figure 11.

[1013] Figure 18 is a cross-sectional perspective view of the patient interface of Figure 43 along line II’ as shown in Figure 11 .

[1014] Figure 19 is a cross-sectional top view of the patient interface of Figure 43 along line II” as shown in Figure 11 .

[1015] Figure 20 is a schematic cross-sectional side view of the patient interface of Figure 43 along line HH’ as shown in Figure 11 fitted to a patient while their mouth is open.

[1016] Figure 21 is a schematic cross-sectional side view of the patient interface of Figure 43 along line HH’ as shown in Figure 11 fitted to a patient while their mouth is closed.

[1017] Figure 22 is an oblique view of a patient interface according to a further embodiment.

[1018] Figure 23 is an exploded oblique view of the patient interface in Figure 22.

[1019] Figure 24 is a front plan view of the cushion module of the patient interface in Figure 22.

[1020] Figure 25 is a side plan view of the alternative cushion module shown in Figure 24;

[1021] Figure 26 is a top plan view of the alternative cushion module shown in Figure 24;

[1022] Figure 27 is a rear plan view of the alternative cushion module shown in Figure 24;

[1023] Figure 28 is a cross-sectional view along the line U-U in Figure 24;

[1024] Figure 29 is a magnified view of the region marked W in the cross-section view of Figure 28;

[1025] Figure 30 is a magnified view of a cross-section view along the line X-X in Figure 26;

[1026] Figure 31 is an oblique cross-sectional view along the line Y-Y in Figure 24;

[1027] Figure 32 is a graph of respiratory gas flow through a flow valve for a range of respiratory therapy pressures for single limb (S) and dual limb (D) respiratory therapy systems.

[1028] Figure 33 is a graph of pressure drop between two chambers of a patient interface for a range of respiratory therapy pressures (represented as flow between the two chambers) for two patient interfaces, one with a fixed size exhaust vent and another pressure valve.

[1029] Figure 34 is a graph of an indicative relationship between the respiratory therapy pressure supplied to a patient interface and the flow rate (leak) through a fixed aperture outlet (i.e. without a flow valve).

[1030] Figure 35 is an oblique front view of a further embodiment of a patient interface with a flow valve.

[1031] Figure 36 is a cross-sectional view of the patient interface of Figure 35 along line J-J in Figure 35.

[1032] Figure 37 is an oblique front view of a frame of the patient interface in Figure 35.

[1033] Figure 38 is a rear view of the frame in Figure 37.

[1034] Figure 39 is an oblique front view of a gasket that fits with the frame in Figure 38.

[1035] Figure 40 is a front view of a cushion module of the patient interface in Figure 35.

[1036] Figure 41 is a rear view of the frame in Figure 36 with the gasket of Figure 39 in an assembled position.

[1037] Figure 42 is a magnified view of part of the flow valve shown in Figure 36.

[1038] Figure 43 is an exploded isometric view of the flow valve shown in Figure 36.

[1039] Figure 44 is an oblique side view of the cushion module shown in Figure 35 with a further alternative flow valve.

[1040] Figure 45 is a magnified view of a cross-section along the line P-P’ in Figure 44 of part of the flow valve in Figure 44.

[1041] Figure 46 is an exploded isometric view of the part of the flow valve shown in Figure 44.

[1042] Figure 47 is a magnified view of a further alternative flow valve as if it were fitted to the patient interface in Figure 44 and sectioned along the line P-P’ shown in Figure 44.

[1043] Figure 48 is an exploded isometric view of the flow valve shown in Figure 47.

[1044] Figure 49 is an oblique side view of a diaphragm of the flow valve shown in Figure 47.

[1045] Figure 50 is magnified view of a further alternative flow valve as if it were fitted to the patient interface in Figure 44 and sectioned along the line P-P’ shown in Figure 44.

[1046] Figure 51 is an exploded isometric view of the flow valve shown in Figure 50.

[1047] Figure 52 is an exploded isometric view of an alternative flow valve.

[1048] Figure 53 is an oblique view of a cross-section along the line X-X through a retaining structure of the flow valve shown in Figure 52.

[1049] Figure 54 is a magnified side view of a portion marked Y of the cross-section shown in Figure 53.

[1050] Figure 55 is an upstream-side view of an alternative retaining structure for the flow valve shown in Figure 52.

[1051] Figure 56 is an oblique view of a cross-section view the line Z-Z through the retaining structure shown in Figure 55.

[1052] Figure 57 is an oblique view from a proximal side of a further embodiment of a flow valve.

[1053] Figure 58 is a cross-sectional-view of the flow valve in Figure 57 along the lineVI-VI in Figure 57.

[1054] Figure 59 is a cross-sectional-view of the flow valve in Figure 57 along the lineVII-VII in Figure 57.

[1055] Figure 60 is an oblique side view of a flow valve fitted to a patient interface.

[1056] Figure 61 is oblique side view of the patient interface in Figure 60 without the flow valve and without a swivel connector that is shown in Figures 60, 62 and 63.

[1057] Figure 62 is a front view of the patient interface in Figure shown 60 with the flow valve in an occluded position.

[1058] Figure 63 is a front view of the patient interface in Figure shown 60 with the flow valve in an unoccluded position.

[1059] Figure 64 is an oblique rear view of the flow valve shown in Figure 60.

[1060] Figure 65 is a side view of a front cover of flow valve shown in Figure 60.

[1061] Figure 66 is a front and left-side oblique view of a clip-on body for coupling with the patient interface shown in Figure 61.

[1062] Figure 67 is a rear and left-side oblique view of the body shown in Figure 66.

[1063] Figure 68 is a top view of the body shown in Figure 66.

[1064] Figure 69 is a side view of a cross-section along the line Q-Q’ shown in Figure 68.

[1065] Figure 70 is an oblique side view of a frame of the patient interface shown in Figure 37 with an alternative flow valve.

[1066] Figure 71 is a schematic representation of a ventilator system with optional inlet points for a supplementary gas source denoted by dashed arrows.

[1067] Figure 72 is a schematic representation of a ventilator system with a humidifier and with optional inlet points for a supplementary gas source.

[1068] Figure 73 is a schematic representation of mouth-to-nose flushing in a dualchamber patient interface with an inlet for a supplementary gas source into the chamber that includes an oral opening.

[1069] Figure 74 is a schematic representation of mouth-and-nose-to-nose flushing in a dual-chamber patient interface with an inlet for a supplementary gas source into the chamber that includes an oral opening.

[1070] Figure 75 is a schematic representation of nose-to-mouth-and-nose flushing in a dual-chamber patient interface with an inlet for a supplementary gas source into the chamber that includes a nasal opening.

[1071] Figure 76 is a schematic representation of nose-to-mouth flushing in a dualchamber patient interface with an inlet for a supplementary gas source into the chamber that includes a nasal opening.

[1072] Figure 77 is schematic representation of the patient interface shown in Figure 1 with one option of a nasotracheal tube for supplying supplementary respiratory gas.

[1073] Figure 78 is schematic representation of the patient interface shown in Figure 1 with another option of a tube for supplying supplementary respiratory gas.

[1074] Figure 79 is schematic representation of the patient interface shown in Figure 1 with another option of a nasotracheal tube for supplying supplementary respiratory gas.

[1075] Figure 80 is a front view of an alternative cushion module for the patient interface shown in Figures 78.

[1076] Figure 81 is a cross-sectional view along the line KK’ of the seal of the cushion module shown in Figure 80.

[1077] Figure 82 is a cross-sectional view along the line LL’ of the seal of the cushion module shown in Figure 80.

[1078] Figure 83 is an oblique side proximal-side view of a region Q of the dividing wall bound by a dashed line in Figure 82.

[1079] Figure 84 is an oblique side rear-side view of a region Q of the dividing wall bound by a dashed line in Figure 82.

[1080] Figure 85 is a cross-section along the line RR’ region Q of the dividing wall bound by a dashed line in Figure 82.

[1081] Figure 86 is an oblique view of a cross-section along the line LL’ in Figure 80 of an alternative cushion module.

[1082] Figure 87 is a view in the proximal direction of a flow insert that is couplable with the cushion module shown in Figure 85.

[1083] Figure 88 is an underside view of the flow insert in Figure 87.

[1084] Figure 89 is an oblique side view of a cross-section through the flow insert along the line MM’ shown in Figure 87.

[1085] Figure 90 is a cross-sectional view of a variation of the cushion module shown in Figures 24 to 31 at a vertical mid-plane, having regard to an upright orientation of a patient interface.

[1086] Figure 91 cross-sectional view a further embodiment of a patient interface at a vertical mid-plane through the patient interface, having regard to an upright orientation of a patient interface.

[1087] Figure 92 is a front oblique view of another embodiment of a patient interface with an elbow.

[1088] Figure 93 is a front oblique view of a cushion module of the patient interface in Figure 92.

[1089] Figure 94 is a front view of the cushion module in Figure 93.

[1090] Figure 95 is a left side view of the cushion module in Figure 93.

[1091] Figure 96 is a rear view of the cushion module in Figure 93.

[1092] Figure 97 is a front view of a frame of the patient interface shown in Figure 92.

[1093] Figure 98 is a rear oblique view of the frame in Figure 97.

[1094] Figure 99 is an underneath oblique view of the frame in Figures 97 and 98 coupled with the cushion module in Figure 93.

[1095] Figure 100 is an exploded isometric oblique view of the patient interface in Figure 92.

[1096] Figure 101 is a cross-section of the patient interface in Figure 92 along the line W-W in Figure 94 with the flap valve closed.

[1097] Figure 102 is a cross-section of the patient interface in Figure 92 along the line W-W in Figure 94 with the flap valve open.

[1098] Figure 103 is a cross-section of the patient interface in Figure 92 along the line X-X in Figure 94 with the flap valve closed.

[1099] Figure 104 is a front oblique view of the elbow of the patient interface shown in Figure 92.

[1100] Figure 105 is a rear oblique view of the elbow shown in Figure 104 with the flap valve closed.

[1101] Figure 106 is a rear oblique view of the elbow shown in Figure 104 with the flap valve open.

[1102] Figure 107 is a rear view of the elbow shown in Figure 104 without a dividing insert and without a flap valve.

[1103] Figure 108 is a top view of the elbow shown in Figure 104, having regard to an upright orientation of a patient interface.

[1104] Figure 109 is a cross-section of the patient interface in Figure 92, without the frame, along the line Y-Y in Figure 96 with the flap valve open.

[1105] Figure 110 is a top view of the dividing insert shown in Figure 105.

[1106] Figure 111 is a top oblique view of the dividing insert coupled with the flap valve shown in Figure 105.

[1107] Figure 112 is a side view of the flap valve shown in Figure 111 .

[1108] Figure 113 is a front oblique view from above of the flap valve shown in Figure 111.

[1109] Figure 114 is a rear oblique view from below of the flap valve shown in Figure 111.

[1110] Figure 115 is a rear oblique view from above of the flap valve shown in Figure 111.

[1111] Figure 116 is a front view of an alternative elbow fitted with a filter.

[1112] Figure 117 is a front oblique view of the elbow in Figure 116 fitted with the filter.

[1113] Figure 118 is a side view of the elbow in Figure 116 without the filter.

[1114] Figure 119 is a front oblique view of the elbow in Figure 116 without the filter.

[1115] Figure 120 is a rear view of the filter shown in Figure 116.

[1116] Figure 121 is a rear oblique view of the filter shown in Figure 116.

[1117] Figure 122 is a front view of an alternative embodiment of the elbow shown in Figures 97 to 111 .

[1118] Figure 123 is a side view of the elbow shown in Figure 122.

[1119] Figure 124 is a cross-section through the elbow along the line BB-BB in Figure 122 with an anti-asphyxiation valve in an open position.

[1120] Figure 125 is an oblique rear view of the elbow shown in Figure 122 with an anti-asphyxiation valve in a closed position.

[1121] Figure 126 is an oblique rear view of the elbow shown in Figure 122 with an anti-asphyxiation valve in an open position.

[1122] Figure 127 is a magnified rear view of the section denoted B in Figure 125.

[1123] Figure 128 is a top view of the elbow shown in Figure 125.

[1124] Figure 129 is a front of view of another embodiment of a patient interface with an elbow and without an anti-asphyxiation valve fitted to the elbow.

[1125] Figure 130 is a rear view of the patient interface in Figure 129.

[1126] Figure 131 is an exploded oblique view of the patient interface in Figure 129.

[1127] Figure 132 is a cross-section of the patient interface in Figure 129 along the line l-l in Figure 129.

[1128] Figure 133 is a cross-section of the seal only of the patient interface in Figure 129 along the line l-l in Figure 129.

[1129] Figure 134 is a cross-section of the patient interface in Figure 129 along the line l-l in Figure 129 without the elbow.

[1130] Figure 135 is a cross-section of a portion of the patient interface in Figure 134 along the line Ill-Ill in Figure 134.

[1131] Figure 136 is a cross-section of a portion of the patient interface in Figure 134 along the line ll-ll in Figure 134.

[1132] Figure 137 is a front oblique view of an alternative patient interface.

[1133] Figure 138 is a rear view of the patient interface shown in Figure 137.

[1134] Figure 139 is an exploded oblique view of the patient interface in Figure 137.

[1135] Figure 140 is a front oblique view of the retaining clip shown in Figure 139.

[1136] Figure 141 is a rear view of the frame shown in Figure 139.

[1137] Figure 142 is a cross-section along the line CB-CB in Figure 138.

[1138] Figure 143 is a cross-section along the line CC-CC in Figure N.

[1139] Figure 144 is a front oblique view of an alternative patient interface.

[1140] Figure 145 is a rear view of the patient interface shown in Figure 144.

[1141] Figure 146 is an exploded oblique view of the patient interface in Figure 144.

[1142] Figure 147 is a cross-section view of the patient interface in Figure 145 along the line CG-CG.

[1143] Figure 148 is a cross-section view of the patient interface in Figure 145 along the line CH-CH in Figure 145.

[1144] Figure 149 is a side view of the retaining clip in Figure 146.

[1145] Figure 150 is a rear oblique view of the retaining clip in Figure 146.

[1146] Figure 151 is a cross-section view through the elbow of the patient interface in Figure 145 along the line CG-CG.

[1147] Figure 152 is a rear oblique view of the elbow in Figure 146.

[1148] Figure 153 is a top view of the elbow shown in Figure 146.

[1149] Figure 154 is an oblique front view of another embodiment of a patient interface.

[1150] Figure 155 is an oblique top view of the patient interface in Figure 154.

[1151] Figure 156 is a side plan view of a cross-sectional of the patient interface in Figure 155 along the VIII-VIII.

[1152] Figure 157 is an oblique view from below of the cross-section shown in Figure 156.

[1153] Figure 158 is an oblique view from above of a pressure valve of the interface shown in Figure 154 and which pressure valve is shown in the cross-section in Figure 156.

[1154] Figure 159 is a top plan view of the pressure valve shown in Figure 158.

[1155] Figure 160 is a rear plan view of the pressure valve shown in Figure 158.

[1156] Figure 161 is a front elevation of an alternative embodiment of a frame and elbow for the patient interface shown in Figure 154.

[1157] Figure 162 is a right-side elevation of the frame and elbow shown in Figure 161.

[1158] Figure 163 is an oblique top view of the frame and elbow shown in Figure 161.

[1159] Figure 164 is a magnified oblique left-side view of the frame and elbow shown in Figure 161.

[1160] Figure 165 is a side view of a cross-section through the frame and elbow along the line IX-IX in Figure 161.

[1161] Figure 166 is a front oblique view of an alternative patient interface.

[1162] Figure 167 is an exploded isometric oblique view of the patient interface in Figure 166.

[1163] Figure 168 is a front view of the patient interface in Figure 166 without the filter.

[1164] Figure 169 is a rear oblique view of the patient interface in Figure 166 without the seal, elbow and swivel connector.

[1165] Figure 170 is a rear oblique view of the frame body patient interface in Figure 166.

[1166] Figure 171 is a front oblique view of the frame body in Figure 170.

[1167] Figure 172 is a front oblique view of the retaining bracket shown in Figure 169.

[1168] Figure 173 is a front view of the retaining bracket shown in Figure 172.

[1169] Figure 174 is a cross-section through the seal of the patient interface shown in Figure 168 along the line V-V.

[1170] Figure 175 is a cross-section of the patient interface shown in Figure 168 along the line V-V without the flow valve, filter and the conduit connector.

[1171] Figure 176 is a cross-section of the patient interface shown in Figure 168 along the line W-W without the flow valve, filter and the conduit connector.

[1172] Figure 177 is a front view of another embodiment of a patient interface.

[1173] Figure 178 is a rear view of the patient interface shown in Figure 177.

[1174] Figure 179 is a cross-section view along the line CL-CL in Figure 177.

[1175] Figure 180 is an exploded isometric view of the patient interface shown in Figure 177.

[1176] Figure 181 is a rear view of the frame of the patient interface shown in Figure 177.

[1177] Figure 182 is an oblique cross-sectional view of the rear of the frame in Figure 181 with a diaphragm of a flow valve.

[1178] Figure 183 is an oblique cross-sectional view of the rear of the frame in Figure 181 without a diaphragm of a flow valve.

[1179] Figure 184 is a rear view of an alternative embodiment of a flow valve for the patient interface in Figure 177 with coverage of a diaphragm indicated by the region bound by a dashed line denoted as XI.

[1180] Figure 185 is a cross-section of the flow valve in Figure 184 along the line X-X with a diaphragm.

[1181] Figure 186 is a cross-section of the flow valve in Figure 184 along the line XII- XII without a diaphragm.

[1182] Figure 187 is a rear oblique view of a further alternative embodiment of a flow valve for the patient interface in Figure 177 with a diaphragm.

[1183] Figure 188 is a rear oblique view of the flow valve in Figure 187 without the diaphragm.

[1184] Figure 189 is a cross-section of the flow valve in Figure 188 along the line XIII-XIII with the diaphragm.

[1185] Figure 190 is an oblique view of the cross-section of the flow valve in Figure 189 without the diaphragm.

[1186] Figure 191 is a front oblique view of a further embodiment of a patient interface.

[1187] Figure 192 is an exploded front oblique view of the patient interface in Figure 191.

[1188] Figures 193 is a cross-section of the patient interface in Figure 191 along the line XIV-XIV.

[1189] Figure 194 is a front elevation of a seal of the patient interface in Figure 191.

[1190] Figure 195 is a front elevation of a retaining bracket of the patient interface in Figure 191 .

[1191] Figure 196 is a side elevation of a retaining bracket of the patient interface in Figure 191 .

[1192] Figure 197 is a rear elevation of a frame of the patient interface in Figure 191.

[1193] Figure 198 is a rear elevation of the frame in Figure AW coupled with a retaining bracket of the patient interface in Figure 191.

[1194] Figure 199 is a rear elevation of the frame in Figure 197 coupled with an alternative embodiment of a retaining bracket.

[1195] Figures 200 to 202 are schematic cross-sectional views through a patient and a patient interface (comprising a pressure valve, a flow valve and a relief valve) coupled to a dual limb circuit at a conduit connector showing the stages of inhalation, exhalation and end of exhalation / end of respiratory pause respectively with mouth and nose breathing (i.e. both airways open).

[1196] Figures 203 to 205 are schematic cross-sectional views through a patient and a patient interface (comprising a pressure valve, a flow valve and a relief valve) coupled to a dual limb circuit at a conduit connector showing the stages of inhalation, exhalation and end of exhalation / end of respiratory pause respectively with nose only breathing (i.e. mouth blocked).

[1197] Figures 206 to 208 are schematic cross-sectional views through a patient and a patient interface (comprising a pressure valve, a flow valve and a relief valve) coupled to a dual limb circuit at a conduit connector showing the stages of inhalation,exhalation and end of exhalation / end of respiratory pause respectively with mouth only breathing (i.e. nose blocked).

[1198] Figures 209 to 211 are schematic cross-sectional views through a patient and a patient interface (comprising a pressure valve, a single flow director in the dividing wall and a fixed aperture outlet from the upper chamber of the patient interface) coupled to a single limb circuit at a conduit connector showing the stages of inhalation, exhalation and end of exhalation / end of respiratory pause respectively with mouth and nose breathing (i.e. both airways open).

[1199] Figures 212 to 214 are schematic cross-sectional views through a patient and a patient interface (comprising a pressure valve, a single flow director in the dividing wall and a fixed aperture outlet from the upper chamber of the patient interface) coupled to a single limb circuit at a conduit connector showing the stages of inhalation, exhalation and end of exhalation / end of respiratory pause respectively with nose only breathing (i.e. mouth blocked).

[1200] Figures 215 to 217 are schematic cross-sectional views through a patient and a patient interface (comprising a pressure valve, a single flow director in the dividing wall and a fixed aperture outlet from the upper chamber of the patient interface) coupled to a single limb circuit at a conduit connector showing the stages of inhalation, exhalation and end of exhalation / end of respiratory pause respectively with mouth only breathing (i.e. nose blocked).

[1201] Figure 218 is a rear view of the patient interface in Figure 22 with a bracket for a sensor module.

[1202] Figure 219 is a cross-sectional view of the patient interface in Figure 218 along the line AA-AA in Figure 22.

[1203] Figure 220 is an oblique cross-sectional of the patient interface in Figure 218 along the line CC-CC in Figure 25.

[1204] Figure 221 is an oblique rear view of the patient interface in Figure 218.

[1205] Figure 222 is an enlarged cross-sectional view of the patient interface in Figure 218 along the line U-U in Figure 24 and showing a sensor module at one location.

[1206] Figure 223 is a front oblique view of the patient interface in Figure 218 showing a sensor module at another location.

[1207] Figure 224 is a front oblique view of the patient interface in Figure 218 showing a sensor module at another location

[1208] Figure 225 is an enlarged cross-sectional view of the patient interface in Figure 218 along the line Y-Y in Figure 24 and showing a sensor module at another location.

[1209] Figure 226 is a cross-sectional view of an alternative embodiment of the patient interface in Figure 218 along the line U-U in Figure 24 and brackets for a sampling tube.DESCRIPTION OF EMBODIMENTS

[1210] Preferred embodiments of the present invention will now be described in the following text which includes reference numerals that correspond to features illustrated in the accompanying figures. Where possible, related reference numerals have been used to identify the same or substantially the substantially similar features in the different embodiments. To maintain clarity of the figures, however, all reference numerals are not included in each figure.

[1211] The aspects of the patient interface disclosed above will be described in detail below by reference to embodiments of a patient interface in the general form shown in Figures 1 to 9. The embodiments described following this are variations on that general form. However, it will be appreciated that the scope of the aspects should not be limited by reference to that general form or to the specific embodiments described below, and, instead, the aspects should be interpreted as relating as well to other forms of patient interfaces that also deliver pressurised respiratory gas to a patient, including full face patient interfaces that do not contact the bridge of the nose (under the nose oro-nasal masks), total-face masks, helmet interfaces, and where suitable, nasal masks that seal with the patients nasal cavity.

[1212] The term “respiratory gas” or “respiratory gasses” as used throughout this specification is taken to mean a gas used in human respiration or human ventilation. The term “inhaled respiratory gas” as used throughout this specification is taken to mean respiratory gas that is inhaled during the inhalation phase of the breathingcycle. The term includes within its scope ambient air or air that is conditioned for treating a patient, such as having elevated humidity or oxygen levels, or both compared to ambient air. The term “exhaled respiratory gas” as used throughout this specification is taken to mean respiratory gas that is exhaled from the lungs and airways of a patient during the exhalation phase of the breathing cycle. It, therefore, includes respiratory gas from the lungs and gas which occupies the anatomical dead space of the patient at the end of the exhalation phase of the breathing cycle.General Form

[1213] Figures 1 to 9 show one general form of a patient interface 100 which comprises a full-face over the nose mask. The patient interface 1000 comprises a cushion module 1010, a frame 1400 and a conduit connector 1300. The conduit connector 1300 comprises structural components for connecting the cushion module 1010 to a source of pressurised respiratory gas, such as a ventilator, humidifier, flow generator or wall source. In this embodiment, the patient interface 1000 is in the form of a full-face mask where the cushion module 1010 comprises a resilient seal 1100 and a housing 1200. Collectively, the resilient seal 1100 and the housing 1200 form a cushion module 1010 having an internal interior volume 1012 configured to be pressurised.

[1214] The housing 1200 is formed of a substantially rigid plastics material to provide structural support to the seal 1100. Additionally, the housing 1200 provides an interface for connecting the seal 1100 to the frame 1400 and / or the conduit connector 1300.

[1215] In an alternative configuration, the housing 1200 may be formed of an elastomeric material, textile, or foam sufficient to provide the rigidity needed to structurally support the seal 1100. It may also be formed of any of the aforementioned materials and reinforced with a secondary more rigid material to provide the required structural support to the seal 1100.

[1216] In an alternative configuration, the housing 1200 and seal 1100 may be a unitary silicone structure with the housing 1200 being defined by a portion of the silicone structure with increased rigidity and structure, and the seal 1100 being defined by a portion of the silicone structure with a decreased rigidity.

[1217] The housing 1200 includes a sleeve 1230 that is sized and shaped to connect with a frame 1400, the connection between the housing 1200 and frame 1400 is detailed further below. The sleeve 1230 defines an inlet 1220 through which respiratory gas can be communicated from the conduit connector 1300 to the interior volume 1012 of the cushion module 1010.

[1218] Respiratory gas may be communicated from the conduit connector 1300 to the interior volume 1012 of the cushion module 1010 via either: an inspiratory conduit of a single-limb NIV circuit which is configured to deliver fresh pressurised respiratory gas from a gas source to the conduit connector 1300, or via a y-piece of a of a dual-limb NIV circuit which is configured to deliver fresh pressurised respiratory gas from a gas source along an inspiratory conduit to the conduit connector 1300 and to return at least some of the excess or exhaled respiratory gas from within the cushion module 1010 out through the conduit connector 1300 and along a expiratory conduit to the gas source.

[1219] It is envisioned that while connecting a y-piece of a dual-limb circuit to the conduit connector 1300, the patient interfaces 1000, 2000, 4000 disclosed herein would maintain outlets 1210, 2210, 4210 on the respective housings 1200, 2200, 4200 through which at least some of the exhaled and excess respiratory gasses from within the cushion module 1010, 2010, 4010 would be exhausted to external of the cushion module. The outlets 1210, 2210, 4210 in such a configuration may exhaust exhaled and excess respiratory gasses from within the cushion module to atmosphere, into the expiratory limb of the dual-limb NIV circuit, and / or back to the flow source either directly or indirectly.

[1220] The y-piece is connected to an inspiratory limb and an expiratory limb of a dual limb ventilation system. The outlet 1210, 2210, 4210 of patient interface 1000, 2000, 4000 is configured to exhaust gasses from within cushion module 1010, 2010, 4010 to atmosphere, into the expiratory limb at a location distal of the y-piece, or back to the flow source either directly or indirectly.

[1221] The sleeve includes key formations 1232 that interact with the frame 1400 to ensure correct alignment of the frame 1400 with the housing 1200 when they are connected. It will be appreciated that these key formations 1232 may be substitutedwith any other suitable structure to ensure correct alignment of the frame 1400 with the housing 1200 or may be omitted entirely.

[1222] The housing 1200 includes a series of tabs 1240 which project outwardly around its perimeter. The outer ends of the tabs 1240 are linked to a bead 1245 which runs continuously across all the tabs 1240, thereby forming a series of discrete over-mould windows 1250 between the tabs 1240 and the bead 1245. The seal 1100 is integrally formed with the housing 1200 by over-moulding a resilient material onto the housing 1200 to fill the series of windows 1250. Therefore, the tabs 1240 and the bead 1245 become embedded in the resilient material and are mechanically interlocked with the seal 1100. The seal 1100 and the housing 1200, therefore, form a unitary cushion module 1010 structure. The tabs, bead and overmould windows are shown in an alternative embodiment of a housing 4200 in Figure 24 as tabs 4240, bead 4245 and over-mould windows 4250. While the perimeter shape of the housing 4200 is different to the perimeter shape of the housing 1200, the over-moulding of the seal 1100 through the over-mould windows is the same for both cushion modules 1010 and 4010.

[1223] The housing 1200 includes an outlet 1210 through which exhaled and excess respiratory gasses can be exhausted from the cushion module 1010 and / or the patient’s airways to external of the cushion module 1010. In the general form the outlet 1210 comprises a bias vent 1215 comprising a plurality of apertures extending through the thickness of the housing 1200. Exhaled and excess respiratory gasses can therefore be exhausted from within the cushion module 1010 through bias vent 1215 to external of the cushion module, or to atmosphere.

[1224] In alternative configurations, the outlet 1210 and bias vent 1215 may be distinct structures located at positions spaced apart from each other. In further alternative configurations the patient interface may also include a supplementary bias vent 1216.

[1225] In a further alternative configuration, the outlet 1210 of cushion module 1010 may be in the form of an outlet configured to connect to, or be in fluid communication with, an expiratory conduit of a respiratory circuit. Such an expiratory conduit may be used in dual-limb NIV therapy. In this configuration exhaled and excess respiratory gasses can be exhausted from within the cushion module 1010 and / or from thepatient’s airways and be transported distally from the patient interface 1000 where they may be filtered, or received by the ventilator, flow generator, or other gas source which supplied the fresh respiratory gas to the cushion module 1010. In such a configuration the outlet 1210 is, or is in fluid communication with, an expiratory conduit connector configured for connection with an expiratory conduit. In this configuration a dual-limb circuit y-piece connection with the conduit connector 1300 is not necessary as the inspiratory conduit 30 connects to the conduit connector 1300 and the expiratory conduit 40 connects to the outlet 1210.

[1226] The seal 1100 is formed of soft, resilient material, such as a silicone or other suitable elastomer, and includes a seal opening 1110. When fitted to a patient, the seal opening 1110 circumscribes the patient’s mouth and nose and a patient contacting surface 1120 of the seal 1100 forms a seal about the mouth and nose of the patient. Accordingly, respiratory gas at elevated pressure can be delivered from the interior volume 1012 of the cushion module 1010 to the patient’s mouth and / or nares via the seal opening 1110.

[1227] Although this embodiment of the cushion module 1010 includes a single seal opening 1110, it will be appreciated that other configurations may include an oral opening for delivering pressurised respiratory gas to the patient’s mouth and a nasal opening for delivering pressurised respiratory gas to the patient’s nose. Such an embodiment is shown in Figures 10 to 21 and is described in more detail below. In other embodiments, the cushion module 1010 may include more than one oral opening, more than one nasal opening or multiple oral openings and multiple nasal openings.

[1228] The conduit connector 1300 of patient interface 1000 comprises a hollow connector body 1320 defining a lumen having a ball connector 1322 at a first end 1324, a swivel connector 1350 at a second end 1326 and an anti-asphyxiation valve (AA valve) 1330 located between the first and second ends. The connector body 1320, swivel connector 1350, and ball connector 1322 form a flow path for respiratory gas into the cushion module 1010 from a conduit of a respiratory circuit.

[1229] The ball connector 1322 includes a convex spherical segment that is configured to be received in a corresponding concave spherical segment of a ball socket 1402 of the frame 1400 to form a ball-and-socket joint which allows threedegrees of rotational movement between the frame 1400 and conduit connector 1300. The swivel connector 1350 is configured to be connected to a conduit of a source of respiratory gas to supply pressurised respiratory gas to the cushion module 1010. The swivel connector 1350 can rotate with a single degree of freedom, otherwise known as swiveling. Together, the swivel connector 1350 and ball connector 1322 serve to decouple forces applied by the conduit from the patient interface 1000.

[1230] The connector body 1320 comprises a bend between the first end 1324 and second end 1326 such that gas flow through the conduit connector 1300 undergoes a change in direction from the first end 1324 to the second end 1326. Said another way, the longitudinal axes of the first end 1324 and the second end 1326 of the connector body 1320 are set at an oblique angle.

[1231] It will be appreciated by those skilled in the art that the connector body 1320 may in alternative configurations be provided without a bend between the first end 1324 and second end 1326 such that the flow path through the connector body 1320 is substantially straight or linear.

[1232] In an alternative configuration the conduit connector 1300 may comprise a ball connector 1322 at each end of the connector body (replacing the swivel connector 1350), a swivel connector 1350 at each end of the connector body (replacing the ball connector 1322), a single swivel connector 1350 or single ball connector at one of the first end 1324 or second end 1326 of the connector body 1320, or omit the ball connector 1322 and swivel connector 1350 entirely to form a fixed connector body 1320 between the cushion module 1010 and conduit.

[1233] The second end 1326 of the conduit connector 1300 further includes a structure configured to co-operate with an anti-asphyxiation valve 1330 to permit ambient air into the patient interface if the source of respiratory gas fails or the conduit for conveying the gas from the gas source to the patient interface 1010 becomes obstructed. More specifically, the second end 1326 includes an opening 1327. A spine 1328 is disposed adjacent the opening 1327 and supports a panel 1329 that is spaced from the opening 1327. The spacing of the panel from the opening 1327 creates a gap through which ambient air can access the opening 1327.

[1234] The anti-asphyxiation valve 1330 includes a valve seat 1331 and a valve seal 1336. The valve seat 1331 includes a sealing surface 1332 against which the valve seal 1336 seals the anti-asphyxiation valve 1330. The valve seat 1331 further includes a sleeve 1333 with a radially outwardly projecting bead 1334. The bead1334 is at the end of the sleeve 1333. The valve seat 1331 further includes a spigot1335 for coupling with the valve seal 1336.

[1235] The valve seal 1336 includes a flap 1337 which can transition between an open position in which the conduit connector 1300 is open to flow of respiratory gas from a gas source and a closed position in which the conduit connector 1300 is closed to flow of respiratory gas from a gas source. In the open position, access of ambient air to the inside of the conduit connector 1300 is inhibited and in the closed position, access of ambient air to the inside of the conduit connector 1300 is permitted. In the illustrated embodiment, the flap 1337 is formed of a flexible material. The flap 1337 is joined to a lug 1338 by a hinge 1339. The hinge 1338 comprises a section of flexible material with a reduced wall thickness. The lug 1338 is configured to assist with locating the valve seal 1336 within the end of the second end 1326 of connector body 1320. Additionally, the lug 1338 includes a recess 1340 which is adapted to receive the spigot 1335. Mating of the spigot 1335 within the recess 1340 correctly orients the valve seal 1336 on the valve seat 1331 .

[1236] When pressurised respiratory gas is supplied from a source, it flows through the conduit connector 1300 and into the cushion module 1010. The elevated pressure of the respiratory gas causes the flap 1337 to swing about the hinge 1339 to cover the opening 1327 in the second end 1326 of the connector body 1320. This represents the “open position” described above in that the flap 1337 prevents ambient air from entering the conduit connector 1300 via the opening 1327. In the event that the source of respiratory gas fails or the conduit connecting to the source becomes obstructed, the anti-asphyxiation valve 1330 closes because the air pressure in the conduit connector 1300 equalizes with the air pressure outside the conduit connector 1300 so that the flap 1337 transitions to the “closed position” described above owing to the inherent resilience in the flexible material which forms the hinge 1339. In the closed position, the opening 1327 is revealed to the interior of the conduit connector 1300 so that the natural breathing cycle of the patient will drawair into the conduit connector 1300 and the cushion module 1010 via the opening 1327.

[1237] The valve seat 1331 includes a radially projecting step which is configured to couple with the conduit connector 1300. In particular, the step is configured to fit within the second end 1326 of the connector body 1320. The coupling may comprise a snap-fit connection or may comprise a permanent fixing, such as welding or fixing with adhesive.

[1238] The valve seat 1331 couples with the swivel connector 1350 which is configured to connect with a conduit from a respiratory gas source. The swivel connector 1350 includes a radially inwardly projecting shoulder 1352 which is cooperable with the step of the valve seat 1331 to connect the valve seat 1331 to the swivel connector 1350. The connection is a snap-fit connection. The snap-fit connection may be removable or may be a one-time connection. In other configurations, however, the connection may comprise a permanent fixing, such as welding or fixing with adhesive.

[1239] The frame 1400 includes a central body portion 1401 that includes one or more channels for conveying respiratory gas from a gas source via the conduit connector 1300 to the cushion module 1010 and therefore to the patient. The frame 1400 includes one or more upper headgear connectors 1410 and one or more lower headgear connectors 1420 which are configured to co-operate with a headgear 1900 (such as resilient straps) for fitting the patient interface 1000 to the patient. The one or more upper headgear connectors 1410 are configured to co-operate with respective one or more upper straps of a headgear 1900 while the one or more lower headgear connectors are configured to co-operate with respective one or more lower straps of a headgear 1900. The headgear 1900 operates by pulling the patient interface 1000 into contact with the patients face to form a substantially air-tight seal between the seal 1100 and the patient’s face when respiratory gas at elevated gas pressure is delivered to the patient via the patient interface 1000.

[1240] In the illustrated embodiment the one or more upper headgear connectors 1410 comprise a first upper headgear connector slot 1412 on a first lateral side of the notional midplane of the frame 1400 and a second upper headgear connector slot 1414 on a second lateral side of the notional midplane of the frame 1400. Eachslot being configured to receive a respective upper strap of a headgear 1900. The strap may be received within the slot either permanently or removably such as by being inserted through the slot, looped back on itself, and fixed in place with a hook and loop connection. In alternative configurations the slot may be replaced by any suitable structure for permanently or removably co-operating with an upper headgear strap. Suitable connection structures may include connectors to releasably receive clips of a respective strap either through a mechanical, magnetic or adhesive connection. Suitable headgear may comprise four straps 1902, 1904 with two upper headgear straps 1902 couplable by looping about respective upper headgear connectors 1410 and with two lower headgear straps 1904 couplable by clips 1906 to respective lower headgear connectors. Clips 1906 may be utilized to couple the upper headgear straps 1902 to the upper headgear connectors 1410 in other embodiments, including in embodiments of the full-face, under-nose patient interfaces as shown in Figure 22 and described below, for example.

[1241] In the illustrated embodiment the one or more lower headgear connectors 1420 comprise a first lower headgear connector 1422 on the first lateral side of the notional midplane of the frame 1400 and a second lower headgear connector on the second lateral side of the notional midplane of the frame 1400. Each headgear connector being configured to receive a respective lower strap of a headgear. Each lower headgear connector comprises a bar configured to removably receive a clip of the respective lower headgear strap via a mechanical connection such as a hook and post connection. In an alternative configuration the connector may be replaced by any suitable structure for permanently or removably co-operating with a lower headgear strap and / or a clip of a lower headgear strap such as the connection methods described above in relation to the upper straps and one or more upper headgear connectors 1410. Specifically, suitable connection structures may include one or more lower headgear connectors 1420 on the frame 1400 to releasably receive clips of a respective lower strap either through a mechanical, magnetic or adhesive connection

[1242] The frame 1400 further includes a connector sleeve 1430 that includes one or more arcuate fingers 1432. In the illustrated embodiment the connector sleeve 1430 includes four arcuate fingers 1432. The connector sleeve 1430 has an inner wall 1434 which comprises the ball socket 1402 which is configured to receive the ballconnector 1322 of the conduit connector 1300. The outer wall 1346 of the connector sleeve 1430 is shaped to fit within the sleeve 1230 of the housing 1200. The arcuate fingers 1432 are spaced by notches which are shaped to fit with the key formations 1232. The location of the key formations 1232 and the notches ensures that the frame aligns correctly with the housing 1200 when they are fitted together.

[1243] It will be appreciated that as mentioned above, the connector sleeve 1430 of the frame 1400 may receive the conduit connector 1300 in fixed manner without the need for a ball socket 1402. In such a configuration the conduit connector 1300 would connect permanently, either directly or indirectly, or be integrally formed with the connector sleeve 1430.

[1244] Each arcuate finger 1432 has an end with an arcuate flange portion 1433 which forms a snap-fit with a radially inwardly projecting lip 1231 of the sleeve 1230. The snap-fit holds the frame 1400 to the housing 1200. The snap-fit may be releasable or may be a permanent fit between the frame 1400 and the housing 1200.

[1245] Alternatively, the arcuate fingers 1432 of the frame 1400 and / or the radially inwardly projecting lip 1231 of the housing may be omitted and instead the frame 1400 may be connected to the housing 1200 by any conventional means, such as with adhesives or welding. For example, the frame 1400 may be permanently connected to the housing 1200 by ultrasonically welding the housing 1200 and the frame 1400 together.

[1246] Having regard to the comments above regarding variations on the general form of the patient interface 1000, one such variation of the general form, and which is applicable to the aspects and embodiments described below, is where the housing 1200 and the frame 1400 are formed integrally. In other words, the patient interface 1000 may include a unitary structure that performs the same function of the housing 1200 and frame 1400. For example, the headgear connection points may be integrated with or connected to the housing 1200. If so, the frame 1400 is not necessary and could be omitted while the housing 1200 integrates these features. While the housing 1200 and the frame 1400 are described as being separate components of the patient interface 1000, the description should be read as including the option of an integrally formed component that functions in the same way as both the housing 1200 and frame 1400.

[1247] Having further regard to variations on the general form of the patient interface 1000, another variation of the general form, and which is applicable to the aspects and embodiments described below, is where the housing 1200 and the seal 1100 are formed integrally of the same material. In other words, the patient interface 1000 may include a unitary structure of a single material that performs the same function as both housing 1200 and seal 1100. While the housing 1200 and the seal 1100 are described as being separate components of the patient interface 1000, the description should be read as including the option of an integrally formed component that functions in the same way as the housing 1200 and the seal 1100 combined. In such a configuration the housing 1200 could be formed of the same material as the seal 1100, for example an elastomer material such as silicone. It is contemplated that in a variation where additional rigidity is required in the unitary elastomer housing 1200 and seal 1100, the thickness and / or hardness of the elastomer material may be varied in localized regions to provide such rigidity. The varying hardness may be achieved by any suitable known manufacturing technique such as two shot injection moulding, or over-moulding. Furthermore, the housing 1200 and seal 1100 may be formed integrally by a silicone material and a further rigid component, such as a rigid connection ring, may be used to connect the frame 1400 to the integrally formed housing 1200 and seal 1100.

[1248] Figures 10 to 21 show an embodiment of a patient interface 2000. In those figures, the patient interface 2000 is a variation of the patient interface 1000 of the general form and incorporates all components and functions of the patient interface 1000 unless stated otherwise. More specifically the patient interface 2000 incorporates at least the frame 1400, headgear 1900, and conduit connector 1300 of the patient interface 1000. The housing 2200 and seal 2100, and as a result the cushion module 2010, of patient interface 2000 differs from the housing 1200, seal 1100, and cushion module 1010 of patient interface 1000 due to inclusion of a dividing wall 2700 within the interior volume 1012 of the cushion module 1010. The differences in housing 2200, seal 2100, and cushion module 2010, will be described below, otherwise it should be appreciated that housing 2200, seal 2100, and cushion module 2010, includes all features and functions of housing 1200, seal 1100, and cushion module 1010, respectively.

[1249] In the illustrated embodiment, the patient interface 2000 is in the form of an over the nose full-face mask where the cushion module 2010 comprises a seal 2100 and a housing 2200. Seal 2100 is connected to housing 2200 and collectively the seal 2100 and housing 2200 form a cushion module 2010 having an outer wall 4011 which defines an interior volume 2012. The interior volume 2012 of cushion module 2010 is configured to be pressurised via an inlet 2220 through which respiratory gas can be communicated from the conduit connector 1300 into the interior volume 2012.

[1250] Patient interface 2000 further comprises a dividing wall 2700 that separates the interior volume 2012 of cushion module 2010 into a first chamber 2014 and a second chamber 2016. The dividing wall 2700 joins to both housing 2200 and seal 2100 to separate the first chamber 2014 from the second chamber 2016.

[1251] Seal 2100 is formed of a soft, resilient material, such as a silicone or other suitable elastomer, and includes a seal opening 2110. When fitted to a patient, the seal opening 2110 is configured to circumscribe the patient’s mouth and nose and a patient contacting surface 2120 of the seal 2100 forms a seal about the mouth and nose of the patient. Accordingly, respiratory gas at elevated pressure can be delivered from the cushion module 2010 to the patient’s mouth and / or nares via the seal opening 2110.

[1252] As mentioned, the dividing wall 2700 is a physical barrier that extends across and separates the interior volume 2012 into a separate first chamber 2014 and second chamber 2016. To enable this separation, the dividing wall 2700 joins with both housing 2200 and seal 2100 along a portion of the perimeter of the dividing wall 2700. In the illustrated embodiment another portion of the perimeter of the dividing wall 2700 bifurcates the seal opening 2110 such that an oral opening 2114 and a nasal opening 2116 is formed.

[1253] In an alternative embodiment comprising an under the nose seal having a separate oral opening and one or more nasal openings, the dividing wall 2700 joins with the seal at a region of the seal located between the oral opening and the one or more nasal openings.

[1254] The oral opening 2114 is configured in use to circumscribe the patient’s mouth and, a portion of the patient contacting surface 2120 of the seal 2100 and aportion of the perimeter of the dividing wall 2700 together form a seal about the mouth of the patient.

[1255] The nasal opening 2116 is configured in use to circumscribe the patient’s nose and a portion of the patient contacting surface 2120 of the seal 2100 and a portion of the perimeter of the dividing wall 2700 together form a seal about the nose of the patient.

[1256] Alternatively, the seal 2100 may comprise a section of the patient contacting surface 2120 which extends between the oral opening 2114 and the nasal opening 2116 and which seals with the patient’s upper lip in use. The dividing wall 2700 may join with this region of the seal 2100 such that the dividing wall 2700 does not directly form a seal with, or contact, the patient.

[1257] Accordingly, respiratory gas at elevated pressures can be delivered from the cushion module 2010 to the patient’s mouth via the oral opening 2114, and from the cushion module 2010 to the patient’s nose via the nasal opening 2116.

[1258] The housing 2200 comprises an inlet 2220 through which pressurized respiratory gas can be communicated from the conduit connector 1300 to the interior volume 2012 of the cushion module 2010. It will be appreciated that in alternative configurations the conduit connector 1300 may be omitted and instead pressurized respiratory gas can be communicated from a flow source directly to the inlet 2220 of housing 2200. It is also contemplated that the inlet 2220 may instead be located on the seal 2100 and therefore pressurised respiratory gas may be communicated to the interior volume 2012 of the cushion module 2010 through an inlet 2220 in the seal 2100.

[1259] The housing 2200 comprises an outlet 2210 through which exhaled and excess respiratory gasses can be exhausted from the cushion module 2010 and / or the patient’s airways. In the illustrated embodiment the outlet 2210 is a bias vent 2215 comprising a plurality of apertures extending through the thickness of the housing 2200.

[1260] In alternative configurations, the outlet 2210 and bias vent 2215 may be distinct structures located at positions spaced apart from each other. In further configurations the patient interface may also include a supplementary bias vent 1416in fluid communication with the first chamber 2014 while the outlet 2210 is in fluid communication with the second chamber 2016.

[1261] In a further alternative configuration, the outlet 2210 of cushion module 2010 may be in the form of an opening configured to connect to, or be in fluid communication with, an expiratory conduit of a respiratory circuit. In this configuration exhaled and excess respiratory gasses can be exhausted from the cushion module 2010 and / or from the patient’s airways and transported distally from the patient interface 2000 where they may either be vented to atmosphere or received by the ventilator, flow generator, or other gas source.

[1262] In the illustrated embodiment the perimeter of the dividing wall 2700 joins with the housing 2200 at a position between the inlet 2220 and outlet 2210 such that the inlet 2220 is located in the first chamber 2014, and the outlet 2210 is located in the second chamber 2016.

[1263] In an alternative embodiment, the housing 2200 may comprise a single aperture which is bifurcated by the dividing wall thereby forming the inlet 2220 and outlet 2210.

[1264] As a result of the perimeter of the dividing wall 2700 joining with the housing 2200 and seal 2100, and bifurcating the seal opening 2410, at the positions described above, the inlet 2220 and oral opening 2114 are located in the first chamber 2014, and the outlet 2210 and nasal opening 2116 are located in the second chamber 2016.

[1265] In the illustrated embodiment the housing 2200 and seal 2100 are described as separate components that are permanently connected to form cushion module 2010. However, it will be appreciated that housing 2200 and seal 2100 could instead be a single component which incorporates the features and functions of housing 2200 and seal 2100. It is to be appreciated that disclosure relating to the cushion module 2010 comprising a distinct housing 2200 and seal 2100 is equally applicable to a configuration comprising a combined housing 2200 and seal 2100, or a configuration comprising a singular component incorporating the features and functions of housing 2200 and seal 2100.

[1266] Dividing wall 2700 further comprises one or more flow directors 2730 located on the dividing wall 2700. In the illustrated embodiment the one or more flow directors 2730 extend from the dividing wall 2700 into the second chamber 2016. The one or more flow directors 2730 each comprise a flow path extending through the one or more flow directors 2730 and the dividing wall 2700. This flow path allows gas to flow from the first chamber 2014 through the one or more flow directors 2730, and into the second chamber 2016. In the illustrated embodiment, the flow path extending through the one or more flow directors 2730 and dividing wall 2700 is the only flow path through the dividing wall 2700.

[1267] In the illustrated embodiment, the one or more flow directors 2730 comprises a first flow director 2732 and a second flow director 2736. The first flow director 2732 comprising a first flow director inlet 2733 through dividing wall 2700, and extending from the dividing wall 2700 to a free end of first flow director 2734 located within the second chamber 2016, the free end of first flow director 2734 comprising a first flow director outlet 2735. The second flow director 2736 comprising a second flow director inlet 2737 through the dividing wall 2700, and extending from the dividing wall 2700 to a free end of second flow director 2738 located within the second chamber 2016, the free end of second flow director 2738 comprising a second flow director outlet 2739.

[1268] In alternative configuration, the one or more flow directors 2730 may only comprise first flow director 2732 comprising a first flow director inlet 2733 through dividing wall 2700, and extending from the dividing wall 2700 to a free end of first flow director 2734 located within the second chamber 2016, the free end of first flow director 2734 comprising a first flow director outlet 2735.

[1269] In the illustrated embodiment, the dividing wall 2700 comprises a spacing element 2731 extending between first flow director 2732 and second flow director 2736 and configured to maintain a spacing between the flow directors in use. In the illustrated embodiment the spacing element 2731 is in the form of a rib extending between, and connected to, the first flow director 2732 and the second flow director 2736. It will be appreciated that in alternative embodiments the dividing wall 2700 may provide sufficient rigidity around the location of the first flow director 2732 andsecond flow director 2736 such that the spacing element 2731 could be omitted and / or its function achieved by the dividing wall 2700.

[1270] In alternative configurations, the first flow director 2732 and / or second flow director 2736 may not extend from the dividing wall 2700 and may instead be formed within the dividing wall 2700. It is envisioned that in such an configuration the first flow director inlet 2733 and / or second flow director inlet 2737 could be located on a surface of the dividing wall 2700 within the first chamber 2014, and the first flow director outlet 2735 and / or second flow director outlet 2739 could be located on a surface of the dividing wall 2700 within the second chamber 2016 with the first flow director 2732 and / or second flow director 2736 each comprising a flow path through the dividing wall 2700. In such a configuration there may be only a first flow director 2732, or a first flow director 2732 and a second flow director 2736, or more than two flow directors.

[1271] In the illustrated embodiment, dividing wall 2700 comprises a deformation region 2720 located at a position on the dividing wall 2700 between the one or more flow directors 2730 and the portion of the perimeter of the dividing wall 2700 that joins the housing 2200 in the proximal-distal direction. The deformation region 2720 is a localized region of reduced thickness of the dividing wall 2700 that is configured to preferentially deform in response to forces applied to the dividing wall 2700 while the patient interface 2000 is in use. This preferential deformation is configured to absorb some, or all, of the unintended forces applied to the dividing wall 2700 in use to minimize deformation or collapse of the one or more flow directors 2730.

[1272] The deformation region 2720 comprises a first thickened region 2724 and a second thickened region 2726 joined by a thin region 2721. The thin region 2721 having a thickness that is less than both the first thickened region 2724 and the second thickened region 2726. The deformation region 2720 is configured to deform by the first thickened region 2724 moving towards the second thickened region 2726 and preferentially deforming the thin region 2721 in the process.

[1273] In the illustrated embodiment, the thin region 2721 comprises a first thin wall 2722 and a second thin wall 2723. The first thin wall 2722 extends from the first thickened region 2724, the second thin wall 2723 extends from the second thickened region 2726, and the first thin wall 2722 and second thin wall 2723 join one anotherto form an angle less than 180 degrees between them. During deformation of the deformation region 2720, when the first thickened region 2724 moves towards the second thickened region 2726, the angle formed between the first thin wall 2722 and second thin wall 2723 is reduced.

[1274] It will be appreciated that the purpose of the deformation region 2720 is to allow preferential deformation to occur at a predetermined location on the dividing wall 2700 in order to absorb undesired forces applied to the dividing wall 2700 and to minimize undesired deformation or collapse of the one or more flow directors 2730. In this way it is envisioned that any suitable structure which enables preferential deformation to occur at a predetermined location on the dividing wall 2700 may be incorporated into patient interface 2000 such as bellows, folds, pleats, corrugations, concertinas, or contractable joints located in the dividing wall 2700, preferably at a position on the dividing wall 2700 between the one or more flow directors 2730 and the portion of the perimeter of the dividing wall 2700 that joins housing 2200.

[1275] The dividing wall 2700 may comprise a single material such as an elastomer or a plastic, or multiple materials such as an elastomer and a plastic. In the illustrated embodiment the dividing wall comprises a rigid portion 2710 comprising a plastic material and an elastomeric portion 2712 comprising an elastomeric material. The rigid portion 2710 comprises the portion of the dividing wall 2700 which joins with the housing 2200, and the elastomeric portion 2712 comprises the portion of the dividing wall 2700 which joins the seal 2100. Additionally, or alternatively, the elastomeric portion 2712 comprises the deformation region 2720 and one or more flow directors 2730. Said another way, the deformation region 2720 and one or more flow directors 2730 comprise an elastomeric material.

[1276] In the illustrated embodiment the rigid portion 2710 comprises a polycarbonate material, and the elastomeric portion 2712 comprises a silicone material. It is envisioned that in alternative configurations any other suitable plastic and / or elastomeric materials may be used, however. Furthermore, in the illustrated embodiment the rigid portion 2710 and elastomeric portion 2712 are permanently connected (optionally by over-moulding), however it is envisioned that in alternative configurations these could be removably connected by any suitable connection means.

[1277] Alternatively, the entire dividing wall may be formed of the same silicone material as the seal 2100 and formed integrally with the seal 2100 during the overmoulding of the seal 2100 to the housing 2200. Alternatively, the entire dividing wall may be formed of the same plastics material as the housing 2200. In this alternative embodiment, the housing 2200 is joined with the seal 2100 when moulding the seal 2100 to the housing 2200.

[1278] The flow director outlet 2740 has a cross-sectional flow area comprising the first flow director outlet 2735 and where applicable the second flow director outlet 2739. In the illustrated embodiment, this cross-sectional flow area of the flow director outlet 2740 is configured to be less than the cross-sectional flow area of the inlet 2220 of housing 2200. In the illustrated embodiment, all gas entering the cushion module 2010 enters through the inlet 2220, and excluding unintentional leaks, substantially all gas exiting the cushion module 2010 exits through the outlet 2210. The inlet 2220 is located in the first chamber 2014, the outlet 2210 is located in the second chamber 2016, and the only flow path through the dividing wall 2700 separating the chambers is through the one or more flow directors 2730. As such, the reduced cross-sectional flow area of the flow director outlet 2740 compared with the inlet 2220 of housing 2200 creates a flow restriction which accelerates gas flow through the one or more flow directors 2730 when pressurised gas flows into the first chamber 2014 of the cushion module 2010 via the inlet 2220, through the one or more flow directors 2730, and the into second chamber 2016 to exit the cushion module 2010 through outlet 2210. The reduced cross-section in the flow path creates a resistance which accelerates gas flow entering second chamber 2016. The significance of this acceleration of gas flow is explained in the following paragraphs. This restriction additionally creates a pressure differential between the first chamber 2014 and the second chamber 2016, the significance of which is also explained in the following paragraphs. In some embodiments, creating the pressure differential may be prioritized more than any gas acceleration and so the one or more flow directors may be designed to create a certain restriction without specific focus on acceleration.

[1279] In the illustrated embodiment the flow restriction mentioned in the above paragraph is created by the flow director outlet 2740 having a cross-sectional flow area that is less than the cross-sectional flow area of the inlet 2220 of the housing2200. However, it is contemplated by the inventors that this flow restriction could be placed elsewhere in the one or more flow directors 2730. Additionally the flow restriction could be achieved by other suitable means and / or the flow director outlet 2740 may have a cross-sectional flow area that is equivalent to or larger than the cross-sectional are of the inlet 2220.

[1280] In the illustrated embodiment of patient interface 2000 the ratio of the cross- sectional flow area of the first flow director outlet 2735 to the second flow director outlet 2739 is 1 :1, meaning the cross-sectional flow area of both flow director outlets is equal. However, in alternative configurations the cross-sectional flow area of the first flow director outlet 2735 may be unequal to the cross-sectional flow area of the second flow director outlet 2739. The ratio of the cross-sectional flow area of the first flow director outlet 2735 to the cross-sectional flow area of the second flow director outlet 2739 can range from 1 :1 .1 to 1 :4. In one configuration the ratio of the cross- sectional flow area of the first flow director outlet 2735 to the cross-sectional flow area of the second flow director outlet 2739 is 1 :3, and in another configuration it is 1 :4.

[1281] In the illustrated embodiment, the first flow director 2732 and / or the second flow director 2736, comprises a tapering cross-sectional flow area from the first flow director inlet 2733 to the first flow director outlet 2735, and from the second flow director inlet 2737 to the second flow director outlet 2739, respectively. This tapering cross-sectional flow area may improve acceleration of gas flow through the first flow director 2732 and / or second flow director 2736.

[1282] In addition to, or instead of, the differing flow director outlet cross-sectional flow areas, the first flow director 2732 and the second flow director 2736 may differ in shape and / or size in at least one aspect such as the flow director diameter, length, wall thickness, or shape. Such a configuration where the first flow director 2732 and second flow director 2736 have differing shapes and / or sizes may be described as having asymmetrical first and second flow directors 2732, 2736.

[1283] Referring to Figures 20 and 21 for illustrative purposes, the patient interface 2000 is shown in cross-section along line H-H’ fitted to an anatomical model of a patient (also shown in cross-section). In Figure 20 the patient interface 2000 is illustrated fitted to a patient with their mouth open. In Figure 21 the patient interface2000 is illustrated fitted to a patient with their mouth closed. Arrows indicate the direction of gas flow into the cushion module 2010 via inlet 2220, and out of the cushion module 2010 via outlet 2210, while fitted to a patient without respiration occurring, for example at the end of exhalation but before inhalation. It will be appreciated that during respiration there will be additional gas flow paths formed beyond which are described. However, for the purpose of explanation it is believed the general operation of patient interface 2000 can be adequately described while ignoring respiration. In fact, it is believed by the inventors that an improved function of the patient interface 2000 occurs at the end of the exhalation cycle, which can be realistically likened to a situation in which no respiration is occurring.

[1284] In configurations comprising a first flow director outlet 2735 and a second flow director outlet 2739, the first flow director outlet 2735 is configured to be positioned at a position that is below the first one of a patient’s nares and adjacent a lip superior of the patient, or to be positioned at a position that is immediately adjacent the first one of the patients nares, while the second flow director outlet 2739 is configured to be positioned at a position that is below the second one of a patient’s nares and adjacent a lip superior of the patient, or to be positioned at a position that is immediately adjacent the second one of the patients nares. In other embodiments, the first flow director outlet 2735 and the second flow director outlet 2739 may be positioned so that respiratory gas isn’t directed or is only partially directed toward the patient’s nares in use.

[1285] Referring to Figure 20, where the patient interface 2000 is fitted to a patient with the patients mouth open, without respiration occurring, and where pressurised gas is being delivered to the patient interface 2000 via conduit connector 1300. The flow of pressurised gas enters the first chamber 2014 of cushion module 2010 via inlet 2220. Pressurised gas within the first chamber 2014 then flows: (1) through the one or more flow directors 2730 and into the second chamber 2016, or (2) into the patient’s oral cavity via their mouth, through the patient’s throat, into the patient’s nasal cavity, out of the patient’s nares and into the second chamber 2016. Excess pressurised gas and / or gas from within the anatomical deadspace of the patient’s airways then flows out of second chamber 2016 through outlet 2210 of cushion module 2010 to exit the cushion module 2010. The dividing wall 2700, first chamber 2014, second chamber 2016, and one or more flow directors 2730 which allow flowbetween the first chamber 2014 and second chamber 2016, therefore create the first and second flow paths from inlet 2220 of cushion module 2010 to outlet 2210 of cushion module 2010 mentioned above.

[1286] The first flow path extends from inlet 2220 of cushion module, through the first chamber 2014 of cushion module 2010 into the patient’s oral cavity via their mouth, through the patient’s throat, into the patient’s nasal cavity, out of the one or more nares of the patient into the second chamber 2016, and through outlet 2210 to exit the cushion module 2010. It is believed that this unidirectional flow of gas entering the patient’s oral cavity and exiting through the nasal cavity will cause anatomical deadspace flushing of at least some of the patient’s oral cavity, throat, and nasal cavity.

[1287] The second flow path extends from inlet 2220 of cushion module, into the first chamber 2014, through the one or more flow directors 2730 where it is believed acceleration of the gas will likely cause at least some gas flow to enter the patient’s nasal cavity via one or more nares before decelerating and / or changing direction and exiting the nasal cavity via one or more nares into the second chamber 2016, and through outlet 2210 to exit the cushion module 2010. It is also anticipated that some gas will flow through the one or more flow directors 2730 and into the second chamber 2016 without entering the patient’s nasal cavity. Although the first and second flow paths are described in reference to Figure 20, the respiratory gas flow through each flow path is unlikely to be equal. It is believed that with the patients mouth open most respiratory gas flowing through the flow directors 2730 is likely to flow into the second chamber 2016 without entering the patient’s nasal cavity. As described below in reference to Figure 21 , the second flow path plays a larger role when the patient’s mouth is closed.

[1288] The design of the one or more flow directors 2730 may be modified to encourage more or less accelerated gas to enter the patient’s nasal cavity along the second flow path - for example the one or more flow directors 2730 may be configured such that when the patient’s mouth is open the gas flow through the one or more flow directors enters the second chamber 2016 without substantially entering the nares of the patient. It is believed the gas flow being directed through the one or more flow directors 2730, which are configured to create acceleration ofthe gas flow, and are configured to be positioned at a position that is below the patient’s nares and adjacent a lip superior of the patient, or to be positioned at a position that is immediately adjacent the patients nares, may cause some gas flow to enter the patient’s nasal cavity via the one or more nares before decelerating and / or changing direction and exiting the nasal cavity.

[1289] In alternative embodiments where the one or more flow directors 2730 are asymmetrically sized it is believed that a larger volume of flow through a first flow director compared to through the second flow director will create an asymmetric resultant gas flow within the patient’s nasal cavity where the resultant flow enters one nare and exits the other nare of the patient. This one-way resultant flow is thought to have additional benefits for deadspace flushing of the nasal cavity.

[1290] Referring to Figure 21 , where the patient interface 2000 is fitted to a patient with the patient’s mouth closed, without respiration occurring, and where pressurised gas is being delivered to the patient interface 2000 via conduit connector 1300. The flow of pressurised gas enters the first chamber 2014 of cushion module 2010 via inlet 2220, pressurised gas from within the first chamber 2014 then flows through the one or more flow directors 2730 and into the second chamber 2016, excess pressurised gas and / or gas from within the patient’s airways then flows out of second chamber 2016 through outlet 2210 of cushion module 2010 to exit the cushion module 2010. Due to the patient’s mouth being closed only the second flow path is formed. The second flow path is discussed in detail in the paragraphs immediately preceding this paragraph.

[1291] Because gas flow through the first flow path and the second flow path are both thought to cause anatomical deadspace flushing to some extent, it is believed that the patient interface 2000 provides a significant benefit beyond traditional non- invasive ventilation masks. The ability to provide pressure support and simultaneous deadspace flushing with either the patients mouth open or closed is believed to lead to improved ventilation and improved patient outcomes over traditional NIV masks.

[1292] The flow directors 2730 provide some resistance to gas flowing from the first chamber 2014 to the second chamber 2O16.This resistance causes the gas pressure in the second chamber 2016 to be lower than the gas pressure in the first chamber 2014. This pressure differential serves to drive respiratory gas from the first chamber2014 through the oral cavity via their mouth, through the patient’s throat, into the patient’s nasal cavity, out of the patient’s nares and into the second chamber 2016. That is, the pressure differential established by respiratory gas flowing through the flow directors 2730 drives gas flow through the first flow path described in the preceding paragraphs. The mechanism of anatomical deadspace flushing via the first flow path may provide benefits in addition to or separate from the effect of accelerating respiratory gas into the nares via the one or more flow directors 2730.

[1293] Figures 22 to 31 show the general form of a two chamber under the nose full face patient interface 4000 with a dividing wall 4700. Having regard to Figures 22 to 31, the patient interface 4000 which includes a cushion module 4010, a frame 4400 and a conduit connector 1300. The conduit connector 1300 comprises structural components for connecting the cushion module to a source of respiratory gas, such as a ventilator, humidifier, flow generator or wall source. The cushion module 4010 comprises a resilient seal 4100 and a housing 4200. Collectively, the resilient seal 4100 and a housing 4200 form an outer wall 4288 of the cushion module 4010.

[1294] The housing 4200, as shown in Figure 23 without the seal 4100, is formed of substantially rigid plastics material to provide structural support to the seal 4100. Additionally, the housing 4200 provides an interface for connecting the seal 4100 to the frame 4400 and the conduit connector 1300.

[1295] The housing 4200 includes a sleeve 4230 that is sized and shaped to connect with the frame 4400. The sleeve 4230 forms an inlet 4220 through which respiratory gas can be communicated from the conduit connector 1300 to interior of the cushion module 4010. The sleeve 4230 includes key formations 4222 that interact with the frame 4400 to ensure correct alignment of the frame 4400 with the housing 4200 when they are fitted together.

[1296] The housing 4200 includes a series of tabs 4240 which project outwardly around its perimeter. The outer ends of the tabs 4240 are linked to a bead 4245 which runs continuously across all of the tabs 4240, thereby forming a series of discrete outer over-mould windows 4250 between the tabs 4240 and the bead 4245. The seal 4100 is integrally formed with the housing 4200 by over-moulding a resilient material onto the housing 4200 to fill the series of windows. Therefore, the tabs 4240 and the bead 4245 become embedded in the resilient material and are mechanicallyinterlocked with the seal 4100. The seal 4100 and the housing 4200, therefore, form a unitary cushion module 4010 structure.

[1297] The housing 4200 further includes a bias vent 4215 comprising one or more apertures extending through the housing 4200. The housing 4200 further includes a series of inner over-mould windows 4252 through which the seal 4100 is also overmoulded with the housing 4200. The inner over-mould windows 4252 are located in a region of the housing 4200 that is within the perimeter formed by the outer 4250 over-mould windows 4250. The bias vent 4215 is bound on one side by the outer 4250 over-mould windows 4250 and on another side by the inner over-mould windows 4252. As shown in Figure 23, the bias vent 4215 is surrounded by the outer 4250 over-mould windows 4250 and the inner over-mould windows 4252. The material used to form the seal 4100 flows through the inner and outer 4250 overmould windows 4250, 4252 during moulding so that the material conforms to the shape of the housing 4200 and the windows 4250, 4252 prior to solidifying or curing. Having the material extend through the windows 4250, 4252 results in a mechanical connection with the housing. The windows 4250, 4252 may take the form of apertures which extend completely through the housing 4200.

[1298] The seal 4100 is formed of soft, resilient material, such as silicone, and includes an oral opening 4114 and a nasal opening 4116. When fitted to a patient, the oral opening 4114 circumscribes the patient’s mouth and a patient-contact surface 4120 of the outer wall forms a seal about the mouth. Accordingly, respiratory gas at elevated pressure can be delivered to the patient via the oral opening 4114. The seal 4100 is formed with a nare-sealing portion 4236 in the valley of which is located the nasal opening 4116. The patient-contact surface 4120 includes the nare- sealing portion 4236 and a wall portion 4276 located between the oral opening 4114 and the nasal opening 4116. The nare-sealing portion 4236 is arranged to contact the underside of the patient’s nose and to form a seal with the patient’s nares so that respiratory gas at elevated pressure can be delivered to the patient via the nasal opening 4116. The nasal opening 4116 is located to align with the nares of the patient when the patient interface 4000 is fitted.

[1299] Although this embodiment of the cushion module 4010 includes a single oral opening 4114 and a single nasal opening 4116, it will be appreciated that otherembodiments may include more than one oral opening, more than one nasal opening or multiple oral openings and multiple nasal openings. In another nonillustrated embodiment, the cushion module includes a single oral opening 4114 with two nasal openings 4116 wherein each nasal opening 4116 located to align with a respective one of the patient’s nares when the patient interface is fitted.

[1300] The cushion module 4010 defines an interior volume which comprises a first chamber 4014 and a second chamber 4016. The second chamber 4016 is located in an upper portion of the internal volume of the seal 4100. The first chamber 4014 is located in the lower portion of the internal volume of the cushion module 4010. The first and second chambers 4014, 4016 are separated by a dividing wall 4700. As shown in Figure 28, the oral opening 4114 is associated with the first chamber 4014 to enable transfer of respiratory gas between a first chamber 4014 and the patient’s mouth. The inlet 4220 of the housing 4200 is also associated with the first chamber 4014. The nasal opening 4116 is associated with the second chamber to enable transfer of respiratory gas between a second chamber 4016 and the patient’s nares. The outlet 4210 in the form of a bias vent 4215 is also associated with the second chamber 4016. The bias vent 4215, therefore, enables respiratory gas to be vented from the cushion module to an outside environment. In this embodiment, the bias vent 4215 vents the respiratory gas to the ambient atmosphere.

[1301] The dividing wall 4700 partitions the cushion module 4010 internally to define the first chamber 4014 and the second chamber 4016. The dividing wall 4700 separates the first chamber 4014 from the second chamber 4016 by extending all the way across the internal volume of the cushion module 4010. In other words, the perimeter of the dividing wall 4700 seals with the outer wall 4288. A meeting line 4282, which notionally shows where the dividing wall 4700 meets the outer wall 4288, is shown in Figures 25 and 27. In particular, it extends all the way across between the first chamber 4014 and the second chamber 4016. The sealing of the first chamber 4014 from the second chamber 4016 means that the only flow of respiratory gas between the first chamber 4014 and the second chamber 4016 is through the flow directors 4730. So, while the dividing wall 4700 seals the first chamber 4014 from the second chamber 4016, the dividing wall 4700 permits respiratory gas to flow from the first chamber 4014 to the second chamber 4016 only via a pair of flow directors 4730 (see Figures 30 and 31).

[1302] Figures 27 and 28 show the dividing wall 4700 seals with the outer wall 4288 between the nasal opening 4116 and the oral opening 4114. In terms of the wall portion 4276, this means that the dividing wall 4700 seals with the wall portion 4276 across the entire width of the wall portion 4276. In other words, the dividing wall 4700 seals with the outer wall 4288 at a location spaced from the nasal opening 4116. It can further be seen in Figure 29 that the dividing wall 4700 seals with the outer wall 4288 closer to the oral opening 4114 than to the nasal opening 4116. In other words, the seal between the dividing wall 4700 and the wall portion 4276 is located in a lower half of the wall portion 4276.

[1303] In this embodiment, the dividing wall 4700 comprises a first resilient region 4724 and a second resilient region 4726 which are linked by a deformation region 4720. The deformation region 4720 comprises a first thin wall 4722 and a second thin wall 4723. The first thin wall 4722 projects from the first resilient region 4724 (see Figure 29), the second thin wall 4723 extends from the second resilient region 4726 between the flow directors 4730 and the second thin wall 4723 joins with the first thin wall 4722. The second thin wall 4723 has a curved profile which extends from the first thin wall 4722 to the second resilient region 4726. The undeformed configuration of the first thin wall 4722 and the second thin wall 4723 is shown in Figure 29.

[1304] The flow directors 4730 are disposed in the second resilient region 4726 of the dividing wall 4700. The flow directors 4730 extend into the second chamber 4016. In other embodiments, the flow directors 4730 may extend into the first chamber 4014 and the second chamber 4016 or into the first chamber 4014 only. In another embodiment, the flow directors 4730 may not extend from either side of the dividing wall 4700. For example, the dividing wall 4700 may have a wall thickness that is sufficient to include a flow director 4730 between the surfaces of the dividing wall 4700 exposed to the first chamber 4014 and to the second chamber 4016 respectively.

[1305] The flow directors 4730 define a gas flow path from the first chamber 4014 to the second chamber 4016 and the flow directors 4730 surround the gas flow path. Each flow director 4730 had a flow director inlet 4733, 4737 and a flow director outlet 4735, 4739. The flow director inlets 4733, 4737 open into the first chamber 4014 andthe flow director outlets 4735, 4739 open into the second chamber 4016. This means that the flow directors 4730 are the only avenue for respiratory gas to flow between the first chamber 4014 and the second chamber 4016.

[1306] In this embodiment, the entire seal 4100, including the elastomeric portion of the dividing wall 4700, is integrally formed and is over-moulded onto the housing 4200. This integral moulding of the dividing wall 4700 with the outer wall 4288 forms a gas-tight joint. The same applies with the flow directors 4730 joining with the dividing wall 4700.

[1307] The flow director outlets 4735, 4739 are positioned to direct respiratory gas towards and through the nasal opening 4116. This directs respiratory gas to the patient’s nares from the first chamber 4014 via the flow director outlet 4739 and through the nasal opening 4116. Such directed respiratory gas assists breathing during the respiratory cycle and contributes to anatomical dead-space flushing in the nasal cavity and / or the throat of a patient. It is to be appreciated that whilst at least a portion of the gas flow directed by the flow directors 4730 toward the nasal opening 4116 will generally flow through the nasal opening 4116, some of the directed gas may not flow through the nasal opening 4116. Furthermore, at some times during use of the patient interface the directed respiratory gas may not flow through the nasal opening 4116 at all. Gas flow through the nasal opening 4116 will depend upon the gas flow rate, gas pressure and the point in the breathing cycle. Any directed respiratory gas flow from the flow directors 4730 that doesn’t flow through the nasal opening 4116 will flow through the second chamber 4016 to the bias vent 4215 and external of the patient interface 4000.

[1308] The position and shape of the flow director outlets 4735, 4739 affects the flow of respiratory gas into the second chamber and through the nasal opening 4116. In the embodiment shown in Figure 31 , each flow director 4730 has a flow director outlet 4739 within the second chamber 4016 and the flow director outlet 4739 is spaced from the nasal opening 4116. The flow director outlet 4739 is defined by a free end 4734 that is contoured so that at least a portion of the free end 4734 has a substantially consistent spacing from the nasal opening 4116. The portion of the free end 4734 that is substantially consistently spaced from the nasal opening 4116 is adjacent to the outer wall 4288 between the at least nasal opening 4116 and the oralopening 4114. The free end 4734 of each flow director outlet 4739 extends further from the dividing wall 4700 at a laterally outer side of the flow director 4730 than the free end 4734 extends from the dividing wall 4700 at a laterally inner side of the flow director 4730. This means that the free end 4734 is recessed further from the nasal opening 4116 at a laterally inner side of the flow director 4730 than the free end 4734 is recessed from the nasal opening 4116 at the laterally outer side of the flow director 4730. The lower height of the free end 4734 relative to the dividing wall 4700 on the laterally inner side of each flow director 4730 assists with the flow of respiratory gas from the first chamber 4014 into the second chamber 4016. The higher height of the free end 4734 relative to the dividing wall 4700 on the laterally outer side of each flow director 4730 assists with directing respiratory gas from the first chamber 4014 through the second chamber 4016 and through the nasal opening 4116. In another embodiment the free end 4734 is recessed furthest from the nasal opening 4116 at a point between the laterally outer side of the flow director 4730 and the laterally inner side of the flow director 4730 such that in cross section the free end 4734 is concave or curved inwardly. In a further embodiment, the free end 4734 of each flow director 4730 is not recessed and in cross-section each free end 4734 is substantially flat.

[1309] The recessed position of the flow director outlet 4739 relative to the nasal opening 4116 enables excess respiratory gas from the first chamber 4014 (including exhaled respiratory gas from the mouth) to pass into the second chamber 4016 and be vented to externally of the patient interface 4000 through the bias vent 4215. The nasal opening 4116 is defined, at the outer wall 4288 of the seal 4100, by a rim 4286. However, given that the flow director outlet 4739 is recessed from the nasal opening 4116, the spacing between the flow director outlet 4739 and the rim 4286 enables respiratory gas to flow from the first chamber 4014 to the second chamber 4016 and then out through the bias vent 4215 to ambient atmosphere. This generally occurs during part of the exhalation phase of the respiratory cycle. For example, when the patient exhales through their nose (excess respiratory gas delivered from a flow source to the first chamber 4014 flows into the second chamber 4016). In another example, it also occurs when the patient exhales through their mouth (the exhaled gas flows from the mouth and into the first chamber and then into the second chamber with excess respiratory gas delivered from a flow source). At timesduring inhalation through the nose or during dead space flushing via the nasal cavity, the respiratory gas may flow from the first chamber 4014, into the second chamber 4016 and then through the nasal opening 4116 and into the nares of the patient.

[1310] In the embodiment shown in Figures 22 to 31 , the patient interface 4000 includes two flow directors 4730 that are spaced apart. That is, the two flow directors 4730 comprise two separate structures. They do not share a common wall which defines the flow path through each of the flow directors 4730. The flow directors 4730 are spaced apart by a gap through which respiratory gas from the first chamber 4014 and exhaled respiratory gas from the nares entering the second chamber via the nasal opening 4116 can flow into the second chamber 4016. The free end 4734 of each flow director 4730 extends from the dividing wall 4700 less on the same side of the flow director 4730 as the gap than the free end 4734 extends on the side of the flow director 4730 that is remote from the gap. In this embodiment, the flow directors 4730 are configured with the lateral outer side of the rims 254 adjacent to a laterally outer rim 4286 of the nasal opening 4116 having regard to a direction of gas flow from the flow director 4730. More specifically, the free end 4734 is located laterally inwardly of the laterally outer rim 4286 of the nasal opening 4116. However, in other embodiments, the free end 4734 may be located laterally outwardly of the laterally outer rim 4286 of the nasal opening 4116 or the lateral outer side of the free end 4734 may be aligned with a laterally outer rim 4286 of the nasal opening 4116 having regard to a direction of gas flow from the flow director 4730.

[1311] The deformation region 4720 structurally decouples the first resilient region 4724 from the second resilient region 4726. The decoupling occurs because the deformation region 4720 accommodates a reduction in distance between the first resilient region 4724 and the second resilient region 4726.

[1312] Deformation of the deformation region 4720 occurs in two stages. The second resilient region 4726 includes the flow directors 4730 and, therefore, is relatively resistant to deformation in the area of the flow directors 4730 compared to the first and second thin walls 4722, 4723. Accordingly, the deformation region 4720 will deform more readily than the remainder of the second resilient region 4726. The first stage of deformation involves a force being applied to the patient-contact surface 4120 such that the second resilient region 4726 is displaced toward the first resilientregion 4724. This causes the first thin wall 4722 to fold about its line of connection with the first resilient region 4724 until it contacts, or is located adjacent an underside of the first resilient region 4724. In the second stage of deformation, as the second resilient region 4726 continues to be displaced towards the first resilient region 4724, the second thin wall 4723 and the section of the second resilient region 4726 buckle and translate over the first thin wall 4722 until the flow directors 4730 contact, or are located adjacent to, the first resilient region 4724. This buckling and translating motion may be referred to as “rolling”. The bucking occurs on account of the curvature of the second thin wall 4723. This sequence of deflection is shown and described in international patent application PCT / NZ202 / 050072, with reference in particular to Figures 59A to 59D and associated description. The content of the international application is incorporated in this specification by this reference so they are read as a single disclosure.

[1313] In an alternative embodiment, the dividing wall 4700 may be configured so that deformation of the deformation region 4720 is limited to the first stage of deformation described above. For example, the second thin wall 4723 may be omitted or the second wall may be reduced in size or have an altered shape which avoids the “rolling” motion. In a further alternative, the first thin wall 4722 may be extend further from the first resilient region 4724 so that the first stage of deformation occurs for all displacements of the second resilient region 4726 toward the first resilient region 4724. In a further alternative, the first thin wall 4722 and the second thin wall 4723 may be replaced with a combined single thin wall which deforms instead as the first resilient region 4724 and the second resilient region 4726 move toward one another.

[1314] During use, when the patient interface 4000 is fitted, force will be applied to the patient contact surface 4120 to account for differing facial geometries, headgear preferences and pressure settings. These forces and the locations they are applied will differ. The configuration described above, however, focusses the forces and deflection into the deformation region 4720 to provide a predictable collapse and rebound movement. The predictable buckling pattern achieved via the preferable deformable region allows the patient interface 4000 to be designed in such a way that, when forces are applied to the seal, the resulting deformation and compression that occurs in the elastomeric material that forms the seal 4100 happens in such away that the nasal opening 4116 and the flow director outlets 4735, 4739 are likely to remain unobstructed. Furthermore, the positioning of the nasal opening 4116 and the flow director outlets 4735, 4739 relative to each other will be substantially maintained during deformation. Without this preferential deformation, collapse of the dividing wall 4700 would be unpredictable, potentially leading to inconsistent flow through the flow director outlets 4735, 4739 or inconsistent positioning of the flow director outlets 4735, 4739 relative to the nasal opening 4116 and / or patient’s nares. This could cause inconsistencies in the therapy achieved, comfort, fitting procedure and in overall performance both between uses for the same patient and between different patients.

[1315] In a variation of this embodiment, the seal 4100 may have more than one deformation region. For example, the additional deformation regions may be incorporated into the dividing wall 4700 or may be incorporated into the seal 4100 at other locations that enable the second chamber 4016 and / or nasal opening 4116 and the flow director outlets 4735, 4739 to substantially retain their shape.

[1316] The geometries of the first and second thin walls 4722, 4723 and their thicknesses are selected so that the cushion module 4010 can accommodate a wide range of facial geometries and deformation forces associated with application and use of the patient interface. However, it is possible for different cushion modules to be produced to fit specific ranges of facial geometries which fall toward the ends of the facial geometry spectrum.

[1317] It can be seen in Figure 28 and Figure 31 that the dividing wall 4700 includes flow directors 4730 disposed distally of the wall portion 4276 and that a deformation region 4720 is disposed distally of the flow directors 4730. This means that the deformation region 4720 in the cushion module 4010 is configured to deform in preference to the flow directors 4730 and the second resilient region 4726. The dividing wall 4700 includes lateral side portions 4800 which are disposed laterally outwardly of the flow directors 4730 and which join with the outer wall 4288. The lateral side portions 4800 are proximal of the deformation region. In this embodiment, the deformation region is configured to deform also in preference to the lateral side portions 4800. As shown in Figure 30, the lateral side portions 4800 join the outer wall 4288 at a position that is spaced from the top of the outer wall 4288. Inthis particular embodiment, the level of the lateral side portions 4800 where they join with the outer wall 4288 is considerably below the level of the top of the outer wall 4288. More specifically, the lateral side portions 4800 join the outer wall 4288 along a line (i.e. the meeting line 4282) that extends at least partly above and partly below the lowest level of the nasal opening 4116 and the meeting line 4282 does not extend above the highest level of the nasal opening 4116, having regard to an upright orientation of the patient interface 4000.

[1318] In another embodiment, however, the lateral side portions 4800 may join the outer wall 4288 at a level below the lowest level of the nasal opening 4116. In a further embodiment, part of the lateral side portions 4800 join the outer wall 4288 along a line that extends between the highest and lowest levels of the nasal opening 4116 and that does not extend above the highest level of the nasal opening 4116, having regard to an upright orientation of the patient interface 4000. In a further alternative embodiment, part of the lateral side portions 4800 join with the outer wall 4288 along a line that extends above the highest level of the nasal opening 4116 having regard to an upright orientation of the patient interface 4000. In another alternative embodiment, the lateral side portions 4800 join with the outer wall 4288 at a level lower than or substantially equal to the uppermost level of the flow directors 4730, having regard to an upright orientation of the patient interface 4000. In another alternative embodiment, the lateral side portions 4800 join with the outer wall 4288 at a level between the highest level of the oral opening 4114 and the lowest level of the nasal opening 4116, when viewed from the front. In this embodiment, the dividing wall 4700 is substantially flat.

[1319] Figures 28 to 31 show the flow directors 4730 in greater detail. The flow directors 4730 enable gas flow between the first chamber 4014 and the second chamber 4016. Each flow director 4730 has a base 806 which joins with the dividing wall 4700 and which defines the first opening 4250 into the first chamber 4014, a body 4248 extending from the base 806 and the free end 4734 remote from the base 806. The free end 4734 defines a second opening 4252 which opens into the second chamber 4016. As with other embodiments, a gas flow channel 812 extends from the first opening 4250 in the base 806 to the second opening 4252 of the free end 4734.

[1320] The dividing wall 4700 further includes a spacing element 4731 disposed between the bodies 4248 of the flow directors 4730, as shown in Figures 28 to 31 . The spacing element 4731 joins with the flow directors 4730 at a position spaced from the free end 4734. In this embodiment, the spacing element 4731 extends from the dividing wall 4700 between the flow directors 4730 and joins with the base 806 but is spaced from the free end 4734. Spacing the spacing element 4731 from the free end 4734, and therefore further from the nasal opening 4116 opening than the free end 4734 is from the nasal opening 4116, reduces the chance that the patient’s nose will come into contact with the spacing element 4731 during use. Spacing element 4731 is disposed in a plane which intersects longitudinal axes of the flow directors 4730. Accordingly, the spacing element 4731 is disposed mid-way between the proximal and distal sides of the flow directors 4730.

[1321] As shown in Figure 29, the spacing element 4731 has an inverted U-shaped profile. The spacing element 4731 reinforces the flow directors 4730 and makes them more resilient to buckling inwardly or outwardly. Reducing the likelihood of buckling assists to retain the alignment of the flow directors 4730 in a direction that, in use, directs a flow of respiratory gas toward the nasal opening 4116. Furthermore, the position of the spacing element 4731 and the reinforcement section 4264 means that deflection of the wall portion 4276 is transferred through the spacing element 4731 and the reinforcement section 4264 and, therefore, causes the flow directors 4730 to track movement of the wall portion 4276 and the nasal opening 4116.

[1322] The spacing element 4731 has a generally upright orientation, having regard to an upright orientation of the patient interface 4000. Given that the dividing wall 4700 is inclined downwardly from the wall portion 4276 to the deformation region 4720, the spacing element 4731 is inclined relative to the dividing wall 4700. That is, the spacing element 4731 joins the dividing wall 4700 at its proximal side in an acute angle. The spacing element 4731 includes a fillet-shaped transition join with the flow directors 4730. This provides a smooth transition 802 from the spacing element 4731 to the base 806 and to the body 4248 of the flow directors 4730.

[1323] The thickness of the spacing element 4731 in the distal-proximal direction is considerably greater than the wall thickness of the flow directors 4730. More specifically, the spacing element 4731 has a wall thickness in the distal-proximaldirection that is 5 to 20%, 20 to 40% or 40 to 60% of the maximum width dimension of the flow director 4730.

[1324] The spacing element 4731 (Figures 29 to 31) overlaps a reinforcement section 4264 which is arranged on an underside of the dividing wall 4700 between the respective first openings 4250 of the flow directors 4730. The reinforcement section 4264 comprises a thickened section of the dividing wall 4700. The reinforcement section 4264 extends in a distal-proximal direction. Furthermore, it is spaced from the wall portion 4276 and from the deformation region 4720. The reinforcement section 4264 increases the stiffness of the dividing wall 4700 in the region between the wall portion 4276 and the deformation region 4720 and, therefore, contributes to transferring deformation forces applied to the wall portion 4276 around the flow directors 4730 and through to the deformation region 4720. Accordingly, the reinforcement section 4264 assists to retain the position of the dividing wall 4700 (and the flow directors 4730) relative to the nasal opening 4116. In other words, the reinforcement section 4264 assists to brace the dividing wall 4700 in position relative to the wall portion 4276. This enables a patient treatment to continue with little interference to the flow of respiratory gas (a) through the flow directors 4730, and / or (b) through the nasal opening 4116 and / or (c) through the second chamber 4016 during deformation of the patient-contact surface 4120 of the outer wall 4288. The deformations contemplated here and throughout the description and claims are deformations consistent with normal use of the patient interface 4000.

[1325] The reinforcement section 4264 is assisted in transferring deformation forces from the wall portion 4276 through to the deformation region 4720 by the second resilient region 4726. The second resilient region 4726 comprises portions 4808, 4810 of the dividing wall 4700 having a wall thickness that is greater than the wall thickness of other parts of the dividing wall 4700 that are proximal of the deformation region 4720. The portions 4808, 4810 are respectively proximal and distal of the flow directors 4730. In some embodiments, proximal and distal portions 4808, 4810 are respectively proximal and distal of the spacing element 4731. In some embodiments, the proximal and distal portions 4808, 4810 include the respective portions of the dividing wall 4700 that are respectively proximal and distal of the flow directors 4730. The proximal portion 4808 is between the lateral side portions 4800 of the dividing wall 4700. Additionally, the proximal portion may be between the flow directors 4730.The distal portion 4810 is between the lateral side portions 4800 of the dividing wall 4700. For embodiments that don’t include the spacing element 4731 , the proximal and distal portions 4808, 4810 are respectively proximal and distal of a notional line through the centres of the respective second opening 4252 of the flow directors 4730. The wall thickness of the distal portion 4810 is represented by the wall thickness excluding the wall thickness of the reinforcement section 4264. Figure 36 shows a distal portion 4810 which has a wall thickness that is greater than the wall thickness of the lateral side portions 4800. The distal portion 4810 extends from the spacing element 4731 and around the bases 4806 of the flow directors 4730. The distal portion 810 also extends toward the deformation region 4270 but is spaced from the second thin wall 4723 of the deformation region 4720. Accordingly, the distal portion 4810 overlaps the reinforcement section 4264. The same applies to the proximal portion 4808, as shown in Figure 29. The proximal portion 4808 joins with the spacing element 4731 and overlaps the reinforcement section 264. The proximal portion 4808 extends proximally from the spacing element 4731 and around the bases 806 of the flow directors 4730. The proximal portion 4808 joins with the wall portion 4276.

[1326] These portions 4808, 4810, on account of their greater wall thickness compared to other parts of the dividing wall 4700 that are proximal of the deformation region 4720, have a greater resistance to deformation. It follows that deformation forces imparted upon the wall portion 4276 are transferred through the dividing wall 4700 to the deformation region 4720 which will deform in preference to the portions 4808, 4810. The presence of the portions 4808, 4810 in conjunction with the reinforcement section 4264 and the spacing element 4731 resists undesirable deformation of the dividing wall 4700 by improving the transfer of deformation forces into the deformation region 4720. Therefore, the likelihood of the flow directors 4730 collapsing or buckling on account of the dividing wall 4700 buckling is reduced. There is a limit, however, to the wall thickness of the portions 4808, 4810 because increasing the wall thickness of the portions has the effect of localising the pressure forces experienced by the patient at the wall portion 4276. In other words, increased wall thickness of the portion increases the likelihood of pressure sores. Conversely, making the wall thickness too small will result in buckling of the dividing wall 4700 outside of the deformation region 4720 and possible buckling of the flow directors4730 because the deformation forces aren’t transferred to the deformation region 4720.

[1327] The greater wall thickness of the portions 4808, 4810 means that the reinforcement section 4264 doesn’t need to extend all the way to the wall portion 4276 or all the way to the deformation region 4720 in order to transfer deformation forces from the wall portion 4276 into the deformation region 4720.

[1328] Deadspace flushing of the anatomical deadspace of a patient has been discussed as an intended benefit of patient interfaces 2000 and 4000.

[1329] The anatomical deadspace of a patient consists of the total volume of the respiratory tract segments of a patient that are responsible for conducting air to the alveoli and respiratory bronchioles but do not take part in the process of gas exchange itself. The anatomical deadspace is therefore the total volume of the conducting airways from the nose or mouth to the terminal bronchioles of a patient including the oral cavity, nasal cavity, and pharynx (also referred to as the throat).

[1330] During respiration by a patient, lower CO2 content air is inhaled into the lungs and higher CO2 content air is exhaled from the lungs. At the end of an exhalation cycle a portion of the exhaled higher CO2 content air remains in the anatomical deadspace of the patient. This higher CO2 content air is then inhaled, or rebreathed, during the next respiration cycle. This rebreathing of high CO2 content air leads to a reduced efficiency in the gas exchange occurring within a patient’s lungs.

[1331] The process of deadspace flushing replaces at least a portion of the exhaled higher CO2 content air present in the anatomical deadspace of a patient with fresh lower CO2 content air so that during the following inhalation cycle a reduced amount of exhaled higher CO2 content air is inhaled, or rebreathed. This reduction in rebreathing of higher CO2 content air improves the efficiency of gas exchange occurring within a patient’s lungs.

[1332] As discussed in the preceding paragraphs, the flow director outlet 2740, 4740 has a cross-sectional flow area that is configured to be less than the cross-sectional flow area of the inlet 2220, 4220 of the housing 2200, 4200. The smaller cross- sectional flow area of the flow director outlet 2740, 4740 compared with the inlet 2220, 4220 of housing 2200, 4200 forms a flow restriction which creates anacceleration of gas flow and / or a reduction in gas pressure. However, it is to be appreciated that in alternative configurations the flow restriction may be located anywhere within the one or more flow directors 2730, 4730 to create this desired acceleration of gas and / or a reduction in gas pressure through the one or more flow directors 2730, 4730.

[1333] In addition or alternatively, the outlet 2210, 4210 of the cushion module 2010, 4010 is configured to have a resistance to flow that is lower than the resistance to flow through the one or more flow directors 2730, 4730. This difference in resistance to flow is configured to create a pressure differential between the first chamber 2014, 4014 and the second chamber 2016, 4016, with the second chamber 2016, 4016 being configured to be at a lower pressure than the first chamber 2014, 4014 in use.

[1334] The pressure differential described in respect of the patient interfaces 2000, 4000 is caused by the flow directors 2730, 4730. They restrict gas flow from the first chamber 2014, 4014 to the second chamber 2016, 4016, which causes a pressure drop between the first chamber 2014, 4014 and the second chamber 2016, 4016. The extent of the pressure drop, or pressure differential, depends in part on the resistance to flow through the flow directors 2730, 4730. One variable which may affect the resistance to flow of the flow directors 2730, 4730 is the cross-sectional area of the one or more flow paths through the flow directors 2730, 4730. That is, a greater cross-sectional flow area will result in a smaller gas pressure drop between the first chamber 2014, 4014 and the second chamber 2016, 4016. Another variable which may affect the resistance to flow of the flow directors 2730, 4730 is the length of the one or more flow paths through the flow directors 2730, 4730. That is, a greater length of the one or more flow paths through the flow directors 2730, 4730 will result in a larger gas pressure drop between the first chamber 2014, 4014 and the second chamber 2016, 4016.

[1335] It is believed by the inventors that, during use with the patient’s mouth open, and with pressurised gas being supplied to the first chamber 2014, 4014 of cushion module 2010, 4010, that gas flow from the first chamber 2014, 4014 through the patient’s oral cavity, through the throat, into the nasal cavity, out of the nasal cavity via the nares and into the second chamber 2016 4016, may be encouraged by this configured pressure differential in which the second chamber 2016, 4016 is at alower pressure than the first chamber 2014, 4014. It is this gas flow through the oral cavity and then the nasal cavity that comprises anatomical deadspace flushing in this instance.

[1336] The pressure differential described above is achieved by configuring the resistance to flow through flow directors 2730, 4730 and / or the outlet 2210, 4210. However, it should be appreciated that any suitable method to create a lower pressure within the second chamber 2016, 4016 than within the first chamber 2014, 4014 may be incorporated into a further alternative embodiment to encourage the mechanism of anatomical deadspace flushing through the oral cavity and out of the nasal cavity.

[1337] In the preceding paragraphs several patient interfaces 1000, 2000, 4000 have been described with each comprising a respective outlet 1210, 2210, 4210.

[1338] As explained previously, in one configuration each outlet 1210, 2210, 4210 is in the form of an outlet configured to connect to, or to be in fluid communication with, an expiratory limb of a respiratory circuit.

[1339] In a further configuration each outlet 1210, 2210, 4210 comprises a respective bias vent 1215, 2215, 4215 configured to exhaust gasses from within the patient interface to externally of the patient interface, with each bias vent comprising a plurality of apertures.

[1340] Referring generally to the operation of such bias vents which comprise a plurality of fixed dimension apertures, it can be understood that the dimensions of the apertures, such as the cross-sectional flow area and length of the apertures, and the pressure within the patient interface, will be responsible for the resultant volumetric gas flow rate through the bias vents. As such, the bias vent flow rate may be significantly lower at a lower treatment pressure than at a higher treatment pressure. Generally speaking, there is a proportional relationship between therapy pressure and the flow rate through the fixed aperture bias flow vent, or outlet 1210, 2210, 4210.

[1341] In practice this means that the bias vent aperture dimensions need to be selected to enable gas flow rates through the bias vent which are suitable to remove adequate levels of exhaled CO2 rich gas from within the patient interface at thelowest intended treatment pressure. However, this also means that at the highest intended treatment pressure the gas flow rate through the bias vent may be significantly higher than what is required to remove adequate levels of exhaled CO2 rich gas from within the patient interface.

[1342] Among other things, this excess gas flow through the bias vent at higher treatment pressures may increase the burden on the pressurised gas flow source or humidification system, increase the noise and draft created by the bias vent, and / or increase the burden on an antibacterial or antiviral gas filter that may be in fluid communication with the bias vent.

[1343] The inventors of this application believe that one way to ameliorate this problem in a patient interface 1000, 2000, 4000 may be to replace the fixed aperture bias vents 1215, 2215, 4215 with a flow valve that, across a range of respiratory therapy pressures, maintains a gas flow rate within a gas flow range from the second chamber 1016, 2016, 4016 to external of the patient interface 1000, 2000, 4000.

[1344] In one embodiment, the flow valve enables a pre-set gas flow through the outlet 1210, 2210, 4210 regardless of the pressure within the patient interface, across an intended range of treatment pressures. In another embodiment, the flow valve may be pre-set to a desired gas flow rate during manufacture or may be adjustable to a desired gas flow rate prior to, or during, treatment with the patient interface 1000, 2000, 4000. Figure 32 shows two curves which indicate the relationship between therapy pressure and the flow rate through an exemplar flow valve (as described below) fitted to a single limb (S) therapy system and to a dual limb (D) therapy system. In each of the S and D curves, the flow rate initially increases proportionally with the therapy pressure. Beyond this initial increase, the flow rate through the flow valve departs from the proportional flow rate relationship of fixed dimension bias vents. That is, the flow rate through the flow valve adopts a generally steady rate over the typical range of gas pressures used in positive pressure respiratory therapy.

[1345] Alternatively, the flow valve may be configured to provide a gas flow rate that is below an upper limit and above a lower limit across a range of respiratory therapy pressures. The range between the lower and upper limits cover an initial increase in the gas flow rate before becoming relatively steady. The range also covers thecircumstance where the gas flow rate may initially increase, then decrease and then become steady across a range of respiratory therapy pressures

[1346] It is believed by the inventors that the minimum effective bias vent flow rate for a full-face vented mask used in non-invasive respiratory therapy is generally accepted as being 10 L / min. For patient safety, and correct functioning of a dual chamber patient interface, it may therefore be desirable to have a bias vent flow rate of 16L / min, for example, to ensure adequate CO2 clearance is achieved from the patient interface. In such a configuration the flow valve would be configured to allow 16L / min of flow from within the patient interface to exhaust to atmosphere at all pressures within the range of intended respiratory treatment pressures. In this way adequate CO2 clearance would be achieved at all treatment pressures, without excess bias vent flow occurring at the higher treatment pressures. For dual limb ventilation systems, the steady rate may be in the range of 10 to 20 L / m. For single limb ventilation systems, the steady rate may be in the range of 10 to 50 L / m or 20 to 50 L / m.

[1347] It will be appreciated that although the optimal outcome for the flow valve is a fixed flow rate across the full range of intended treatment pressures, the actual flow rate may vary from the lowest intended pressures to the highest intended pressures. The aim of the flow valve therefore is to provide a substantially constant flow rate while accepting that in use variations may occur. For example, a pre-set flow rate of 16L / min may be chosen with the understanding that in use this could increase to 25L / min or even 30L / min at the highest intended treatment pressures, but that this difference in flow rate from the lowest intended treatment pressure to the highest intended treatment pressure would be significantly lower than the difference in a bias vent flow rate from the lowest intended treatment pressure to the highest intended treatment pressure with a traditional (fixed dimension) bias vent. Alternatively, flow valves may be selected with pre-set flow rates given in ranges. For example from 10 L / min to 20 L / min indicating that from the lowest intended treatment pressure to the highest intended treatment pressure that the flow rate through the flow valve will stay within the 10-20 L / min range.

[1348] It will also be appreciated that there are multiple existing flow valves known in the art, any of which could be adopted as a flow valve. For example, any diaphragm-controlled, piston-actuated, needle-controlled, float-controlled, balanced spool, or rotary disc flow valve could be incorporated into the flow valve. A range of flow valve embodiments are described below.

[1349] In another configuration, the flow valve may comprise an external dial or controller which is adjustable to adjust the pre-set gas flow rate through the flow valve. This would allow a patient, physician, or other person to adjust the desired gas flow rate through the flow valve to ensure adequate anatomical deadspace flushing and / or patient interface deadspace flushing is occurring.

[1350] Further, it will be appreciated that in each of the patient interfaces 1000, 2000, 4000 the flow valve described above could be located on, or in, the respective housing 1200, 2200, 4200, respective frame 1400, 2400, 4400 or respective seal 1100, 2100, 4100, or could instead be in fluid communication with a respective outlet 1210, 2210, 4210 of the cushion module and located distally of said outlet. The only overlapping requirement is that the flow valve is in fluid communication with the second chamber 1016, 2016, 4016.

[1351] An alternative embodiment of a patient interface 6000 incorporating a constant flow bias vent 300 is shown in Figures 35 to 43. The patient interface 6000 comprises a cushion module 6010. The cushion module 6010 comprises a seal 6100 and a housing 6200. The patient interface 6000 further comprises a frame 6400. The frame 6400 includes headgear connectors 6410, 6420. The frame 6400 further includes part of the constant flow bias vent 300. In alternative embodiments, the constant flow bias vent 300 may be a separate component attachable to either of the frame 6400 or the housing 6200. The patient interface 6000 further comprises a conduit connector 6300. The conduit connector 6300 is the same as the conduit connector 1300 of the patient interface 1000. The conduit connector 6300 couples with the frame 6400 and the housing 6200 in the same way as described above in respect of patient interface 1000.

[1352] The housing 6200 (Figure 40) comprises a sleeve 6230 which defines an inlet 6220. The sleeve 6230 includes key formations 6232 which co-operate with the frame 6400 to align the frame 6400 for connection with the housing 6200. The housing 6200 further comprises an outlet 6210. The seal 6100 is over-moulded to the housing 6200 in the same way as described above in respect of the patientinterface 1000. This includes over-moulding the resilient material of the seal 6100 through over-mould windows which extend about the outlet 6210. Accordingly, the outlet 6210 is surrounded by resilient material of the seal 6100. In contrast to embodiments disclosed above, the outlet 6210 comprises a single opening through the housing 6200. The outlet 6210 is sized to enable relatively free flow of respiratory gas. In alternative embodiments the outlet 6210 may comprise a plurality of openings or a gas impermeable material.

[1353] The frame 6400 (Figure 37, 38 and 41) comprises a ball socket 6402 for receiving the conduit connector 6300. The frame 6400 further comprises part of the constant flow bias vent 300 in the form of a stem 302. The stem 302 is located to align with the outlet 6210 of the housing 6200. The stem 302 comprises an external thread 306 and an end face 304. The stem 302 further comprises a feed opening 308. When the frame 6400 is fitted to the housing 6200, the feed opening 308 aligns with the outlet 6210. The thread 306 and the end face 304 are operable with other parts of the constant flow bias vent 300 which are described below.

[1354] The patient interface 6000 further comprises a gasket 6450. The gasket 6450 is formed of a compressible resilient material. The gasket 6450 includes an aperture. The gasket 6450 is positioned on the rear side of the frame 6400 (Figure 41) so that the aperture aligns with the feed opening 308 and with the outlet of the housing 6200. When the frame 6400 is fitted to the housing 6200 (as shown in Figure 36), the gasket 6450 is compressible between the frame 6400 and the housing 6200 to form a substantially gas-tight connection between the outlet 6210 and the feed opening 308. In alternative embodiments the gasket may be removed.

[1355] As shown in Figures 35 and 36, the flow valve 300 further comprises a body 310 and an end cap 336. The body 310 comprises an internal thread 312 which is co-operable with the external thread 306 of the stem 302. The body 310 further comprises an external thread 352 at an end of the body 310 remote from the internal thread 312. The external thread 352 is co-operable with an internal thread 354 of the end cap 336. It will be appreciated that other suitable connection methods may be used between the stem 302, body 310 and end cap 336 such as an interference fit.

[1356] The stem 302, body 310 and end cap 336 define a cavity through which the pressurised respiratory gas can flow through from within the cushion module. Theend cap 336 comprises an exhaust vent 338. The exhaust vent 338 transfers respiratory gas from the cavity to the external atmosphere. In other embodiments, the stem 302 and the body 310 may be integrally formed as a single component. As such they will still incorporate the features and benefits of both as described herein.

[1357] The flow valve 300 controls the flow rate of respiratory gas from within the second chamber 6016 of the cushion module 6010 to external of the cushion module 6010 in response to the pressure of the respiratory gas within the second chamber 6016. This is achieved by a pressure-displaceable diaphragm 316 within the flow valve 300. The pressure-displaceable diaphragm 316 is disposed at least partly within a flow path of respiratory gas heading to an outlet of the patient interface 6000. Variations in respiratory therapy pressure cause the pressure-displaceable diaphragm 316 to deform in a way that changes a cross-sectional flow area of the flow path so that the flow rate of the respiratory gas is affected.

[1358] In the illustrated embodiment, referring to Figures 35, 41 and 42, the flow valve 300 further comprises an O-ring 314, a diaphragm 316 and a splint 332. The O-ring 314 includes a recess 344. The recess 344 is shaped correspondingly to a protrusion 348 on an inside wall of the body 310. The O-ring 314 is compressible to form a gas tight seal between the diaphragm 316 and the end face 304 of the stem 302. In alternative embodiments the function of the O-ring may be achieved by the diaphragm 316 or may be omitted entirely.

[1359] The diaphragm 316 further comprises an outer portion 324, a central portion 320 and a spring portion 322 connecting the outer and central portions 320, 324. In this embodiment, the outer portion 324, the central portion 320 and the spring portion 322 are annular. The wall thickness of the central portion 320 and the outer portion 324 is greater than the wall thickness of the spring portion 322. The smaller wall thickness of the spring portion 322 enables the central portion 320 to deflect relative to the outer portion 324 under the influence of the respiratory therapy pressure and to provide a bias to return the central portion 320 to its initial, un-deflected position. In this embodiment, the spring portion 322 is curved. That is, the spring portion 322 has a generally U-shaped curve in cross-section. The curve is concave when viewed from the feed opening 308. In other embodiments, however, the spring portion 322 may be convex when viewed from the feed opening 308.

[1360] The diaphragm 316 comprises a recess 346. The recess 346 is shaped correspondingly to the shape of the protrusion 348. When assembled, as shown in Figure 42, the recesses 344, 346 of the O-ring 314 and the diaphragm 316 are aligned on the protrusion 348. Screwing the body 310 onto the stem 302 compresses the O-ring 314 and the diaphragm 316 between the end face of the stem 302 and the shoulder of the body 310. This securely retains the diaphragm 316 in position within the cavity and forms a seal 6100 which limits gas passing between the protrusion 348 and the recesses.

[1361] The recess 346 further enables less restrictive deformation of the diaphragm 316. That is, the recess 346 enables the diaphragm 316 to deform without restriction through changes in forces around the perimeter of the diaphragm 316. As the diaphragm 316 deforms under changes in the respiratory therapy pressure, forces act along the perimeter of the diaphragm 316. The recess 346 ensures that these forces are decoupled. In other embodiments, the recess 316 may comprise an alternative shape. Furthermore, an organised pattern of recesses 316 may be arranged about the perimeter of the diaphragm 316.

[1362] The central portion 320 comprises a flow opening 318. The flow opening 318 enables respiratory gas to pass through the diaphragm 316. A splint 332 is aligned with and spaced from the flow opening 318. The spacing between the splint 332 and the flow opening 318 defines a throttle channel 334. The splint 332 is tapered outwardly in a direction away from the diaphragm 316. The cross-sectional area of the splint 332 increases in a direction away from the diaphragm 316. Deflection of the flow opening 318 under the influence of respiratory therapy pressure pushes the flow opening 318 closer to the splint 332. The change in position of the flow opening 318 reduces the cross-sectional dimension of the throttle channel 334 through which respiratory gas can flow between the flow opening 318 and the splint 332. In other words, the flow opening 318 and the splint 332 are configured to reduce the cross- sectional dimension in response to an increase in respiratory therapy pressure. Similarly, the flow opening 318 and the splint 332 are configured to increase the cross-sectional dimension in response to a decrease in respiratory therapy pressure. The result is a substantially constant gas flow or a gas flow between upper and lower limits through the flow valve 300 across the range of intended treatment pressures.

[1363] In the illustrated embodiment the splint 332 is supported on positioning arms 330. The positioning arms 330 extend from the side walls to the splint 332. The flow valve 300 incorporates three positioning arms 330. The positioning arms 330 are equally spaced about the splint 332. Each positioning arm has a convex surface facing into the direction of flow of respiratory gas through the flow valve 300. The convex surface reduces turbulence in the flow of respiratory gas. While this embodiment includes a convex surface on the positioning arms 330, alternative surface shapes may be adopted to reduce turbulence or may not be shaped to reduce turbulence. Further, alternative means of positioning and securing the splint 332 may be incorporated.

[1364] As shown in Figure 36, the flow valve 300 includes a filter 340. The filter 340 is disposed between the positioning arms 330 and an end wall 350 of the end cap 336. The filter 340 is omitted from Figures 42 and 43 simply to show the end wall 350 in reference to other features of the flow valve 300. As with other embodiments, the filter 340 may be replaced by a diffuser or may be omitted entirely.

[1365] The end wall 350 comprises an exhaust vent 338. The exhaust vent 338 enables respiratory gas to flow from the flow valve 300 to the external atmosphere. In this embodiment, the exhaust vent 338 comprises an arrangement of holes in the end cap 336. The holes are arranged concentrically around the splint 332. In this embodiment, the arrangement comprises two concentrically arranged rings of holes.

[1366] The screw fitting of the end cap 336 to the body 310 enables the end cap 336 to be removed to access the filter 340 for maintenance or replacement. This enables replacement of the filter 340 without disassembling other parts of the flow valve.

[1367] Although this embodiment comprises a fixed splint 332, other embodiments may comprise a splint 332 which is adjustable in its position relative to the flow opening 318. In that way the splint 332 positioning could be adjusted to adjust the desired gas flow rate through the flow valve 300. For example, the end cap 336 may be adjustably mounted to adjust the position of the splint 332 relative to the flow opening 318. Although the positioning arms 330 are located downstream of the diaphragm 316 in this embodiment, other embodiments may involve the positioning arms 330 being upstream of the diaphragm 316 with the splint 332 suspended on a support arm projecting through the flow opening 318 from the positioning arms 330.

[1368] While the stem 302 incorporates an external thread 306 for coupling with the body 310, alternative coupling arrangements may be adopted. For example, the body 310 and stem 302 may include snap-fit, bayonet-fit, friction-fit or an adhesive connection between them. In other embodiments, the external thread 306 on the stem 302 may be an internal thread and the body 310 may have an external thread to couple with the internal thread of the stem 302. Similarly, the threads 352, 354 of the body 310 and the end cap 336 which couple may be internal and external, respectively or replaced by alternative coupling arrangements.

[1369] Furthermore, the stem 302 may be integrally formed or directly connected to the housing 6200 instead of to the frame 6400. In such an embodiment, the integral formation or the direct connection provides a substantially air-tight path between the second chamber 6016 and the cavity of the flow valve 300. The gasket 6450 or a similar seal is unlikely to be required in this embodiment. The remaining components of the flow valve 300 would interact with the stem 302 as described above.

[1370] An alternative embodiment of a flow valve 400 is shown in Figures 44 to 46. The patient interface 6000 shown in Figure 43 is the same patient interface 6000 shown in Figure 35, except for part of the flow valve 400. This flow valve 400 includes the same stem 302 described above in respect of the flow valve 300. However, the flow valve 400 doesn’t include a body. Instead, the flow valve 400 comprises an end cap 402. The end cap 402 comprises an internal thread 404 which is co-operable with the external thread 306 of the stem 302.

[1371] The end cap 402 further comprises an exhaust vent 428. The exhaust vent 428 is located centrally on an end wall 430 of the end cap 402. The end wall 430 includes ridges 418 (Figure 46 Between the ridges 418 are grooves 420. The ridges 418 and grooves 420 are aligned radially relative to the exhaust vent 428. The ridges 418 taper inwardly in a radially inward direction toward the exhaust vent 428. The grooves 420 taper inwardly in a radially inward direction toward the exhaust vent 428.

[1372] A pressure-displaceable diaphragm 416 rests on the ridges 418 or is spaced a small distance from the ridges 418. The diaphragm 416 is supported on positioning arms 414. The positioning arms 414 are part of a retaining structure 408. Thepositioning arms 414 extend radially from a hub. The retaining structure 408 has an outer perimeter.

[1373] The end cap 402 comprises an internal shoulder 406. The shoulder 406 is annular and extends around the inner wall of the end cap 402. The perimeter of the retaining structure 408 rests on the shoulder 406. The retaining structure 408 further includes a recess 410. The recess 410 is co-operable with a protrusion 412 on the side wall of the end cap 402. When assembled, the protrusion 412 is seated in the recess 410 to correctly align the retaining structure 408 within the end cap 402. In the correct alignment, the positioning arms 414 align with the ridges 418 so that parts of the diaphragm 416 between the positioning arms 414 extend across respective grooves 420. The positioning arms 414 may comprise a concave surface when viewed from the feed inlet. The concave surface reduces turbulence of gas deflected by the positioning arms 414 onto the diaphragm 416. Furthermore, when the end cap 402 is coupled to the stem 302, the end face 304 abuts the retaining structure 408. The retaining structure 408 is clamped between the stem 302 and the end cap 402 when the flow valve 400 is assembled.

[1374] In other embodiments, the diaphragm 416 is captured between the ridges 418 and the retaining structure 408. In such embodiments, the diaphragm 416 is not supported from the retaining structure 408 or any other part of the flow valve 400. In other words, the diaphragm 416 floats in the flow valve 400. For example, the retaining structure 408 may be omitted so the diaphragm 416 may be captured between the stem 302 and the end cap 402.

[1375] In the illustrated embodiment, the diaphragm 416 is connected to the retaining structure 408. The connection may be formed by integrally forming the diaphragm 416 with the retaining structure 408. Alternatively, the diaphragm 416 may be formed separately and then connected to the retaining structure 408. Such connection may be through mechanical connection, through adhesion, or through over-moulding of the diaphragm 416 with the retaining structure 408. Although shown in Figure 46 as a separate component, the diaphragm 416 is connected centrally to the retaining structure 408. This leaves the outer region of the diaphragm 416 free to be displaced toward the end wall 430 under the influence of respiratory therapy pressure. The retaining structure 408 includes detents 422. When the recess 410 is located on theprotrusion 412, the detents 422 are aligned with the outer ends of the grooves 420. This alignment provides a gap for respiratory gas to flow around the outer perimeter of the diaphragm 416 and into an outer end of the grooves 420. The respiratory gas can then flow through the grooves 420 and then through the exhaust vent 428 to the atmosphere.

[1376] Throttle channels 426 are formed by the groove 420 and the diaphragm 416. The outer end of the groove 420 forms an inlet to the throttle channel 426. The opposite end of the groove 420 delivers respiratory gas to the exhaust vent 428. A dimension of the throttle channel 426 changes as the respiratory therapy pressure within the second chamber varies. That is, an increase in the respiratory therapy pressure at least partly pushes the diaphragm 416 into the groove 420 between adjacent ridges 418. This reduces the cross-sectional flow area for the flow of respiratory gas through the throttle channels 426 formed by the groove 420 and the diaphragm 416, thereby limiting respiratory gas flow in response to an increase in the respiratory therapy pressure. The reverse occurs when the respiratory therapy pressure decreases.

[1377] The diaphragm 416 comprises an elastomeric material. The elastomeric material at least partly deforms into the groove 420 under respiratory therapy pressures. The extent of deformation depends on the respiratory therapy pressure. The extent of deformation also depends on the material composition and the dimensions of the diaphragm. The deformation, and therefore, the gas flow rate can be controlled by selecting appropriate material compositions and dimension to suit the respiratory therapy pressures to be applied to a patient.

[1378] Although this embodiment comprises six grooves 420 and six throttle channels 426, other embodiments may have more or fewer grooves 420. For example, an alternative embodiment may comprise a single groove 420 with an exhaust vent 428 at one end and a respiratory gas inlet at another end and with a diaphragm 416 configured to deform into the groove 420 under the influence of respiratory therapy pressure. The diaphragm 416 in such an example may be noncircular, such as a rectangular, triangular, trapezoidal or semi-circular shape. The diaphragm for any of the flow valves 300, 400, 500, 600, 700, 1800, 1850, 2300 or any other suitable flow valve which performs the function described in thisspecification may be non-circular, such as a polygon (including rectangular, triangular, trapezoidal), annular, semi-annular, semi-circular or a segment of any one of those shapes.

[1379] In a further alternative of embodiment, the internal thread 404 of the end cap 402 may be replaced with an external thread 404 which is couplable with an internal thread 404 on the stem 302. In this embodiment, the retaining structure 408 is configured to couple with the end cap 402 to retain it in position when the flow valve 400 is assembled. A diffuser or filter may be incorporated at the exhaust vent 428 or downstream of the exhaust vent 428. Furthermore, the end cap 402 may alternatively connect to the stem 302 in any suitable way such as by friction fit, interference fit, welding or adhering.

[1380] Another alternative embodiment of a flow valve 500 is shown in Figures 47 to 49. The flow valve 500 comprises an end cap 502 which couples with the stem 302. The end cap 502 comprises an internal thread 504 to couple with the external thread 306 of the stem 302. The end cap 502 further comprises an exhaust vent 518. The exhaust vent 518 is formed in the end wall 520. The exhaust vent 518 comprises a series of arcuate openings.

[1381] The flow valve 500 comprises a pressure displaceable diaphragm. The diaphragm comprises an umbrella panel 506 which is concave when viewed from the feed opening. The umbrella panel 506 comprises a convex side. The convex side faces the exhaust vent 518. The umbrella panel 506 extends across and is spaced from the exhaust vent 518 to define a throttle channel 516 between the umbrella panel 506 and the exhaust vent 518. The spacing between the umbrella panel 506 and the exhaust vent 518 varies depending upon the respiratory therapy pressure within the second chamber of the patient interface. Deformation of the umbrella panel 506 to reduce the spacing between the umbrella panel 506 and the exhaust vent 518 reduces the dimension of the throttle channel 516 and, in turn, reduces respiratory gas flow through the flow valve 500.

[1382] The umbrella panel 506 is mounted to the end wall 520. The umbrella panel 506 is formed of an elastomeric material. This enables the umbrella panel 506 to deform under the influence of respiratory therapy pressure. Figures 47 and 49 show that the umbrella panel 506 is integrally formed with a neck 508 and a stop 510. Theneck 508 projects from a convex side of the umbrella panel 506. The neck 508 is aligned centrally on the umbrella panel 506. The umbrella panel 506 is mounted to the end wall 520 by pushing the stop 510 through a hole 522. The stop 510 deforms to move through the hole but reverts to the shape shown in Figure 49 once it is through the hole 522, as shown in Figure 47. An enlarged dimension of the stop 510 prevents it from being pulled back through the hole 522 during regular use. In alternative embodiments, the umbrella panel 506 may be over-moulded to the end wall 520 or connected mechanically in a way that enables removal of the umbrella panel 506 or may be connected permanently. The umbrella panel may additionally be non-circular and have a rectangular shape for example.

[1383] The umbrella panel 506 includes a central region 512 and a perimeter 514. The central region 512 has a wall thickness that is less than the wall thickness of the umbrella panel 506 at the perimeter 514. That is, the wall thickness of the umbrella panel 506 increases from the central region 512 to the perimeter 514. Under the influence of respiratory therapy pressure, the central region 512 is less resilient than the perimeter 514. Therefore, the central region 512 deforms initially by flattening against the end wall 520. This flattening brings the perimeter 514 closer to the exhaust vent 518 and decreases a dimension of the throttle channel 516. The reduction in the dimension reduces the flow rate of respiratory gas around the perimeter 514 of the umbrella panel 506 and through the exhaust vent 518. A ratio of the wall thickness of the perimeter 514 to the wall thickness of the central region 512 is >1 .0 to 3.0. Once this central region 512 has deformed, and therapy pressure increased, the more resilient outer perimeter 514 begins to deform to control the gas flow rate through the flow valve 500.

[1384] Although Figures 47 and 48 show four arcuate openings forming the exhaust vent 518, there may be more or fewer openings in the end wall 520 to form the exhaust vent 518.

[1385] Another alternative flow valve 1800 is shown in Figures 52 to 54. This flow valve 1800 comprises an end cap 1802 which is couplable to the stem 302. The end cap 1802 is the same as the end cap 1802 of the flow valve 1800. The end cap 1802 comprises an internal thread 1806 to couple with the external thread 304 of the stem 302. The end cap 1802 further comprises an outlet. The outlet is in an end wall 1808.In this embodiment, the outlet comprises a single opening 1804. In other embodiments, the outlet may comprise more than one opening 1804. For example, the outlet may comprise an array of holes.

[1386] The flow valve 1800 comprises a diaphragm 1830 and a retaining structure 1810. The retaining structure 1810 comprises a panel 1816. The panel 1816 is surrounded by a perimeter wall 1814. The perimeter wall 1814 extends in an upstream direction from the panel 1816. The perimeter wall 1814 terminates at a rim 1840. The panel 1816 is recessed from the rim 1840. The panel 1816 comprises a contact surface 1818. The contact surface 1818 is an upstream side of the panel 1816. The contact surface 1818 is convex, when viewed from the feed opening 1804. The panel 1816 further comprises as a central boss 1824. The boss 1824 comprises a through-hole 1826 which forms an anchor point for the diaphragm 1830. A series of exhaust vents are formed in the panel 1816 about the boss 1824. In this embodiment, the flow valve 1800 comprises an array of radially inner exhaust vents 1820 and an array of radially outer exhaust vents 1822 relative to the boss 1824. A cross-sectional flow area of each of the radially inner exhaust vents 1820 is less than a cross-sectional flow area of each of the radially outer exhaust vents 1822. In other embodiments, all of the exhaust vents may have the same cross-sectional flow area or the cross-sectional flow area of the radially inner exhaust vents 1820 may be greater than the cross-sectional flow area of the radially outer exhaust vents 1822. In this embodiment, half of the radially outer exhaust vents 1822 are spaced from the perimeter wall 1814. The other half of the radially outer exhaust vents 1822 include a recess 1828 from the contact surface 1818. The recess 1828 extends to the perimeter wall 1814.

[1387] The retaining structure 1810 further comprises a shoulder 1812. The shoulder 1812 extends generally orthogonally from the perimeter wall 1814. The shoulder 1812 extends from an end of the perimeter wall 1814 that is remote from the rim 1840. This location of the shoulder 1812 is downstream of the panel 1816. The shoulder 1812 has an annual form. The shoulder 1812 has an outer radial dimension that fits within the inner radial dimension of the end cap 1802.

[1388] The diaphragm 1830 is substantially flat at rest, when viewed from the feed opening 1804. The diaphragm 1830, in this embodiment, is a disc, but may inalternative embodiments be rectangular or non-circular. Diaphragm 1830 is formed of elastomeric material. The elastomeric material makes the diaphragm 1830 deformable under respiratory therapy pressures. The diaphragm 1830 further comprises a neck 1832 which is couplable to the hole 1826 of the boss 1824. The neck 1832 comprises a bead 1842. The bead 1842 has an enlarged diameter compared to the diameter of hole 1826. The neck 1832 further comprises an end 1834 with a diameter that is less than the diameter of the hole 1826. The reduced diameter of the end 1834 assists with insertion of the neck 1832 into the hole 1826. The diaphragm 1830 is coupled to the boss 1824 by inserting the neck 1832 into the hole 1826. In doing so, the bead 1842 compresses to fit within the hole 1826. The compressed elastomeric material has a tendency to expand. That tendency causes the diaphragm 1830 to be retained in the boss 1824 by a friction fit. In one alternative embodiment, the diaphragm 1830 may be coupled to the panel 1816 in the same way that the diaphragm 1830 is coupled to the end wall 1808 of the flow valve 1800. In alternative embodiments, the diaphragm 1830 may be over-moulded to the panel 1816, may be adhered to the panel 1816 or may connected mechanically in a way that enables removal of the diaphragm 1830 or may be connected permanently to the panel 1816.

[1389] When the diaphragm 1830 is coupled to the panel 1816, a spacing is formed between the diaphragm 1830 and the convex contact surface 1818 of the panel 1816. The spacing between the diaphragm 1830 and the exhaust vents 1822 formed in the contact surfae1818 defines a throttle channel 1838. The spacing between the diaphragm 1830 and the exhaust vents 1822 varies depending upon the respiratory therapy pressure within the upper chamber of the patient interface. Deformation of the diaphragm 1830 to reduce the spacing between the diaphragm 1830 and the exhaust vents 1822 reduces the dimension of the throttle channel 1838 and, in turn, reduces respiratory gas flow through the flow valve 1800. That is, as the respiratory therapy pressuring increases, the point at which the diaphragm 1830 contacts the contact surface 1818 extends radially outwardly from the boss 1824. As the respiratory therapy pressure increases the throttle channel 1838 leading to the radially inner exhaust events decreases until the diaphragm 1830 contacts the contact surface 1818 at a location radially outwardly of the inner exhaust vents 1820. At this point, the radially inner exhaust vents 1820 are closed by the diaphragm1830. As the respiratory therapy pressure increases further, the diaphragm 1830 wraps further over the contact surface 1818, further reducing the throttle channel 1838. The radial dimension of the diaphragm 1830 is less than the radial dimension of the perimeter wall 1814. This leaves a gap between the radially outer edge 1836 of the diaphragm 1830 and the perimeter wall 1814. The gap combined with the recesses 1828 maintain the throttle channel 1838 even at respiratory therapy pressures which cause the diaphragm 1830 to wrap entirely across the contact surface 1818. This ensures a minimum continued flow of respiratory gas through the flow valve 1800 for all respiratory therapy pressures.

[1390] The curvature of the convex contact surface 1818 affects the spacing between the contact surface 1818 and the diaphragm 1830. That is, a smaller radius of curvature will provide for a larger spacing and, therefore, a larger throttle channel 1838. A smaller throttle channel 1838 is provided by a larger radius of curvature for the contact surface 1818. Providing a range of flow valve 1800s with different curvature of the contact surface 1818 allows for an appropriate flow valve 1800 to be selected for a given patient’s respiratory therapy needs. Alternatively, providing a range of diaphragm 1830s with different moduli of elasticity allows for variations in response to different respiratory therapy pressures. For example, a lower modulus of elasticity will make a diaphragm 1830 more susceptible to deformation at a given respiratory therapy pressure than a diaphragm 1830 with a higher modulus of elasticity. The lower modulus of elasticity will result in smaller throttle channels 1838 for a given respiratory therapy pressure than compared to the throttle channels 1838 of a diaphragm 1830 with a higher modulus of elasticity at the same respiratory therapy pressure.

[1391] The flow valve 1800 may be incorporated into a patient interface at any location that is in fluid communication with the upper chamber. This means that the flow valve 1800 may be incorporated into the housing or into the frame or into the elbow or into the seal.

[1392] An alternative embodiment of a retaining structure 1850 for the flow valve 1800 is shown in Figures 55 and 56. In this embodiment, the retaining structure 1850 comprises a perimeter wall 1854, a panel 1856 and a shoulder 1852. The panel 1856 is at a downstream end of the perimeter wall 1854. The shoulder 1852 projectsfrom an upstream end of the perimeter wall 1854. The shoulder 1852 has the same form as the shoulder 1852 described above in respect of the retaining structure 1810.

[1393] The panel 1856 comprises a contact surface 1858. The contact surface 1858 has a convex curvature when viewed from the upper chamber. The comments above in respect of the contact surface 1858 of the retaining structure 1810 apply equally here in respect of the contact surface 1858. In this embodiment, the retaining structure 1810 further comprises an anchor member 1864. The anchor member 1864 is integrally formed with the retaining structure 1810. The anchor member 1864 comprises a neck 1866 projecting from the panel 1856 and lip 1868 protecting radially from the neck 1866. This configuration provides a groove between the lip 1868 and the panel 1856. A retaining structure 1810 further comprises a diaphragm 1870. The diaphragm 1870 has the same form as described above in respect of the flow valve 1800, save for comprising a central opening 1804 that is capable with the anchor member 1864. That is, central opening 1804 is stretched over the lip 1868 so that the opening 1804 seats in the groove. This couples the diaphragm 1870 to the retaining structure 1810. Any suitable configuration for coupling the diaphragm 1870 to the retaining structure 1810 may be adopted in place of the retaining structure 1810. Such suitable coupling configuration may enable permanent or removable coupling.

[1394] As shown in Figure 56, a spacing between the diaphragm 1870 and the contact surface 1858 forms a throttle channel 1874. The panel 1856 comprises an array of exhaust vents 1860. In this embodiment, each of the exhaust vents 1860 have a different cross-sectional flow area shape. That is, the shape of the cross- sectional flow area of each exhaust vent 1860 is different to the shape of the cross- sectional flow area of another exhaust vent 1860 in the panel 1856. For example, exhaust vent 1860-A in Figure 55 has a cross-sectional flow area shape that is a stadium shape. Exhaust vent 1860-B has a cross-sectional flow area shape that diverges in a direction radially away from the anchor member 1864 and that is spaced from the perimeter wall 1854. Furthermore, exhaust vent 1860-C has a cross-sectional flow area shape that also diverges in a direction radially away from the anchor member 1864, but is narrower in the circumferential direction, and that extends to the perimeter wall 1854. Exhaust vent 1860-A extends beyond the umbraof the diaphragm 1870 when viewed from the upper chamber. As the diaphragm 1870 wraps over the contact surface 1858 as a result of increasing respiratory therapy pressure, each of the exhaust vents 1860 will be concealed to different extents due to their different cross-sectional flow areas, shapes and locations. The selection of different cross-sectional flow areas, shapes and locations of the exhaust vents 1860 controls the flow rate of respiratory gas through the flow valve 1800 in response to different respiratory therapy pressures. The selection allows for an appropriate flow valve 1800 to be provided for a given patient’s respiratory therapy needs and / or for a given flow valve 1800 behavior.

[1395] Figures 57 to 59 show another embodiment of a flow valve 3000. The flow valve is a variation of the flow valve 300. As with the flow valve 300, the flow valve 3000 controls the flow rate of respiratory gas from within the second chamber 6016 of the cushion module 6010 to external of the cushion module 6010 in response to the pressure of the respiratory gas within the second chamber 6016. This is achieved by a pressure-displaceable diaphragm 2316 within the flow valve 2300. The pressure-displaceable diaphragm 2316 is formed of a resilient material. The pressure-displaceable diaphragm 2316 comprises an outer portion 2324, a central portion 2320 and a spring portion 2322 connecting the outer and central portions 2320, 2324.

[1396] The flow valve further comprises a stem and a body. The stem may be integrally formed with the housing or the frame or may be linked to the seal. The body is couplable with the stem. Any suitable mechanical coupling of the body and the stem may be utilised. The mechanical coupling may be releasable or may be permanent. In an alternative embodiments, the body and the stem may be integrally formed as a single component. In this embodiment, the body and the stem are couplable by a bayonet fit. That is the body comprises three fingers. The fingers are equally spaced about the body. The stem comprises a radial shoulder at an inlet end of the stem. The stem further comprises three slots. The slo...

Claims

CLAIMS1 . A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of the patient, the patient interface comprising:• a first chamber and a second chamber, the first and second chamber are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across a range of respiratory therapy pressures.

2. The patient interface defined in claim 1 , wherein the flow valve is configured to control the flow of respiratory gas from the second chamber in response to variations in the respiratory therapy pressure.

3. The patient interface defined in claim 1 or claim 2, wherein the flow valve comprises a flow path from the second chamber to a flow outlet and a pressure-displaceable diaphragm positioned at least partially within the flow path.

4. The patient interface defined in claim 3, wherein the pressure-displaceable diaphragm is deformable in response to the respiratory therapy pressure so that a cross-sectional area of the flow path is less for higher respiratory therapy pressures than the cross-sectional area of the flow path is for lower respiratory pressures.

5. The patient interface defined in any one of the preceding claims, wherein the flow valve is manually adjustable to control the flow of respiratory gas from the second chamber.

6. The patient interface defined in any one of the preceding claims, wherein the flow outlet comprises a plurality of apertures.

7. The patient interface defined in claim 6, wherein the one or more apertures of the plurality of apertures have a cross-sectional flow area that is different to the cross-sectional flow area of the other apertures.

8. The patient interface defined in any one of the preceding claims, wherein the preferred range is 10 L / m to 30 L / m or the preferred range is 10 L / m to 20 L / m across the range of respiratory therapy pressures.

9. The patient interface defined in any one of claims 1 to 7, wherein the flow valve enables the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of intended respiratory therapy pressures.

10. The patient interface defined in claim 9, wherein the flow valve enables the respiratory gas flow rate to be greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

11. The patient interface defined in any one of the preceding claims, wherein the range of respiratory therapy pressures is 4cmH20 to 35cmH20, or 5cmH20 to 30cmH20, or 6cmH20 to 25cmH20, or 7cmH20 to 20cmH20, or 8cmH20 to 25cmH20.

12. The patient interface defined in any one of the preceding claims, wherein the flow valve comprises a diffuser or a filter.

13. The patient interface defined in any one of the preceding claims, wherein the first chamber is configured to communicate respiratory gas with the mouth, and the second chamber is configured to communicate respiratory gas with the one or more nares.

14. The patient interface defined in any one of claims 1 to 12, wherein the first chamber is configured to communicate respiratory gas with the one or more nares, and the second chamber is configured to communicate respiratory gas with the mouth.

15. The patient interface defined in any one of the preceding claims, wherein the patient interface further comprises a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient.

16. The patient interface defined in claim 15, wherein the seal is configured to enable fluid communication between the first and second chambers and the mouth and the one or more nares.

17. The patient interface defined in claim 15 or claim 16, wherein the patient interface further comprises a housing that structurally supports the seal.

18. The patient interface defined in claim 17, wherein the housing and seal together form a cushion module comprising the first chamber and second chamber.

19. The patient interface defined in claim 17 or claim 18, wherein the patient interface further comprises a frame that is couplable to headgear and to either the housing or the seal.

20. The patient interface defined in any claims 17 to 19, wherein at least part of the flow valve is integrally formed with the housing.

21. The patient interface defined in claim 19, wherein at least part of the flow valve is integrally formed with the frame.

22. The patient interface defined in any one of claims 17 to 19, wherein at least part of the flow valve is integrally formed with the seal.

23. The patient interface defined in claim 18, wherein at least part of the flow valve is integrally formed with the cushion module.

24. The patient interface defined in claim 19, wherein the flow valve is removably couplable to the housing or to the frame.

25. The patient interface defined in claim 18, wherein the flow valve is removably couplable to the cushion module.

26. The patient interface defined in any one of the preceding claims, wherein the patient interface comprises a dividing wall that separates the first chamber from the second chamber.

27. The patient interface defined in claim 18, wherein the cushion module comprises a dividing wall that separates the first chamber from the second chamber.

28. The patient interface defined in claim 26 or claim 27, wherein the dividing wall comprises one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber.

29. The patient interface defined in claim 28, wherein the or each flow director has a cross-sectional flow area.

30. The patient interface defined in claim 29, wherein the dividing wall comprises two or more flow directors and each flow director comprises the same cross- sectional flow area as the or each of the other flow directors.

31. The patient interface defined in claim 29, wherein the dividing wall comprises two or more flow directors and at least one flow director comprises a cross- sectional flow area that is different to the cross-sectional flow area of the or each of the other flow directors.

32. The patient interface defined in claim 26 or claim 27, wherein the dividing wall comprises a single flow director.

33. A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising:• a first chamber configured to communicate respiratory gas with the mouth of the patient;• a second chamber configured to communicate respiratory gas with one or both nares of the patient;• the first and second chambers are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber• a respiratory gas outlet in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface; and• a pressure valve that is configured to control the flow of respiratory gas between the first chamber and the second chamber to provide a respiratory gas pressure in the second chamber that is lower than a respiratory gas pressure in the first chamber across a range of respiratory therapy pressures.

34. The patient interface defined in claim 33, wherein the pressure valve enables the respiratory gas pressure in the second chamber that is in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first chamber across the range of respiratory therapy pressures.

35. The patient interface defined in claim 33, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is less than 4.0 cmH2O, less than 3.5 cmFhO, less than 3.0 cmFhO, less than 2.5 cmFhO, less than 2.0 cmH2O, less than 1 .5 cmFLO, less than 1.4 cmFLO, less than 1.3 cmFLO, less than 1 .2 cmFhO, less than 1 .1 cmFhO, less than 1 .0 cmFhO, less than 0.9 cmH2O, less than 0.8 cmH2O, less than 0.7 cmH2O, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of respiratory therapy pressures.

36. The patient interface defined in claim 33, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is greater than 0.2 cmH2O, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5 greater than cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmH2O, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1.0 cmFhO, greater than 1 .1 cmFhO or greater than 1 .2 cmFhO lower than the respiratory gas pressure in the first chamber across the range of respiratory therapy pressures.

37. The patient interface defined in any one of claims 33 to 36, wherein the pressure valve is configured to control the flow of respiratory gas from the first chamber to the second chamber in response to the respiratory gas pressure in the second chamber.

38. A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface comprising:• a first chamber configured to communicate respiratory gas with the mouth of the patient;• a second chamber configured to communicate respiratory gas with one or both nares of the patient;• the first chamber and the second chamber being in fluid communication within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a respiratory gas outlet in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface; and• a pressure valve that is configured to permit gas flow from the first chamber to the second chamber when the pressure in the second chamber is at least a first threshold amount lower than the pressure in the first chamber, the first threshold amount being maintained across a range of respiratory therapy pressures.

39. The patient interface defined in claim 38, wherein the first threshold amount is in the range of 0.2 to 4.0 cmH2O, 0.3 to 3.5 cmH2O, 0.4 to 3 cmH2O, 0.5 to 2.5 cmH2O, or 0.6 to 2 cmH2O.

40. The patient interface defined in claim 38, wherein the first threshold amount is greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5 cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmH2O, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1 .0 cmH2O, greater than 1 .1 cmFhO or greater than 1 .2 cmFhO.

41. The patient interface defined in any one of claims 33 to 40, wherein the pressure valve comprises a pressure-displaceable diaphragm.

42. The patient interface defined in any one of claims 33 to 40, wherein the pressure valve comprises a flap valve.

43. The patient interface defined in any one of claims 33 to 42, wherein the patient interface comprises a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient and a housing that structurally supports the seal.

44. The patient interface defined in claim 43, wherein the seal is configured to enable fluid communication between the first and second chambers and the mouth and the one or more nares.

45. The patient interface defined in claim 44, wherein the seal and housing together define a cushion module.

46. The patient interface defined in claim 45, wherein the cushion module comprises the first chamber and the second chamber.

47. The patient interface defined in claim 45 or claim 46, wherein the patient interface comprises a frame that is couplable to headgear and to the cushion module.

48. The patient interface defined in any one of claims 33 to 47, wherein the patient interface comprises a dividing wall that separates the first chamber from the second chamber.

49. The patient interface defined in any one of claims 45 to 47, wherein the cushion module comprises a dividing wall that separates the first chamber from the second chamber.

50. The patient interface defined in any one of claims 43 to 47, wherein the seal comprises the dividing wall.

51. The patient interface defined in any one of claims 43 to 47, wherein the housing comprises the dividing wall.

52. The patient interface defined in claim 51 , wherein the dividing wall is formed in part by the seal and in part by the housing.

53. The patient interface defined in claim 51 or claim 52, wherein the pressure valve is integral with the dividing wall.

54. The patient interface defined in claim 51 or claim 52, wherein the pressure valve is couplable with the dividing wall.

55. The patient interface defined in claim 51 or claim 52, wherein the pressure valve is part of an insert that is co-operable with the dividing wall to separate the first chamber from the second chamber.

56. The patient interface defined in claim 47, wherein the pressure valve is part of an insert that is couplable with the frame, the housing or the seal.

57. The patient interface defined in claim 44, wherein the pressure valve is located externally of the cushion module.

58. The patient interface defined in claim 44, wherein the pressure valve is located within a conduit connector which is configured to connect to the cushion module.

59. The patient interface defined in claim 49, wherein the dividing wall comprises one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber within the patient interface.

60. The patient interface defined in claim 59, wherein the or each flow director has a cross-sectional flow area.

61. The patient interface defined in claim 59, wherein the dividing wall comprises two or more flow directors and each flow director comprises the same cross- sectional flow area as the or each of the other flow directors.

62. The patient interface defined in claim 59, wherein the dividing wall comprises two or more flow directors and at least one flow director comprises a cross- sectional flow area that is different to the cross-sectional flow area of the or each of the other flow directors.

63. The patient interface defined in claim 59, wherein the dividing wall comprises a single flow director.

64. A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of a patient, the patient interface comprising:• a first chamber and a second chamber, the second chamber being configured to communicate a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to control the flow of respiratory gas from the first chamber to the second chamber within the patient interface to provide a respiratory gas pressure in the second chamber that is lower than the respiratory gas pressure in the first chamber across a range of respiratory therapy pressures;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber toexternal of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across the range of respiratory therapy pressures; and• a relief valve that is configured to communicate respiratory gas from the second chamber to the first chamber within the patient interface when the respiratory gas pressure in the second chamber is greater than the respiratory gas pressure in the first chamber.

65. The patient interface defined in claim 64, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

66. The patient interface defined in claim 64, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is less than 4.0 cmH2O, less than 3.5 cmFhO, less than 3.0 cmFhO, less than 2.5 cmFhO, less than 2.0 cmH2O, less than 1 .5 cmFLO, less than 1 .4 cmFLO, less than 1 .3 cmFLO, less than 1 .2 cmFhO, less than 1 .1 cmFhO, less than 1 .0 cmFhO, less than 0.9 cmH2O, less than 0.8 cmH2O, less than 0.7 cmH2O, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

67. The patient interface defined in claim 64, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is greater than 0.0 cmH2O, greater than 0.1 cmFhO, greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than O.ScmfW, greater than 0.6 cmFhO, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmH2O, greater than 1 .0 cmFhO, greater than 1 .1 cmFhO or greater than 1 .2 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

68. A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas withthe mouth and with one or both nares of a patient, the patient interface comprising:• a first chamber and a second chamber, the second chamber being in fluid communication with the first chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to permit gas flow from the first chamber to the second chamber when the pressure in the second chamber is at least a first threshold amount lower than the pressure in the first chamber, the first threshold amount being maintained across a range of respiratory therapy pressures;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be within a preferred range across the range of respiratory therapy pressures; and• a relief valve that is configured to permit gas flow from the second chamber to the first chamber when the pressure in the second chamber is at least a second threshold amount greater than pressure in the first chamber.

69. The patient interface defined in claim 68, wherein the first threshold amount is in the range of 0.2 to 4.0 cmH2O, 0.3 to 3.5 cmH2O, 0.4 to 3 cmH2O, 0.5 to 2.5 cmH2O, or 0.6 to 2 cmH2O.

70. The patient interface defined in claim 68, wherein the first threshold amount is greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5 cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmH2O, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1 .0 cmH2O, greater than 1 .1 cmFhO or greater than 1 .2 cmFhO.

71. The patient interface defined in claim 68, wherein the second threshold amount is greater than O.OcmFhO, greater than 0.05 cmFhO, greaten than 0.1 cmFhO, greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4cmH2O, or greater than 0.5 cmFhO.

72. The patient interface defined in any one of claims 64 to 71 , wherein the flow valve is configured to control the flow of respiratory gas from the second chamber in response to variations in the respiratory therapy pressure.

73. The patient interface defined in any one of claims 64 to 71 , wherein the flow valve is manually adjustable to control the flow of respiratory gas from the second chamber.

74. The patient interface defined in any one of claims 64 to 73, wherein the flow valve comprises a flow path from the second chamber to a flow outlet and comprises a pressure-displaceable diaphragm positioned at least partially within the flow path.

75. The patient interface defined in claim 74, wherein the pressure-displaceable diaphragm is deformable in response to the respiratory therapy pressure so that a cross-sectional area of the flow path is less for higher respiratory therapy pressures than the cross-sectional area of the flow path is for lower respiratory pressures.

76. The patient interface defined in any one of claims 64 to 75, wherein the preferred range is 10 L / m to 30 L / m or the preferred range is 10 L / m to 20 L / m across the range of respiratory therapy pressures.

77. The patient interface defined in any one of claims 64 to 75, wherein the flow valve enables the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m less than 13 L / m, or less than 12 L / m across the range of respiratory therapy pressures.

78. The patient interface defined in claim 64, wherein the flow valve enables the respiratory gas flow rate to be is greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

79. The patient interface defined in any one of claims 64 to 78, wherein the range of respiratory therapy pressures is 4 cmH20 to 35 cmH20, or 5 cmH20 to 30 cmH20, or 6 cmH2O to 25 cmH20, or 7 cmH20 to 20 cmH20, or 8 cmH20 to 25 cmH20.

80. The patient interface defined in any one of claims 64 to 79, wherein the flow valve comprises a diffuser or a filter.

81. The patient interface defined in any one of claims 64 to 80, wherein the pressure valve is configured to control the flow of respiratory gas from the first chamber to the second chamber in response to the respiratory gas pressure in the second chamber.

82. The patient interface defined in claim 81 , wherein the pressure valve comprises a first pressure-displaceable diaphragm.

83. The patient interface defined in claim 81 , wherein the pressure valve comprises a flap valve.

84. The patient interface defined in any one of claims 64 to 83, wherein the relief valve comprises a second pressure-displaceable diaphragm.

85. The patient interface defined in claim 84, wherein the relief valve comprises a flap valve.

86. The patient interface defined in any one of claims 64 to 85, wherein the patient interface comprises a dividing wall that separates the first chamber from the second chamber.

87. The patient interface defined in claim 86, wherein the relief valve comprises a flap valve portion of the dividing wall.

88. The patient interface defined in claim 86 or claim 87, wherein the patient interface comprises an insert that is co-operable with the dividing wall to separate the first chamber from the second chamber.

89. The patient interface defined in claim 88, wherein the flap valve portion overlays part of one side of the insert that defines the first chamber.

90. The patient interface defined in claim 88 or claim 89, wherein the flap valve portion is configured to be urged into contact with the insert when the respiratory gas pressure in the first chamber is greater than the respiratory gas pressure in the second chamber and is configured to form an gap with the insert which enables respiratory gas to flow from the second chamber to the first chamber when the respiratory gas pressure in the second chamber is greater than the respiratory gas pressure in the first chamber.

91. The patient interface defined in any one of claims 64 to 90, wherein the patient interface further comprises a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient.

92. The patient interface defined in claim 91 , wherein the patient interface further comprises a housing that structurally supports the seal.

93. The patient interface defined in claim 92, wherein the housing and seal together form a cushion module comprising the first chamber and second chamber.

94. The patient interface defined in claim 93, wherein the cushion module comprises a dividing wall that separates the first chamber from the second chamber.

95. The patient interface defined in any one of claims 91 to 94, wherein the patient interface comprises a frame that is couplable to headgear and to either the housing or the seal.

96. The patient interface defined in claim 93 or claim 94, wherein at least part of the flow valve is integrally formed with the housing.

97. The patient interface defined in claim 95, wherein at least part of the flow valve is integrally formed with the frame.

98. The patient interface defined in any one of claims 91 to 94, wherein at least part of the flow valve is integrally formed with the seal.

99. The patient interface defined in claim 93 or claim 94, wherein at least part of the flow valve is integrally formed with the cushion module.

100. The patient interface defined in claim 92 or claim 95, wherein at flow valve is removably couplable to the housing or to the frame.101 . The patient interface defined in claim 93 or claim 94, wherein at flow valve is removably couplable to the cushion module.

102. The patient interface defined in claim 86 or claim 94, wherein the dividing wall comprises one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber within the patient interface.

103. The patient interface defined in claim 102, wherein the or each flow director has a cross-sectional flow area.

104. The patient interface defined in claim 102 or claim 103, wherein the dividing wall comprises two or more flow directors and each flow director comprises the same cross-sectional flow area as the or each of the other flow directors.

105. The patient interface defined in claim 102 or claim 103, wherein the dividing wall comprises two or more flow directors and at least one flow director comprises a cross-sectional flow area that is different to the cross-sectional flow area of the or each of the other flow directors.

106. The patient interface defined in claim 102 or claim 103, wherein the dividing wall comprises a single flow director.

107. The patient interface defined in claim 94, wherein the dividing wall is formed in part by the housing and in part by the seal.

108. The patient interface defined in claim 91 when dependent upon claim 86, wherein the dividing wall partly comprises the relief valve.

109. A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of the patient, the patient interface comprising:• a first chamber and a second chamber, the first and second chambers are in fluid communication to enable a flow of respiratory gas from the first chamber to the second chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to control the fluid communication between the first chamber and the second chamber to provide a respiratory gas pressure in the second chamber that is lower than the respiratory gas pressure in the first chamber across a range of different respiratory therapy pressures;• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from the second chamber to external of the patient interface and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be below an upper limit across the range of respiratory therapy pressures.

110. The patient interface defined in claim 109, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

111. The patient interface defined in claim 109, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is less than 4.0 cmH2O, less than 3.5 cmFhO, less than 3.0 cmFhO, less than 2.5 cmFhO, less than 2.0 cmH2O, less than 1 .5 cmFLO, less than 1 .4 cmFLO, less than 1 .3 cmFLO, less than 1 .2 cmFhO, less than 1 .1 cmFhO, less than 1 .0 cmFhO, less than 0.9 cmH2O, less than 0.8 cmH2O, less than 0.7 cmH2O, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

112. The patient interface defined in claim 111 , wherein the pressure valve enables a respiratory gas pressure in the second chamber that is greater than 0.0 cmH2O, greater than 0.1 cmFhO, greater than 0.2 cmFhO, greater than 0.3 cmH2O, greater than 0.4 cmFhO, greater than 0.5cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1 .0 cmFhO, greater than 1 .1 cmFhO or greater than 1 .2 cmH2O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

113. A patient interface for delivering positive pressure respiratory therapy to a patient, the patient interface is configured to communicate respiratory gas with the mouth and with one or both nares of a patient, the patient interface comprising:• a first chamber and a second chamber, the second chamber being in fluid communication with the first chamber within the patient interface;• a respiratory gas inlet in fluid communication with the first chamber;• a pressure valve that is configured to permit gas flow from the first chamber to the second chamber when the pressure in the second chamber is at least a first threshold amount lower than the pressure in the first chamber, the first threshold amount being maintained across a range of respiratory therapy pressures; and• a flow valve in fluid communication with the second chamber and through which respiratory gas is exhaustible from within the second chamber to external of the patient interface and which flow valve is configured to controla respiratory gas flow rate through the flow valve to be within a preferred range across the range of respiratory therapy pressures.

114. The patient interface defined in claim 113, wherein the first threshold amount is in the range of 0.2 to 4.0 cmH2O, 0.3 to 3.5 cmH2O, 0.4 to 3 cmH2O, 0.5 to 2.5 cmH2O, or 0.6 to 2 cmH2O.

115. The patient interface defined in claim 109, wherein the first threshold amount is greater than 0.2 cmFhO, greater than 0.3 cmFhO, greater than 0.4 cmFhO, greater than 0.5 cmH2O, greater than 0.6 cmH2O, greater than 0.7 cmH2O, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1 .0 cmH2O, greater than 1 .1 cmFhO or greater than 1 .2 cmFhO.

116. The patient interface defined in any one of claims 109 to 115, wherein the flow valve is configured to control the flow of respiratory gas from the second chamber in response to variations in the respiratory therapy pressure.

117. The patient interface defined in any one of claims 109 to 116, wherein the flow valve comprises a flow path from the second chamber to a flow outlet and a pressure-displaceable diaphragm positioned at least partially within the flow path.

118. The patient interface defined in claim 117, wherein the flow outlet comprises a plurality of apertures.

119. The patient interface defined in claim 118, wherein the one or more of the plurality of apertures have a cross-sectional flow area that is different to the cross-sectional flow area of the other apertures.

120. The patient interface defined in any one of claims 117 to 119, wherein the pressure-displaceable diaphragm is deformable in response to the respiratory therapy pressure so that a cross-sectional area of the flow path is less for higher respiratory therapy pressures than the cross-sectional area of the flow path is for lower respiratory pressures.

121. The patient interface defined in any one of claims 109 to 115, wherein the flow valve is manually adjustable control of the flow of respiratory gas from the second chamber.

122. The patient interface defined in any one of claims 109 to 121 , wherein the flow valve enables a flow rate within the range of 10 L / m to 30 L / m or within the range of 10 L / m to 20 L / m across the range of respiratory therapy pressures.

123. The patient interface defined in any one of claims 109 to 121 , wherein the flow valve enables the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of respiratory therapy pressures.

124. The patient interface defined in claim 123, wherein the flow valve enables the respiratory gas flow rate to be is greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

125. The patient interface defined in any one of claims 109 to 124, wherein the range of respiratory therapy pressures is 4 cmh^O to 35 cmh^O, or 5 cmh^O to 30 cmh O, or 6 cmh^O to 25 cmh^O, or 7 cmhhO to 20 cmh^O, or 8 cmh^O to 25 cmh O.

126. The patient interface defined in any one of claims 109 to 125, wherein the pressure valve enables a respiratory gas pressure in the second chamber that is in the range of 0.2 to 4.0 cmh^O lower than the respiratory gas pressure in the first chamber across the range of different respiratory therapy pressures.

127. The patient interface defined in any one of claims 109 to 126, wherein the pressure valve is configured to control the flow of respiratory gas from the first chamber to the second chamber in response to the respiratory gas pressure in the second chamber.

128. The patient interface defined in any one of claims 109 to 127, wherein the pressure valve comprises a deformable diaphragm.

129. The patient interface defined in any one of claims 109 to 127, wherein the pressure valve comprises a flap valve.

130. The patient interface defined in any one of claims 109 to 129, wherein the flow valve comprises a diffuser or a filter.

131. The patient interface defined in any one of claims 109 to 130, wherein the patient interface comprises a dividing wall that separates the first chamber from the second chamber.

132. The patient interface defined in any one of claims 109 to 131 , wherein the patient interface further comprises a seal that is configured to form a substantially airtight seal about the nares and mouth of a patient.

133. The patient interface defined in claim 132, wherein the patient interface further comprises a housing that structurally supports the seal.

134. The patient interface defined in claim 133, wherein the housing and seal together form a cushion module comprising the first chamber and second chamber.

135. The patient interface defined in claim 134, wherein the cushion module comprises a dividing wall that separates the first chamber from the second chamber.

136. The patient interface defined in any one of claims 133 to 135, wherein the patient interface comprises a frame that is couplable to headgear and to either the housing or the seal.

137. The patient interface defined in claim 133, wherein at least part of the flow valve is integrally formed with the housing.

138. The patient interface defined in claim 136, wherein at least part of the flow valve is integrally formed with the frame.

139. The patient interface defined in claim 132, wherein at least part of the flow valve is integrally formed with the seal.

140. The patient interface defined in claim 134, wherein at least part of the flow valve is integrally formed with the cushion module.

141. The patient interface defined in any one of claims 133 to 136, wherein the flow valve is removably couplable to the housing or to the frame.

142. The patient interface defined in claim 134, wherein the flow valve is removably couplable to the cushion module.

143. The patient interface defined in claim 135, wherein the seal comprises the dividing wall.

144. The patient interface defined in claim 135, wherein the housing comprises the dividing wall.

145. The patient interface defined in claim 134, wherein the dividing wall is formed in part by the seal and in part by the housing.

146. The patient interface defined in claim 131 or claim 135, wherein the dividing wall comprises one or more flow directors that enable respiratory gas to flow from the first chamber to the second chamber.

147. The patient interface defined in claim 146, wherein the or each flow director has a cross-sectional flow area.

148. The patient interface defined in claim 131 or claim 135, wherein the dividing wall comprises two or more flow directors and each flow director comprises the same cross-sectional flow area as the or each of the other flow directors.

149. The patient interface defined in claim 131 or claim 135, wherein the dividing wall comprises two or more flow directors and at least one flow director comprises a cross-sectional flow area that is different to the cross-sectional flow area of the or each of the other flow directors.

150. The patient interface defined in claim 131 or claim 135, wherein the dividing wall comprises a single flow director.

151. The patient interface as defined in any one of the preceding claims, wherein the first chamber and the second chamber are separate components.

152. A conduit connector configured to provide fluid communication between a respiratory gas supply conduit and a patient interface, the conduit connector comprising:• a first cavity and a second cavity, the first and second cavity are in fluid communication to enable a flow of respiratory gas from the first cavity to the second cavity within the conduit connector;• a respiratory gas inlet in fluid communication with the first cavity;• a respiratory gas outlet in fluid communication with the second cavity and through which respiratory gas is exhaustible from the second cavity to external of the conduit connector; and• a pressure valve that is configured to control the flow of respiratory gas from the first cavity to the second cavity to provide a respiratory gas pressure in the second cavity that is lower than a respiratory gas pressure in the first cavity across a range of respiratory therapy pressures.

153. The conduit connector defined in claim 152, wherein the conduit connector is releasably couplable to a patient interface.

154. The conduit connector defined in claim 152 or claim 153, wherein the conduit connector is releasably couplable to a seal or a housing or a frame or a cushion module of a patient interface.

155. The conduit connector defined in any one of claims 152 to 154, wherein the pressure valve enables a respiratory gas pressure in the second cavity that is in the range of 0.2 to 4.0 cmH2O lower than the respiratory gas pressure in the first cavity across the range of respiratory therapy pressures.

156. The conduit connector defined in any one of claims 152 to 154, wherein the pressure valve enables a respiratory gas pressure in the second cavity that is less than 4.0 cmFhO, less than 3.5 cmFhO, less than 3.0 cmFhO, less than 2.5 cmH2O, less than 2.0 cmFLO, less than 1 .5 cmFLO, less than 1 .4 cmFLO, less than 1 .3 cmFhO, less than 1 .2 cmFhO, less than 1 .1 cmFhO, less than 1 .0 cmH2O, less than 0.9 cmH2O, less than 0.8 cmH2O, less than 0.7 cmH2O, less than 0.6 cmH2O or less than 0.5 cmH2O lower than the respiratory gas pressure in the first cavity across the range of respiratory therapy pressures.

157. The conduit connector defined in claim 156, wherein the pressure valve enables a respiratory gas pressure in the second cavity that is greater than 0.0 cmH2O, greater than 0.1 cmFhO, greater than 0.2 cmFhO, greater than 0.3 cmH2O, greater than 0.4 cmFhO, greater than 0.5 greater than cmFhO, greater than 0.6 cmFhO, greater than 0.7 cmFhO, greater than 0.8 greater than cmFhO, greater than 0.9 cmFhO, greater than 1 .0 cmFhO, greater than 1 .1 cmFhO or greater than 1 .2 cmH2O lower than the respiratory gas pressure in the first cavity across the range of respiratory therapy pressures.

158. The conduit connector defined in any one of claims 152 to 157, wherein the pressure valve is configured to control the flow of respiratory gas from the first cavity to the second cavity in response to the respiratory gas pressure in the second cavity.

159. The conduit connector defined in any one of claims 152 to 158, wherein the pressure valve comprises a deformable diaphragm.

160. The conduit connector defined in any one of claims 152 to 158, wherein the pressure valve comprises a flap valve.

161. The conduit connector defined in any one of claims 152 to 160, wherein the conduit connector comprises a dividing panel that separates the first cavity from the second cavity.

162. The conduit connector defined in claim 161, wherein the pressure valve is integral with the dividing panel.

163. The conduit connector defined in claim 161, wherein the pressure valve is couplable with the dividing panel.

164. The conduit connector defined in claim 161, wherein the dividing panel is cooperable with a dividing wall of the patient interface.

165. The conduit connector defined in claim 164, wherein, in a patient interface comprising a first chamber and a second chamber and comprising a dividing wall separating the first chamber from the second chamber, the dividing panel is co-operable with the dividing wall.

166. The conduit connector defined in claim 164, wherein the dividing panel is configured to be co-operable with the dividing wall to enable respiratory gas to flow from the first cavity of the conduit connector to the first chamber of the patient interface and to enable respiratory gas to flow from the second chamber of the patient interface to the second cavity of the conduit connector.

167. The conduit connector defined in any one of claims 152 to 166, wherein the respiratory gas outlet comprises a flow valve in fluid communication with the second cavity and through which respiratory gas is exhaustible from the second cavity to external of the conduit connector and which flow valve is configured to control a respiratory gas flow rate through the flow valve to be below an upper limit across a range of different respiratory therapy pressures.

168. The conduit connector defined in claim 167, wherein the flow valve enables a flow rate within the range of 10 L / min to 30 L / m or within the range of 10 L / min to 20 L / m across the range of different respiratory therapy pressures.

169. The conduit connector defined in claim 167, wherein the flow valve enables the respiratory gas flow rate to be less than 20 L / m, less than 19 L / m, less than 18 L / m, less than 17.5 L / m, less than 17 L / m, less than 16 L / m, less than 15 L / m, less than 14 L / m, less than 13 L / m, or less than 12 L / m across the range of respiratory therapy pressures.

170. The conduit connector defined in claim 169, wherein the flow valve enables the respiratory gas flow rate to be is greater than 10 L / m, greater than 11 L / m, greater than 12 L / m, greater than 12.5 L / m, greater than 13 L / m, greater than 14 L / m or greater than 15 L / m across the range of respiratory therapy pressures.

171. A respiratory therapy assembly comprising:• the patient interface of any one of the claims 1 to 151 ; and• headgear that is couplable with the patient interface and which is operable to maintain a seal with between a patient’s face and the patient interface across the range of respiratory therapy pressures.

172. The respiratory therapy assembly defined in claim 171 , wherein the respiratory therapy assembly further comprises a conduit connector.

173. The respiratory therapy assembly defined in claim 172, wherein the conduit connector comprises the conduit connector of any one of claims 152 to 170.

174. The respiratory therapy assembly defined in any one of claims 171 to 173, wherein the pressure valve is within the conduit connector and is not within the patient interface.

175. The respiratory therapy assembly defined in any one of claims 171 to 174, wherein the patient interface comprises a dividing wall that separates the first and second chambers of the patient interface.

176. The respiratory therapy assembly defined in any one of claims 171 to 175, wherein a dividing panel separates the first and second cavities of the conduit connector.

177. The respiratory therapy assembly defined in claim 176 when dependent upon claim 175, wherein the dividing panel is co-operable with the dividing wall.

178. The respiratory therapy assembly defined in claim 177, wherein the dividing panel is co-operable with the dividing wall to enable respiratory gas to flow from the first cavity of the conduit connector to the first chamber of the patient interface and to enable respiratory gas to flow from the second chamber of the patient interface to the second cavity of the conduit connector.

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