Patient interface

Abstract

A nasal interface 3100 comprising an interface body 3110 with a first nasal delivery element 3111 that is configured to seal with a first naris of a patient and a second nasal delivery element 3112 th

Description

[0001] This application claims priority from United States Provisional Application No. 63 / 496,838 filed on 18 April 2023, entitled 'Patient Interface', and from United States Provisional Application No. 63 / 597,649 filed on 9 November 2023, entitled 'Patient Interface', the entire contents of which are hereby incorporated by reference. Technical Field

[0002] The present disclosure generally relates to a patient interface for delivering breathing gases to airways of a patient. Background

[0003] Humidifiers are used to provide humidified respiratory gases to a patient. Gases are delivered to the patient via a patient interface. Examples of a patient interface include an oral mask, a nasal mask, a nasal cannula, a combination of oral and nasal mask, and the like.

[0004] Patient interfaces comprising nasal interfaces can be used to deliver a flow of gases to a patient. Nasal delivery elements are inserted into the nose of a patient to deliver the required therapy. The nasal delivery elements may be required to seal or semiseal at the nose, or may not be required to seal at the nose, to deliver the therapy. Summary

[0005] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a nasal delivery element, wherein the nasal delivery element is configured to seal with a naris of a patient, and a gases inlet for delivery of respiratory gases into the nasal interface, wherein the gases inlet and the nasal delivery element are in fluid communication with a gases flow channel of the interface body to deliver the respiratory gases from the gases inlet through the nasal delivery element, wherein the gases inlet has a portion that extends externally to the interface body, wherein the portion is in a fixed position that is offset from a midline plane bisecting the nasal interface and is obliquely angled relative to the midline plane to position an opening of the gases inlet away from the midline plane.

[0006] In some configurations, an end of the portion that is proximal to the gases flow channel is offset at a distance of up to about 40 mm from the midline plane, optionally at a distance of between about 10 mm and about 40 mm from the midline plane.

[0007] In some configurations, the portion is obliquely angled at more than 0 degrees and up to about 70 degrees relative to the midline plane, optionally between about 10 degrees and about 70 degrees relative to the midline plane.

[0008] In some configurations, the nasal delivery element comprises a first nasal delivery element, wherein the interface body comprises a second nasal delivery element that is configured to seal with a respective naris of the patient, wherein the second nasal delivery element is in fluid communication with the gases inlet via the gases flow channel, and wherein the first nasal delivery element and the second nasal delivery element each comprise a base and an outlet.

[0009] In some configurations, the portion is angled at more than 0 degrees and up to about 40 degrees relative to a second plane that extends through the first and second nasal delivery elements from their bases to their outlets.

[0010] In some configurations, the gases inlet comprises an opening into the gases flow channel of the interface body, and wherein the opening is configured to direct incoming gases flow from the gases inlet toward a base of the nasal delivery element.

[0011] In some configurations, the gases inlet comprises an opening into the gases flow channel of the interface body, and wherein the opening is configured to direct more of incoming gases flow toward a base of the first nasal delivery element than toward a base of the second nasal delivery element.

[0012] In some configurations, the gases inlet comprises an opening into the gases flow channel of the interface body, and wherein the opening is configured to direct incoming gases flow toward a plenum wall between the base of the first nasal delivery element and the base of the second nasal delivery element.

[0013] In some configurations, the interface body comprises first and second interface body side arms, wherein the interface body side arms each comprise an unsealed cavity to enhance flexibility of the side arms.

[0014] In some configurations, each interface body side arm comprises a patient-proximate wall that is configured to be in contact with a patient's cheeks in use, and a patient-distal wall that is configured to be spaced from the patient's cheeks in use, wherein the patient-proximate wall is spaced from the patient-distal wall, with the unsealed cavity between the patient-proximate wall and the patient-distal wall.

[0015] In some configurations, the interface body comprises first and second interface body side arms, the patient interface comprising a frame with first and second frame side arms, wherein the first and second interface body side arms each comprise a through passage to enable a respective one of the first and second frame side arms to extend therethrough to couple the first and second frame side arms with the first and second interface body side arms, wherein when the first and second frame side arms are coupled with the first and second interface body side arms, proximal portions of the first and second interface body side arms are located behind proximal portions of the first and second frame side arms, so as to be positioned between a patient's face and the proximal portions of the first and second frame side arms in use.

[0016] In some configurations, the interface body comprises a softer material than the frame which comprises a more rigid material.

[0017] In some configurations, the interface body side arms each comprise a respective compliant cheek portion.

[0018] In some configurations, each through passage is positioned adjacent an outer end of the respective interface body side arm.

[0019] In some configurations, each through passage comprises an aperture or a slot.

[0020] In some configurations, the nasal interface is configured to create an asymmetrical flow of gases at a patient's nares in use.

[0021] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the nasal interface is configured to receive incoming gases from the gases inlet and to provide, from the incoming gases, a first flow stream of gases configured to be substantially provided to the first naris of the patient in use and a second flow stream of gases configured to be substantially provided to the second naris of the patient in use, and is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[0022] In some configurations, the first nasal delivery element comprises a first outlet configured to substantially deliver gases to the first naris of the patient, and the second nasal delivery element comprises a second outlet configured to substantially deliver gases to the second naris of the patient.

[0023] In some configurations, the gases inlet is at least partly aligned with the first outlet and is less aligned or is not aligned with the second outlet.

[0024] In some configurations, the gases inlet is substantially axially aligned with the first outlet.

[0025] In some configurations, at least half of a transverse cross-sectional area of the gases inlet is axially aligned with at least half of a transverse cross-sectional area of the first outlet.

[0026] In some configurations, the gases inlet comprises an outer portion for connecting to a respiratory conduit to provide a flow of gases for a gases source to the interface body, and further comprises an inner portion in fluid communication with the interface body.

[0027] In some configurations, the inner portion of the gases inlet is at least partly aligned with the first outlet.

[0028] In some configurations, the gases inlet is angled toward the first outlet.

[0029] In some configurations, the first flow stream of gases has at least one dimension that is larger than a corresponding dimension of the second flow stream of gases.

[0030] In some configurations, the at least one dimension comprises a lateral dimension of the first flow stream of gases, and wherein the corresponding dimension comprises a lateral dimension of the second flow stream of gases.

[0031] In some configurations, the first flow stream of gases has a larger diameter, cross-sectional area, and / or volume than a corresponding diameter, cross-sectional area, and / or volume of the second flow stream of gases.

[0032] In some configurations, a ratio of the cross-sectional area of the first flow stream of gases to the corresponding cross-sectional area of the second flow stream of gases is between about 2:1 and about 5:1, optionally between about 2:1 and about 4:1, optionally between about 2.5:1 and about 3.5: 1, optionally about 3:1.

[0033] In some configurations, the first outlet and the second outlet comprise substantially the same cross-sectional areas.

[0034] In some configurations, the nasal interface is configured to deliver a lower velocity of gases flow through the first outlet than a velocity of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[0035] In some configurations, the nasal interface is configured to deliver a higher pressure of gases flow through the first outlet than a pressure of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[0036] In some configurations, the nasal interface comprises a flow directorthat is configured to direct more of the incoming gases from the gases inlet to the first flow stream of gases than to the second flow stream of gases.

[0037] In some configurations, the nasal interface comprises a connector or elbow for connecting a respiratory conduit to the patient interface.

[0038] In some configurations, the connector or elbow comprises or is the flow director.

[0039] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet or first outlet portion.

[0040] In some configurations, the nasal interface is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases during an inhalation phase of the respiratory cycle.

[0041] In some configurations, the interface body is a nasal cushion.

[0042] In some configurations, the nasal interface is configured to simultaneously deliver the respiratory gases from the gases inlet through the interface body to both the first naris and second naris of the patient in use.

[0043] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface is configured to provide a larger dynamic pressure at the first naris of the patient in use and to provide a smaller dynamic pressure at the second naris of the patient in use, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[0044] In some configurations, the first nasal delivery element comprises a first outlet configured to substantially deliver gases to the first naris of the patient, and the second nasal delivery element comprises a second outlet configured to substantially deliver gases to the second naris of the patient.

[0045] In some configurations, the nasal interface comprises a flow director that is configured to direct more of the incoming gases from the gases inlet to the first outlet than to the second outlet.

[0046] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet.

[0047] In some configurations, the nasal interface is configured to receive incoming gases from the gases inlet and provide, from the incoming gases, a first flow stream of gases configured to be substantially provided to the first naris of the patient in use and a second flow stream of gases configured to be substantially provided to the second naris of the patient in use, and is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases.

[0048] In some configurations, the nasal interface comprises a flow splitter configured to unevenly split the flow from the gases inlet into the first flow stream of gases and the second flow stream of gases.

[0049] In some configurations, the nasal interface is configured to simultaneously deliver the respiratory gases from the gases inlet through the interface body to both the first naris and second naris of the patient in use.

[0050] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface comprises a flow splitter to unevenly split the flow from the gases inlet into a first flow stream of gases configured to be substantially provided to the first nasal delivery element and a second flow stream of gases configured to be substantially provided to the second nasal delivery element, wherein the first flow stream of gases is configured to deliver a greater flow of gases along the first flow stream of gases than a flow of gases along the second flow stream of gases, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[0051] In some configurations, the first nasal delivery element comprises a first outlet configured to substantially deliver gases to the first naris of the patient, and the second nasal delivery element comprises a second outlet configured to substantially deliver gases to the second naris of the patient.

[0052] In some configurations, the gases inlet is at least partly aligned with the first outlet and is less aligned or is not aligned with the second outlet.

[0053] In some configurations, the gases inlet is substantially axially aligned with the first outlet.

[0054] In some configurations, at least half of a transverse cross-sectional area of the gases inlet is axially aligned with at least half of a transverse cross-sectional area of the first outlet.

[0055] In some configurations, the gases inlet comprises an outer portion for connecting to a respiratory conduit to provide a flow of gases for a gases source to the interface body, and further comprises an inner portion in fluid communication with the interface body.

[0056] In some configurations, the inner portion of the gases inlet is at least partly aligned with the first outlet.

[0057] In some configurations, the gases inlet is angled toward the first outlet.

[0058] In some configurations, the first flow stream of gases has at least one dimension that is larger than a corresponding dimension of the second flow stream of gases.

[0059] In some configurations, the at least one dimension comprises a lateral dimension of the first flow stream of gases, and wherein the corresponding dimension comprises a lateral dimension of the second flow stream of gases.

[0060] In some configurations, the first flow stream of gases has a larger diameter, cross-sectional area, and / or volume than a corresponding diameter, cross-sectional area, and / or volume of the second flow stream of gases.

[0061] In some configurations, a ratio of the cross-sectional area of the first flow stream of gases to the corresponding cross-sectional area of the second flow stream of gases is between about 2:1 and about 5:1, optionally between about 2:1 and about 4:1, optionally between about 2.5:1 and about 3.5:1, optionally about 3:1.

[0062] In some configurations, the first outlet or first outlet portion and the second outlet or second outlet portion comprise substantially the same cross-sectional areas.

[0063] In some configurations, the nasal interface is configured to deliver a lower velocity of gases flow through the first outlet than a velocity of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[0064] In some configurations, the nasal interface is configured to deliver a higher pressure of gases flow through the first outlet than a pressure of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[0065] In some configurations, the nasal interface comprises a gases manifold, and the interface body, the gases manifold, and / or the gases inlet comprise(s) the flow splitter.

[0066] In some configurations, the flow splitter comprises a wall portion that extends towards or into the gases inlet, wherein the first flow stream of gases is located on one side of the wall portion and the second flow stream of gases is located on an opposite side of the wall portion.

[0067] In some configurations, the flow splitter extends into the gases inlet, and splits the gases inlet into a first gases flow stream portion on said one side of the flow splitter and a second gases flow stream portion on an opposite side of the flow splitter.

[0068] In some configurations, the flow splitter is substantially rigid.

[0069] In some configurations, the interface body is a nasal cushion.

[0070] In some configurations, the nasal cushion comprises the flow splitter, and wherein the flow splitter is configured to move and / or deform upon compression of the nasal cushion.

[0071] In some configurations, the flow splitter comprises a first wall portion and a second wall portion.

[0072] In some configurations, the first wall portion and the second wall portion are hingedly connected to each other, and wherein relative angles of the wall portions are configured to change upon compression of the nasal cushion.

[0073] In some configurations, the first wall portion and the second wall portion overlap each other in a relaxed state of the nasal cushion, and wherein an extent of overlap of the wall portions increases upon compression of the nasal cushion.

[0074] In some configurations, the nasal interface is configured such that the first flow stream of gases is configured to be substantially delivered to the first nasal delivery element and the second flow stream of gases is configured to be substantially delivered to the second nasal delivery element, and wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient.

[0075] In some configurations, the nasal interface comprises a flow directorthat is configured to direct more of the incoming gases from the gases inlet to the first flow stream of gases than to the second flow stream of gases.

[0076] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet or first outlet portion.

[0077] In some configurations, the nasal interface is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases during an inhalation phase of the respiratory cycle.

[0078] In some configurations, the interface body is a nasal cushion.

[0079] In some configurations, the nasal interface is configured to simultaneously deliver the respiratory gases from the gases inlet through the interface body to both the first naris and second naris of the patient in use.

[0080] In some configurations, the nasal interface comprises a bias flow restriction comprising at least one aperture for the flow of gases from the nasal interface to an ambient environment.

[0081] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[0082] In some configurations, the nasal interface is configured such that a pressure differential of gases flow through the first outlet or first outlet portion and the second outlet or second outlet portion is higher during an expiration phase than during an inspiration phase.

[0083] In some configurations, the nasal interface is configured to achieve a patient pressure at the first outlet or first outlet portion and the second outlet or second outlet portion of between about 2 cmH20 and about 30 cmH20 in use, optionally between about 2 cmH20 and about 25 cmH20 in use, optionally between about 2 cmH20 and about 20 cmH20 in use, optionally between about 2 cmH20 and about 15 cmH20 in use, optionally between about 2 cmH20 and about 14 cmH20 in use, optionally between about 2 cmH20 and about 13 cmH20 in use, optionally between about 2 cmH20 and about 12 cmH20 in use, optionally between about 2 cmH20 and about 11 cmH20 in use, optionally between about 2 cmH2O and about 10 cmH20 in use.

[0084] In some configurations, a pressure differential between the first outlet or first outlet portion and the second outlet or second outlet portion is configured to provide an asymmetric flow through upper airways of a patient of at least about 1 liter per minute (Ipm), optionally between about 1 Ipm and about 5 Ipm.

[0085] In some configurations, the asymmetric flow promotes clearing of CO2 from anatomical dead space of the patient.

[0086] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface comprises a bypass restriction to provide a pressure drop through the nasal interface between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element, and wherein the nasal interface comprises a bias flow restriction for a flow of gases out of the nasal interface.

[0087] In some configurations, the nasal interface comprises a gases manifold comprising the gases flow channel.

[0088] In some configurations, the pressure drop through the gases flow channel is such that when there is a flow of gases from the gases inlet to the first nasal delivery element and the second nasal delivery element, the flow of gases from the gases inlet to the first nasal delivery element is greater than the flow of gases from the gases inlet to the second nasal delivery element.

[0089] In some configurations, the bypass restriction provides a reduced cross-sectional area of a portion of the gases flow channel.

[0090] In some configurations, the portion of the gases flow channel is between the first nasal delivery element and the second nasal delivery element and / or is adjacent the second nasal delivery element.

[0091] In some configurations, the bypass restriction comprises at least one protrusion extending into the gases flow channel, optionally wherein the bypass restriction comprises a plurality of protrusions extending into the gases flow channel.

[0092] In some configurations, the gases manifold comprises a proximal bypass protrusion that is proximal to the nasal delivery elements and / or a distal bypass protrusion that is distal from the nasal delivery elements.

[0093] In some configurations, the gases manifold comprises both a proximal bypass protrusion and a distal bypass protrusion which in combination define a predetermined bypass dimension for the restricted flow of gases through the gases manifold between the first nasal delivery element and the second nasal delivery element.

[0094] In some configurations, the bypass restriction comprises an angled leading edge and an angled trailing edge that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element to the second nasal delivery element.

[0095] In some configurations, the bias flow restriction comprises at least one aperture for the flow of gases from the nasal interface to an ambient environment, optionally wherein the bias flow restriction comprises a plurality of apertures for the flow of gases from the nasal interface to an ambient environment.

[0096] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[0097] In some configurations, the nasal interface comprises a filter unit between the gases manifold and the bias flow restriction.

[0098] In some configurations, the bias flow restriction is in fluid communication with the gases manifold, optionally wherein the gases manifold comprises the bias flow restriction or is coupled to the bias flow restriction, optionally wherein the bias flow restriction is in fluid communication with the gases manifold but is positioned remotely from the gases manifold.

[0099] In some configurations, the gases inlet is in fluid communication with a respiratory conduit.

[00100] In some configurations, the respiratory conduit has an internal diameter of between about 12 mm and about 23 mm, optionally more than about 12 mm and up to about 23 mm, optionally more than 12 mm and up to about 22 mm, optionally more than about 12 mm and up to about 21 mm, optionally more than about 12 mm and up to about 20 mm, optionally more than about 12 mm and up to about 19 mm, optionally more than about 12 mm and up to about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00101] In some configurations, the gases manifold comprises sealing flanges or collars for engagement with the first and second nasal delivery elements.

[00102] In some configurations, the bypass restriction comprises an insert for attachment to the gases manifold.

[00103] In some configurations, the first and second nasal delivery elements are attached to or integral with a base portion of an interface body.

[00104] In some configurations, the base portion is arranged to locate between a patient's face and the gases manifold in use.

[00105] In some configurations, the interface body comprises two side arms that extend laterally from either side of the base portion.

[00106] In some configurations, the nasal interface comprises headgear with ends that connect to the side arms of the interface body.

[00107] In some configurations, the bypass restriction provides a cross-sectional area of a portion of the gases flow channel, and the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times a combined cross-sectional area of the nasal delivery elements.

[00108] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface is configured to create a pressure differential between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to both the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00109] In some configurations, the pressure differential is such that when there is a flow of gases from the gases inlet to the first nasal delivery element and the second nasal delivery element, the flow of gases from the gases inlet to the first nasal delivery element is greater than the flow of gases from the gases inlet to the second nasal delivery element.

[00110] In some configurations, the gases inlet is in fluid communication with a respiratory conduit.

[00111] In some configurations, the respiratory conduit has an internal diameter of between about 12 mm and about 23 mm, optionally between about 12 mm and about 22 mm, optionally between about 12 mm and about 21 mm, optionally between about 12 mm and about 20 mm, optionally between about 12 mm and about 19 mm, optionally between about 12 mm and about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00112] In some configurations, when gases are delivered from the gases inlet to both the first nasal delivery element and the second nasal delivery element, the pressure of gases flow at the second nasal delivery element is up to about 1 cmH20 less than the pressure of gases flow at the first nasal delivery element.

[00113] In some configurations, the nasal interface is configured such that the pressure differential of gases flow between the first nasal delivery element and the second nasal delivery element is higher during an inspiration phase than during an expiration phase.

[00114] In some configurations, the nasal interface is configured such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element during both the inspiration phase and the expiration phase.

[00115] In some configurations, the nasal interface is configured to achieve a patient pressure at the first and second nasal delivery elements of between about 2 cmH20 and about 30 cmHzO in use, optionally between about 2 cmH20 and about 25 cmH20 in use, optionally between about 2 cmH20 and about 20 cmH20 in use, optionally between about 2 cmH20 and about 15 cmH20 in use, optionally between about 2 cmH20 and about 14 cmH20 in use, optionally between about 2 cmH20 and about 13 cmH20 in use, optionally between about 2 cmH20 and about 12 cmH20 in use, optionally between about 2 cmH20 and about 11 cmH20 in use, optionally between about 2 cmH2O and about 10 cmH20 in use.

[00116] In some configurations, the pressure differential between the first nasal delivery element and the second nasal delivery element is configured to provide an asymmetric flow through upper airways of a patient of at least about 1 liter per minute (Ipm), optionally between about 1 Ipm and about 5 Ipm.

[00117] In some configurations, the asymmetric flow promotes clearing of CO2 from anatomical dead space of the patient.

[00118] In some configurations, the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of a gases flow channel, and the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times a combined cross-sectional area of the nasal delivery elements.

[00119] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface comprises at least one gases flow restriction to gases flow through the nasal interface, such that when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element, pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00120] In some configurations, the at least one gases flow restriction comprises a bypass restriction to provide a pressure drop through the gases flow channel between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00121] In some configurations, the nasal interface comprises a gases manifold part comprising the gases flow channel.

[00122] In some configuration, the bypass restriction provides a cross-sectional area of a portion of a gases flow channel, and the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times a combined cross-sectional area of the nasal delivery elements.

[00123] In some configurations, the nasal interface comprises the gases flow channel in the gases manifold part, wherein the bypass restriction provides a reduced cross-sectional area of a portion of the gases flow channel.

[00124] In some configurations, the portion of the gases flow channel is between the first nasal delivery element and the second nasal delivery element and / or is adjacent the second nasal delivery element.

[00125] In some configurations, the bypass restriction comprises at least one protrusion extending into the gases flow channel, optionally wherein the bypass restriction comprises a plurality of protrusions extending into the gases flow channel.

[00126] In some configurations, the gases manifold part comprises a proximal bypass protrusion that is proximal to the nasal delivery elements and / or a distal bypass protrusion that is distal from the nasal delivery elements.

[00127] In some configurations, the gases manifold part comprises both a proximal bypass protrusion and a distal bypass protrusion which in combination define a predetermined bypass dimension for the restricted flow of gases through the gases manifold between the first nasal delivery element and the second nasal delivery element.

[00128] In some configurations, the bypass restriction comprises an angled leading edge and an angled trailing edge that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element to the second nasal delivery element.

[00129] In some configurations, the bypass restriction comprises an insert for attachment to the gases manifold part.

[00130] In some configurations, the nasal interface further comprises a bias flow restriction for a flow of gases out of the nasal interface.

[00131] In some configurations, the bias flow restriction comprises at least one aperture for the flow of gases from the nasal interface to an ambient environment, optionally wherein the bias flow restriction comprises a plurality of apertures for the flow of gases from the nasal interface to an ambient environment.

[00132] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[00133] In some configurations, the nasal interface comprises a filter unit between the gases manifold part and the bias flow restriction.

[00134] In some configurations, the bias flow restriction is in fluid communication with the gases manifold part, optionally wherein the gases manifold comprises the bias flow restriction or is coupled to the bias flow restriction, optionally wherein the bias flow restriction is in fluid communication with the gases manifold part but is positioned remotely from the gases manifold part.

[00135] In some configurations, the gases inlet is in fluid communication with a respiratory conduit.

[00136] In some configurations, the respiratory conduit has an internal diameter of between about 12 mm and about 23 mm, optionally between about 12 mm and about 22 mm, optionally between about 12 mm and about 21 mm, optionally between about 12 mm and about 20 mm, optionally between about 12 mm and about 19 mm, optionally between about 12 mm and about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00137] In some configurations, the gases manifold part comprises sealing flanges or collars for engagement with the first and second nasal delivery elements when the interface body part is engaged with the gases manifold part.

[00138] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of the gases flow channel, wherein each of the first nasal delivery element and the second nasal delivery element comprises an inner cross-sectional area, wherein the inner cross-sectional areas together provide a combined cross-sectional area of the nasal delivery elements, and wherein the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements.

[00139] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area of the nasal delivery elements, optionally upto about 1 / 3 of the combined cross-sectional area of the nasal delivery elements.

[00140] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at a smallest transverse dimension of the respective nasal delivery element.

[00141] In some configurations, the smallest transverse dimension is in a direction that is transverse to a direction of gases flow through the nasal delivery elements.

[00142] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at an outlet of the respective nasal delivery element.

[00143] In some configurations, the portion of the gases flow channel is between the first nasal delivery element and the second nasal delivery element and / or is adjacent the second nasal delivery element.

[00144] In some configurations, the bypass restriction comprises at least one protrusion extending into the gases flow channel, optionally wherein the bypass restriction comprises a plurality of protrusions extending into the gases flow channel.

[00145] In some configurations, the nasal interface comprises a gases manifold comprising the gases flow channel.

[00146] In some configurations, the gases manifold comprises a proximal bypass protrusion that is proximal to the nasal delivery elements and / or a distal bypass protrusion that is distal from the nasal delivery elements.

[00147] In some configurations, the gases manifold comprises both a proximal bypass protrusion and a distal bypass protrusion which in combination define a predetermined bypass dimension for the restricted flow of gases through the gases manifold between the first nasal delivery element and the second nasal delivery element.

[00148] In some configurations, the bypass restriction comprises an angled leading edge and an angled trailing edge that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element to the second nasal delivery element.

[00149] In some configurations, the nasal interface comprises an interface body and a gases manifold part, wherein the interface body and the gases manifold part together form the gases manifold.

[00150] In some configurations, the gases inlet is at a side of the gases manifold.

[00151] In some configurations, an open area for gases flow through the bias flow restriction is between about 10 mm2 and about 30 mm2, optionally between about 25 mm2 and about 30 mm2, and optionally about 27.5 mm2.

[00152] In some configurations, an open area for gases flow through the bias flow restriction is more than 0 mm2 to about 40 mm2, optionally between about 2 mm2 and about 40mm2, optionally between about 2 mm2 and about 5 mm2, optionally between about 12 mm2 and about 40mm2, optionally between about 20 mm2 and about 30 mm2.

[00153] In some configurations, the bias flow restriction is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is more than 0 Ipm to about 80 Ipm when a pressure of more than 0 cmH20 and up to about 30 cmH20 is provided to the gases inlet in use and the nasal delivery elements are occluded.

[00154] In some configurations, the bias flow restriction is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is between about 4 Ipm and about 15 Ipm when a pressure of between about 3 cmH2O and about 10 cmH20 is provided to the gases inlet in use and the nasal delivery elements are occluded.

[00155] In some configurations, the bias flow restriction is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is between about 15 Ipm and about 80 Ipm when a pressure of between about 4 cmH20 and about 30 cmH20 is provided to the gases inlet in use and the nasal delivery elements are occluded.

[00156] In some configurations, the bias flow restriction comprises at least one aperture for the flow of gases from the nasal interface to an ambient environment, optionally wherein the bias flow restriction comprises a plurality of apertures for the flow of gases from the nasal interface to an ambient environment.

[00157] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[00158] In some configurations, the nasal interface comprises a filter unit between the gases manifold and the bias flow restriction.

[00159] In some configurations, the bias flow restriction is in fluid communication with the gases manifold, optionally wherein the gases manifold comprises the bias flow restriction or is coupled to the bias flow restriction, optionally wherein the bias flow restriction is in fluid communication with the gases manifold but is positioned remotely from the gases manifold.

[00160] In some configurations, the cross-sectional area of the portion of the gases flow channel is between about 10% and up to about 100% of a first cross-sectional area of an adjacent part of the gases flow channel, optionally about 10% or more and less than 100% of the first cross-sectional area, optionally up to about 90% of the first cross-sectional area, optionally up to about 80% of the first cross-sectional area, optionally up to about 70% of the first cross-sectional area, optionally up to about 60% of the first cross-sectional area, optionally up to about 55% of the first cross-sectional area, optionally up to about 40% of the first cross-sectional area, optionally up to about 30% of the first cross-sectional area, and optionally up to about 25% of the first cross-sectional area.

[00161] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 300 mm2, optionally up to about 280 mm2, optionally up to about 270 mm2, optionally up to about 200 mm2, optionally up to about 160 mm2, optionally up to about 110 mm2, optionally up to about 80 mm2, optionally up to about 60 mm2, and optionally up to about 50 mm2.

[00162] In some configurations, the combined cross-sectional area of the nasal delivery elements is more than 0 mm2 and up to about 250 mm2, optionally between about 1 mm2 and about 250 mm2, optionally between about 1.6 mm2 and about 250 mm2, optionally between about 50 mm2 and about 250 mm2, optionally between about 50 mm2 and about 200 mm2, optionally between about 30 mm2 and about 200 mm2, optionally between about 30 mm2 and about 155 mm2, optionally between about 50 mm2 and about 155 mm2, and optionally between about 70 mm2 and about 155 mm2.

[00163] In some configurations, the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements and the combined cross-sectional area of the nasal delivery elements is between about 1 mm2 and about 250 mm2.

[00164] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area of the nasal delivery elements, optionally upto about 1 / 3 of the combined cross-sectional area of the nasal delivery elements.

[00165] In some configurations, the combined cross-sectional area of the nasal delivery elements is between about 1.6 mm2 and about 250 mm2, optionally between about 50 mm2 and about 250 mm2, optionally between about 50 mm2 and about 200 mm2, optionally between about 30 mm2 and about 200 mm2, optionally between about 30 mm2 and about 155 mm2, optionally between about 50 mm2 and about 155 mm2, and optionally between about 70 mm2 and about 155 mm2.

[00166] In some configurations, the bypass restriction provides a pressure drop through the nasal interface between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00167] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of the gases flow channel, wherein each of the first nasal delivery element and the second nasal delivery element comprises an inner cross-sectional area, and wherein the inner cross-sectional areas of the nasal delivery elements and the cross-sectional area of the portion of the gases flow channel are related so as to create an asymmetrical flow of gases from the nasal delivery elements in use.

[00168] In some configurations, the inner cross-sectional areas together provide a combined cross-sectional area of the nasal delivery elements, and wherein the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements.

[00169] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area of the nasal delivery elements, optionally upto about 1 / 3 of the combined cross-sectional area of the nasal delivery elements.

[00170] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at a smallest transverse dimension of the respective nasal delivery element.

[00171] In some configurations, the smallest transverse dimension is in a direction that is transverse to a direction of gases flow through the nasal delivery elements.

[00172] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at an outlet of the respective nasal delivery element.

[00173] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 times, optionally up to about 2 / 3 times, the combined cross-sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through a bias flow restriction of 20 Ipm when a pressure of 4 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded.

[00174] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 times, optionally up to about 2 / 3 times, the combined cross sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through a bias flow restriction of 32 Ipm when a pressure of 8 cmH2O is provided to the gases inlet and the nasal delivery elements are occluded.

[00175] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through the bias flow restriction of 20 Ipm when a pressure of 4 cmH2O is provided to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow through the bias flow restriction of 32 Ipm when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow through the bias flow restriction of 41 Ipm when a pressure of 12 cmH20 is applied to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow of 48 Ipm through the bias flow restriction when a pressure of 16 cmH20 is applied to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow through the bias flow restriction of 53 Ipm when a pressure of 20 cmH20 is applied to the gases inlet and the nasal delivery elements are occluded.

[00176] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through the bias flow restriction of 32 Ipm or higher when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded.

[00177] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 / 3 times the combined cross-sectional area of the nasal delivery elements and the nasal interface is configured to provide a bias flow through the bias flow restriction of 32 Ipm or higher when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded, or wherein the cross-sectional area of the portion of the gases flow channel is up to about 2 / 5 times the combined cross-sectional area of the nasal delivery elements and the nasal interface is configured to provide a bias flow through the bias flow restriction of 41 Ipm or higher when a pressure of 12 cm H2O is provided to the gases inlet and the nasal delivery elements are occluded, or wherein the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements and the nasal interface is configured to provide bias flow through the bias flow restriction of 48 Ipm or higher when a pressure of 16 cmH2O is provided to the gases inlet and the nasal delivery elements are occluded.

[00178] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00179] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a nasal delivery element, wherein the nasal delivery element is configured to seal with a naris of a patient, and a gases inlet for delivery of respiratory gases into the nasal interface, wherein the gases inlet and the nasal delivery element are in fluid communication with a gases flow channel of the interface body to deliver the respiratory gases from the gases inlet through the nasal delivery element, wherein the nasal delivery element comprises a plurality of convolutions that form a bellows portion between the gases flow channel and an outlet of the nasal delivery element, and wherein the nasal interface is configured to create an asymmetrical flow of gases at a patient's nares in use.

[00180] In some configurations, the interface body comprises a flex region, wherein the plurality of convolutions is located between the flex region and the outlet of the nasal delivery element.

[00181] In some configurations, the flex region extends around less than an entire perimeter of the nasal delivery element, at or adjacent a base of the nasal delivery element.

[00182] In some configurations, the flex region extends around at least a front portion, a rear portion, and a laterally inward portion of the perimeter of the nasal delivery element.

[00183] In some configurations, the nasal interface comprises a frame, wherein the interface body comprises a softer material than the frame which comprises a more rigid material, and wherein a portion of the frame is in contact with a portion of the interface body adjacent the flex region, to reduce or inhibit flexing of the portion of the interface body adjacent the flex region.

[00184] In some configurations, a cross-sectional shape of the convolutions corresponds to the cross-sectional shape of a base of the outlet portion of the nasal delivery element.

[00185] In some configurations, the gases inlet comprises an opening into the gases flow channel of the interface body, and wherein the opening is configured to direct incoming gases flow from the gases inlet toward a base of the nasal delivery element.

[00186] In some configurations, the nasal delivery element comprises a first nasal delivery element, wherein the interface body comprises a second nasal delivery element that is configured to seal with a respective naris of the patient, wherein the second nasal delivery element is in fluid communication with the gases inlet via the gases flow channel, and wherein the first nasal delivery element and the second nasal delivery element each comprise a base and an outlet.

[00187] In some configurations, the first nasal delivery element and the second nasal delivery element each comprise a plurality of convolutions that form a respective bellows portion between the gases flow channel and an outlet of the respective nasal delivery element.

[00188] In some configurations, the interface body comprises at least one flex region, wherein the plurality of convolutions of each nasal delivery element is located between the at least one flex region and the outlet of the respective nasal delivery element.

[00189] In some configurations, the at least one flex region comprises two flex regions, wherein the plurality of convolutions of each nasal delivery element is located between a respective one of the two flex regions and the outlet of the respective nasal delivery element.

[00190] In some configurations, the at least one flex region extends around less than an entire perimeter of each nasal delivery element, at or adjacent a base of each nasal delivery element.

[00191] In some configurations, the at least one flex region extends around at least a front portion, a rear portion, and a laterally inward portion of the perimeter of each nasal delivery element.

[00192] In some configurations, the nasal interface comprises a frame, wherein the interface body comprises a softer material than the frame which comprises a more rigid material, and wherein a portion of the frame is in contact with a portion of the interface body adjacent the at least one flex region, to reduce or inhibit flexing of the portion of the interface body adjacent the at least one flex region.

[00193] In some configurations, a cross-sectional shape of the convolutions corresponds to the cross-sectional shape of a base of the outlet portion of the respective nasal delivery element.

[00194] In some configurations, the interface body comprises first and second interface body side arms, wherein the interface body side arms each comprise an unsealed cavity to enhance flexibility of the side arms.

[00195] In some configurations, each interface body side arm comprises a patient-proximate wall that is configured to be in contact with a patient's cheeks in use, and a patient-distal wall that is configured to be spaced from the patient's cheeks in use, wherein the patient-proximate wall is spaced from the patient-distal wall, with the unsealed cavity between the patient-proximate wall and the patient-distal wall.

[00196] In some configurations, the interface body comprises first and second interface body side arms, the patient interface comprising a frame with first and second frame side arms, wherein the first and second interface body side arms each comprise a through passage to enable a respective one of the first and second frame side arms to extend therethrough to couple the first and second frame side arms with the first and second interface body side arms, wherein when the first and second frame side arms are coupled with the first and second interface body side arms, proximal portions of the first and second interface body side arms are located behind proximal portions of the first and second frame side arms, so as to be positioned between a patient's face and the proximal portions of the first and second frame side arms in use.

[00197] In some configurations, the interface body comprises a softer material than the frame which comprises a more rigid material.

[00198] In some configurations, the interface body side arms each comprise a respective compliant cheek portion.

[00199] In some configurations, each through passage is positioned adjacent an outer end of the respective interface body side arm.

[00200] In some configurations, each through passage comprises an aperture or a slot.

[00201] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the nasal interface is configured to receive incoming gases from the gases inlet and to provide, from the incoming gases, a first flow stream of gases configured to be substantially provided to the first naris of the patient in use and a second flow stream of gases configured to be substantially provided to the second naris of the patient in use, and is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[00202] In some configurations, the first nasal delivery element comprises a first outlet configured to substantially deliver gases to the first naris of the patient, and the second nasal delivery element comprises a second outlet configured to substantially deliver gases to the second naris of the patient.

[00203] In some configurations, the gases inlet is at least partly aligned with the first outlet and is less aligned or is not aligned with the second outlet.

[00204] In some configurations, the gases inlet is substantially axially aligned with the first outlet.

[00205] In some configurations, at least half of a transverse cross-sectional area of the gases inlet is axially aligned with at least half of a transverse cross-sectional area of the first outlet.

[00206] In some configurations, the gases inlet comprises an outer portion for connecting to a respiratory conduit to provide a flow of gases for a gases source to the interface body, and further comprises an inner portion in fluid communication with the interface body.

[00207] In some configurations, the inner portion of the gases inlet is at least partly aligned with the first outlet.

[00208] In some configurations, the gases inlet is angled toward the first outlet.

[00209] In some configurations, the first flow stream of gases has at least one dimension that is larger than a corresponding dimension of the second flow stream of gases.

[00210] In some configurations, the at least one dimension comprises a lateral dimension of the first flow stream of gases, and wherein the corresponding dimension comprises a lateral dimension of the second flow stream of gases.

[00211] In some configurations, the first flow stream of gases has a larger diameter, cross-sectional area, and / or volume than a corresponding diameter, cross-sectional area, and / or volume of the second flow stream of gases.

[00212] In some configurations, a ratio of the cross-sectional area of the first flow stream of gases to the corresponding cross-sectional area of the second flow stream of gases is between about 2:1 and about 5:1, optionally between about 2:1 and about 4:1, optionally between about 2.5:1 and about 3.5: 1, optionally about 3:1.

[00213] In some configurations, the first outlet and the second outlet comprise substantially the same cross-sectional areas.

[00214] In some configurations, the nasal interface is configured to deliver a lower velocity of gases flow through the first outlet than a velocity of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[00215] In some configurations, the nasal interface is configured to deliver a higher pressure of gases flow through the first outlet than a pressure of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[00216] In some configurations, the nasal interface comprises a flow director that is configured to direct more of the incoming gases from the gases inlet to the first flow stream of gases than to the second flow stream of gases.

[00217] In some configurations, the nasal interface comprises a connector or elbow for connecting a respiratory conduit to the patient interface.

[00218] In some configurations, the connector or elbow comprises or is the flow director.

[00219] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet or first outlet portion.

[00220] In some configurations, the nasal interface is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases during an inhalation phase of the respiratory cycle.

[00221] In some configurations, the interface body is a nasal cushion.

[00222] In some configurations, the nasal interface is configured to simultaneously deliver the respiratory gases from the gases inlet through the interface body to both the first naris and second naris of the patient in use.

[00223] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface is configured to provide a larger dynamic pressure at the first naris of the patient in use and to provide a smaller dynamic pressure at the second naris of the patient in use, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[00224] In some configurations, the first nasal delivery element comprises a first outlet configured to substantially deliver gases to the first naris of the patient, and the second nasal delivery element comprises a second outlet configured to substantially deliver gases to the second naris of the patient.

[00225] In some configurations, the nasal interface comprises a flow directorthat is configured to direct more of the incoming gases from the gases inlet to the first outlet than to the second outlet.

[00226] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet.

[00227] In some configurations, the nasal interface is configured to receive incoming gases from the gases inlet and provide, from the incoming gases, a first flow stream of gases configured to be substantially provided to the first naris of the patient in use and a second flow stream of gases configured to be substantially provided to the second naris of the patient in use, and is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases.

[00228] In some configurations, the nasal interface comprises a flow splitter configured to unevenly split the flow from the gases inlet into the first flow stream of gases and the second flow stream of gases.

[00229] In some configurations, the nasal interface is configured to simultaneously deliver the respiratory gases from the gases inlet through the interface body to both the first naris and second naris of the patient in use.

[00230] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface comprises a flow splitter to unevenly split the flow from the gases inlet into a first flow stream of gases configured to be substantially provided to the first nasal delivery element and a second flow stream of gases configured to be substantially provided to the second nasal delivery element, wherein the first flow stream of gases is configured to deliver a greater flow of gases along the first flow stream of gases than a flow of gases along the second flow stream of gases, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[00231] In some configurations, the first nasal delivery element comprises a first outlet configured to substantially deliver gases to the first naris of the patient, and the second nasal delivery element comprises a second outlet configured to substantially deliver gases to the second naris of the patient.

[00232] In some configurations, the gases inlet is at least partly aligned with the first outlet and is less aligned or is not aligned with the second outlet.

[00233] In some configurations, the gases inlet is substantially axially aligned with the first outlet.

[00234] In some configurations, at least half of a transverse cross-sectional area of the gases inlet is axially aligned with at least half of a transverse cross-sectional area of the first outlet.

[00235] In some configurations, the gases inlet comprises an outer portion for connecting to a respiratory conduit to provide a flow of gases for a gases source to the interface body, and further comprises an inner portion in fluid communication with the interface body.

[00236] In some configurations, the inner portion of the gases inlet is at least partly aligned with the first outlet.

[00237] In some configurations, the gases inlet is angled toward the first outlet.

[00238] In some configurations, the first flow stream of gases has at least one dimension that is larger than a corresponding dimension of the second flow stream of gases.

[00239] In some configurations, the at least one dimension comprises a lateral dimension of the first flow stream of gases, and wherein the corresponding dimension comprises a lateral dimension of the second flow stream of gases.

[00240] In some configurations, the first flow stream of gases has a larger diameter, cross-sectional area, and / or volume than a corresponding diameter, cross-sectional area, and / or volume of the second flow stream of gases.

[00241] In some configurations, a ratio of the cross-sectional area of the first flow stream of gases to the corresponding cross-sectional area of the second flow stream of gases is between about 2:1 and about 5:1, optionally between about 2:1 and about 4:1, optionally between about 2.5:1 and about 3.5:1, optionally about 3:1.

[00242] In some configurations, the first outlet or first outlet portion and the second outlet or second outlet portion comprise substantially the same cross-sectional areas.

[00243] In some configurations, the nasal interface is configured to deliver a lower velocity of gases flow through the first outlet than a velocity of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[00244] In some configurations, the nasal interface is configured to deliver a higher pressure of gases flow through the first outlet than a pressure of gases flow through the second outlet during an inhalation phase of a respiratory cycle.

[00245] In some configurations, the nasal interface comprises a gases manifold, and the interface body, the gases manifold, and / or the gases inlet comprise(s) the flow splitter.

[00246] In some configurations, the flow splitter comprises a wall portion that extends towards or into the gases inlet, wherein the first flow stream of gases is located on one side of the wall portion and the second flow stream of gases is located on an opposite side of the wall portion.

[00247] In some configurations, the flow splitter extends into the gases inlet, and splits the gases inlet into a first gases flow stream portion on said one side of the flow splitter and a second gases flow stream portion on an opposite side of the flow splitter.

[00248] In some configurations, the flow splitter is substantially rigid.

[00249] In some configurations, the interface body is a nasal cushion.

[00250] In some configurations, the nasal cushion comprises the flow splitter, and wherein the flow splitter is configured to move and / or deform upon compression of the nasal cushion.

[00251] In some configurations, the flow splitter comprises a first wall portion and a second wall portion.

[00252] In some configurations, the first wall portion and the second wall portion are hingedly connected to each other, and wherein relative angles of the wall portions are configured to change upon compression of the nasal cushion.

[00253] In some configurations, the first wall portion and the second wall portion overlap each other in a relaxed state of the nasal cushion, and wherein an extent of overlap of the wall portions increases upon compression of the nasal cushion.

[00254] In some configurations, the nasal interface is configured such that the first flow stream of gases is configured to be substantially delivered to the first nasal delivery element and the second flow stream of gases is configured to be substantially delivered to the second nasal delivery element, and wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient.

[00255] In some configurations, the nasal interface comprises a flow director that is configured to direct more of the incoming gases from the gases inlet to the first flow stream of gases than to the second flow stream of gases.

[00256] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet or first outlet portion.

[00257] In some configurations, the nasal interface is configured to direct more of the incoming gases to the first flow stream of gases than to the second flow stream of gases during an inhalation phase of the respiratory cycle.

[00258] In some configurations, the interface body is a nasal cushion.

[00259] In some configurations, the nasal interface is configured to simultaneously deliver the respiratory gases from the gases inlet through the interface body to both the first naris and second naris of the patient in use.

[00260] In some configurations, the nasal interface comprises a bias flow restriction comprising at least one aperture for the flow of gases from the nasal interface to an ambient environment.

[00261] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[00262] In some configurations, the nasal interface is configured such that a pressure differential of gases flow through the first outlet or first outlet portion and the second outlet or second outlet portion is higher during an expiration phase than during an inspiration phase.

[00263] In some configurations, the nasal interface is configured to achieve a patient pressure at the first outlet or first outlet portion and the second outlet or second outlet portion of between about 2 cmH20 and about 30 cmH20 in use, optionally between about 2 cmH20 and about 25 cmH20 in use, optionally between about 2 cmH20 and about 20 cmH20 in use, optionally between about 2 cmH20 and about 15 cmH20 in use, optionally between about 2 cmH20 and about 14 cmH20 in use, optionally between about 2 cmH20 and about 13 cmH20 in use, optionally between about 2 cmH2O and about 12 cmH20 in use, optionally between about 2 cmH20 and about 11 cmH20 in use, optionally between about 2 cmH20 and about 10 cmH20 in use.

[00264] In some configurations, a pressure differential between the first outlet or first outlet portion and the second outlet or second outlet portion is configured to provide an asymmetric flow through upper airways of a patient of at least about 1 liter per minute (Ipm), optionally between about 1 Ipm and about 5 Ipm.

[00265] In some configurations, the asymmetric flow promotes clearing of CO2 from anatomical dead space of the patient.

[00266] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface comprises a bypass restriction to provide a pressure drop through the nasal interface between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element, and wherein the nasal interface comprises a bias flow restriction for a flow of gases out of the nasal interface.

[00267] In some configurations, the nasal interface comprises a gases manifold comprising the gases flow channel.

[00268] In some configurations, the pressure drop through the gases flow channel is such that when there is a flow of gases from the gases inlet to the first nasal delivery element and the second nasal delivery element, the flow of gases from the gases inlet to the first nasal delivery element is greater than the flow of gases from the gases inlet to the second nasal delivery element.

[00269] In some configurations, the bypass restriction provides a reduced cross-sectional area of a portion of the gases flow channel.

[00270] In some configurations, the portion of the gases flow channel is between the first nasal delivery element and the second nasal delivery element and / or is adjacent the second nasal delivery element.

[00271] In some configurations, the bypass restriction comprises at least one protrusion extending into the gases flow channel, optionally wherein the bypass restriction comprises a plurality of protrusions extending into the gases flow channel.

[00272] In some configurations, the gases manifold comprises a proximal bypass protrusion that is proximal to the nasal delivery elements and / or a distal bypass protrusion that is distal from the nasal delivery elements.

[00273] In some configurations, the gases manifold comprises both a proximal bypass protrusion and a distal bypass protrusion which in combination define a predetermined bypass dimension for the restricted flow of gases through the gases manifold between the first nasal delivery element and the second nasal delivery element.

[00274] In some configurations, the bypass restriction comprises an angled leading edge and an angled trailing edge that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element to the second nasal delivery element.

[00275] In some configurations, the bias flow restriction comprises at least one aperture for the flow of gases from the nasal interface to an ambient environment, optionally wherein the bias flow restriction comprises a plurality of apertures for the flow of gases from the nasal interface to an ambient environment.

[00276] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[00277] In some configurations, the nasal interface comprises a filter unit between the gases manifold and the bias flow restriction.

[00278] In some configurations, the bias flow restriction is in fluid communication with the gases manifold, optionally wherein the gases manifold comprises the bias flow restriction or is coupled to the bias flow restriction, optionally wherein the bias flow restriction is in fluid communication with the gases manifold but is positioned remotely from the gases manifold.

[00279] In some configurations, the gases inlet is in fluid communication with a respiratory conduit.

[00280] In some configurations, the respiratory conduit has an internal diameter of between about 12 mm and about 23 mm, optionally more than about 12 mm and up to about 23 mm, optionally more than 12 mm and up to about 22 mm, optionally more than about 12 mm and up to about 21 mm, optionally more than about 12 mm and up to about 20 mm, optionally more than about 12 mm and up to about 19 mm, optionally more than about 12 mm and up to about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00281] In some configurations, the gases manifold comprises sealing flanges or collars for engagement with the first and second nasal delivery elements.

[00282] In some configurations, the bypass restriction comprises an insert for attachment to the gases manifold.

[00283] In some configurations, the first and second nasal delivery elements are attached to or integral with a base portion of an interface body.

[00284] In some configurations, the base portion is arranged to locate between a patient's face and the gases manifold in use.

[00285] In some configurations, the interface body comprises two side arms that extend laterally from either side of the base portion.

[00286] In some configurations, the nasal interface comprises headgear with ends that connect to the side arms of the interface body.

[00287] In some configurations, the bypass restriction provides a cross-sectional area of a portion of the gases flow channel, and the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times a combined cross-sectional area of the nasal delivery elements.

[00288] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface is configured to create a pressure differential between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to both the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00289] In some configurations, the pressure differential is such that when there is a flow of gases from the gases inlet to the first nasal delivery element and the second nasal delivery element, the flow of gases from the gases inlet to the first nasal delivery element is greater than the flow of gases from the gases inlet to the second nasal delivery element.

[00290] In some configurations, the gases inlet is in fluid communication with a respiratory conduit.

[00291] In some configurations, the respiratory conduit has an internal diameter of between about 12 mm and about 23 mm, optionally between about 12 mm and about 22 mm, optionally between about 12 mm and about 21 mm, optionally between about 12 mm and about 20 mm, optionally between about 12 mm and about 19 mm, optionally between about 12 mm and about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00292] In some configurations, when gases are delivered from the gases inlet to both the first nasal delivery element and the second nasal delivery element, the pressure of gases flow at the second nasal delivery element is up to about 1 cmH20 less than the pressure of gases flow at the first nasal delivery element.

[00293] In some configurations, the nasal interface is configured such that the pressure differential of gases flow between the first nasal delivery element and the second nasal delivery element is higher during an inspiration phase than during an expiration phase.

[00294] In some configurations, the nasal interface is configured such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element during both the inspiration phase and the expiration phase.

[00295] In some configurations, the nasal interface is configured to achieve a patient pressure at the first and second nasal delivery elements of between about 2 cmH20 and about 30 cmH2O in use, optionally between about 2 cmH20 and about 25 cmH2O in use, optionally between about 2 cmH20 and about 20 cmH20 in use, optionally between about 2 cmH20 and about 15 cmH20 in use, optionally between about 2 cmH20 and about 14 cmH20 in use, optionally between about 2 cmH20 and about 13 cmH20 in use, optionally between about 2 cmH20 and about 12 cmH20 in use, optionally between about 2 cmH20 and about 11 cmH20 in use, optionally between about 2 cmH2O and about 10 cmH20 in use.

[00296] In some configurations, the pressure differential between the first nasal delivery element and the second nasal delivery element is configured to provide an asymmetric flow through upper airways of a patient of at least about 1 liter per minute (Ipm), optionally between about 1 Ipm and about 5 Ipm.

[00297] In some configurations, the asymmetric flow promotes clearing of CO2 from anatomical dead space of the patient.

[00298] In some configurations, the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of a gases flow channel, and the cross sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times a combined cross-sectional area of the nasal delivery elements.

[00299] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the nasal interface comprises at least one gases flow restriction to gases flow through the nasal interface, such that when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element, pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00300] In some configurations, the at least one gases flow restriction comprises a bypass restriction to provide a pressure drop through the gases flow channel between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00301] In some configurations, the nasal interface comprises a gases manifold part comprising the gases flow channel.

[00302] In some configuration, the bypass restriction provides a cross-sectional area of a portion of a gases flow channel, and the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times a combined cross-sectional area of the nasal delivery elements.

[00303] In some configurations, the nasal interface comprises the gases flow channel in the gases manifold part, wherein the bypass restriction provides a reduced cross-sectional area of a portion of the gases flow channel.

[00304] In some configurations, the portion of the gases flow channel is between the first nasal delivery element and the second nasal delivery element and / or is adjacent the second nasal delivery element.

[00305] In some configurations, the bypass restriction comprises at least one protrusion extending into the gases flow channel, optionally wherein the bypass restriction comprises a plurality of protrusions extending into the gases flow channel.

[00306] In some configurations, the gases manifold part comprises a proximal bypass protrusion that is proximal to the nasal delivery elements and / or a distal bypass protrusion that is distal from the nasal delivery elements.

[00307] In some configurations, the gases manifold part comprises both a proximal bypass protrusion and a distal bypass protrusion which in combination define a predetermined bypass dimension for the restricted flow of gases through the gases manifold between the first nasal delivery element and the second nasal delivery element.

[00308] In some configurations, the bypass restriction comprises an angled leading edge and an angled trailing edge that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element to the second nasal delivery element.

[00309] In some configurations, the bypass restriction comprises an insert for attachment to the gases manifold part.

[00310] In some configurations, the nasal interface further comprises a bias flow restriction for a flow of gases out of the nasal interface.

[00311] In some configurations, the bias flow restriction comprises at least one aperture for the flow of gases from the nasal interface to an ambient environment, optionally wherein the bias flow restriction comprises a plurality of apertures for the flow of gases from the nasal interface to an ambient environment.

[00312] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[00313] In some configurations, the nasal interface comprises a filter unit between the gases manifold part and the bias flow restriction.

[00314] In some configurations, the bias flow restriction is in fluid communication with the gases manifold part, optionally wherein the gases manifold comprises the bias flow restriction or is coupled to the bias flow restriction, optionally wherein the bias flow restriction is in fluid communication with the gases manifold part but is positioned remotely from the gases manifold part.

[00315] In some configurations, the gases inlet is in fluid communication with a respiratory conduit.

[00316] In some configurations, the respiratory conduit has an internal diameter of between about 12 mm and about 23 mm, optionally between about 12 mm and about 22 mm, optionally between about 12 mm and about 21 mm, optionally between about 12 mm and about 20 mm, optionally between about 12 mm and about 19 mm, optionally between about 12 mm and about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00317] In some configurations, the gases manifold part comprises sealing flanges or collars for engagement with the first and second nasal delivery elements when the interface body part is engaged with the gases manifold part.

[00318] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of the gases flow channel, wherein each of the first nasal delivery element and the second nasal delivery element comprises an inner cross-sectional area, wherein the inner cross-sectional areas together provide a combined cross-sectional area of the nasal delivery elements, and wherein the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements.

[00319] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area of the nasal delivery elements, optionally upto about 1 / 3 of the combined cross-sectional area of the nasal delivery elements.

[00320] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at a smallest transverse dimension of the respective nasal delivery element.

[00321] In some configurations, the smallest transverse dimension is in a direction that is transverse to a direction of gases flow through the nasal delivery elements.

[00322] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at an outlet of the respective nasal delivery element.

[00323] In some configurations, the portion of the gases flow channel is between the first nasal delivery element and the second nasal delivery element and / or is adjacent the second nasal delivery element.

[00324] In some configurations, the bypass restriction comprises at least one protrusion extending into the gases flow channel, optionally wherein the bypass restriction comprises a plurality of protrusions extending into the gases flow channel.

[00325] In some configurations, the nasal interface comprises a gases manifold comprising the gases flow channel.

[00326] In some configurations, the gases manifold comprises a proximal bypass protrusion that is proximal to the nasal delivery elements and / or a distal bypass protrusion that is distal from the nasal delivery elements.

[00327] In some configurations, the gases manifold comprises both a proximal bypass protrusion and a distal bypass protrusion which in combination define a predetermined bypass dimension for the restricted flow of gases through the gases manifold between the first nasal delivery element and the second nasal delivery element.

[00328] In some configurations, the bypass restriction comprises an angled leading edge and an angled trailing edge that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element to the second nasal delivery element.

[00329] In some configurations, the nasal interface comprises an interface body and a gases manifold part, wherein the interface body and the gases manifold part together form the gases manifold.

[00330] In some configurations, the gases inlet is at a side of the gases manifold.

[00331] In some configurations, an open area for gases flow through the bias flow restriction is between about 10 mm2 and about 30 mm2, optionally between about 25 mm2 and about 30 mm2, and optionally about 27.5 mm2.

[00332] In some configurations, an open area for gases flow through the bias flow restriction is more than 0 mm2 to about 40 mm2, optionally between about 2 mm2 and about 40mm2, optionally between about 2 mm2 and about 5 mm2, optionally between about 12 mm2 and about 40mm2, optionally between about 20 mm2 and about 30 mm2.

[00333] In some configurations, the bias flow restriction is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is more than 0 Ipm to about 80 Ipm when a pressure of more than 0 cmH20 and up to about 30 cmH20 is provided to the gases inlet in use and the nasal delivery elements are occluded.

[00334] In some configurations, the bias flow restriction is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is between about 4 Ipm and about 15 Ipm when a pressure of between about 3 cmH20 and about 10 cmH20 is provided to the gases inlet in use and the nasal delivery elements are occluded.

[00335] In some configurations, the bias flow restriction is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is between about 15 Ipm and about 80 Ipm when a pressure of between about 4 cmH2O and about 30 cmH20 is provided to the gases inlet in use and the nasal delivery elements are occluded.

[00336] In some configurations, the bias flow restriction comprises at least one aperture for the flow of gases from the nasal interface to an ambient environment, optionally wherein the bias flow restriction comprises a plurality of apertures for the flow of gases from the nasal interface to an ambient environment.

[00337] In some configurations, the bias flow restriction comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s).

[00338] In some configurations, the nasal interface comprises a filter unit between the gases manifold and the bias flow restriction.

[00339] In some configurations, the bias flow restriction is in fluid communication with the gases manifold, optionally wherein the gases manifold comprises the bias flow restriction or is coupled to the bias flow restriction, optionally wherein the bias flow restriction is in fluid communication with the gases manifold but is positioned remotely from the gases manifold.

[00340] In some configurations, the cross-sectional area of the portion of the gases flow channel is between about 10% and up to about 100% of a first cross-sectional area of an adjacent part of the gases flow channel, optionally about 10% or more and less than 100% of the first cross-sectional area, optionally up to about 90% of the first cross-sectional area, optionally up to about 80% of the first cross-sectional area, optionally up to about 70% of the first cross-sectional area, optionally up to about 60% of the first cross-sectional area, optionally up to about 55% of the first cross-sectional area, optionally up to about 40% of the first cross-sectional area, optionally up to about 30% of the first cross-sectional area, and optionally up to about 25% of the first cross-sectional area.

[00341] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 300 mm2, optionally up to about 280 mm2, optionally up to about 270 mm2, optionally up to about 200 mm2, optionally up to about 160 mm2, optionally up to about 110 mm2, optionally up to about 80 mm2, optionally up to about 60 mm2, and optionally up to about 50 mm2.

[00342] In some configurations, the combined cross-sectional area of the nasal delivery elements is more than 0 mm2 and up to about 250 mm2, optionally between about 1 mm2 and about 250 mm2, optionally between about 1.6 mm2 and about 250 mm2, optionally between about 50 mm2 and about 250 mm2, optionally between about 50 mm2 and about 200 mm2, optionally between about 30 mm2 and about 200 mm2, optionally between about 30 mm2 and about 155 mm2, optionally between about 50 mm2 and about 155 mm2, and optionally between about 70 mm2 and about 155 mm2.

[00343] In some configurations, the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements and the combined cross-sectional area of the nasal delivery elements is between about 1 mm2 and about 250 mm2.

[00344] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area of the nasal delivery elements, optionally upto about 1 / 3 of the combined cross-sectional area of the nasal delivery elements.

[00345] In some configurations, the combined cross-sectional area of the nasal delivery elements is between about 1.6 mm2 and about 250 mm2, optionally between about 50 mm2 and about 250 mm2, optionally between about 50 mm2 and about 200 mm2, optionally between about 30 mm2 and about 200 mm2, optionally between about 30 mm2 and about 155 mm2, optionally between about 50 mm2 and about 155 mm2, and optionally between about 70 mm2 and about 155 mm2.

[00346] In some configurations, the bypass restriction provides a pressure drop through the nasal interface between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00347] In some configurations, the nasal interface comprises a or the first nasal delivery element and a or the second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the first nasal delivery element and the second nasal delivery element are in fluid communication with the gases inlet via the gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, wherein the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of the gases flow channel, wherein each of the first nasal delivery element and the second nasal delivery element comprises an inner cross-sectional area, and wherein the inner cross-sectional areas of the nasal delivery elements and the cross-sectional area of the portion of the gases flow channel are related so as to create an asymmetrical flow of gases from the nasal delivery elements in use.

[00348] In some configurations, the inner cross-sectional areas together provide a combined cross-sectional area of the nasal delivery elements, and wherein the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements.

[00349] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area of the nasal delivery elements, optionally upto about 1 / 3 of the combined cross-sectional area of the nasal delivery elements.

[00350] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at a smallest transverse dimension of the respective nasal delivery element.

[00351] In some configurations, the smallest transverse dimension is in a direction that is transverse to a direction of gases flow through the nasal delivery elements.

[00352] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements is at an outlet of the respective nasal delivery element.

[00353] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 times, optionally up to about 2 / 3 times, the combined cross sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through a bias flow restriction of 20 Ipm when a pressure of 4 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded.

[00354] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 times, optionally up to about 2 / 3 times, the combined cross-sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through a bias flow restriction of 32 Ipm when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded.

[00355] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through the bias flow restriction of 20 Ipm when a pressure of 4 cmH2O is provided to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow through the bias flow restriction of 32 Ipm when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow through the bias flow restriction of 41 Ipm when a pressure of 12 cmHzO is applied to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow of 48 Ipm through the bias flow restriction when a pressure of 16 cmH20 is applied to the gases inlet and the nasal delivery elements are occluded, or is configured to provide a bias flow through the bias flow restriction of 53 Ipm when a pressure of 20 cmH20 is applied to the gases inlet and the nasal delivery elements are occluded.

[00356] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements, and the nasal interface is configured to provide a bias flow through the bias flow restriction of 32 Ipm or higher when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded.

[00357] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 / 3 times the combined cross-sectional area of the nasal delivery elements and the nasal interface is configured to provide a bias flow through the bias flow restriction of 32 Ipm or higher when a pressure of 8 cmH20 is provided to the gases inlet and the nasal delivery elements are occluded, or wherein the cross-sectional area of the portion of the gases flow channel is up to about 2 / 5 times the combined cross-sectional area of the nasal delivery elements and the nasal interface is configured to provide a bias flow through the bias flow restriction of 41 Ipm or higher when a pressure of 12 cm H20 is provided to the gases inlet and the nasal delivery elements are occluded, or wherein the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements and the nasal interface is configured to provide bias flow through the bias flow restriction of 48 Ipm or higher when a pressure of 16 cmH2O is provided to the gases inlet and the nasal delivery elements are occluded.

[00358] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00359] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a first nasal delivery element comprising a first outlet configured to deliver gases to a first naris of a patient and a second nasal delivery element comprising a second outlet configured to deliver gases to a second naris of a patient, and a gases inlet for delivery of respiratory gases into the nasal interface, the interface body comprising first and second interface body side arms, a frame comprising first and second frame side arms, wherein the first and second interface body side arms each comprise a through passage to enable a respective one of the first and second frame side arms to extend therethrough to couple the first and second frame side arms with the first and second interface body side arms, wherein when the first and second frame side arms are coupled with the first and second interface body side arms, proximal portions of the first and second interface body side arms are located behind proximal portions of the first and second frame side arms, so as to be positioned between a patient's face and the proximal portions of the first and second frame side arms in use.

[00360] In some configurations, the interface body comprises a softer material than the frame which comprises a more rigid material.

[00361] In some configurations, the interface body side arms each comprise a respective compliant cheek portion.

[00362] In some configurations, each through passage is positioned adjacent an outer end of the respective interface body side arm.

[00363] In some configurations, each through passage comprises an aperture or a slot.

[00364] In some configurations, the frame side arms are configured to attach to a headgear.

[00365] In some configurations, the frame side arms comprise headgear attachment features adjacent an outer end of the frame side arms.

[00366] In some configurations, the interface body comprises a central interface body portion, and wherein the frame comprises a central frame body portion, wherein the central interface body portion and the central frame body portion are configured to couple together to define a gases flow channel for delivery of respiratory gases from a gases inlet through the first nasal delivery element and the second nasal delivery element.

[00367] In some configurations, the central frame body portion comprises the gases inlet.

[00368] In some configurations, the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient.

[00369] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00370] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a cushion and configured to substantially form a seal with a patient's nasal airways, the interface body configured to deliver gases to a first naris of the patient and to a second naris of the patient, a frame that is configured to engage with the interface body, wherein the interface body comprises a softer material than the frame which comprises a more rigid material, and wherein the interface body and the frame are configured such that one or more bias flow vents are formed between the interface body and the frame when the interface body and the frame are engaged with each other.

[00371] In some configurations, the interface body comprises a part of the bias flow vent(s).

[00372] In some configurations, the frame comprises a part of the bias flowvent(s).

[00373] In some configurations, the interface body comprises a first part of the bias flow vent(s) and the frame comprises a second part of the bias flow vent(s).

[00374] In some configurations, the part(s) of the bias flow vent(s) comprise channel(s).

[00375] In some configurations, the nasal interface comprises a plurality of the bias flow vents.

[00376] In some configurations, the bias flow vents are arranged in at least one array about a portion of the nasal interface.

[00377] In some configurations, the at least one array is configured to direct gases from the nasal interface in a diverging pattern.

[00378] In some configurations, the diverging pattern comprises flow that is at least partly laterally outward from the interface body and / or from the frame.

[00379] In some configurations, the diverging pattern includes flow that is at least partly upward and / or downward from the interface body and / or from the frame.

[00380] In some configurations, the diverging pattern is at least substantially conical.

[00381] In some configurations, the interface body comprises a central interface body portion, and wherein the frame comprises a central frame body portion, wherein the central interface body portion and the central frame body portion are configured to engage with each other to define a gases flow channel for delivery of respiratory gases from a gases inlet through interface body to the first naris of the patient and to the second naris of the patient in use.

[00382] In some configurations, the central frame body portion comprises the gases inlet.

[00383] In some configurations, the gases inlet is provided at or near one side of the central frame body portion and wherein at least one of the one or more bias flow vents is provided at or near an opposite side of the central frame body portion, between the interface body and the frame.

[00384] In some configurations, the nasal interface comprises a single outlet for delivering gases to the first naris and second naris of the patient.

[00385] In some configurations, the interface body comprises a first nasal delivery element comprising a first outlet and a second nasal delivery element comprising a second outlet, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient.

[00386] In some configurations, the interface body comprises first and second interface body side arms, wherein the interface body side arms each comprise an unsealed cavity to enhance flexibility of the side arms.

[00387] In some configurations, each interface body side arm comprises a patient-proximate wall that is configured to be in contact with a patient's cheeks in use, and a patient-distal wall that is configured to be spaced from the patient's cheeks in use, wherein the patient-proximate wall is spaced from the patient-distal wall, with the unsealed cavity between the patient-proximate wall and the patient-distal wall.

[00388] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00389] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a first nasal delivery element that is configured to seal with a first naris of a patient and a second nasal delivery element that is configured to seal with a second naris of the patient, a gases inlet for delivery of respiratory gases into the nasal interface, wherein the gases inlet is positioned closer to the first nasal delivery element than to the second nasal delivery element, and a bias flow vent for a flow of gases out of the nasal interface, wherein the bias flow vent is positioned closer to the second nasal delivery element than to the first nasal delivery element, and wherein the bias flow vent comprises one or more elongate bias flow apertures.

[00390] In some configurations, the nasal interface comprises a gases flow channel in the nasal interface, wherein at least one of the one or more elongate bias flow apertures extends from a position proximal to the gases inlet to a position at or toward an end of the gases flow channel.

[00391] In some configurations, an end of said at least one of the one or more elongate bias flow apertures is proximal to a peripheral edge of an exit of the gases inlet.

[00392] In some configurations, the nasal interface comprises the interface body and a frame, wherein the interface body comprises the first and second nasal delivery elements, wherein the frame comprises the bias flow vent.

[00393] In some configurations, the frame comprises a recess, and wherein the bias flow vent is located in the recess.

[00394] In some configurations, the recess has an irregular shape.

[00395] In some configurations, the recess has an irregular polygonal shape.

[00396] In some configurations, the at least one bias flow aperture has one dimension larger than another dimension.

[00397] In some configurations, the bias flow vent comprises a plurality of the elongate bias flow apertures.

[00398] In some configurations, the plurality of the elongate bias flow apertures are arranged substantially parallel to one another.

[00399] In some configurations, the bias flow vent comprises a diffuser to diffuse gases flowing through the one or more elongate bias flow apertures.

[00400] In some configurations, the gases inlet and the first and second nasal delivery elements are in fluid communication with a or the gases flow channel of the interface body to deliver the respiratory gases from the gases inlet through the first and second nasal delivery elements.

[00401] In some configurations, the one or more elongate bias flow apertures is / are elongate in a direction extending across the nasal interface.

[00402] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00403] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a first nasal delivery element that is configured to seal with a first naris of a patient and a second nasal delivery element that is configured to seal with a second naris of the patient, a gases inlet for delivery of respiratory gases into the nasal interface, and a bias flow vent for a flow of gases out of the nasal interface, wherein an internal surface of the gases inlet transitions at an exit to an internal surface of the nasal interface, wherein the exit comprises a periphery having portions that are differently radiused to one another, wherein a portion of the periphery proximal to the bias flow vent has a radius greater than other portions of the periphery.

[00404] In some configurations, the gases inlet is positioned closer to the first nasal delivery element than to the second nasal delivery element.

[00405] In some configurations, the bias flow vent is positioned closer to the second nasal delivery element than to the first nasal delivery element.

[00406] In some configurations, the exit has a non-circular cross-sectional shape.

[00407] In some configurations, the bias flow vent comprises one or more elongate bias flow apertures.

[00408] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00409] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a first nasal delivery element that is configured to seal with a first naris of a patient and a second nasal delivery element that is configured to seal with a second naris of the patient, a gases inlet for delivery of respiratory gases into the nasal interface, wherein the gases inlet is positioned closer to the first nasal delivery element than to the second nasal delivery element, and a bias flow vent for a flow of gases out of the nasal interface, the bias flow vent positioned closer to the second nasal delivery element than to the first nasal delivery element, wherein an internal surface of the interface body comprises a protrusion extending from a base of the first nasal delivery element towards the gases inlet, the protrusion extending radially outwards as it extends towards the gases inlet.

[00410] In some configurations, the protrusion comprises a loop around the base of the first nasal delivery element.

[00411] In some configurations, the protrusion defines a protrusion gases flow channel, and wherein the protrusion gases flow channel has a larger cross-sectional area at its terminal region closer to the gases inlet compared to a region closer to the first nasal delivery element.

[00412] In some configurations, the protrusion forms a funnel to guide flow from the gases inlet into the first nasal delivery element.

[00413] In some configurations, the protrusion is integral with the interface body.

[00414] In some configurations, the protrusion comprises a plurality of protrusion portions.

[00415] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00416] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a nasal interface is disclosed, the nasal interface comprising: an interface body comprising a first nasal delivery element that is configured to seal with a first naris of a patient, a second nasal delivery element that is configured to seal with a second naris of the patient, a first gases flow channel in fluid communication with the first nasal delivery element, a second gases flow channel in fluid communication with the second nasal delivery element, and a wall configured to pneumatically isolate the first gases flow channel and the second gases flow channel within the interface body, a gases inlet for delivery of respiratory gases to the first gases flow channel, and a bias flow vent for a flow of gases out of the nasal interface, wherein the bias flow vent is in fluid communication with the second gases flow channel.

[00417] In some configurations, the gases inlet is configured to direct a flow of respiratory gases from the gases inlet to an outlet of the first nasal delivery element.

[00418] In some configurations, at least an exit of the gases inlet is arranged to direct the flow of respiratory gases to the outlet of the first nasal delivery element.

[00419] In some configurations, the nasal interface comprises the interface body and a frame, wherein the interface body comprises the first and second nasal delivery elements, wherein the wall is provided by the frame, by the interface body, or by the frame and the interface body.

[00420] In some configurations, the nasal interface comprises an insert for positioning in, or in, the interface body, wherein the insert comprises the wall.

[00421] In some configurations, the insert comprises two wing portions that project laterally outwardly in opposite directions from the wall.

[00422] In some configurations, the wing portions project laterally outwardly in opposite directions from a rear section of the wall.

[00423] In some configurations, the wing portions are configured to contact an inner surface of the interface body proximal to bases of the first and second nasal delivery elements.

[00424] In some configurations, the wing portions each comprise a loop member that is at least a size of, or is larger than, bases of the first and second nasal delivery elements.

[00425] In some configurations, the wing portions are configured to form a seal against an inner surface of the interface body.

[00426] In some configurations, the insert, the interface body, and / or a or the frame of the nasal interface comprise one or more engagement features for engaging the insert in the nasal interface.

[00427] In some configurations, the nasal interface is configured such that, in use, the bias flow vent generates a pressure in the second gases flow channel to minimise a pressure differential between a pressure generated in the first gases flow channel and the second gases flow channel.

[00428] In some configurations, the wall is configured to cause a unidirectional flow during use.

[00429] In some configurations, the wall is configured to cause the unidirectional flow during a phase of the patient's respiratory cycle.

[00430] In some configurations, the wall comprises a shape that corresponds to a cross-sectional shape of the first gases flow channel, the second gases flow channel, or both the first gases flow channel and the second gases flow channel.

[00431] In some configurations, the wall has the same rigidity as the interface body or has a different rigidity from the interface body.

[00432] In some configurations, the wall comprises the same material as the interface body or comprises a different material from the interface body.

[00433] In some configurations, the nasal interface comprises the interface body and a frame, and wherein the wall has the same rigidity as the frame or has a different rigidity from the frame.

[00434] In some configurations, the bias flow vent comprises one or more elongate bias flow apertures.

[00435] The nasal interface of this aspect may have one or more of the features outlined in relation to any of the other aspects.

[00436] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a respiratory therapy system is disclosed, the respiratory therapy system comprising: a gases source for respiratory gases and configured to provide pressure controlled respiratory gases; a breathing tube to receive the pressure controlled respiratory gases; and the nasal interface outlined above or herein in fluid communication with the breathing tube to deliver the respiratory gases to a patient.

[00437] In some configurations, the interface body comprises a first outlet or first outlet portion configured to deliver gases to the first naris of the patient, and comprises a second outlet or second outlet portion configured to deliver gases to the second naris of the patient, and wherein the nasal interface is configured to create a pressure differential between the first outlet or first outlet portion and the second outlet or second outlet portion when gases are delivered from the gases inlet to both the first outlet or first outlet portion and the second outlet or second outlet portion such that pressure at the first outlet or first outlet portion is higher than pressure at the second outlet or second outlet portion.

[00438] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a respiratory therapy system is disclosed, the respiratory therapy system comprising: a gases source for respiratory gases and configured to provide pressure controlled respiratory gases; a breathing tube to receive the pressure controlled respiratory gases; and a nasal interface having a gases inlet in fluid communication with the breathing tube to deliver the respiratory gases to a patient, the nasal interface comprising a first nasal delivery element and a second nasal delivery element, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient, wherein the nasal interface is configured to create a pressure differential between the first nasal delivery element and the second nasal delivery element when gases are delivered from the gases inlet to both the first nasal delivery element and the second nasal delivery element such that pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00439] In some configurations, the respiratory therapy system comprises a respiratory conduit to receive the pressure controlled respiratory gases from the breathing tube, wherein the respiratory conduit is in fluid communication with the breathing tube and the gases inlet of the nasal interface.

[00440] In some configurations, the respiratory therapy system further comprises a respiratory gases filter.

[00441] In some configurations, the respiratory gases filter is located between the breathing tube and the respiratory conduit.

[00442] In some configurations, the respiratory gases filter is located between the gases manifold and a bias flow restriction.

[00443] In some configurations, the respiratory therapy system further comprises a humidifier configured to humidify said pressure controlled respiratory gases prior to their delivery to the nasal interface.

[00444] In some configurations, the breathing tube is a heated breathing tube, and is configured to receive the pressure controlled respiratory gases from the humidifier.

[00445] In some configurations, a temperature of gases flow exiting the first and second nasal delivery elements is between about 31°C and about 41°C, optionally more than 31°C and up to about 41°C, optionally between about 36°C and about 39°C, optionally about 37°C.

[00446] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a method of providing respiratory support to a patient is provided, the method comprising: providing a respiratory therapy system comprising: a gases source for respiratory gases and configured to provide pressure controlled respiratory gases; a breathing tube to receive the pressure controlled respiratory gases; and a nasal interface having a gases inlet in fluid communication with the breathing tube to deliver the respiratory gases to a patient, the nasal interface comprising a first nasal delivery element and a second nasal delivery element; sealing each of the first nasal delivery element and the second nasal delivery element with a respective naris of a patient; operating the respiratory therapy apparatus to provide a flow of gases to the nasal interface; and delivering an asymmetrical flow of gases from the respiratory therapy apparatus through the first nasal delivery element and the second nasal delivery element at a patient's nares.

[00447] In some configurations, the nasal delivery elements are in fluid communication with the gases inlet via a gases flow channel, wherein the first nasal delivery element is proximal to the gases inlet and the second nasal delivery element is distal from the gases inlet, and wherein the nasal interface comprises a bypass restriction that provides a cross-sectional area of a portion of the gases flow channel, wherein each of the first nasal delivery element and the second nasal delivery element comprises an inner cross-sectional area, wherein the inner cross-sectional areas together provide a combined cross-sectional area of the nasal delivery elements, and wherein the cross-sectional area of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area of the nasal delivery elements.

[00448] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 times, optionally up to about 2 / 3 times, the combined cross-sectional area of the nasal delivery elements, and wherein the method comprises providing a pressure of 4 cmH20 to the gases inlet such that there is a bias flow through a bias flow restriction of 20 Ipm.

[00449] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 times, optionally up to about 2 / 3 times, the combined cross-sectional area of the nasal delivery elements, and wherein the method comprises providing a pressure of 8 cmH2O to the gases inlet such that there is a bias flow through a bias flow restriction of 32 Ipm.

[00450] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements, and wherein the method comprises providing a pressure of 4 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 20 Ipm, or wherein the method comprises providing a pressure of 8 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 32 Ipm, or wherein the method comprises providing a pressure of 12 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 41 Ipm, or wherein the method comprises providing a pressure of 16 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 48 Ipm, or wherein the method comprises providing a pressure of 20 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 53 Ipm.

[00451] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements, and wherein the method comprises providing a pressure of 8 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 32 Ipm or higher.

[00452] In some configurations, the cross-sectional area of the portion of the gases flow channel is up to about 1 / 3 times the combined cross-sectional area of the nasal delivery elements and wherein the method comprises providing a pressure of 8 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 32 Ipm or higher, or wherein the cross-sectional area of the portion of the gases flow channel is up to about 2 / 5 times the combined cross-sectional area of the nasal delivery elements and wherein the method comprises providing a pressure of 12 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 41 Ipm or higher, or wherein the cross-sectional area of the portion of the gases flow channel is up to about 2 / 3 times the combined cross-sectional area of the nasal delivery elements and wherein the method comprises providing a pressure of 16 cmH20 to the gases inlet such that there is a bias flow through the bias flow restriction of 48 Ipm or higher.

[00453] In some configurations, a temperature of gases flow exiting the first and second nasal delivery elements is between about 31°C and about 41°C, optionally more than 31°C and up to about 41°C, optionally between about 36°C and about 39°C, optionally about 37°C.

[00454] In some configurations, the nasal interface is as outlined above or herein.

[00455] In some configurations, the respiratory therapy system is as outlined above or herein.

[00456] In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, a method of providing respiratory support to a patient is provided, the method comprising: providing a respiratory therapy system comprising: a gases source for respiratory gases and configured to provide pressure controlled respiratory gases; a breathing tube to receive the pressure controlled respiratory gases; and a nasal interface in fluid communication with the breathing tube to deliver the respiratory gases to a patient; sealing the nasal interface with a patient's nasal airways; operating the respiratory therapy apparatus to provide a flow of gases to the nasal interface; and receiving incoming gases at a gases inlet of the nasal interface and creating an asymmetric flow of gases at a patient's nasal airways.

[00457] In some configurations, the method comprises creating an asymmetric flow of gases at the patient's nasal airways throughout a respiratory cycle of the patient.

[00458] In some configurations, the nasal interface is as outlined above or herein.

[00459] In some configurations, the respiratory therapy system is as outlined above or herein.

[00460] Features from one or more embodiments or configurations may be combined with features of one or more other embodiments or configurations. Additionally, more than one embodiment or configuration may be used together in a respiratory support system during a process of respiratory support of a patient.

[00461] As used herein the term "(s)" following a noun means the plural and / or singular form of that noun.

[00462] As used herein the term "and / or" means "and" or "or", or where the context allows both.

[00463] The term "comprising" as used in this specification means "consisting at least in part of". When interpreting each statement in this specification that includes the term "comprising", features other than that orthose prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

[00464] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

[00465] This disclosure may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

[00466] Where specific integers are mentioned herein which have known equivalents in the art to which this disclosure relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[00467] The disclosure consists in the foregoing and also envisages constructions of which the following gives examples only. Brief Description of the Drawings

[00468] Specific embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which:

[00469] Figure 1 is a front perspective view of an exemplary configuration patient interface of the present disclosure comprising a nasal interface.

[00470] Figure 2 is a close-up perspective view of the nasal interface.

[00471] Figure 3 is a rear perspective view of the patient interface.

[00472] Figure 4 is a close-up perspective view of the nasal interface.

[00473] Figure 5 is a front perspective view of the patient interface, showing the gases manifold part separated from the interface body part that comprises the nasal delivery elements, a bias flow restriction part separated from the gases manifold part, and a respiratory conduit separated from the gases manifold part.

[00474] Figure 6(a) is a front perspective view of the bias flow restriction part.

[00475] Figure 6(b) is an exploded front perspective view of components of the bias flow restriction part.

[00476] Figure 7(a) is a perspective sectional view of the bias flow restriction part.

[00477] Figure 7(b) is an orthogonal sectional view of the bias flow restriction part.

[00478] Figure 8 is an orthogonal view towards the front of the bias flow restriction part.

[00479] Figure 9 is a front partial sectional view of the nasal interface showing a gases flow restriction in the gases manifold.

[00480] Figure 10(a) is a front perspective sectional view of the nasal interface schematically showing gases flow directions through the nasal interface.

[00481] Figure 10(b) is an orthogonal front sectional view of the nasal interface schematically showing gases flow directions through the nasal interface.

[00482] Figure 11 shows views of the gases manifold, where Figure 11(a) is a front perspective view, Figure 11(b) is a front perspective view sectioned through a horizontal plane, and Figure 11(c) is a front perspective view sectioned through a vertical plane.

[00483] Figure 12 shows views of the gases manifold, where Figure 12(a) is a top view, Figure 12(b) is a sectional view along line b-b of Figure 12(d), Figure 12(c) is a front view, Figure 12(d) is an end view, and Figure 12(e) is a sectional view along line e-e of Figure 12(d).

[00484] Figure 13 shows views of the face mount part or interface body part of the nasal interface, where Figure 13(a) is a rearview, Figure 13(b) is a front view, and Figure 13(c) is a sectional view along line c-c of Figure 13(b).

[00485] Figure 14 is a sectional view through the gases manifold and one of the nasal delivery elements.

[00486] Figure 15 is a schematic diagram of the functionality and effect of use of the patient interface.

[00487] Figure 16 shows side-swapping functionality where the respiratory conduit is coupled to the right side of the gases manifold in Figure 16(a) and the respiratory conduit is coupled to the left side of the gases manifold in Figure 16(b).

[00488] Figure 17(a) shows remote positioning of the bias flow restriction part.

[00489] Figure 17(b) shows remote positioning of the bias flow restriction part with a filter between the gases manifold and the bias flow restriction part.

[00490] Figure 18 is an exploded view of components of the headgear of the patient interface.

[00491] Figure 19 schematically shows the configuration of the nasal interface of Figures 1 to 18.

[00492] Figure 20 schematically shows an alternative configuration of the nasal interface.

[00493] Figure 21 schematically shows another alternative configuration of the nasal interface.

[00494] Figure 22 shows a respiratory therapy system incorporating the patient interface and nasal interface of the present disclosure.

[00495] Figure 23 shows the results of testing different ratios of bypass restriction to combined nasal delivery element area for 15 breaths per minute 10i:20e 500Vt (tidal volume) breath pattern, at pressures of 4 cmH20 and 8 cmH20.

[00496] Figure 24 shows the results of testing different ratios of bypass restriction to combined nasal delivery element area for 25 breaths per minute ARDS (acute respiratory distress syndrome) breath pattern, at pressures of 4 cmH20, 8 cmH20, 12 cmH20, 16 cmH20, and 20 cmH20.

[00497] Figure 25 shows the results of testing different ratios of bypass restriction to combined nasal delivery element area for 45 breaths per minute 350 Vt (tidal volume) sinusoidal breath pattern, at pressures of 4 cmH20, 8 cmH20, 12 cmH20, 16 cmH20, and 20 cmH20.

[00498] Figure 26 shows modelled effects of different nasal delivery element sizes, different bypass restriction cross-sectional areas, different set pressures, and different bias flow restriction openness on rebreathing with the nasal interface for 15 breaths per minute.

[00499] Figure 27 shows modelled effects of different nasal delivery element sizes, different bypass restriction cross-sectional areas, different set pressures, and different bias flow restriction openness on rebreathing with the nasal interface for 25 breaths per minute.

[00500] Figure 28 shows modelled effects of different nasal delivery element sizes, different bypass restriction cross-sectional areas, different set pressures, and different bias flow restriction openness on rebreathing with the nasal interface with for 45 breaths per minute.

[00501] Figure 29 schematically shows an alternative configuration nasal interface for use in the patient interface.

[00502] Figure 30 shows a front perspective view of an exemplary configuration of the nasal interface.

[00503] Figure 31 shows a front sectional view of the nasal interface showing gases flow paths.

[00504] Figure 32 shows a front sectional view of the nasal interface showing an exhaust gas flow path.

[00505] Figure 33 shows an overhead part sectional view of the nasal interface.

[00506] Figure 34 shows another overhead part sectional view of the nasal interface.

[00507] Figure 35 shows an overhead front perspective view of an interface body / nasal cushion of the nasal interface.

[00508] Figure 36 shows an underside front perspective view of an interface body / nasal cushion of the nasal interface.

[00509] Figure 37 shows a front sectional view of an alternative exemplary configuration nasal interface.

[00510] Figure 38 shows a front perspective sectional view of another alternative exemplary configuration nasal interface.

[00511] Figure 39 shows a front perspective view of another alternative exemplary configuration nasal interface.

[00512] Figure 40 shows a part sectional view of the nasal interface.

[00513] Figure 41 shows a front perspective sectional view of an alternative exemplary configuration nasal interface.

[00514] Figure 42 shows a front perspective sectional view of an alternative exemplary configuration nasal interface.

[00515] Figure 43 shows a top view of an alternative exemplary configuration nasal interface.

[00516] Figure 44 shows front section views of an alternative exemplary configuration nasal interface, where Figure 44(a) shows the nasal cushion in an at-rest state and Figure 44(b) shows the nasal cushion in a compressed state.

[00517] Figure 45 shows a front perspective view of an alternative exemplary configuration nasal cushion for use in the nasal interfaces.

[00518] Figure 46 shows a rear perspective view of the nasal cushion.

[00519] Figure 47 shows deformation or movement of a flow director or flow splitter of the nasal cushion.

[00520] Figure 48 shows alternative deformation or movement of a flow director or flow splitter of the nasal cushion.

[00521] Figure 49 shows an alternative exemplary configuration nasal cushion for use in the nasal interfaces, where Figure 49(a) is a first front perspective view and Figure 49(b) is a second front perspective view.

[00522] Figures 50(a) - 50(c) show three alternative exemplary configuration nasal cushions for use in the nasal interfaces.

[00523] Figure 51 shows an alternative exemplary configuration nasal cushion for use in the nasal interfaces, where Figure 51(a) is a top perspective view and Figure 51(b) is a front view.

[00524] Figure 52 shows an alternative exemplary configuration nasal cushion for use in the nasal interfaces, where Figure 52(a) is a rear view and Figure 52(b) is a top perspective view.

[00525] Figure 53 is a front perspective view of an alternative exemplary configuration nasal interface.

[00526] Figure 54 is an exploded front perspective view of the nasal interface.

[00527] Figure 55 is an exploded rear perspective view of the nasal interface.

[00528] Figure 56 is an overhead sectional view of the nasal interface.

[00529] Figure 57 is a front perspective view of a patient interface comprising an alternative exemplary configuration nasal interface.

[00530] Figure 58 is an overhead sectional view of the nasal interface.

[00531] Figure 59 is a front perspective view of the nasal cushion of the nasal interface.

[00532] Figure 60 is a front perspective view of an alternative exemplary configuration patient interface comprising an alternative exemplary configuration nasal interface.

[00533] Figure 61 is a front perspective view of the nasal interface.

[00534] Figure 62 is a front perspective view of an interface body of the nasal interface.

[00535] Figure 63 is a front perspective view of a frame of the nasal interface.

[00536] Figure 64 is a front perspective view of a headgear of the patient interface.

[00537] Figure 65 is a front perspective view of the interface body of the nasal interface.

[00538] Figure 66 is a rear perspective view of the interface body of the nasal interface.

[00539] Figure 67 is an overhead sectional view of one of the side arms of the interface body showing one of the side arms of the frame.

[00540] Figure 68 is an overhead sectional view of one of the side arms of the interface body.

[00541] Figure 69 is a sectional view of the interface body.

[00542] Figure 70 is a sectional view of the nasal interface showing one configuration of the nasal delivery elements.

[00543] Figure 71 is an overhead sectional view of the nasal interface.

[00544] Figure 72 is a transverse sectional view of the nasal interface showing one of the nasal delivery elements.

[00545] Figure 73 is an overhead sectional view of the nasal interface showing an alternative configuration of the nasal delivery elements.

[00546] Figure 74 shows sectional views of one of the nasal delivery elements of the nasal interface of Figure 73.

[00547] Figure 75 is an overhead sectional view of the nasal interface showing one configuration of the gases inlet.

[00548] Figure 76 is a side sectional view of the nasal interface.

[00549] Figure 77 is an overhead sectional view showing more detail of the configuration of the gases inlet.

[00550] Figure 78 is an overhead sectional view showing an alternative configuration of the gases inlet.

[00551] Figure 79 is a front perspective view of the nasal interface showing bias flow vent(s).

[00552] Figure 80 is a side view of the nasal interface.

[00553] Figure 81 is a rearview of the interface body of the nasal interface.

[00554] Figure 82 is an enlarged overhead view of the nasal interface showing the bias flow vent(s).

[00555] Figure 83 is a sectional view of the nasal interface showing bias flow passages.

[00556] Figure 84 is an enlarged sectional view showing one of the bias flow passages.

[00557] Figure 85 shows exemplary configurations of nozzles for use in the nasal interfaces.

[00558] Figure 86 is a front perspective view of an alternative exemplary configuration patient interface comprising an alternative exemplary configuration nasal interface.

[00559] Figure 87 is another front perspective view of the patient interface of Figure 86.

[00560] Figure 88 is an exploded front perspective view of the patient interface of Figure 86.

[00561]

[00562]

[00563] 86. Figure 89 is a front view of the nasal interface of Figure 86. Figure 90 is a front perspective view of the nasal interface of Figure 86. Figure 91 is another front perspective view of the nasal interface of Figure

[00564] 86. Figure 92 is another front perspective view of the nasal interface of Figure

[00565] Figure 93 is a front perspective view of the interface body of the nasal interface of Figure 86.

[00566]

[00567]

[00568]

[00569]

[00570]

[00571] Figure 94 is a side sectional view of the nasal interface of Figure 86. Figure 95 is a front view of the nasal interface of Figure 86. Figure 96 is a front view of a frame of the nasal interface of Figure 86. Figure 97 is a rear view of the frame of Figure 96. Figure 98 is a front perspective view of the nasal interface of Figure 86. Figure 99 is an overhead sectional view of the nasal interface of Figure 98, showing a gases flow channel in the nasal interface body.

[00572] Figure 100 is an overhead sectional view through the frame of the nasal interface of Figure 98.

[00573] Figure 101 is a diagram showing a relationship between bias flow rates (Ipm) and pressure (cmH20) at a patient.

[00574] Figure 102 is a diagram showing (a) a 'fan-out' zone for a low aspect ratio aperture of a bias flow vent and (b) a 'fan-out' zone for an elongate high aspect ratio aperture of a bias flow vent.

[00575] Figure 103 is a front perspective view of an alternative configuration nasal interface for use in the patient interface of Figure 86, the nasal interface having a higher aspect ratio aperture for the bias flow vent when compared to that of Figure 95.

[00576] Figure 104 is a front perspective view of an alternative configuration frame for use in an alternative configuration nasal interface in the patient interface of Figure 86, the frame interface having a lower aspect ratio aperture for the bias flow vent when compared to that of Figure 95 for example and a lower aspect ratio for the bias flow vent when compared to that of Figure 103.

[00577] Figure 105 is a rear perspective view of the frame of Figure 104.

[00578] Figure 106 is a top sectional view of an interface body of an alternative configuration nasal interface, the interface body comprising a protrusion extending from a base of the first nasal delivery element towards the gases inlet.

[00579] Figure 107 is a top sectional view of the interface body of Figure 106 and frame, showing a gases flow direction from the gases inlet of the nasal interface.

[00580] Figure 108 is a front sectional view of the interface body of Figure 106, showing two protrusions.

[00581] Figure 109 is a front perspective view of an interface body of an alternative configuration nasal interface, the nasal interface comprising a wall configured to pneumatically isolate a first gases flow channel and a second gases flow channel within the interface body;

[00582] Figure 110 is a sectional perspective view showing the nasal interface with the wall of Figure 109;

[00583] Figure 111 is a front perspective view showing an insert for the interface body that may provide the wall.

[00584] Figure 112 is a sectional perspective view showing the nasal interface with the wall provided by part of the frame.

[00585] Figure 113 is another sectional perspective view showing the nasal interface with the wall provided by part of the frame.

[00586] Figure 114 is a rear perspective view of the frame of the nasal interface of Figure 112.

[00587] Figure 115 is another rear perspective view of the frame of Figure 114.

[00588] Figure 116 is a front perspective view of an interface body of an alternative configuration nasal interface, the nasal interface comprising a wall with a channel that provides a bypass restriction for a gases flow channel of the nasal interface.

[00589] Figure 117 is a sectional perspective view showing the nasal interface with the wall and channel of Figure 116;

[00590] Figure 118 is a front perspective view showing an insert for the interface body that may provide the wall and channel.

[00591] Figure 119 is a rear perspective view of the nasal interface of the patient interface of Figure 96.

[00592] Figure 120 is a first front perspective view of a headgear for use in the nasal interface.

[00593] Figure 121 is a second front perspective view of the headgear of Figure 120.

[00594] Figure 122 is a front perspective view of a frame of a nasal interface with a plurality of elongate bias flow apertures. Detailed Description

[00595] Patient interfaces can be used for delivering breathing gases to airways of a patient. The patient interfaces may comprise nasal interfaces that can be used to deliver a flow of gases to a patient. In some configurations, nasal delivery elements, such as nasal prongs or pillows, are inserted into the nose of a patient to deliver the required therapy. The nasal delivery elements may be desired to seal at the nose to deliver the therapy. One or more of the nasal delivery elements may comprise a nasal pillow to seal at the nose.

[00596] Disclosed is a system to deliver gases to a patient through a nasal interface.

[00597] The system provides a pressure differential at first and second nasal delivery elements of the nasal interface, with a resulting differential gases flow at the first and second nasal delivery elements. This allows an asymmetrical flow to be delivered through the nasal interface to both nares. Asymmetrical flow as described herein refers to a flow that differs within the nasal interface or within the nose. In this way, a different flow may be delivered by each nasal delivery element. An asymmetrical flow may also include partial unidirectional flow.

[00598] Delivery of asymmetrical flow may improve clearance of dead space in the upper airways. A nasal interface as described is configured to produce such asymmetrical flow through nasal delivery elements.

[00599] Flow generated by respiratory therapy depends on flow through the nasal interface, which depends on the pressure at each nasal delivery element. If the pressure is different at each nasal delivery element, an asymmetric flow of gases will be generated.

[00600] If flow, leak, or a combination of flow and leak, is asymmetrical through the nasal interface, the flow through the nose may become asymmetrical during breathing. Partial unidirectional flow may be a type of asymmetrical flow. Partial unidirectional flow may provide improved clearance of anatomical dead space as the air is flushed from the upper airways. Partial unidirectional flow may be more comfortable than total unidirectional flow. Total unidirectional flow herein includes all flow entering one naris by a nasal delivery element and exiting via the other naris via a nasal delivery element, venting to the atmosphere, due to the absence of a nasal delivery element, or the like. Partial unidirectional flow as described herein includes flow that may enter the nose via both nares and leave the nose from one naris, flow that may enter the nose through one naris and leave the nose via both nares, or different proportions of flow that may enter the nose through both nares and / or different proportions of flow that may leave the nose through both nares, and may be flow that may enter the nose via both nares and leave the nose from one or both nares and optionally via the mouth. If there is a pressure differential between the first and second nasal delivery elements, during inspiration the first nasal delivery element will receive more gases flow from a gases inlet than the second nasal delivery element. During expiration, the second nostril associated with the second nasal delivery element will expel more gases flow than the first nostril associated with the first nasal delivery element. The pressure differential between the first and second nasal delivery elements can change depending on whether the patient's breathing cycle is in an inspiration phase or expiration phase.

[00601] The asymmetrical flow assessment may be applied over a suitable period. For example, the asymmetrical flow assessment may be applied over one breath cycle of the patient or alternatively over a different number of breath cycles of the patient.

[00602] The partially unidirectional flow may reduce turbulence in the patient's nasal cavity, which could improve comfort.

[00603] Figures 1-5 show an exemplary patient interface 1 that comprises a nasal interface 100 with nasal delivery elements comprising a first nasal delivery element 111 and a second nasal delivery element 112.

[00604] The nasal interface 100 provides a patient with a patient interface suitable for the delivery of pressure-controlled, optionally high humidity, gas flow to the patient's nasal cavity / nares. In some configurations, the nasal interface 100 is adapted to deliver a high flow of gases over a wide flow range (e.g. about 8 Ipm, or higher depending on other therapy applications, perhaps such as 10 - 50 Ipm, 20 - 40 Ipm, or higher). The flow rates may be bias flows averaged over time. In some configurations, the nasal interface 100 is adapted to deliver a lower flow of gases. The flow is dependent on pressure so it can fluctuate depending on different breathing pressures and set pressures. Wherein set pressure(s) relates to the therapy and / or patient pressure(s) which are maintained by an ancillary respiratory therapy apparatus when used in conjunction with the nasal interface of the disclosure.

[00605] The nasal interface 100 comprises a face mount part or interface body 110 part including a pair of hollow nasal delivery elements 111 and 112, integrally moulded with or removably attached to the interface body 110. The nasal interface 100 comprises a gases manifold 120 part that comprises a gases inlet 121. The gases manifold 120 may be removably attached or integrally moulded to the respiratory conduit 300.

[00606] The interface body 110 part may be connectable to or engageable with the gases manifold 120 part, or may be integrally formed or permanently engaged with the gases manifold 120 part. If the interface body 110 part is engageable with the gases manifold part 120, that engagement brings the first nasal delivery element 111 and the second nasal delivery element 112 into fluid communication with the gases inlet 121 such that the first nasal delivery element 111 is more proximal the gases inlet 121 and the second nasal delivery 112 element is more distal the gases inlet 121.

[00607] The interface body 110 may be formed from a soft, flexible material such as silicone, thermoplastic elastomers, or other polymers known in the art. The nasal delivery elements 111 and 112 may be supple and may be formed from a sufficiently thin layer of silicone or other suitable material to achieve this property. The interface body 110 and nasal delivery elements 111, 112 may, for example, be formed from an elastomeric material that is able to confirm to the geometry of a patient's nostril and / or cheek and provide an effective pneumatic seal.

[00608] The gases manifold 120 may be formed from a relatively harder material such as Polycarbonate, a High-Density Polyethylene (HDPE) or any other suitable plastics material known in the art. The interface body 110 provides a soft interfacing component to the patient for comfortably delivering the flow of gases through the nasal delivery elements 111 and 112, while the gases manifold 120 fluidly couples the respiratory conduit 300 to the nasal delivery elements 111 and 112 of the interface body 110.

[00609] The nasal delivery elements 111 and 112 are substantially hollow.

[00610] The first and second nasal delivery elements 111, 112 may have the same shape and configuration as each other, i.e. may be symmetrical. In other configurations, the first and second nasal delivery elements may have a different shape and / or configuration from each other, i.e. may be asymmetrical.

[00611] The interface body 110 is shaped to generally follow the contours of a patient's face around the upper lip area. The interface body 110 is moulded or pre-formed to be able to conform to and / or is pliable to adapt, accommodate and / or correspond with the contours of the user's face, in the region of the face where the nasal interface is to be located.

[00612] Referring to Figures 13(a)-(c), the interface body 110 comprises a base portion 118 from which the nasal delivery elements 111 and 112 extend.

[00613] The base portion 118 is arranged to locate between a patient's face and the gases manifold 120 in use. The base portion 118 may act as a cushion to avoid the gases manifold 120 from touching the patient's face.

[00614] In the configuration shown, the interface body 110 comprises two side arms that extend laterally from either side of the base portion 118.

[00615] In the configuration shown, the side arms comprise wing portions 113 and 114 extending laterally from either side of the base portion 118. The wing portions 113 and 114 are integrally formed with the base portion 118 but may alternatively be separate parts.

[00616] In some configurations, the nasal delivery elements 111, 112 extend generally upwardly and rearwardly from the base portion 118 of the interface body 110.

[00617] Adhesive pads (not shown) may be provided on each wing portion 113, 114 to facilitate coupling of the nasal interface 100 to the patient.

[00618] The gases manifold 120 is generally tubular in shape having a gases port 121, 122 at at least one side thereof, and optionally at either side thereof (Figures 5, 11, and 12). At least one of the gases ports 121, 122 may be removably attachable to a respiratory conduit 300, such as via a threaded engagement but alternatively via a snap-fit or any other type of coupling known in the art. That enables the at least one of the gases ports 121, 122 to act as a gases inlet for the gases manifold 120 and thereby for the nasal interface 100. Alternatively, the port 121, 122 may be fixedly coupled or integrally formed with a respiratory conduit 300.

[00619] By having the respiratory conduit 300 extending from a side of the gases manifold 120 and thereby from a side of the nasal interface 100, a patient's mouth may be readily accessible while wearing the nasal interface for feeding / eating, drinking, or verbal communication for example.

[00620] Flow enters the nasal interface 100 through the gases inlet and travels through the gases manifold 120 in a direction that a substantially transverse to the direction the flow is intended to travel into the first and second nasal delivery elements 111, 112.

[00621] The gases inlet is in fluid communication with the respiratory conduit 300.

[00622] In some configurations, the respiratory conduit 300 has an internal diameter of between about 12 mm and about 23 mm, optionally more than about 12 mm and up to about 23 mm, optionally more than about 12 mm and up to about 22 mm, optionally more than about 12 mm and up to about 21 mm, optionally more than about 12 mm and up to about 20 mm, optionally more than about 12 mm and up to about 19 mm, optionally more than about 12 mm and up to about 18 mm, optionally between about 13 mm and about 17 mm, optionally between about 14 mm and about 16 mm, optionally about 12 mm, optionally about 13 mm, optionally about 14 mm, optionally about 15 mm, optionally about 16 mm, optionally about 17 mm, optionally about 18 mm, optionally about 19 mm, optionally about 20 mm, optionally about 21 mm, optionally about 22 mm, optionally about 23 mm, or optionally any value between any two of those values.

[00623] Referring to Figures 11 and 12, a gases flow path is defined by a lumen or flow channel 125 in the gases manifold 120.

[00624] The flow channel 125 extends from the gases port 121 at one side of the gases manifold 120, through the gases manifold, to the gases port 122 at the other side of the gases manifold 120.

[00625] The flow channel 125 is in fluid communication with a first gases outlet 123 and a second gases outlet 124. The first gases outlet 123 is configured to deliver gases to the first nasal delivery element 111 and the second gases outlet 124 is configured to deliver gases to the second nasal delivery element 112.

[00626] The shape of the gases outlets 123, 124 corresponds with and fits with the interface body 110 e.g. with a friction fit or snap fit engagement, such that substantial force, or at least a deliberate force applied by a user or a carer, is required to separate the manifold 120 from the interface body 110.

[00627] An effective seal is formed between the gases outlets 123, 124 and the interface body 110 upon engagement of the gases manifold 120 with the interface body 110.

[00628] In the configuration shown, each of the gases outlets is provided in a respective outlet portion 123a, 124a of the gases manifold 120.

[00629] Each outlet portion 123a, 124a comprises a sealing flange 123b, 124b for engagement with the first and second nasal delivery elements 111, 112.

[00630] The sealing flanges 123b, 124b extend transversely outward from an adjacent section of the respective outlet portion 123a, 123b. The sealing flanges 123b, 124b are received in a respective portion lllx, 112x of the nasal delivery elements 111, 112.

[00631] In the configuration shown, the sealing flanges 123b, 124b are generally annular in shape, and the respective portions lllx, 112x of the nasal delivery elements comprise annular channels in an inner surface of the nasal delivery elements 111, 112.

[00632] In alternative configurations, the sealing flanges 123b, 124b and the respective portions lllx, 112x could have different shapes. For example, they could each comprise one or more discrete members that do not extend around the entire periphery of the outlet portions 123a, 124a and the nasal delivery elements 111, 112.

[00633] In the configuration shown, the outlet portions 123a, 124a and the sealing flanges 123b, 124b are received in the interior of the nasal delivery elements 111, 112. In an alternative configuration, that could be reversed so that bases of the nasal delivery elements 111, 112 are received in the interior of the outlet portions 123a, 124a. In that configuration, the outlet portions 123a, 124a may comprise sealing collars for engagement with the first and second nasal delivery elements. The sealing collars may engage with the exterior of the nasal delivery elements to provide a seal therebetween.

[00634] The nasal delivery elements 111, 112 may comprise projections that are received in respective recesses in the sealing collars. The projections and recesses may be generally annular in shape, or could have a different configuration as described above for the sealing flanges 123b, 124b and complementary portions lllx, 112x.

[00635] In some configurations, the sealing flanges or collars and complementary portions on the nasal delivery elements additionally act as retention features to maintain the interface body 110 and gases manifold 120 in engagement with each other. In alternative configurations, the interface body 110 and gases manifold 120 may comprise one or more other retention features such as clips or fasteners or the like for example, to maintain the interface body 110 and gases manifold 120 in engagement with each other.

[00636] The gases manifold 120 may consist of a single part or may comprise a plurality of components that assemble together. For example, the gases manifold 120 may have a first body portion that provides the gases flow channel 125, and that optionally provides the gases ports 121, 122. The gases manifold 120 may have a second body portion that provides the gases outlets 123, 124. Alternatively, the gases manifold 120 may be a single component. In an alternative configuration, the gases manifold 120 may comprise a single outlet, and the interface body 110 may comprise a single complementary gases entry that couples with the single outlet of the gases manifold 120 and that is in fluid communication with the first and second nasal delivery elements 111, 112 to deliver the gases to the first and second nasal delivery elements 111, 112.

[00637] Referring to Figures 1 to 14 and 18, in some configurations a nasal interface 100 of the present disclosure comprises a first nasal delivery element 111 and a second nasal delivery element 112. The first nasal delivery element 111 and the second nasal delivery element 112 are each configured to seal with a respective naris of a patient. The first nasal delivery element is configured to seal with a first naris of the patient and the second nasal delivery element is configured to seal with a second naris of the patient.

[00638] In some configurations, the first nasal delivery element 111 and the second nasal delivery element 112 are configured to seal with an entrance to the nares of the patient. In some configurations, the first nasal delivery element 111 and the second nasal delivery element 112 are configured to seal with an interior of the nares of the patient. In some configurations, the first nasal delivery element 111 and the second nasal delivery element 112 are configured to seal with both the entrance to the nares and the interior of the nares of the patient.

[00639] The nasal interface comprises a gases manifold 120 comprising a gases inlet 121 for delivery of respiratory gases to the gases manifold. The first nasal delivery element 111 and the second nasal delivery element 112 are in fluid communication with the gases inlet 121 via the gases manifold 120.

[00640] The gases inlet 121 is in communication with a single gases entry portion of a gases flow channel 125 of the gases manifold. With this configuration, respiratory gases enter the gases manifold 120 from a single region, for example from a single side, of the gases manifold, and are delivered to the first and second nasal delivery elements 111, 112 from that single region.

[00641] The gases flow generally in one direction from the single side of the gases manifold to the opposite side of the gases manifold, in addition to passing through the first and second nasal delivery elements 111, 112.

[00642] The gases manifold 120 may comprise a single gases inlet 121.

[00643] With reference to Figures 9, 10, and 11, the nasal interface comprises a bypass restriction 130 to provide a pressure drop through the nasal interface 100 between the first nasal delivery element 111 and the second nasal delivery element 112 when gases are delivered from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112 such that pressure at the first nasal delivery element 111 is higher than pressure at the second nasal delivery element 112.

[00644] As used herein, a bypass restriction 130 may be any feature or geometry that provides a pressure drop through the nasal interface 100 between the first nasal delivery element 111 and the second nasal delivery element when gases are delivered from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112 such that pressure at the first nasal delivery element 111 is higher than pressure at the second nasal delivery element 112. In some configurations, the bypass restriction 130 may be a physical restriction relative to an adjacent part of the gases flow channel 125, relative to the gases inlet 121, relative to the combined cross-sectional area A3+A4 of the first and second nasal delivery elements 111, 112, and / or relative to any other part of the nasal interface 100.

[00645] In some configurations, the bypass restriction 130 may be a flow splitter or flow director.

[00646] The pressure drop is such that gases pressure upstream of the bypass restriction will be higher than gases pressure downstream of the bypass restriction.

[00647] The pressure at the first nasal delivery element 111 may be at an outlet of the first nasal delivery element and / or along the first nasal delivery element and / or adjacent the first nasal delivery element. The pressure at the second nasal delivery element 112 may be at an outlet of the second nasal delivery element and / or along the second nasal delivery element and / or adjacent the second nasal delivery element.

[00648] The pressure drop through the gases manifold 120 may be such that when there is a flow of gases from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112, the flow of gases from the gases inlet 121 to the first nasal delivery element 111 is greater than the flow of gases from the gases inlet 121 to the second nasal delivery element 112.

[00649] The bypass restriction 130 may restrict the flow of gases through the gases manifold 120 between the first nasal delivery element 111 and the second nasal delivery element 112.

[00650] In some configurations, when gases are delivered from the gases inlet 121 to both the first nasal delivery element 111 and the second nasal delivery element 112, the pressure of gases flow at the second nasal delivery element 112 is up to about 1 cmH20 less than the pressure of gases flow at the first nasal delivery element.

[00651] The pressure drop caused by the bypass restriction 130 and thereby the pressure differential of gases flow between the first nasal delivery element 111 and the second nasal delivery element 112 will typically be higher during an inspiration phase than during an expiration phase. That is because, when a patient expires gases, more of the expiratory gases will pass through the second nasal delivery element 112 than through the first nasal delivery element 111. For example, during an inspiration phase the pressure of gases flow at the second nasal delivery element 112 may be about 0.6 cmH2O less than the pressure pf gases flow at the first nasal delivery element 111, and during an expiration phase the pressure of gases flow at the second nasal delivery element 112 may be about 0.3 cmH20 less than the pressure of gases flow at the first nasal delivery element 111. The magnitude of the difference between the pressure of gases flow at the first nasal delivery element 111 and the pressure of the gases flow at the second nasal delivery element 112, for a given bypass restriction 130, will be dependent on the set pressure as well as the phase of the breathing cycle.

[00652] In some configurations, the nasal interface 100 is configured to achieve a patient pressure at the first and second nasal delivery elements 111, 112 of between about 2 cmH2O and about 30 cmH2O in use, optionally between about 2 cmH20 and about 25 cmH20 in use, optionally between about 2 cmH2O and about 20 cmH2O in use, optionally between about 2 cmH2O and about 15 cmH20 in use, optionally between about 2 cmH20 and about 14 cmH20 in use, optionally between about 2 cmH20 and about 13 cmH20 in use, optionally between about 2 cmH20 and about 12 cmH20 in use, optionally between about 2 cmH20 and about 11 cmH20 in use, optionally between about 2 cmH20 and about 10 cmH20 in use.

[00653] The nasal interface 100 may be configured such that pressure at the first nasal delivery element 111 is higher than pressure at the second nasal delivery element 112 during both the inspiration phase and the expiration phase.

[00654] A set pressure may be delivered to the second nasal delivery element 112 and a higher pressure may be delivered to the first nasal delivery element 111.

[00655] As the set pressure increases, the pressure differential between the first nasal delivery element and the second nasal delivery element increases, with that increase providing increased dead space clearance or washout.

[00656] In some configurations, the pressure differential between the first nasal delivery element 111 and the second nasal delivery element 112 is configured to provide an asymmetric flow through upper airways of a patient of at least about 1 liter per minute (Ipm), optionally between about 1 Ipm and about 2 Ipm, optionally between about 1 Ipm and about 5 Ipm. In some configurations, the asymmetric flow may be less than 1 Ipm.

[00657] The nasal interface 100 is configured to cause an asymmetrical flow of gases at a patient's nares through the first nasal delivery element 111 and the second nasal delivery element 112, due to the pressure drop through the gases manifold and the resulting pressure differential between the first nasal delivery element 111 and the second nasal delivery element 112. The resulting asymmetrical flow of gases can provide improved dead space clearance.

[00658] In some configurations, the gases manifold 120 comprises a gases flow channel 125 in the gases manifold 120, and the bypass restriction 130 provides a reduced cross-sectional area of a portion of the gases flow channel 125.

[00659] This is illustrated in Figure 10 for example, where it can be seen that the spacing through the gases flow channel 125 in the region of the bypass restriction 130 is significantly reduced compared to the spacing through the gases flow channel 125 on either side of the bypass restriction 130.

[00660] The portion of the gases flow channel 125 that is restricted may be between the first nasal delivery element 111 and the second nasal delivery element 112 and / or may be adjacent the second nasal delivery element 112. In particular, the portion of the gases flow channel that is restricted may be between the first gases outlet 123 and a second gases outlet 124 of the gases manifold.

[00661] Figure 19 schematically shows the configuration of the nasal interface of Figures 1 to 18, but additionally showing relative cross-sectional areas of the bypass restriction region (area A2) and an adjacent or main part of the gases flow channel 125 (area Ai). The bypass restriction 130 is shown in this configuration as being between the first nasal delivery element 111 and the second nasal delivery element 112.

[00662] In some configurations, the volume of the plenums at the base of the first and second nasal delivery elements 111, 112 are substantially the same. The bypass restriction 130 may be a localised restriction.

[00663] Figure 20 schematically shows an alternative configuration of the nasal interface where the bypass restriction 130 is adjacent to the second nasal delivery element 112. The bypass restriction 130 is positioned opposite the base of the second nasal delivery element 112.

[00664] Figure 21 schematically shows an alternative configuration of the nasal interface where the bypass restriction 130 is both between the first nasal delivery element 111 and the second nasal delivery element 112, but is also adjacent to the second nasal delivery element. The bypass restriction 130 is partly opposite the base of the second nasal delivery element.

[00665] The volume in the gases flow channel 125 at the base of the second nasal delivery element 112 is less than the volume in the gases flow channel at the base of the first nasal delivery element 111.

[00666] The bypass restriction 130 may extend into the gases flow channel in one or more directions (i.e. from one or more wall portions of the gases flow channel 125). In some configurations, the bypass restriction 130 may extend into the gases flow channel in one direction - e.g. in an upward direction, a downward direction, a forward direction, or a rearward direction. In some configurations, the bypass restriction 130 may extend into the gases flow channel in more than one direction - e.g. in more than one of an upward direction, a downward direction, a forward direction, ora rearward direction.

[00667] The bypass restriction 130 may comprise at least one protrusion 130a, 130b extending into the gases flow channel 125. In some configurations, the bypass restriction 130 may comprise a plurality of protrusions extending into the gases flow channel 125.

[00668] For example, the bypass restriction 130 may comprise diametrically opposed protrusions that extend into the flow channel.

[00669] In some configurations, the gases manifold 120 comprises a proximal bypass protrusion 130a that is proximal to the first and second nasal delivery elements 111, 112 and / or a distal bypass protrusion 130b that is distal from the first and second nasal delivery elements 111, 112.

[00670] In the configuration shown, the gases manifold 120 comprises both a proximal bypass protrusion 130a and a distal bypass protrusion 130b which in combination define a predetermined bypass dimension BD for the restricted flow of gases through the gases manifold 120 between the first nasal delivery element 111 and the second nasal delivery element 112.

[00671] The predetermined bypass dimension BD will generally be substantially smaller than a dimension of an adjacent or main part of the gases flow channel 125.

[00672] The predetermined bypass dimension BD may relate to the cross-sectional area A2 outlined below.

[00673] When a plurality of protrusions are provided, they may be discrete protrusions, semi-continuous, or continuous. Figures 11(a) and 11(b) for example show that a portion of the bypass restriction extends around substantially the entire periphery of the gases flow channel 125 to form the upper and lower bypass protrusions 130a, 130b.

[00674] With reference to Figure 11(c), the bypass restriction 130 comprises an angled leading edge 130a', 130b' and an angled trailing edge 130a", 130b" that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element 111 to the second nasal delivery element 112.

[00675] The angled leading edge 130a', 130b' and / or the angled trailing edge 130a", 130b" may be substantially straight or planar, or alternatively may be curved. If curved, the curved surfaces may be convex so as to be bowed in a direction toward a centre of the gases flow channel 125 or may be concave so as to be bowed in a direction away from a centre of the gases flow channel 125.

[00676] Any suitable combination of shapes could be provided. For example, at least one of the leading edges 130a', 130b' may be one of straight, concave, or convex, and at least one of the trailing edges 130a", 130b" may be another one of straight, concave, or convex.

[00677] The leading edge 130a', 130b' and the trailing edge 130a", 130b" may have the same configuration as each other or may have different configurations from each other. For example, the gradient and / or curvature of the upstream side may differ from the gradient and / or curvature of the downstream side.

[00678] When a plurality of projections are provided for the bypass restriction 130, the projections may be the same shape and configuration as each other or may have a different shape and configuration from each other.

[00679] In the configuration shown, the upper projection 130a has a shorter width in a direction along the gases flow channel than the lower projection 130b. In alternative configurations, the upper projection 130a may be the same width as the lower projection 130b or may have a shorter width than the lower projection.

[00680] In the configuration shown, the upper projection 130a extends substantially the same distance into the gases flow channel 125 as the lower projection 130b. In alternative configurations, the upper projection 130a may extend further into the gases flow channel 125 than the lower projection 130b or the lower projection 130b may extend further into the gases flow channel 125 than the upper projection 130a.

[00681] The bypass restriction 130 may be integrally formed with the gases manifold 120. Alternatively, the bypass restriction 130 may comprise an insert for attachment to the gases manifold 120. For example, the bypass restriction may be formed as a sleeve or plug. The sleeve or plug may be attached to the gases manifold in any suitable manner. For example, the sleeve or plug may be press-fit, screwed, fastened, or the like into the gases flow channel 125 of the gases manifold.

[00682] The bypass restriction 130 may be provide by the gases manifold 120, by the base portion 118 of the interface body, or by both the gases manifold 120 and the base portion 118 of the interface body.

[00683] The bypass restriction 130 is configured to provide the reduced second cross-sectional area A2 in the gases flow channel 125 compared to the first cross-sectional area Ai of an adjacent or main part of the gases flow channel 125.

[00684] In some configurations, the second cross-sectional area A2 may be between about 10% and about 40% of the first cross-sectional area Ai. In some configurations, the second cross-sectional area A2 may be between about 10% and about 35% of the first cross-sectional area Ai., optionally between about 10% and about 30% of the first cross-sectional area Ai, optionally between about 10% and about 25% of the first cross-sectional area Ai, and optionally about 17.5% of the first cross-sectional area Ai. In some configurations, the second cross-sectional area A2 may be about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, or about 40% of the first cross-sectional area Ai, or may be any percentage between any two of those percentages.

[00685] In one exemplary configuration, the first cross-sectional area may be about 200 mm2 (corresponding to a radius of about 8 mm), and the second cross sectional area may be between about 20 mm2 and about 80 mm2, optionally between about 20 mm2 and about 70 mm2, optionally between about 20 mm2 and about 60 mm2, optionally between about 20 mm2 and about 50 mm2, optionally between about 30 mm2 and about 40 mm2, and optionally about 35 mm2.

[00686] The predetermined bypass dimension BD may, for example, be between about 5 mm and about 10 mm, optionally between about 5 mm and about 9.5 mm, optionally between about 5 mm and about 8.75 mm, optionally between about 5 mm and about 8 mm, optionally between about 6 mm and about 7 mm, optionally between about 6.5 mm and about 7 mm, and optionally about 6.7 mm.

[00687] In some configurations, the nasal interface 100 comprises an interface body 110 comprising the first nasal delivery element 111 and the second nasal delivery element 112.

[00688] In some configurations, the gases manifold 120 is integral with the interface body 110 or is separate from and couplable with the interface body 110.

[00689] The first nasal delivery element 111 has a first outlet Illa defined by an opening at its tip or terminal end 111b for delivery of gases from the first nasal delivery element 111. Gases delivered through the first nasal delivery element 111 exit the first nasal delivery element 111 via the first outlet Illa.

[00690] The second nasal delivery element 112 has a second outlet 112a defined by an opening at its tip or terminal end 112b for delivery of gases from the second nasal delivery element 112. Gases delivered through the second nasal delivery element 112 exit the second nasal delivery element via the second outlet 112a.

[00691] The first and second nasal delivery elements 111, 112 may have any suitable shape to seal with the nares of the patient. For example, in one configuration, the first and second nasal delivery elements 111, 112 may be substantially tubular and may be sized to be larger than the nares of a patient, but may be supple or flexible to deform and seal with the nares upon insertion into the nares. In some configurations, the nasal delivery elements 111, 112 are more supple or flexible than the body portion 118.

[00692] As another example, and as shown, the first and second nasal delivery elements 111, 112 may comprise nostril locators or pillows to seal with the nares of the patient.

[00693] In the illustrated configuration, as shown in Figures 13 and 14 for example, each pillow can generally taper such that it narrows toward its respective outlet Illa, 112a at the tip or terminal end 111b, 112b thereof. As such, the proximal opening Illa, 112a may have a smaller diameter or transverse dimension than a distal opening 111c, 112c at a base of the pillow. Generally speaking, the pillows can taper in a proximal direction toward their tip or terminal ends 111b, 112b.

[00694] In the configuration shown, the tip or terminal ends 111b, 112b of the pillows configured to be received in the nares of a patient, while enlarged regions llld, 112d of the pillows adjacent to the tip or terminal ends 111b, 112b are configured to seal against the entrance to the nares. In other configurations, the tip or terminal ends 111b, 112b and part of the enlarged regions llld, 112d may be configured to be received in the nares to seal therewith.

[00695] The pillows may be supple or flexible to deform and seal with the nares upon insertion into the nares or contact with the nares. In some configurations, the pillows are more supple or flexible than the body portion 118.

[00696] The pillows also desirably are sufficiently stiff to reduce the likelihood of ballooning or being insufficiently self-supporting to provide an indication to the user of correct location and orientation of the nasal interface 100 relative to the face. The pillows may have sufficient stiffness to inhibit or prevent significant collapse in response to positioning of the pillows relative to the patient's nares. In some configurations, the pillows can have a thickness of about 0.7 mm with some variation being possible slightly higher and lower keeping in mind a desire to reduce user discomfort while still assisting with nasal interface positioning.

[00697] The pillows may comprise one or more stiffening elements or features to inhibit collapse of the pillows.

[00698] The first and second nasal delivery elements 111, 112 may be movable relative to the body portion 118 to enable the angle and positioning of the nasal delivery elements 111, 112 to be adjusted in response to contact with the patient's nares.

[00699] The pillows and nasal interface may have any one or more of the features described in relation to the nostril locators of US patent no. 10,918,818. The contents of that specification are incorporated herein in their entirety by way of reference.

[00700] If any leakage occurs between the nasal delivery elements 111, 112 and the patient's nares, that leakage will be minimal and can be compensated for or controlled by adjusting the therapy gases flow rate.

[00701] The nasal interface 100 is configured to cause an asymmetrical flow of gases at a patient's nares, due to the pressure drop through the gases flow channel 125 of the nasal interface 100.

[00702] The nasal interface 100 may be configured such that such that about 10 Ipm to about 50 Ipm is delivered out of the nasal interface 100 through the nasal delivery elements 111, 112. The proportion that is delivered through each nasal delivery element will vary depending on the patient, pressure differential, and stage of the breath cycle.

[00703] Having a differential of flow rates between the nasal delivery element 111, 112 can provide the benefits of asymmetrical flow described below.

[00704] In some configurations, there is a relatively constant pressure differential between the nasal delivery elements 111, 112 and a resulting relatively constant asymmetric flowthrough the nasal delivery elements 111, 112. In some configurations, the pressure differential and the resulting asymmetric flow may vary. As long as there is a pressure drop through the gases manifold 120 for at least some portion of the breath cycle, asymmetric flow will occur.

[00705] The proportion of the total volumetric flow rate being delivered through each prong 111, 112 can be determined by delivering gases with a known volumetric flow rate to the gases inlet 121 of the nasal interface 100 while the nasal interface is not applied to a patient's nares. The volumetric flow rate exiting each outlet Illa, 112a can be measured by a suitable flow meter or sensor to determine the proportion of the total volumetric flow rate of gases flow into the gases inlet 121 that is exiting the outlet Illa, 112a of each nasal delivery element 111, 112.

[00706] The nasal interface 100 comprises a bias flow restriction 140 for a flow of gases out of the nasal interface 100, and optionally for a flow of gases out of the gases manifold 120.

[00707] With reference to Figures 1-5, 16, and 18, the bias flow restriction 140 is in fluid communication with the gases manifold 120 and, more particularly, with the gases port 122 of the gases manifold 120.

[00708] The bias flow restriction 140 is positioned downstream in the patient interface 100 from the first and second nasal delivery elements 111, 112 and opposite to the gases port 121, so gases may pass from the first and second nasal delivery elements 111, 112 and out of the nasal interface via the bias flow restriction 140. Some ofthe gases that enter the gases inlet port 121 may travel out of the bias flow restriction 140 without passing through the first and second nasal delivery elements 111, 112. The gases that travel out ofthe nasal interface via the bias flow restriction may comprise expiratory gases and may further comprise some inlet gases that have not passed through the first and second nasal delivery elements 111, 112.

[00709] The bias flow restriction 140 allows for the provision of a pressure therapy to the nares of a patient. The bias flow restriction 140 enables a restricted flow of gases through the bias flow restriction out of the nasal interface 100. If there was no bias flow restriction 140 and the gases port 122 was closed, all exhaled gases would be rebreathed. If there was no bias flow restriction and the gases port 122 was open, the respiratory therapy apparatus would not be able to apply a pressure through the nasal interface.

[00710] The open area for gases flow through the bias flow restriction may be selected to provide sufficient area for bias flow while minimizing noise from the bias flow. In one exemplary configuration, when a patient pressure about 10 cmH20 is provided, gases flow through the nasal interface 100 may be about 25-45 Ipm, and the open area for gases flow through the bias flow restriction may be between about 10 mm2 and about 15 mm2. However, this is one example only, and these values may vary depending on system parameters and patient requirements. In another example, the open area for gases flow through the bias flow restriction may be between about 10 mm2 and about 30 mm2, optionally between about 25 mm2 and about 30 mm2, and optionally about 27.5 mm2.

[00711] The gases manifold 120 may comprise the bias flow restriction 140 or may be coupled to the bias flow restriction 140. In an alternative configuration illustrated in Figure 18, the bias flow restriction 140 may be in fluid communication with the gases manifold 120 but positioned remotely from the gases manifold 120. In this alternative configuration, an expiratory gases conduit 160 is coupled to the gases port 122 of the gases manifold 120 and to the bias flow restriction 140. The expiratory gases conduit 160 can have any suitable length. This configuration enables expiratory gases and any inlet gases that bypass the first and second nasal delivery elements 111, 112 to be vented through the bias flow restriction 140 at a location spaced apart from the patient.

[00712] Referring to Figures 6-9, the bias flow restriction 140 comprises one or more gases outlets for the flow of gases from the nasal interface 100, and optionally from the gases manifold 120, to an ambient environment.

[00713] The one or more gases outlets may comprise one or more apertures. In the configuration shown, the one or more gases outlets comprises a plurality of apertures 142 for the flow of gases from the nasal interface 100, and optionally from the gases manifold 120, to the ambient environment.

[00714] The plurality of apertures 142 may be provided in any suitable arrangement or array. For example, in the configuration shown, the plurality of apertures 142 are provided in an array of four long rows and two outer short rows. However, any other suitable arrangement could be provided, such as a larger or smaller number of rows of apertures, a larger or smaller number of apertures in each row, or a random arrangement of apertures.

[00715] The bias flow restriction 140 may comprise 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more apertures.

[00716] Additionally, or alternatively, the one or more gases outlets may comprise one or more slots which may be straight, curved, wavy, sinuous, or any other suitable shape.

[00717] The one or more gases outlets will typically have outlet dimension(s) that is / are substantially smaller than the size of a gases inlet into the bias flow restriction 140, to create a pressure drop or resistance to flow out of the one or more gases outlets. The pressure drop is such that gases pressure upstream of the one or more gases outlets will be higher than gases pressure downstream of the one or more gases outlets.

[00718] However, when a plurality of outlets are provided, the sum of the outlet dimensions may approach the size of the gases inlet.

[00719] In some configurations, the gases inlet 148 and the one or more gases outlets are arranged in the bias flow restriction 140 so that gases flow F needs to undertake a change in direction between entering the bias flow restriction and exiting the bias flow restriction. This is represented by arrow F in Figure 7 for example.

[00720] In some configurations, the one or more gases outlets is / are provided in a restriction component body 144. The restriction component body 144 defines a body gases flow passage 146 that is in fluid communication with a body gases inlet 148. The one or more gases outlets is / are in fluid communication with the body gases flow passage 146 such that gases pass from the gases port 122 of the gases manifold, into the body gases flow passage 146, and out of the one or more gases outlets (e.g. the apertures 142).

[00721] As shown in Figure 7(b) for example, the restriction component body 144 may have a tapered configuration in which the body gases flow passage 146 becomes smaller more distal from the body gases inlet 148 than proximal to the body gases inlet 148. A ceiling, an end wall 144b, and / or a wall 144c of the body that contains the one or more gases outlets may be angled so as to be non-parallel and non-perpendicular relative to each other, to encourage flow from the body gases inlet 148 to pass through the one or more gases outlets.

[00722] In some configurations, the bias flow restriction 140 is configured to direct the flow of gases out of the bias flow restriction away from a patient's face. In the configuration shown, the bias flow restriction 140 is configured to direct the flow of gases at least partly in a forward direction and in some configurations entirely in a forward direction away from the patient's face.

[00723] The bias flow restriction 140 enables the venting of carbon dioxide (CO2) via the use of the one or more gases outlets. In the embodiment illustrated, the nasal interface 100 has aperture(s) 142 for expelling gases from inside the nasal interface 100 to the environment. The aperture(s) 142 or other openings can help expel carbon dioxide gases from the user to reduce the rebreathing of the carbon dioxide gases.

[00724] The one or more gases outlets create a controlled or known leak to enable the exhausting of the user's exhaled carbon dioxide gases. There may be a performance trade-off between the location of the one or more openings (relative to the patient's nose) and the amount of bias flow required. As used herein, bias flow refers to the flow of gases to the environment through the bias flow restriction 140. The flow rate of the bias flow and the design geometry of the one or more openings can have an effect on the noise level and draft that the bias flow produces, as well as the amount of entrainment that the exiting gas flow may cause.

[00725] The one or more gases outlets may comprise a plurality of through holes 142 that expel gases from the nasal interface. In other configurations, the gases outlets can be slits or large openings instead of or in addition to small through holes. In some configurations, the gases outlets can be disposed on other portions of the interface. Generally, relatively smaller hole sizes produce less airflow noises compared to a larger hole size given the same flow velocity through both hole sizes. The plurality of holes helps reduce airflow noises compared to having one or a few holes with the same vent area when expelling a given volume of gas.

[00726] The one or more gases outlets may have any one or more of the features or functionality described for the vents in US patent no. 10,898,866. The contents of that specification are incorporated herein in their entirety by way of reference.

[00727] The bias flow restriction 140 may comprise an optional filter or diffuser to filter or diffuse gases flowing through the one or more gases outlets, e.g. through the aperture(s).

[00728] The filter may mitigate respiratory contaminants being released through the bias flow restriction.

[00729] The diffuser may diffuse gases existing the bias flow restriction to reduce noise.

[00730] Figure 6 shows a filter or diffuser member 150 that is configured to cover the at least one or more gases outlets to filter or diffuse gases as they exit the one or more gases outlets. The filter or diffuser member 150 may comprise any suitable material, such as one or more of non-woven fibrous material (including polymer fibres), open cell foam, sintered polymer.

[00731] In some configurations, the restriction component body 144 comprises a filter or diffuser recess 145 to receive the filter or diffuser member 150.

[00732] The bias flow restriction 140 may comprise a shroud 152 that is configured to attach to the restriction component body 144 and to maintain the filter or diffuser member 150 in place over the one or more gases outlets.

[00733] The shroud 152 comprises an aperture 153 that is at least the size of the at least one opening of the restriction component body 144.

[00734] The shroud 152 may carry the filter or diffuser member 150 in the aperture 153 or the filter or diffuser member 150 may be sandwiched between the shroud 152 and the recess 145.

[00735] The shroud 152 may be removably attachable to the restriction component body 144 to enable the filter or diffuser member 150 to be cleaned or replaced.

[00736] The shroud 152 may attach to the restriction component body 144 by any suitable arrangement, such as clip(s), fastener(s) or the like. In the configuration shown, the shroud 152 comprises two inwardly directed engagement components 154 that are a snap fit into complementary engagement recess(es) 147 on the restriction component body 144.

[00737] The shroud may comprise one or more gripping portions 156 to enable the engagement components 154 to be released from the recess(es) 147 to remove the shroud 152 from the restriction component body 144. In the configuration shown, the gripping portion(s) 156 comprise an outward projection to enable the user to apply force in an outward and downward direction to force the engagement component(s) out of engagement from the restriction component body 144, but any other suitable configuration could be used.

[00738] In some configurations and as shown in Figure 17(b), a filter unit 500' may be provided between the gases manifold 120 and the bias flow restriction 140. The filter unit 500' may have any one or more of the features described herein for the filter unit 500.

[00739] In some configurations a nasal interface 100 of the present disclosure comprises a first nasal delivery element 111 and a second nasal delivery element 112, wherein the first nasal delivery element 111 and the second nasal delivery element 112 are each configured to seal with a respective naris of a patient, and a gases manifold 120 comprising a gases inlet 121 for delivery of respiratory gases to the gases manifold, wherein the first nasal delivery element 111 and the second nasal delivery element 112 are in fluid communication with the gases inlet 121 via the gases manifold 120, wherein the first nasal delivery element 111 is proximal to the gases inlet 121 and the second nasal delivery element 112 is distal from the gases inlet 121, wherein the nasal interface 100 is configured to create a pressure differential between the first nasal delivery element 111 and the second nasal delivery element 112 when gases are delivered from the gases inlet 121 to both the first nasal delivery element 111 and the second nasal delivery element 112 such that pressure at the first nasal delivery element 111 is higher than pressure at the second nasal delivery element 112.

[00740] In some configurations, the pressure differential is such that when there is a flow of gases from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112, the flow of gases from the gases inlet 121 to the first nasal delivery element 111 is greater than the flow of gases from the gases inlet 121 to the second nasal delivery element 112.

[00741] In some configurations, the gases inlet 121 is in fluid communication with the respiratory conduit 300.

[00742] In some configurations, when gases are delivered from the gases inlet to both the first nasal delivery element and the second nasal delivery element, the pressure of gases flow at the second nasal delivery element 112 is up to about 1 cmH20 less than the pressure of gases flow at the first nasal delivery element 111.

[00743] For example, the pressure of gases flow at the second nasal delivery element 112 may be about 0.1 cmH2O, about 0.2 cmH20, about 0.3 cmH20, about 0.4 cmH20, about 0.5 cmH20, about 0.6 cmH20, about 0.7 cmH20, about 0.8 cm H2O, about 0.9 cmH20, or about 1 cmH20 less than the pressure of gases flow at the first nasal delivery element 111, orthe difference may be any value between any two of those values.

[00744] The pressure differential of gases flow between the first nasal delivery element and the second nasal delivery element may be higher during an inspiration phase than during an expiration phase.

[00745] The nasal interface may be configured to achieve a patient pressure at the first and second nasal delivery elements of between about 2 cmH20 and about 30 cmH20 in use, optionally between about 2 cmH2O and about 25 cmH2O in use, optionally between about 2 cmH2O and about 20 cmH2O in use, optionally between about 2 cmH20 and about 15 cmH20 in use, optionally between about 2 cmH2O and about 14 cmH2O in use, optionally between about 2 cmH2O and about 13 cmH20 in use, optionally between about 2 cmH20 and about 12 cmH20 in use, optionally between about 2 cmH20 and about 11 cmH2O in use, optionally between about 2 cmH20 and about 10 cmH20 in use.

[00746] In some configurations, the pressure differential between the first nasal delivery element 111 and the second nasal delivery element 112 is configured to provide an asymmetric flow through upper airways of a patient of between about 1 liter per minute (Ipm) and about 5 Ipm.

[00747] For example, the asymmetric flow through the upper airways of the patient may be about 1 Ipm, about 1.25 Ipm, about 1.5 Ipm, about 1.75 Ipm, about 2 Ipm, about 2.25 Ipm, about 2.5 Ipm, about 2.75 Ipm, about 3 Ipm, about 3.25 Ipm, about 3.5 Ipm, about 3.75 Ipm, about 4 Ipm, about 4.25 Ipm, about 4.5 Ipm, about 4.75 Ipm, about 5 Ipm, or may be any value between any two of those values.

[00748] The asymmetric flow promotes clearing of CO2 from anatomical dead space of the patient.

[00749] As outlined above, the interface body 110 may be engageable with the gases manifold 120. Accordingly, in some configurations a nasal interface 100 of the present disclosure comprises an interface body 110 part comprising a first nasal delivery element 111 and a second nasal delivery element 112, wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient. The nasal interface 100 of the present disclosure further comprises a gases manifold 120 part comprising a gases inlet 121 for delivery of respiratory gases to the gases manifold part. The interface body 110 part is engageable with the gases manifold 120 part to bring the first nasal delivery element 111 and the second nasal delivery element 112 into fluid communication with the gases inlet 121 such that the first nasal delivery element 111 is more proximal the gases inlet 121 and the second nasal delivery element 112 is more distal the gases inlet 121. The nasal interface 100 comprises at least one gases flow restriction 130 to gases flow through the nasal interface, such that when gases are delivered from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112, pressure at the first nasal delivery element is higher than pressure at the second nasal delivery element.

[00750] The at least one flow restriction may comprise a bypass restriction. The bypass restriction may have any one or more of the features and functionality described herein for the bypass restriction 130.

[00751] In some configurations, the nasal interface further comprises a bias flow restriction. The bias flow restriction may have any one or more of the features and functionality described herein for the bias flow restriction 140.

[00752] Therefore, the nasal interface described herein may comprise a bypass restriction, a bias flow restriction, or may comprise both a bypass restriction and a bias flow restriction.

[00753] By providing asymmetrical flow, use of the nasal interfaces 100 of the present disclosure may provide a reduction of dead space (i.e. the volume of air not involved in the gases exchange within the lungs) compared to conventional continuous positive airway pressure (CPAP) therapy. It is understood that within the upper airway of the patient, some proportion of the gas moves in a unidirectional manner, flowing in one nostril and out the other, reducing the upper airway dead space. This may be most notable at higher set pressures which lead to an increase in the asymmetrical flow and hence an increase in the dead space clearance.

[00754] The bypass restriction 130 promotes asymmetrical flow. The bias restriction 140, in combination with the sealing nasal elements 111, 112, allows for provision of a CPAP-style therapy. The nasal interface 100 enables CPAP with increased dead space clearance. The bypass restriction 130 enables the dead space clearance. The sealing nasal delivery elements 111, 112 enable the CPAP therapy.

[00755] Inspiratory and expiratory flows will be present in both nostrils. However, the flow is a partial unidirectional flow in which a greater proportion of the inspiratory flow will be through the nostril that is closes to the gases inlet 121 and thereby to the flow source.

[00756] The nasal interface 100 may be used for a pressure-controlled therapy, but with higher humidity than traditional CPAP therapy. The higher humidity is believed to beneficially work in conjunction with the increased dead space clearance.

[00757] In some configurations, the nasal interface 100 may be suitable for use in, or may be used in, pressure-controlled therapy with a therapy pressure of between about 2 cmH20 and about 10 cmH20, depending on patient and therapy requirements.

[00758] For example, the nasal interface may be suitable for use in, or may be used in, pressure-controlled therapy with a therapy pressure of about 2 cmH20, 2.5 cmH20, 3 cmH20, 3.5 cmH20, 4 cmH20, about 4.5 cmH20, about 5 cmH20, about 5.5 cmH20, about 6 cmH2O, about 6.5 cmH2O, about 7 cmH2O, about 7.5 cmH2O, about 8 cmH2O, about 8.5 cmH2O, about 9 cmH2O, about 9.5 cmH2O, or about 10 cmH20.

[00759] The pressure may be set or controlled by the respiratory therapy system, an example of which is described below.

[00760] To maintain a desired pressure, a flow of gases is provided and the flow rate will depend on the phase of the breath cycle and the geometry of the bias flow restriction 130, amongst other factors.

[00761] Figures 10(a) and (b) show the gases flow through the nasal interface 100. As the flow of gases F enters the flow channel 125 of the gases manifold 120, a portion Fl of the flow will proceed through the upstream first nasal delivery element 111 and through the patient's upper airway. A portion F2 of the flow will proceed past the bypass restriction 130. The portion F2 of the flow that proceeds past the bypass restriction 130 enables flow F3 through the downstream second nasal delivery element 111 so inspiration can occur through both nasal delivery elements 111, 112 (presuming neither nostril is blocked).

[00762] There is a preference for the flow F to enter the upstream nostril on inspiration, and slightly more flow will enter the upstream nostril than the downstream nostril. On expiration, the flow will have a preference to exit the downstream nostril (flow F5) and more flow will exit that nostril than the upstream nostril (flow F4), due to lesser flow F3 than Fl.

[00763] When breath holding, some portion of the flow will travel into the upstream nostril and out of the downstream nostril, due to the higher flow Fl into the upstream nostril than flow F3 into the downstream nostril.

[00764] The geometry of the bias flow restriction 140 will define the volume of positive flow through the nasal interface 100. A larger area for bias flow will result in higher flow rate required for the gas source to reach the desired therapeutic pressure.

[00765] The bypass restriction 130 results in a pressure drop between the gases delivered to the upstream and downstream nostrils Fl, F3, with a resulting pressure differential at the first and second nasal delivery elements 111, 112.

[00766] The pressure drop results in asymmetric flow which leads to "flushing" or "clearance" of the dead space, the dead space being the volume of the gas which is not involved in gases exchange within the alveoli and consists largely of CO2.

[00767] In some configurations, the configuration of the asymmetric flow may be between about 1 and about 5 Ipm.

[00768] In some configurations, the pressure at downstream nostril may be about 1 cmH20 less than the pressure delivered to the upstream nostril, e.g. about 6 cmH20 at the upstream nostril and about 5 cmH20 at the downstream nostril.

[00769] The bias flow restriction 140 may be configured to avoid negative flows during the provision of respiratory therapy.

[00770] It is recognised that negative flows contribute to dead space or rebreathing. Therefore, the bias flow restriction 140 should be large enough to enable a bias flow that is high enough so that the occurrence of negative flows and the amount of rebreathing are either reduced or eliminated.

[00771] Asymmetric flow will reduce the amount of gas that is rebreathed throughout a respiratory cycle as the upper airway volume is ventilated.

[00772] This may alternatively be described as reducing the dead space or reducing the amount of gas that does not take part in the gas exchange during a breath cycle.

[00773] The effects of reducing dead space are also seen in for example high flow therapy.

[00774] This reduces CO2 rebreathing and increases the amount of oxygen available for gas exchange.

[00775] The delivered gas may require additional humidity than is typically used for non-invasive ventilation (NIV) or continuous positive airway pressure (CPAP) therapy. This additional humidity is to prevent drying of the upper airways as gas within the dead space is replaced by the gas provided by the therapy.

[00776] The anatomical dead space volume for a given patient may typically be between 100 ml and 150 ml.

[00777] The bypass flow caused by the bypass restriction 130 is such that there is a pressure difference between the two nostrils in response to the apparatus delivering flow in combination with respiration, or during an apnoea. Some possible configurations of the bypass restriction may be as described, however, in alternative configurations of the bypass restriction this may be achieved by one or a combination of two or more of the following: • Having the bypass flow restricted for example by having a reduced crosssection or some element to create this restriction such as one or a plurality of projections or nozzles or some other reduction in cross-section. • The bypass restriction geometry may be designed so that there is a preference for it to travel one way rather than the other, for example by making use of geometry that has a higher pressure drop in one direction than the other such as a bell-mouth shaped nozzle or restriction, a low-pressure ejector, or a non-return valve. • A flexible element or valve that creates a preferential (but not exclusive) flow from the upstream to downstream direction. • A user-adjustable valve by means of a screw or some other mechanism to alter the cross-sectional area for the bypass flow to pass through. • Flow enters the first nasal delivery element either axially, radially, tangentially at an angle or some combination of these flows, to preferentially direct the gases flow at the first nasal delivery element rather than the second nasal delivery element. • The bypass restriction comprises a sparse network of material to create a pressure drop such as a filter, nonwoven polypropylene, foamed plastic, sintered material, or any other material that creates a pressure drop across it when flow is present.

[00778] The bypass restriction may comprise any one or more of the features described in US 2016 / 0228665. The contents of that specification are incorporated herein in their entirety by way of reference.

[00779] The overall bias flow is mostly controlled by selection of the geometry across the bias flow restriction 140. Some possible configurations of the bias flow restriction by may be as described, however, in alternative configurations the pressure drop of the bias flow restriction may be achieved by one or a combination of two or more of the following: • Having the bias flow restricted for example by having a reduced cross section or some element to create this restriction such as one or multiple members or nozzles or some other reduction in cross-section. • A flexible element or valve that creates a preferential, and possibly exclusive, flow out of the nasal interface to reduce or prevent entrainment of ambient air. • A non-return valve may be used to reduce / prevent entrainment of ambient air. • A flexible element may be used to create a pressure drop that is less likely to occlude in the presence of water or sputum than rigid holes / nozzles. • A sparse network of material may be present that would create a pressure drop such as a filter, nonwoven polypropylene, foamed plastic, sintered material, or any other material that create a pressure drop across it when flow is present • A user-adjustable valve by means of a screw or some other mechanism to alter the cross-sectional area of the flow. • Altering the direction of the flow multiple times.

[00780] The pressure drop across the nasal interface 100 may be relatively constant across the patient's breath cycle, or alternatively may vary across the patient's breath cycle.

[00781] Table 1 summarises different gases flows that may be encountered during use of the nasal interface 100, with reference to Figure 15. Arrow Inspiration Expiration Apnoea / breath holding Inspiration with upstream nostril blocked Expiration with upstream nostril blocked Inspiration with downstream nostril blocked Expiration with downstream nostril blocked 1 Positive Either Positive Positive Either Positive Either 2 Positive Either Positive Zero Zero Positive Negative 3 Positive Either Positive Positive Either Either Positive 4 Either Positive Positive Negative Positive Zero Zero 5 Either Positive Positive Either Positive Either Positive Table 1 - Summary of f ows

[00782] In Figure 15, positive flow is in the direction of the arrow, negative flow is opposite to the direction of the arrow. Either means that flow may be moving in either direction based on a number of factors. Zero means there is no nett flow in this scenario.

[00783] If the upstream nostril is completely blocked then the patient will receive flow to the downstream nostril.

[00784] If the downstream nostril is completely blocked then the patient will receive flow through the upstream nostril.

[00785] In both of these cases the patient will not receive any asymmetric flow but will continue to be provided therapy without this component.

[00786] If either nostril is substantially but not completely blocked, a reduced amount of asymmetric flow will be present.

[00787] The device may be used on a similar group of patients that are suitable for non-invasive ventilation (NIV).

[00788] Nasal cycling may introduce fluctuations in the asymmetric flow provided by the nasal interface 100.

[00789] As indicated schematically in Figure 15, the nasal interface 100 forms a circuit with a patient's upper airways and lungs. A first portion of the circuit comprises the first nasal delivery element 111, the patient's upstream nostril associated with that first nasal delivery element 111, the patient's upper airway and lungs, the second nasal delivery element 112, and the patient's downstream nostril associated with that second nasal delivery element 112. A second portion of the circuit comprise the first nasal delivery element 111, the bypass restriction 130, and the second nasal delivery element 112. The bypass restriction provides a pressure drop through the gases manifold between the first nasal delivery element 111 and the second nasal delivery element 112, which results in an asymmetric flow through the first nasal delivery element 111 and the second nasal delivery element 112.

[00790] The nasal interface 100 creates a pressure differential between the two nostrils such that the upstream nostril is at a higher pressure than the downstream nostril for at least some portion of the breath cycle.

[00791] This pressure difference creates a flow within the upper airway where after a full breath cycle more flow has entered the upstream nostril than the downstream nostril and more flow has left the downstream nostril than the upstream nostril. This additional flow into the upstream nostril and out of the downstream nostril is asymmetric flow.

[00792] The asymmetric flow dilutes the gasses in the airways of the patient which is referred to in the art as washout or dead space clearance.

[00793] There are a number of ways of achieving this pressure differential between the entrance to the two nostrils including having a bypass flow between the nostrils that is tuned to provide some pressure drop.

[00794] In some configurations of the nasal interface 100, the gases manifold 120 may be a configuration that allows the respiratory conduit 300 to connect to either the right side of the gases manifold (Figure 16(a)) or the left side of the gases manifold (Figure 16(b)). That is, the respiratory conduit 300, and optionally the bias flow restriction 140, may be side-swappable relative to the gases manifold 120. That enables the respiratory conduit 300 to be positioned on the right side or left side of the patient in use.

[00795] In some configurations, the gases ports 121, 122 may have the same configuration as each other, so that the respiratory conduit 300 can be selectively coupled with either of the gases ports 121, 122. The gases port that the patient breathing conduit is connected to will form the gases inlet for the gases manifold 120, and the opposite gases port will form the gases outlet for the gases manifold. For example, in the configuration of Figure 16(a), the gases port 121 will form the gases inlet, and the first nasal delivery element 111 will form the upstream nasal delivery element that is more proximal to the gases inlet. In the configuration of Figure 16(b), the gases port 122 will form the gases inlet, and the second nasal delivery element 112 will form the upstream nasal delivery element that is more proximal to the gases inlet.

[00796] The internal features of the gases manifold 120 may be symmetrical, so that the performance of the nasal interface 100 doesn't change depending on which side of the gases manifold the respiratory conduit 300 is connected to.

[00797] When a bias flow restriction 140 is provided, that may be able to be selectively coupled with either of the gases ports 121, 122, opposite to the respiratory conduit 300. The respiratory conduit 300 and the bias flow restriction 140 may have the same coupling features as each other.

[00798] Although the respiratory conduit 300 may be selectively connected to either side of the gases manifold 120, at any stage during use of the nasal interface one of the ports 121, 122 will act as a single gases inlet into the gases manifold 120. The other one of the ports 121, 122 will typically act as a gases outlet from the gases manifold to deliver gases to the bias flow restriction 140.

[00799] The nasal interface 100 may be provided with one or more pressure ports to allow pressure measurement for control of a respiratory therapy apparatus or for reporting purposes. The pressure port(s) may be provided upstream and / or downstream and / or within the nasal interface 100.

[00800] Gases entering and / or exiting the nasal interface 100 may be filtered. An upstream and / or downstream filter may be provided for that purpose.

[00801] In the configuration shown, the patient interface 1 comprises a filter 500 that is in fluid communication with the respiratory conduit 300 to filter gases entering the respiratory conduit 300.

[00802] The filter(s) may have any one or more of the features and functionality of the filter of US patent no. 6,619,287. The contents of that specification are incorporated herein in their entirety by way of reference.

[00803] It may be desirable to configure the cross-sectional area through the bypass restriction 130 to be as wide as possible to increase patient comfort. However, increasing the cross-sectional area through the bypass restriction 130 risks decreasing the amount of asymmetric flow. That is, increasing the cross-sectional area through the bypass restriction 130 decreases the degree of restriction, which in turn decreases the pressure difference between the upstream and downstream nasal delivery elements 111, 112 that drives asymmetric flow and washout.

[00804] As outlined above, the bypass restriction 130 may be any feature or geometry that provides a pressure drop through the nasal interface 100 between the first nasal delivery element 111 and the second nasal delivery element when gases are delivered from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112 such that pressure at the first nasal delivery element 111 is higher than pressure at the second nasal delivery element 112. In some configurations, the bypass restriction 130 may be a physical restriction relative to an adjacent part of the gases flow channel 125, relative to the gases inlet 121, relative to the combined cross-sectional area A3+A4 of the first and second nasal delivery elements 111, 112, and / or relative to any other part of the nasal interface 100.

[00805] The inventors have discovered that effective asymmetric flow may be maintained at a wide range of ratios of bypass restriction cross-sectional area to combined nasal delivery element cross-sectional area. This may allow patient comfort to be optimised while retaining therapeutically effective asymmetric flow.

[00806] The therapeutically effective asymmetric flow may be provided by having sufficient washout from the patient's upper airway dead space. The washout level may be at least about 10% of the volume of the patient's upper airway, optionally at least about 20% of that volume, optionally at least about 30% of that volume, optionally at least about 40% of that volume, optionally at least about 50% of that volume, optionally at least about 60% of that volume, optionally at least about 70% of that volume, optionally at least about 80% of that volume, optionally at least about 90% of that volume, optionally about 100% of that volume. In some configurations, the washout level may be determined over a single breath cycle.

[00807] The ratio of bypass restriction 130 cross-sectional area A2 to combined nasal delivery element 111, 112 cross-sectional area A3+A4 contributes to achieving asymmetric flow and thus effective washout. The bypass restriction 130 cross-sectional area A2 and combined nasal delivery element 111, 112 cross-sectional area A3+A4 are cross-sectional areas for the flow of gases or inner cross-sectional areas. The combined nasal delivery element 111, 112 cross-sectional area A3+A4 may be at a smallest transverse dimension of the respective nasal delivery element 111, 112.

[00808] The bypass restriction 130 drives asymmetric flow by restricting gas flow to the downstream nasal delivery element 112 relative to the upstream nasal delivery element 111. The bypass restriction 130 cross-sectional area A2 should therefore be sufficiently narrow (or in other words, sufficiently restrictive) relative to the combined nasal delivery element 111, 112 cross-sectional area A3+A4 such that a restriction, and thus a pressure difference, is achieved.

[00809] It is, however, also desirable for the bypass restriction 130 cross-sectional area A2 to be as wide as possible in order to increase patient comfort and therapeutic versatility. In particular, it is desirable for the bypass restriction 130 cross-sectional area A2 to be sufficiently wide so that if the upstream nasal delivery element 111 or naris becomes blocked during therapy, the patient may still receive CPAP therapy through the downstream nasal delivery element 112. Increasing the effort of inspiration could potentially make a patient feel starved of air. Making the bypass restriction 130 cross-sectional area A2 larger means that a greater fraction of the flow on inspiration goes to the downstream naris via the downstream nasal delivery element 112. This reduces the pressure drop experienced by the patient and decreases this discomfort. However, making the bypass restriction 130 cross-sectional area A2 larger would cause the therapy to move towards traditional CPAP therapy where there is no therapeutically effective asymmetrical flow. Patients undergoing traditional CPAP therapy may feel more comfortable with less restriction because the apparatus can control flows more easily, reducing flow velocities and decreasing noise and the feeling of jetting in the nostrils.

[00810] In some configurations, a nasal interface 100 of the present disclosure comprises a first nasal delivery element 111 and a second nasal delivery element 112, wherein the first nasal delivery element 111 and the second nasal delivery element 112 are each configured to seal with a respective naris of a patient, and a gases manifold 120 comprising a gases inlet 121 for delivery of respiratory gases to the gases manifold 120 and a gases flow channel 125, wherein the first nasal delivery element 111 and the second nasal delivery element 112 are in fluid communication with the gases inlet 121 via the gases flow channel 125, wherein the first nasal delivery element 111 is proximal to the gases inlet 121 and the second nasal delivery element 112 is distal from the gases inlet 121, wherein the nasal interface comprises a bypass restriction 130 that provides a cross-sectional area A2of a portion of the gases flow channel 125, wherein each of the first nasal delivery element 111 and the second nasal delivery element 112 comprises an inner cross-sectional area A3, A4, wherein the inner cross-sectional areas A3, A4 together provide a combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, and wherein the cross-sectional area A2 of the portion of the gases flow channel 125 is more than 0 to about 1.5 times the combined cross-sectional area A3+A4 of the nasal delivery elements.

[00811] Such a configuration with the recited relative cross-sectional areas could be used in any of the nasal interfaces 100 disclosed herein.

[00812] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 0.25 times to about 1.5 times the combined cross-sectional area A3+A4 of the nasal delivery elements.

[00813] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area A3+A4 of the nasal delivery elements, optionally up to about 1 times the combined cross-sectional area A3+A4 of the nasal delivery elements, optionally up to about 2 / 3 of the combined cross-sectional area A3+A4 of the nasal delivery elements, optionally up to about 1 / 2 of the combined cross-sectional area A3+A4 of the nasal delivery elements, optionally up to about 2 / 5 of the combined cross-sectional area A3+A4 of the nasal delivery elements, optionally up to about 1 / 3 of the combined cross-sectional area A3+A4 of the nasal delivery elements.

[00814] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel is more than 0 mm2 and up to about 375 mm2, optionally between about 1 mm2 and about 375 mm2, optionally between about 1 mm2 and about 250 mm2, optionally between about 1 mm2 and about 200 mm2, optionally between about 1 mm2 and about 167 mm2, optionally between about 50 mm2 and about 167 mm2, optionally between about 50 mm2 and about 103 mm2, optionally between about 35 mm2 and about 100 mm2. The bypass restriction 130 cross-sectional area A2 may be any other value or range of values related to the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 recited herein

[00815] In some configurations, the inner cross-sectional area A3, A4of each of the first and second nasal delivery elements 111, 112 is at a smallest transverse dimension of the respective nasal delivery element.

[00816] In some configurations, the inner cross-sectional area of each of the first and second nasal delivery elements 111, 112 is at an outlet Illa, 112a of the respective nasal delivery element 111, 112. Alternatively, the inner cross-sectional area may be elsewhere; for example, part-way along the nasal delivery element 111, 112 or at an inlet or base of the nasal delivery element.

[00817] The inner cross-sectional area A3, A4 of each of the nasal delivery elements 111, 112 may be in a direction that is transverse to a direction of gases flow through the nasal delivery elements 111, 112.

[00818] In some configurations, the bypass restriction 130 comprises at least one protrusion 130a, 130b extending into the gases flow channel 125. In some configurations, the bypass restriction 130 comprises a plurality of protrusions extending into the gases flow channel 125.

[00819] In some configurations, the gases manifold 120 comprises a proximal bypass protrusion 130a that is proximal to the nasal delivery elements 111, 112 and / or a distal bypass protrusion 130b that is distal from the nasal delivery elements 111, 112.

[00820] In some configurations, the gases manifold 120 comprises both a proximal bypass protrusion 130a and a distal bypass protrusion 130b which in combination define a predetermined bypass dimension BD for the restricted flow of gases through the gases manifold 120 between the first nasal delivery element 111 and the second nasal delivery element 112. In some configurations, the predetermined bypass dimension BD may be restricted relative to an adjacent part of the gases flow channel 125, relative to the gases inlet 121, relative to the combined cross-sectional area A3+A4 of the first and second nasal delivery elements 111, 112, and / or relative to any other part of the nasal interface 100.

[00821] The predetermined bypass dimension BD will generally be substantially smaller than a dimension of an adjacent or main part of the gases flow channel 125.

[00822] In some configurations, the bypass restriction 130 comprises an angled leading edge 130a', 130b' and an angled trailing edge 130a", 130b" that define a converging and diverging bypass restriction in a direction of gases flow through the gases manifold from the first nasal delivery element 111 to the second nasal delivery element 112.

[00823] In some configurations, the gases manifold 120 comprises a single inlet and a single outlet.

[00824] In some configurations, the nasal interface 100 comprises an interface body 110 and a gases manifold part, and the interface body 110 and the gases manifold part together form the gases manifold 120.

[00825] In some configurations, the portion of the gases flow channel that provides the cross-sectional area A2 is provided by the interface body 110 and the gases manifold part.

[00826] As outlined above, the interface body 110 may be formed from a soft, flexible material.

[00827] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel may be variable. For example, when the patient wears the nasal interface 100, a portion of the patient's face may impinge on the base of the nasal delivery elements 111, 112 or the interface body 110 to narrow the bypass restriction 130 and thereby the cross-sectional area A2 of the portion of the gases flow channel. This could be affected by the distance of the base of the nasal delivery elements 111, 112 from the patient's septum. In some configurations, the interface body 110 or a portion thereof may be configured to limit the variability of the cross-sectional area A2 of the portion of the gases flow channel when the patient wears the nasal interface 100. For example, a portion of the interface body 110 may be stiffened with another more rigid material, using a more rigid material and / or designed with a specific geometry.

[00828] In some configurations, the gases manifold 120 or the gases manifold part is separable from the interface body 110.

[00829] In some configurations, the gases inlet 121 is ata side of the gases manifold 120.

[00830] In some configurations, the nasal interface 100 comprises a bias flow restriction 140 for a flow of gases out of the nasal interface 100 through the bias flow restriction 140.

[00831] In some configurations, the bias flow restriction 140 comprises at least one aperture 142 for the flow of gases from the nasal interface 100 to an ambient environment. In some configurations, the bias flow restriction 140 comprises a plurality of apertures 142 for the flow of gases from the nasal interface 100 to an ambient environment.

[00832] In some configurations, the bias flow restriction 140 comprises a filter or a diffuser to filter or diffuse gases flowing through the aperture(s) 142.

[00833] In some configurations, the nasal interface comprises a filter unit 500' between the gases manifold 120 and the bias flow restriction 140.

[00834] In some configurations, the bias flow restriction 140 is in fluid communication with the gases manifold 120. In some configurations, the gases manifold 120 comprises the bias flow restriction 140 or is coupled to the bias flow restriction 140. In some configurations, the bias flow restriction 140 is in fluid communication with the gases manifold 120 but is positioned remotely from the gases manifold.

[00835] In some configurations, the bias flow restriction 140 comprises an open area for gases flow out of the nasal interface 100 through the bias flow restriction 140. In some configurations, the open area is more than 0 mm2 to about 40 mm2, optionally between about 2 mm2 and about 40mm2, optionally between about 2 mm2 and about 5 mm2, optionally between about 12 mm2 and about 40mm2, optionally between about 20 mm2 and about 30 mm2.

[00836] In some configurations, the open area for gases flow out of the nasal interface 100 through the bias flow restriction is about 1 mm2, about 2 mm2, about 3 mm2, about 4 mm2, about 5 mm2, about 6 mm2, about 7 mm2, about 8 mm2, about 9 mm2, about 10 mm2, about 11 mm2, about 12 mm2, about 13 mm2, about 14 mm2, about 15 mm2, about 16 mm2, about 17 mm2, about 18 mm2, about 19 mm2, about 20 mm2, about 21 mm2, about 22 mm2, about 23 mm2, about 24 mm2, about 25 mm2, about 26 mm2, about 27 mm2, about 28 mm2, about 29 mm2, about 30 mm2, about 31 mm2, about 32 mm2, about 33 mm2, about 34 mm2, about 35 mm2, about 36 mm2, about 37 mm2, about 38 mm2, about 39 mm2, or about 40 mm2, or is any value between any two of those values.

[00837] The flow through the bias flow restriction 140 fora given pressure difference between the body gases flow passage 146 and the outside of the bias flow restriction 140 is largely determined by the cross-sectional area of the apertures 142 and their geometry. The geometric factor may be known as the discharge coefficient. For example, cylindrical outlet apertures 142 with sharp edges will let through less flow than smooth apertures that are shaped like venturi nozzles or apertures with a substantial radius, chamfer, or other expansion and contraction features on either the inlet or outlet side. Viscous effects such as in long thin channels may also reduce the overall flow rate through the apertures, depending on their shape.

[00838] The size of the apertures 142 could be increased, but the design of the filter or diffuser could additionally or alternatively be adjusted to add resistance.

[00839] Therefore, the upper end of the range of sizes of open area for gases flow out of the nasal interface 100 through the bias flow restriction 140 could be increased by up to 25% (e.g. 50 mm2 rather than 40 mm2) if a suitably configured filter or diffuser is used.

[00840] Similarly, if apertures 142 with a high discharge coefficient are used, the lower end of the range of sizes of open area for gases flow could be reduced by up to 50% (e.g. 6 mm2 rather than 12 mm2).

[00841] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is more than 0 Ipm to about 80 Ipm when a pressure of more than 0 cmH20 and up to about 30 cmH20 is provided to the gases inlet 121 in use.

[00842] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is about 5 Ipm, about 10 Ipm, about 15 Ipm, about 20 Ipm, about 25 Ipm, about 30 Ipm, about 35 Ipm, about 40 Ipm, about 45 Ipm, about 50 Ipm, about 55 Ipm, about 60 Ipm, about 65 Ipm, about 70 Ipm, about 75 Ipm, about 80 Ipm, or is any value between any two of those values when a pressure of about 5 cmH20, about 10 cmH20, about 15 cmH2O, about 20 cmH2O, about 25 cmH20, about 30 cmH20, or of any value between any two of those values is provided to the gases inlet 121 in use.

[00843] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is between about 35 Ipm and about 55 Ipm when a pressure of between about 5 cmH2O and about 10 cmH2O is applied to the gases inlet 121 in use and the nasal delivery elements 111, 112 are occluded.

[00844] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is between about 4 Ipm and about 15 Ipm when a pressure of between about 3 cmH20 and about 10 cmH20 is provided to the gases inlet 121 in use and the nasal delivery elements 111, 112 are occluded.

[00845] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is about 5 Ipm, about 6 Ipm, about 7 Ipm, about 8 Ipm, about 10 Ipm, about 11 Ipm, about 12 Ipm, about 13 Ipm, about 14 Ipm, about 15 Ipm, or is any value between any two of those values when a pressure of about 3 cmH20, about 4 cmH20, about 5 cmH20, about 6 cmH20, about 7 cmH20, about 8 cmH20, about 9 cmH20, about 10 cmH20, or of any value between any two of those values is provided to the gases inlet 121 in use and the nasal delivery elements 111, 112 are occluded.

[00846] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is between about 15 Ipm and about 80 Ipm when a pressure of between about 4 cmH20 and about 30 cmH20 is provided to the gases inlet 121 in use and the nasal delivery elements 111, 112 are occluded.

[00847] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface 100 through the bias flow restriction 140 is about 15 Ipm, about 20 Ipm, about 25 Ipm, about 30 Ipm, about 35 Ipm, about 40 Ipm, about 45 Ipm, about 50 Ipm, about 55 Ipm, about 60 Ipm, about 65 Ipm, about 70 Ipm, about 75 Ipm, about 80 Ipm, or is any value between any two of those values when a pressure of about 5 cmH2O, about 10 cmH20, about 15 cmH20, about 20 cmH20, about 25 cmH20, about 30 cmH20, or of any value between any two of those values is provided to the gases inlet 121 in use and the nasal delivery elements 111, 112 are occluded.

[00848] In some configurations, the nasal interface 100 could, as an addition to or as an alternative to having a bias flow restriction, be connected to an expiratory limb of a ventilator or have a positive end-expiratory pressure (PEEP) valve to control the amount of bias flow out of the nasal interface 100, which affects pressure and washout at the nasal interface 100.

[00849] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is transverse to a direction of gases flow through the portion of the gases flow channel 125.

[00850] The inner cross-sectional area A3+A4 of each nasal delivery element 111, 112 may be the cross-sectional area bounded by the inner wall of the nasal delivery element 111, 112. For non-circular cross-sections, the references herein to a diameter may be interpreted as a transverse dimension. In some configurations, references herein to a diameter include but are not limited to a hydraulic diameter.

[00851] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is reduced in comparison to a cross-sectional area Ai of an adjacent portion of the gases flow channel 125.

[00852] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is between about 10% and up to about 100% of a first cross-sectional area Ai of an adjacent part of the gases flow channel, optionally about 10% or more and less than 100% of the first cross-sectional area, optionally up to about 90% of the first cross-sectional area Ai, optionally up to about 80% of the first cross-sectional area Ai, optionally up to about 70% of the first cross-sectional area Ai, optionally up to about 60% of the first cross-sectional area Ai, optionally up to about 55% of the first cross-sectional area Ai, optionally up to about 40% of the first cross-sectional area Ai, optionally up to about 30% of the first cross-sectional area Ai, and optionally up to about 25% of the first cross-sectional area Ai.

[00853] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel is up to about 300 mm2, optionally up to about 280 mm2, optionally up to about 270 mm2, optionally up to about 200 mm2, optionally up to about 160 mm2, optionally up to about 110 mm2 , optionally up to about 80 mm2, optionally up to about 60 mm2, and optionally up to about 50 mm2.

[00854] In some configurations, the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 is more than 0 mm2 and up to about 250 mm2, optionally between about 1 mm2 and about 250 mm2, optionally between about 1.6 mm2 and about 250 mm2, optionally between about 50 mm2 and about 250 mm2, optionally between about 50 mm2 and about 200 mm2, optionally between about 30 mm2 and about 200 mm2, optionally between about 30 mm2 and up to about 155 mm2, and optionally between about 50 mm2 and up to about 155 mm2.

[00855] In some configurations, the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 is about 1 mm2, about 1.6 mm2, about 5 mm2, about 10 mm2, about 15 mm2, about 20 mm2, about 25 mm2, about 30 mm2, about 35 mm2, about 40 mm2, about 45 mm2, about 50 mm2, about 55 mm2, about 60 mm2, about 65 mm2, about 70 mm2, about 75 mm2, about 80 mm2, about 85 mm2, about 90 mm2, about 95 mm2, about 100 mm2, about 105 mm2, about 110 mm2, about 115 mm2, about 120 mm2, about 125 mm2, about 130 mm2, about 135 mm2, about 140 mm2, about 145 mm2, about 150 mm2, about 155 mm2, about 160 mm2, about 165 mm2, about 170 mm2, about 175 mm2, about 180 mm2, about 185 mm2, about 190 mm2, about 195 mm2, about 200 mm2, about 205 mm2, about 210 mm2, about 215 mm2, about 220 mm2, about 225 mm2, about 230 mm2, about 235 mm2, about 240 mm2, about 245 mm2, or about 250 mm2, or is any value between any two of those values.

[00856] In some configurations, the bypass restriction 130 provides a pressure drop through the nasal interface 100 between the first nasal delivery element 111 and the second nasal delivery element 112 when gases are delivered from the gases inlet 121 to the first nasal delivery element 111 and the second nasal delivery element 112 such that pressure at the first nasal delivery element 111 is higher than pressure at the second nasal delivery element 112.

[00857] In some configurations, a nasal interface 100 of the present disclosure comprises a first nasal delivery element 111 and a second nasal delivery element 112, wherein the first nasal delivery element 111 and the second nasal delivery element 112 are each configured to seal with a respective naris of a patient, and a gases manifold 120 comprising a gases inlet 121 for delivery of respiratory gases to the gases manifold 120 and a gases flow channel, wherein the first nasal delivery element 111 and the second nasal delivery element 112 are in fluid communication with the gases inlet 121 via the gases flow channel 125, wherein the first nasal delivery element 111 is proximal to the gases inlet 121 and the second nasal delivery element 112 is distal from the gases inlet 121, wherein the nasal interface comprises a bypass restriction 130 that provides a cross-sectional area A2 of a portion of the gases flow channel, wherein each of the first nasal delivery element 111 and the second nasal delivery element 112 comprises an inner cross-sectional area A3, A4, and wherein the inner cross-sectional areas A3, A4 of the nasal delivery elements and the cross-sectional area A2 of the portion of the gases flow channel are related so as to create an asymmetrical flow of gases from the nasal delivery elements 111, 112 in use.

[00858] In some configurations, the inner cross-sectional areas A3, A4 together provide a combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, and wherein the cross-sectional area A2of the portion of the gases flow channel 125 is more than 0 to about 1.5 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112.

[00859] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel is up to about 1.3 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally up to about 1 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally up to about 2 / 3 of the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally up to about 1 / 2 of the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally up to about 2 / 5 of the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally up to about 1 / 3 of the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112.

[00860] In some configurations, the inner cross-sectional area A3, A4 of each of the first and second nasal delivery elements 111, 112 is at a smallest transverse dimension of the respective nasal delivery element 111, 112.

[00861] In some configurations, the inner cross-sectional area A3, A4 of each of the first and second nasal delivery elements 111, 112 is at an outlet Illa, 112a of the respective nasal delivery element 111, 112. Alternatively, the inner cross-sectional area may be elsewhere; for example, part-way along the nasal delivery element or at an inlet or base of the nasal delivery element 111, 112.

[00862] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is up to about 1 times, optionally up to about 2 / 3 times, the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, and the nasal interface is configured to provide a bias flow through a bias flow restriction 140 of 20 Ipm when a pressure of 4 cmH20 is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded. This may be in a patient that has an adult breath pattern of 15 breaths per minute (BPM) of 10i:20e 500 Vt for example.

[00863] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is up to about 1 times, optionally up to about 2 / 3 times, the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, and the nasal interface is configured to provide a bias flow through a bias flow restriction 140 of 32 Ipm when a pressure of 8 cmH2O is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded. This may be in a patient that has an adult breath pattern of 15 BPM of 10i:20e 500 Vt, for example.

[00864] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is up to about 2 / 3 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, and the nasal interface is configured to provide a bias flow through the bias flow restriction 140 of 20 Ipm when a pressure of 4 cmH20 is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded (this may be in a patient that has an adult breath pattern of 15 BPM of 10i:20e 500 Vt or in a patient that has ARDS and has an adult breath pattern of 25 BPM for example), or is configured to provide a bias flow through the bias flow restriction 140 of 32 Ipm when a pressure of 8 cmH20 is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded, or is configured to provide a bias flow through the bias flow restriction 140 of 41 Ipm when a pressure of 12 cmH20 is applied to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded, or is configured to provide a bias flow of 48 Ipm through the bias flow restriction 140 when a pressure of 16 cmH20 is applied to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded, or is configured to provide a bias flow through the bias flow restriction 140 of 53 Ipm when a pressure of 20 cmH20 is applied to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded. This may be in a patient that has ARDS and has an adult breath pattern of 25 BPM, for example.

[00865] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is up to about 2 / 3 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, and the nasal interface is configured to provide a bias flow through the bias flow restriction 140 of 32 Ipm or higher when a pressure of 8 cmH20 is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded. This may be in a patient that has an adult breath pattern of 15 BPM of 10i:20e 500 Vt or in a patient that has ARDS and has an adult breath pattern of 25 BPM or in a patient that has an adult breath pattern of 25 BPM of 350 sinusoidal breath pattern, for example.

[00866] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel 125 is up to about 1 / 3 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 and the nasal interface is configured to provide a bias flow through the bias flow restriction 140 of 32 Ipm or higher when a pressure of 8 cmH20 is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded, or wherein the cross-sectional area A2 of the portion of the gases flow channel is up to about 2 / 5 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 and the nasal interface is configured to provide a bias flow through the bias flow restriction 140 of 41 Ipm or higher when a pressure of 12 cm H2O is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded, or wherein the cross-sectional area A2 of the portion of the gases flow channel 125 is up to about 2 / 3 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 and the nasal interface is configured to provide bias flow through the bias flow restriction 140 of 48 Ipm or higher when a pressure of 16 cm H2O is provided to the gases inlet 121 and the nasal delivery elements 111, 112 are occluded.

[00867] The effectiveness of asymmetric flow (and the resulting washout) of the nasal interface 100 was assessed for six different ratios across three different tests.

[00868] Each test comprised a set breathing pattern, upon which the CPAP settings were varied. Tables 2 and 3 show the constant settings and varied settings respectively of the tests. The results of the tests are shown in Figures 23 to 25. Dunaee tr y pd ss restriction cross-sectional area A2 (BRA) -mm2 Nasal delivery element cross-sectional area (CNDEA) - mm2 BRA:CNDEA Crncc-ceetional area through aperture(s) of bias flow restriction -mm2 50 154 (combined A3+A4) 77 (individual A3, A4) 50:154 (about 1 / 3) 27.5 60 60:154 (about 2 / 5) 75 75:154 (about 1 / 2) 102 102:154 (about 2 / 3) 154 154:154 (about 1) 200 200:154 (about 1.5) Table 2 CPAP settings (cmHzO) Breath patterns Test 1 (Figure 23) 4, 8 15 breaths / min (bpm) 10i:20e 500 Vt Test 2 (Figure 24) 4, 8, 12, 16, 20 25 breaths / min (bpm) adult ARDS -approximately 10i:15e and 400 Vt Test 3 (Figure 25) 4, 8, 12, 16, 20 45 breaths / min (bpm) 10i:10e 350 Vt Table 3

[00869] In the tables above xi:ye is a ratio of x inspiratory time to y expiratory time and Vt is the tidal volume and a measure (in ml) of the amount of air that moves in or out of the lungs with each respiratory cycle.

[00870] In each test, asymmetric flow and washout was measured by rebreathing (the lower the rebreathing, the greater the washout). The typical level of rebreathing in CPAP without asymmetric flow is approximately 60 ml. Therefore, for the purposes of these tests, washout may be understood to be equal to '60 ml - x', wherein x = the volume of rebreathing in ml. 60 ml is an exemplary figure for an upper airway model, excluding the interface itself, and presumes no dead space in the interface.

[00871] As shown in Figures 23 to 25, effective washout was generally achieved at ratios of 102:154 (about 2 / 3) and below (bypass restriction cross-sectional area (BRA) : combined nasal delivery element cross-sectional area (CNDEA)).

[00872] Tests at ratios of 1:1 (BRA:CNDEA) and above showed inconsistent and / or minimal washout. However, some washout is shown / expected with ratios as high as 1.5:1 (CRA:CNDEA). In practice, a selected ratio may be below 1:1 (BRA:CNDEA).

[00873] Test 1 (15 bpm; 4, 8 cmH20) showed significant washout at ratios of 102:154 (about 2 / 3) (CRA:CNDEA) and below, inconsistent washout at 1:1 (BRA:CNDEA), and minimal washout at 200:154 (about 1.5) (BRA:CNDEA).

[00874] Test 2 (25 bpm; 4, 8, 12, 16, 20 cmH20) showed significant washout at ratios of 102:154 (about 2 / 3) (BRA:CNDEA) and below, but minimal washout at 1:1 (BRA:CNDEA) and above.

[00875] Test 3 (45 bpm; 4, 8, 12, 16, 20 cmH2O) showed washout at ratios of 102:154 (about 2 / 3) (BRA:CNDEA) and below at higher cmH20 levels, otherwise no significant washout was observed.

[00876] More particularly, and with reference to Figure 23, in Test 1 significant washout was achieved at ratios of 102:154 (about 2 / 3) (BRA:CNDEA) and below. A ratio of 1:1 (CRA:CNDEA) showed effective washout at 8 cmH2O, but minimal washout at 4 cmH2O. Minimal washout was achieved at 200:154 (about 1.5) (BRA:CNDEA).

[00877] With reference to Figure 24, in Test 2 significant washout was achieved at ratios of 102:154 (about 2 / 3) (BRA:CNDEA) and below (with the exception of 102:154 BRA:CNDEA at 4 cmH20). Minimal washout was shown at 4, 8, and 12 cmH2O levels for ratios of 1:1 (BRA:CNDEA) and above. Those ratios were not tested at 16 cmH20 and 20 cmH2O levels.

[00878] At low pressures and high breath rates, rebreathing can occur because of insufficient bias flow. That may affect the results particularly at low pressures since at higher pressures the bias flow increases.

[00879] With reference to Figure 25, in Test 3 significant washout was achieved at ratios 102:154 (about 2 / 3) (BRA:CNDEA) and below for higher cmH2O levels, but not at lower cmH20 levels. Better than baseline washout was achieved at: 8 cmH20 and above for 50:154 (about 1 / 3) (BRA:CNDEA), 12 cmH20 and above for 60:154 (about 2 / 5) (BRA:CNDEA), 16 cmH20 and above for 75:154 (about 1 / 2) and 102:154 (about 2 / 3) (BRA:CNDEA). Washout was not achieved at ratios of 1:1 (BRA:CNDEA) or higher in this test.

[00880] Figures 26 to 28 show modelled effects of different nasal delivery element 111, 112 sizes, different bypass restriction cross-sectional areas, different set pressures, and different bias flow restriction openness on rebreathing with the nasal interface for 15 breaths per minute, 25 breaths per minute, and 45 breaths per minute respectively.

[00881] The Y-axis (dependent axis) on the charts shows rebreathing, where a lower amount is better and shows more washout.

[00882] The 'nasal delivery element size' of each chart shows the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112.

[00883] A is smaller than B. A-B provides a possible range for the combined cross-sectional area A3+A4.

[00884] As outlined herein, in some configurations, the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 is more than 0 mm2 (A) and up to about 250 mm2 (B), optionally between about 1 mm2 and about 250 mm2, optionally between about 1.6 mm2 and about 250 mm2, optionally between about 50 mm2 and about 250 mm2, optionally between about 50 mm2 and about 200 mm2, optionally between about 30 mm2 and about 200 mm2, optionally between about 30 mm2 and about 155 mm2, optionally between about 50 mm2 and about 155 mm2, and optionally between about 70 mm2 and about 155 mm2.

[00885] The 'bypass restriction size' portion of each chart shows the bypass restriction 130 cross-sectional area A2, i.e. the cross-sectional area A2 of the portion of the gases flow channel.

[00886] C is smaller than D. C - D provides a possible range for the bypass restriction cross-sectional area A2.

[00887] As outlined herein, in some configurations, the bypass restriction 130 cross-sectional area A2 is more than 0 to about 1.5 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally about 0.25 times to about 1.5 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112, optionally about 1 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 or less, optionally about 2 / 3 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 or less.

[00888] As outlined herein, in some configurations, the bypass restriction 130 cross-sectional area A2 is more than 0 mm2 (C) and up to about 375 mm2 (D), optionally between about 1 mm2 and about 375 mm2, optionally between about 1 mm2 and about 250 mm2, optionally between about 1 mm2 and about 200 mm2, optionally between about 1 mm2 and about 167 mm2, optionally between about 50 mm2 and about 167 mm2, optionally between about 50 mm2 and about 103 mm2, optionally between about 35 mm2 and about 100 mm2, and optionally about 65 mm2. The bypass restriction 130 cross-sectional area A2 may be any other value or range of values related to the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 recited herein.

[00889] In some configurations, the cross-sectional area A2 of the portion of the gases flow channel is more than 0 to about 1.5 times the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 and the combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 is between about 1 mm2 and about 250 mm2.

[00890] The 'set pressure' portion of each chart shows the pressure applied to the gases inlet 121 of the nasal interface 100.

[00891] E is smaller than F. E - F provides a possible range of pressure applied to the gases inlet 121.

[00892] As outlined herein, in some configurations, a pressure of more than 0 cmH20 (E) and up to about 30 cmH2O (F) is provided to the gases inlet 121 in use.

[00893] In some configurations, a pressure of between about 3 cmH20 and about 10 cmH20 is provided to the gases inlet 121 in use.

[00894] In some configurations, a pressure of between about 4 cm H2O and about 30 cmH20 is applied to the gases inlet 121 in use.

[00895] The 'Bias' portion of each chart shows the effects of the openness of the open area for gases flow out of the nasal interface 100 through the bias flow restriction 140 on rebreathing and washout. 'Filterless' indicates a more open bypass restriction, where no filter or diffuser is in place. 'Filtered' shows a more closed bypass restriction, where a filter or diffuser is in place on the bypass restriction.

[00896] As outlined above, in some configurations, the bias flow restriction 140 comprises an open area for gases flow out of the nasal interface 100 through the bias flow restriction 140. In some configurations, the open area is more than 0 mm2 to about 40 mm2, optionally between about 2 mm2 and about 40mm2, optionally between about 2 mm2 and about 5 mm2, optionally between about 12 mm2 and about 40mm2, optionally between about 20 mm2 and about 30 mm2.

[00897] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is more than 0 Ipm to about 80 Ipm when a pressure of more than 0 cmH20 and up to about 30 cmH20 is provided to the gases inlet 121 in use.

[00898] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is between about 4 Ipm and about 15 Ipm when a pressure of between about 3 cmH20 and about 10 cmH20 is provided to the gases inlet 121 in use.

[00899] In some configurations, the bias flow restriction 140 is configured such that a flow rate of the flow of gases out of the nasal interface through the bias flow restriction is between about 15 Ipm and about 80 Ipm when a pressure of between about 4 cmH20 and about 30 cmH20 is provided to the gases inlet 121 in use.

[00900] The plots show that at lower breath rates such as 15 BPM and 25 BPM, increasing the nasal delivery element combined cross-sectional area, reducing the bypass restriction cross-sectional area, increasing the pressure applied to the gases inlet, and / or increasing the open area for gases flow through the bias flow restriction 140 reduces the amount of rebreathing and increases the amount of washout.

[00901] The combined cross-sectional area A3+A4 of the nasal delivery elements 111, 112 may be maximised to increase washout, up to a size that comfortably fits within a patient's nares.

[00902] The bypass restriction 130 cross-sectional area A2 may be minimised to increase washout, although increasing that cross-sectional area may enhance patient comfort.

[00903] The plots show that at higher breath rates such as 45 BPM, varying the nasal delivery element cross-sectional area or the bypass restriction may have negligible effect, due to rebreathing in the gases conduit (hence the left two boxes in the 45 BPM plot are shaded grey as they are not statistically significant to results). Increasing the pressure applied to the gases inlet 121, and / or increasing the open area for gases flow through the bias flow restriction 140 reduces the amount of rebreathing and increases the amount of washout.

[00904] A headgear may be used to retain the nasal interface 100 against the patient's face. The headgear comprises a head strap 200. The head strap 200 may be a single continuous length and adapted to extend in use along the patient's cheeks, above the ears and about the back of the head, may be adjustable, and / or may extend around other portions of the patient's head.

[00905] The headgear has ends that connect to the side arms of the interface body 110.

[00906] In the exemplary configuration shown (Figure 18), primary end portions 201 and 202 of the strap 200 are adapted to releasably connect respective formations 101 and 102 on either side of the nasal interface 100 to hold the nasal interface 100 in position during use.

[00907] In one configuration, a clip component is provided at each end portion 201, 202 capable of being received and retained within the corresponding formation 101, 102. The clip component may be coupled to the strap at the respective primary end portion. Furthermore, the head strap 200 is adjustable in length to help customise the strap to the wearer's head. The strap 200 may be formed from a soft and stretchable / elastic material such as an elastic, textile material / fabric that is comfortable to the wearer. Alternatively, the strap 200 may be formed from a substantially more rigid, or less flexible, material such as a hard plastics material.

[00908] The headgear may further comprise an additional strap or other headgear component that couples the strap 200 to extend over the patient's crown in use. A crown strap or crown component can have the benefit of pulling the strap 200 up and above the patient's ears in use to improve fit and comfort.

[00909] Rear portions of the strap 200 may extend through a receiver 204. The receiver 204 may allow the rear portions of the strap 200 to be adjusted to adjust the size of the headgear to fit a patient's head.

[00910] Strap segments of a fixed length can be releasably connected to the main strap to extend its length.

[00911] A number of strap segments of varying predetermined lengths may be provided to provide alternative adjustment lengths. For example, one or more strap segments may be provided having a length within the range of about 1cm to about 10cm, or within the range of about 2cm to about 6cm. The strap segments 220 have lengths of, for example, about 2cm, about 4cm or about 6cm. It will be appreciated that these examples are not intended to be limiting and the length of each strap segments can be of any size as it is dependent on the user and / or application.

[00912] Furthermore, each end of each strap segment may be connectable to a respective end of another strap segment and / or to a respective secondary end portion of the main strap 210 to thereby enable a user to combine one or more strap segments of the same or varying lengths to customise the overall length of the extension as desired.

[00913] The additional strap segments may be formed from a soft and stretchable / elastic material such as an elastic, textile material / fabrie that are comfortable to the wearer. For example, a tubular knitted type head strap or sections of the head straps 210 may be utilised, particular for comfort over a user's ears.

[00914] It will be appreciated that particular comfort may be achieved from a head strap which is able to provide suitable locating of the nasal interface 100 in a relatively stable position on a user's face, yet simultaneously provide for a relatively loose fit or low tension fit about the user's head.

[00915] Alternatively, the additional strap segments may be formed from a substantially rigid material such as a hard plastics material.

[00916] Interface connectors 240 are provided at the primary end portions 201 and 202 of the main strap 210. These connectors 240 have a strap connection mechanism to connect the primary end portions 201, 202, but include a clip member, such as a push fit clip 241, at an end of the connector 240 opposing the strap ends. The clip 241 is configured to releasably couple the respective formation 101, 102 at the side of the nasal interface 100. The clip member 241 may be a bendable part, such as a plastic part, that forms a hinged portion relative to the strap. The clip 241 may be preformed to have a curved shape along its length. In an example, the clip 241 may be pre-formed with two or more portions angled relative to one another, for example an angle between 0 and 20 degrees. This curve and / or angle allows the clip 241 to fit the contour of the patient's face in the region of the clip 241.

[00917] The nasal interface may comprise sleeves 270. Each sleeve 270 may be pre-formed to have a curved shape along its length, such as one with an angle between flat and 20 degrees for example. The curve allows the sleeve to fit the contour of the patient's face or cheek in the region of the sleeve in use. Alternatively, the sleeve 270 may take on the shape of a curved sleeve upon engagement with the primary end portion 201, 202 or connector 240 of the head strap 200.

[00918] The sleeve 270 provides a surface region of relatively higher frictional surface material for frictionally engaging with the user's face or facial skin. This surface region is to be positioned for frictional engagement with the facial cheek skin of a user. The surface region is at least localised to the strap or the section of strap which is to be positioned upon the cheeks of a user. The surface region provided with the relatively higher frictional surface material may be of a material that is smooth and comfortable on the skin of the patient. The sleeve 270 or at least the surface region 271 is therefore formed from a relatively softer material than the connector 240.

[00919] In one configuration, the surface region 271 or the sleeve 270 is formed from a soft Thermoplastic Elastomer (TPE), but may alternatively be formed from another plastics material such as silicone, or any other biocompatible materials.

[00920] The surface region 271 may be a surface of wider surface area more adjacent to the patient interface than the surface area more distant from the patient interface. In one configuration, the sleeve 270 tapers from a relatively wider surface area 273 to a relatively lesser surface area 274 in a direction extending away from a connection point between the connector 240 and the nasal interface 100. The width of the sleeve at the end with the wider surface area 273 may be the same or similar to the width of the tapered distal end of the corresponding wing portion 113, 114 of the face mount part 110. This provides a smooth transition between the nasal interface 100 and the headgear for improving aesthetics and achieving a visually appealing effect.

[00921] The sleeves 270 may be coloured to provide an identification of the nasal interface 100. As described herein, the nasal interfaces may be provided in different sizes such as small, medium, and large, for example. The sleeves 270 of each of those sizes may comprise different colours to represent the different sizes. Alternatively, or additionally, the sleeves may be coloured in a specific way to represent that the nasal interfaces have asymmetrical nasal delivery elements rather than symmetrical.

[00922] The headgear may comprise cheek supports 270 as described or similar, at or adjacent either side end of straps of headgear of the interface, which connect to the nasal interface, for frictionally engaging with the user's face to stabilise the mask on the face at the cheeks. Such headgear may again comprise a single head strap adapted to extend in use along the patient's cheeks, above the ears and about the back of the head, with ends comprising clips in any suitable form which couple to the nasal interface on either side (or are permanently attached to the nasal interface).

[00923] The patient interface 1 may comprise a tube retention clip (not shown). The tube retention clip can support the respiratory conduit 300 or other gases supply tube 16 from part of the patient interface 1. By supporting the respiratory conduit 300 or other gases supply tube from or near the nasal interface 100, bending moment applied to the respiratory conduit 300 or other gases supply tube 16 as a result of asymmetrical flow through the first and second nasal delivery elements 111, 112 and / or movement of the patient's head will be resisted by the tube retention clip, thereby enhancing patient comfort.

[00924] The patient interface 1 may have any one or more of the features and functionality described in PCT publication no. WO 2014 / 182179 or US patent no. 10,406,311. The contents of those specifications are incorporated herein in their entireties by way of reference.

[00925] As an alternative to a headgear, the patient interface may comprise a securement system of the type described in PCT publication number WO 2012 / 053910 or US patent no. 10,238,828. The contents of those specifications are incorporated herein in their entirety by way of reference.

[00926] Figure 29 schematically shows an alternative configuration nasal interface 1100 for use in the patient interface 1. Unless described as being different below, the features, functionality, alternatives, and uses of the nasal interface 1100 are as described for nasal interface 100. Like reference numbers indicate like parts with the addition of 1000. Exemplary configurations of the nasal interface are described in more detail below with reference to Figures 30-59.

[00927] The nasal interface 1100 comprises an interface body 1110 configured to substantially form a seal with a patient's nasal airways. The interface body 1110 is configured to deliver gases to a first naris of the patient and to a second naris of the patient.

[00928] The nasal interface 1100 comprises a gases inlet 1121 for delivery of respiratory gases into the nasal interface 1100. The gases inlet 1121 is in fluid - Ill - communication with the interface body 1110 to deliver the respiratory gases from the gases inlet 1121 through the interface body 1110 to the first naris and second naris of the patient in use.

[00929] The nasal interface 1100 is configured to receive incoming gases F0 from the gases inlet 1121 and to provide, from the incoming gases F0, a first flow stream of gases Fl configured to be substantially provided to the first naris of the patient in use and a second flow stream of gases F2 configured to be substantially provided to the second naris of the patient in use.

[00930] The nasal interface 1100 is configured to direct more of the incoming gases to the first flow stream of gases Fl than to the second flow stream of gases F2, to create an asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[00931] Flow generated by respiratory therapy depends on flow through the nasal interface 1100. The flow through the nasal interface 1100 is related to pressure at each outlet 1111a, 1112a of the nasal interface. If the pressure is different at each outlet 1111a, 1112a, an asymmetric flow of gases will be generated.

[00932] The nasal interface may comprise distinct outlets 1111a, 1112a for delivery of the respiratory gases to the respective nares of the patient. Alternatively, the nasal interface may comprise a single outlet that defines a first outlet portion and a second outlet portion for delivery of the respiratory gases to the respective nares of the patient. Therefore, reference herein to "first outlet" and "second outlet" can instead be considered references to "first outlet portion" and "second outlet portion" respectively. Some of the possible exemplary configurations are described in more detail below.

[00933] Asymmetric flow is provided by the nasal interface 1100 by more flow being directed to the first naris / first outlet 1111a than to the second naris / second outlet 1112a. That may be considered flow directionality.

[00934] The nasal interface 1100 may be structured and configured to provide the flow directionality in different ways. For example, the nasal interface 1100 may comprise a flow director and / or a flow splitter and / or at least partial alignment of a gases inlet with the first outlet 1111a to provide the flow directionality. Some of the possible exemplary configurations are described in more detail below.

[00935] In some configurations, the nasal interface 1100 may comprise an interface body 1110 and a gases manifold 1120.

[00936] The interface body 1110 and gases manifold 1120 may cooperate to define a gases plenum 1115 therein. In some alternative configurations, the gases plenum 1115 may instead be defined substantially or solely by the interface body 1110. Instead of having a gases manifold 1120, the nasal interface 1100 may comprise a frame component to support the interface body and / or one or more other components (such as the gases inlet 1121, headgear 200, and / or the interface body 1110). Therefore, reference herein to "gases manifold" can instead be considered references to "frame".

[00937] The interface body 1110 may be configured to contact and seal internally in the nares of the patient, may be configured to contact and seal at the entrance to the nares of the patient, and / or may be configured to seal around the exterior surface of the nose, e.g. the alarand pronasale.

[00938] In some configurations, the interface body 1110 comprises a first outlet 1111a configured to substantially deliver gases to the first naris of the patient, and comprises a second outlet 1111b configured to substantially deliver gases to the second naris of the patient.

[00939] In some configurations, the interface body 1110 comprises first and second nasal delivery elements 1111, 1112 that are configured to engage with respective nares of the patient.

[00940] In some configurations, the interface body 1110 is a nasal cushion. The nasal cushion may comprise a single outlet that provides a first outlet portion and a second outlet portion. Alternatively, the nasal cushion may comprise first and second nasal delivery elements 1111, 1112 that are each configured to engage with a respective naris of the patient.

[00941] The nasal interface 1110 is structured and configured to create the asymmetric flow of gases at a patient's nasal airways throughout a respiratory cycle of a patient.

[00942] In the configuration shown in Figure 29, the gases inlet 1121 is at least partly aligned with the first outlet 1111a and is less aligned or is not aligned with the second outlet 1112a.

[00943] This configuration directs a flow of gases from the gases inlet 1121 to the first outlet Illa. This configuration may provide a substantially direct flow of gases from the gases inlet 1121 to the first outlet 1111a. The alignment of the gases inlet 1121 with the first outlet 1111a may act as a flow director.

[00944] The flow path for the flow of gases from the gases inlet 1121 to the second outlet 1112a is more tortuous than the flow path for the flow of gases from the gases inlet 1121 to the first outlet 1111a. In addition or alternatively, the flow path for the flow of gases from the gases inlet 1121 to the second outlet 1112a may be longer than the flow path for the flow of gases from the gases inlet 1121 to the first outlet 1111a.

[00945] The gases inlet 1121 is offset from a central axis C-A of the nasal interface 1100.

[00946] In some configurations, the gases inlet 1121 is substantially axially aligned with the first outlet 1111a.

[00947] In some configurations, at least half of a transverse cross-sectional area AO of the gases inlet 1121 is axially aligned with at least half of a transverse cross-sectional area Al of the first outlet 1111a.

[00948] The gases inlet comprises an outer portion 1121a for connecting to a respiratory conduit 300 or other gases supply tube 16 to provide a flow of gases from a gases source to the interface body 1110, and further comprises an inner portion 1121b in fluid communication with the interface body 1110.

[00949] The inner portion 1121b of the gases inlet 1121 is at least partly aligned with the first outlet 1111a or first outlet portion.

[00950] The inner portion 1121b and outer portion 1121a may be aligned with each other, or may be angled relative to each other.

[00951] In some configurations, the first outlet 1111a and the second outlet 1112a comprise substantially the same cross-sectional areas. That is, the flow asymmetry is caused by other features in the nasal interface 1100 rather than differing outlet sizes.

[00952] In some configurations, the first outlet 1111a and the second outlet 1112a may be symmetrically and structurally identical.

[00953] In some configurations, the nasal interface 1100 is configured to deliver a lower velocity of gases flow through the first outlet 1111a than a velocity of gases flow through the second outlet 1112a during an inhalation phase of a respiratory cycle.

[00954] Due to the less restricted flow path to the first outlet 1111a, the first flow stream of gases Fl has a lower velocity and higher pressure than the second flow stream of gases F2 along its more restricted flow path to the second outlet 1112a.

[00955] The nasal interface 1100 may comprise a restriction to restrict flow to the second outlet 1112a. The restriction may be provided by one or more of a flow director, a flow splitter, or any other suitable feature. The restriction may comprise a bypass restriction.

[00956] In some configurations, the nasal interface 1100 is configured to deliver a higher pressure of gases flow through the first outlet 1111a than a pressure of gases flow through the second outlet 1112a during an inhalation phase of a respiratory cycle.

[00957] In the configuration shown in Figure 29, the interface body 1110 comprises a first nasal delivery element 1111 comprising the first outlet 1111a and a second nasal delivery element 1112 comprising the second outlet 1112a, wherein the nasal interface 1100 is configured such that the first flow stream of gases Fl is configured to be substantially delivered to the first nasal delivery element 1111 and the second flow stream of gases F2 is configured to be substantially delivered to the second nasal delivery element 1112, and wherein the first nasal delivery element and the second nasal delivery element are each configured to seal with a respective naris of a patient.

[00958] In some configurations, the nasal interface comprises a flow directorthat is configured to direct more of the incoming gases FO from the gases inlet 1121 to the first flow stream of gases Fl than to the second flow stream of gases F2.

[00959] Figure 29 shows a first exemplary configuration of the flow director. In this configuration, the flow director comprises the inner portion of the gases inlet 1121. Because the gases inlet is more aligned with the first outlet 1111a than the second outlet 1112a, the flow director directs more of the incoming gases FO to the first flow stream of gases Fl than to the second flow stream of gases F2.

[00960] In some configurations, and as described below, the nasal interface comprises a connector or elbow for connecting a respiratory conduit 300 to the patient interface.

[00961] The connector or elbow may comprise or may be the flow director. That is, the connector or elbow may be the component that directs the flow more towards the first outlet 1111a than towards the second outlet 1112a.

[00962] In some configurations, the nasal interface 1100 is configured to direct more of the incoming gases to the first flow stream of gases Fl than to the second flow stream of gases F2 during an inhalation phase of the respiratory cycle. Additionally, this may also occur during an exhalation phase of the respiratory cycle. The inhalation phase and exhalation phase may define a respiratory cycle.

[00963] In some configurations, the flow path Fl to the first naris comprises a converging flow path. Additionally, or alternatively, the flow path F2 to the second naris comprises a diverging flow path.

[00964] In some configurations, the flow director comprises a nozzle that is configured to accelerate flow towards the first outlet 1111a.

[00965] In such a configuration, a first portion of the nozzle proximal to the gases inlet 1121 or proximal to an entry 1121a into the gases inlet may have a relatively large cross-sectional dimension, and a second portion of the nozzle distal from the gases inlet 1121 or distal from the entry 1121a into the gases inlet (and proximal to the gases plenum in the interface body 1110 and / or gases manifold 1120) may have a relatively small cross-sectional dimension. Due to the reduction in cross-sectional area, the nozzle will cause the gases to accelerate through the nozzle towards the first outlet 1111a.

[00966] In some configurations, the reduction in cross-sectional area of the nozzle may be a gradual reduction in cross-sectional area between the first portion and the second portion of the nozzle, such as a tapering. In another configuration, the reduction in cross-sectional area of the nozzle may be one or more substantially abrupt reductions in cross-sectional area provided between the first portion and the second portion of the nozzle, such as one or more step changes.

[00967] The nozzle may comprise part of the gases inlet 1121, or may be coupled or in fluid communication with the gases inlet 1121. In some configurations, the nozzle may comprise an insert that is received in the gases inlet 1121.

[00968] The nozzle is configured to increase the velocity of gases entering the gases flow channel 1125, thereby increasing the dynamic pressure at one naris compared to the other naris.

[00969] Figures 85(a)-(c) show three exemplary configurations of nozzle N1-N3 that can be used in any of the nasal interfaces described herein.

[00970] In the nozzle N1 of Figure 85(a), the nozzle reduces in cross-sectional area along its length and then expands again towards its outlet. The reduction and / or expansion in the cross-sectional area may be gradual as shown, or may comprise a plurality of stepped portions.

[00971] In the nozzle N2 of Figure 85(b), the nozzle gradually reduces in cross-sectional area along its length from its inlet to its outlet. The reduction in the cross-sectional area may be gradual as shown, or may comprise a plurality of stepped portions

[00972] In the nozzle N3 of Figure 85(c), the nozzle is a substantially constant crosssection along substantially its entire length, but the nozzle outlet nozzle NO is a much smaller cross-sectional area than the remainder of the nozzle, meaning flow needs to accelerate to pass through the nozzle outlet NO.

[00973] Table 4 shows exemplary relationships between a cross-sectional area of the inlet entry 1121a into the gases inlet and the smallest cross-sectional area of the nozzle. Inlet area (sq. mm) Minimum nozzle area (sq. mm) Average velocity increase Minimum nozzle area / inlet area 225 50 4.5 0.222222222 225 85 2.647058824 0.377777778 225 125 1.8 0.555555556 225 180 1.25 0.8 Table 4

[00974] In some configurations, the minimum nozzle area may be about O.lx the inlet area or greater, optionally about 0.2x the inlet area or greater.

[00975] It may be preferable to have a larger minimum nozzle area to reduce resistance to flow; however, having too much flow may affect dynamic pressures in the nasal interface and at the nares. A nozzle can balance those requirements.

[00976] In alternative configurations, the gases inlet 1121 may comprise a diffuser rather than a nozzle.

[00977] In some configurations, the nozzle may be provided in combination with an additional flow director. Alternatively, the nozzle may act as the flow director.

[00978] The nasal interface 1100 will be configured to simultaneously deliver the respiratory gases from the gases inlet 1121 through the interface body 1110 to both the first naris and second naris of the patient in use.

[00979] The nasal interface 1100 comprises a bias flow restriction 1140 comprising at least one aperture 1140a, and optionally a plurality of apertures 1140a, for the flow of gases from the nasal interface 1100 to an ambient environment.

[00980] The bias flow restriction 1140 may provide the functionality described above for the bias flow restriction 140.

[00981] There will typically be a positive flow of gases out of the patient interface 1100 through the bias flow restriction 1140, during respiratory therapy.

[00982] The bias flow restriction 1140 may comprise a filter and / or a diffuser to filter or diffuse gases flowing through the aperture(s) 1140a. When a filter is used, in some configurations the filter may additionally act as a diffuser.

[00983] In the configuration shown, the bias flow restriction 1140 is provided in the gases manifold 1120.

[00984] In some configurations, the bias flow restriction is positioned closer to the second nasal delivery element 1112 and second outlet 1112a than to the first nasal delivery element 1111 and first outlet 1111a. This encourages exhaled gases to pass through the second nasal delivery element 1112 and out of the nasal interface through the bias flow restriction 1140.

[00985] The bias flow restriction 1140 could be positioned elsewhere rather than the gases manifold 1120.

[00986] There will be an asymmetric flow of gases through the first outlet 1111a and the second outlet 1112a when inlet gases are being delivered to the nasal interface 1100 and the nasal interface is not mounted on a patient and the outlets are free of restrictions. The pressures at the outlets 1111a, 1111b could be checked to determine that there is an asymmetric flow.

[00987] The nasal interface 1100 is configured to provide a larger dynamic pressure at the first naris of the patient in use and to provide a smaller dynamic pressure at the second naris of the patient in use.

[00988] Therefore, the nasal interface 1100 may be considered to comprise an interface body 1110 configured to substantially form a seal with a patient's nasal airways, the interface body 1110 configured to deliver gases to a first naris of the patient and to a second naris of the patient.

[00989] The nasal interface 1100 comprises a gases inlet 1121 for delivery of respiratory gases into the nasal interface, wherein the gases inlet 1121 is in fluid communication with the interface body 1110 to deliver the respiratory gases from the gases inlet 1121 through the interface body 1110 to the fi...

Claims

1. A nasal interface comprising:an interface body comprising a first nasal delivery element that is configured to seal with a first naris of a patient and a second nasal delivery element that is configured to seal with a second naris of the patient,a gases inlet for delivery of respiratory gases into the nasal interface, wherein the gases inlet is positioned closer to the first nasal delivery element than to the second nasal delivery element,and a bias flow vent for a flow of gases out of the nasal interface, the bias flow vent positioned closer to the second nasal delivery element than to the first nasal delivery element,wherein an internal surface of the interface body comprises a protrusion extending from a base of the first nasal delivery element towards the gases inlet, the protrusion extending radially outwards as it extends towards the gases inlet.

2. The nasal interface according to claim 1, wherein the protrusion comprises a loop around the base of the first nasal delivery element.

3. The nasal interface according to claim 1 or 2, wherein the protrusion defines a protrusion gases flow channel, and wherein the protrusion gases flow channel has a larger cross-sectional area at its terminal region closer to the gases inlet compared to a region closer to the first nasal delivery element.

4. The nasal interface according to any one of claims 1 to 3, wherein the protrusion forms a funnel to guide flow from the gases inlet into the first nasal delivery element.

5. The nasal interface according to any one of claims 1 to 4, wherein the protrusion is integral with the interface body.

6. The nasal interface according to any one of claims 1 to 4, wherein the protrusion is provided as an insert that is attachable to the interface body.

7. The nasal interface according to claim 6, wherein the insert is removable from the interface body.

8. The nasal interface according to any one of claims 1 to 7 wherein the protrusion comprises a plurality of protrusion portions.

9. The nasal interface according to claim 8, wherein the plurality of protrusion portions form one or more discontinuous protrusions around at least a portion of the base of the first nasal delivery element.

10. The nasal interface according to any one of claims 1 to 9, wherein the protrusion comprises a continuous protrusion that extends around the base of the first nasal delivery element.

11. The nasal interface according to claim 10, wherein the protrusion is formed as a continuous annular wall.

12. The nasal interface according to any one of claims 1 to 11, wherein the protrusion is configured to maximise the amount of gases flow exiting the gases inlet that is captured and delivered into the first nasal delivery element.

13. The nasal interface according to any one of claims 1 to 12, wherein the internal surface of the interface body comprises a second protrusion that extends from a base of the second nasal delivery element towards the bias flow vent.

14. The nasal interface according to claim 13, wherein the second protrusion extends radially outwards as it extends from towards the bias flow vent from the base of the second nasal delivery element.228

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