System for providing respiratory support

Abstract

A device for providing respiratory support to a patient comprises a flow modulator operable to provide a high flow of gas via a high flow patient interface; and a controller controlling the flow modulator. The controller is operatively configured to: receive one or both of an occlusion signal and a mask signal; determine an occlusion status of a flow path of the high flow of gas to the patient based on the occlusion signal; and / or determine a mask placement status based on the mask signal; and control the flow modulator according to the occlusion status and / or mask placement status.

Description

SYSTEM FOR PROVIDING RESPIRATORY SUPPORTTECHNICAL FIELD

[0001] The present disclosure relates to a system for providing respiratory support to a patient. It relates particularly but not exclusively to a system for providing high flow respiratory support that may be couplable with or incorporated into an anaesthesia machine or ventilator. Aspects of the disclosure relate to improvements in detecting when a mask that is in fluid communication with an anaesthesia machine or ventilator is applied to or removed from a patient having a nasal cannula.BACKGROUND

[0002] Patients with diminished respiratory function or risk of diminished respiratory function can benefit from high flow respiratory support. Patients may lose respiratory function during anaesthesia, or sedation, or more generally during certain medical procedures. Prior to a medical procedure a patient may be pre-oxygenated by a medical professional to provide a reservoir of oxygen saturation, and this preoxygenation can be carried out with a bag and a face mask. Once under general anaesthesia, patients must be intubated to ventilate the patient. In some cases, intubation is often completed in under 60 seconds, but in other cases, particularly if the patient’s airway is difficult to traverse (for example, due to cancer, severe injury, obesity or spasm of the neck muscles), intubation may take significantly longer. While pre-oxygenation provides a buffer against declines in oxygen saturation, for long intubation procedures, it is often necessary to interrupt the intubation process and reapply the face mask to increase the patient's oxygen saturation to adequate levels. The interruption of the intubation process may happen several times for difficult intubation processes, which is time consuming and can potentially put the patient at risk. After approximately three attempts at intubation the medical procedure will be abandoned.

[0003] High flow systems providing high flow respiratory support may be present in the operating theatre for use during anaesthetic or sedation procedures, or other medical procedures. High flow respiratory support has been found effective in meeting or exceeding the patient's normal inspiratory demand, to increaseoxygenation of the patient, reduce the work of breathing or perform Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE). Pre-oxygenation using high flow systems prior to administration of anaesthesia or sedation provides an oxygen reservoir and extends safe apnoea time. Additionally, high gas flows may generate a flushing effect in the nasopharynx such that the anatomical dead space of the upper airways is flushed by the high incoming gas flows. This creates a reservoir of fresh gas available for each and every breath, while minimising re-breathing of carbon dioxide, nitrogen, etc. THRIVE involves the provision of a high flow of respiratory gases to the patient when the patient is apnoeic, which occurs when the anaesthetic agents take effect and before the patient is successfully intubated and mechanically ventilated. High flow respiratory support typically refers to the delivery of heated and humidified respiratory gases to a patient via a non-sealing patient interface (e.g. nasal cannula) at high flow rates that when the patient is spontaneously breathing, are generally intended to meet or exceed inspiratory demand of a patient.

[0004] Once pre-oxygenated, anaesthetic agents can be delivered to a patient to sedate the patient prior to intubation. Post intubation, anaesthetic agents may also be delivered to maintain the anaesthetized state of the patient during a medical procedure. This delivery of anaesthetic agents can be done intravenously or via inhalation of aerosols / vapor - the latter may be achieved by the use of an anaesthesia machine. A system configured for anaesthetic procedures may include an anaesthesia machine which includes a rebreathing system in which expired gases from the patient are returned to the machine. The anaesthesia machine can provide the anaesthetic agents to sedate the patient and / or keep the patient sedated via a sealing mask placed on the patient. Once sedated, patients can be intubated and then mechanically ventilated by the anaesthesia machine (anaesthetic ventilation) that assists or replaces spontaneous breathing.

[0005] A reference herein to a patent document or any other matter identified as prior art, is not to be taken as an admission that the document or other matter was known or that the information it contains was part of the common general knowledge as of the priority date of any of the claims.SUMMARY OF THE INVENTION

[0006] Viewed from one aspect, there is disclosed herein a device for providing respiratory support to a patient, the device comprising: a flow modulator operable to provide a high flow of gas via a high flow patient interface; and a controller controlling the flow modulator, the controller being operatively configured to: receive one or both of an occlusion signal and a mask signal; determine an occlusion status of a flow path of the high flow of gas to the patient based on the occlusion signal; and / or determine a mask placement status based on the mask signal; and control the flow modulator according to the occlusion status and / or mask placement status.

[0007] The controller may control the flow modulator to change the flow of gases when a change in mask placement status is determined based on the occlusion signal and the mask signal.

[0008] The mask signal may be received from an anaesthesia machine or ventilator, or a first sensor associated with an anaesthesia machine or ventilator.

[0009] The mask signal may be provided by a first sensor located at, or sampling gases from, a face mask in fluid communication with an anaesthesia machine or ventilator. The first sensor may sense gases: in an expiratory flow path of a face mask in fluid communication with the anaesthesia machine or ventilator; or in an inspiratory flow path of a face mask in fluid communication with the anaesthesia machine or ventilator; or in a sealing cuff of a face mask in fluid communication with the anaesthesia machine or ventilator.

[0010] The mask signal may be provided by the first sensor. The first sensor may comprise one or more of a pressure, flow rate, gas composition (e.g. 02, CO2 or anaesthesia gas), temperature and humidity sensor.

[0011] The mask signal may indicate a “mask on” mask placement status when the first sensor detects at least one of: in the expiratory flow path (e.g. inside and / or between the anaesthesia machine / ventilator and the face mask): a flow of gas; a change in concentration of one or more of CO2, 02 and an anaesthetic agent, such as an increase in concentration; a gas pressure greater than or less than ambient atmospheric pressure; a change in temperature, such as in increase in temperature; a change in humidity, such as an increase in relative humidity; an increase in pressure and / or temperature in the sealing cuff of the face mask; a change emitted and / or detected light corresponding to the face mask being applied to the patient’s face, in an inspiratory flow path: a flow of gas; a change in flow rate of gas such as an increase in the flow rate; a change in concentration of CO2 and / or an anaesthetic agent, such as an increase in CO2 and / or an anaesthetic agent concentration; and a gas pressure greater than or less than ambient atmospheric pressure.

[0012] The mask signal may indicate a “mask off” mask placement status when the first sensor detects at least one of: in an expiratory flow path (e.g. inside and / or between the anaesthesia machine / ventilator and the face mask): a flow rate of gas such as a decrease in the flow rate; a substantially zero flow rate; a change in CO2 concentration, such as a decrease in CO2 concentration; a change in 02 concentration such as an increase in 02 concentration,; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a decrease in system pressure; a gas pressure at or about ambient atmospheric pressure;a change in temperature, such as a decrease in temperature; a change in humidity, such as an increase in relative humidity; a decrease in pressure and / or temperature in the sealing cuff of the face mask; in an inspiratory flow path: a substantially zero flow rate; a gas pressure at or about ambient atmospheric pressure; a substantially zero CO2 concentration; a change in CO2 concentration, such as a decrease in CO2 concentration; a change of 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a change in temperature, such as a decrease in temperature; a change in humidity, such as an decrease in relative humidity; and a change emitted and / or detected light corresponding to the face mask being removed from the patient’s face.

[0013] The occlusion signal may be received from an occlusion sensor. Moreover, the device may comprise the occlusion sensor.

[0014] The occlusion sensor may comprise a pressure sensor for monitoring pressure of gasses provided by the flow modulator.

[0015] In some embodiments, detection by the pressure sensor of: an increase in pressure to meet or exceed a predetermined occlusion pressure threshold causes the controller to determine the occlusion status as occluded; and a decrease in pressure to fall below the predetermined occlusion pressure threshold causes the controller to determine the occlusion status as unoccluded.

[0016] The controller may be configurable to control the flow modulator based on receiving the mask signal in the absence of an occlusion signal.

[0017] The controller may be configured to perform one or more of, upon receiving the occlusion signal and determining the occlusion status as “occluded”, determinethe mask placement status based on the mask signal; upon receiving the mask signal and determining the mask placement status as “mask on”, determine the occlusion status based on the occlusion signal; receiving the occlusion signal and / or the mask signal substantially continuously or at regular intervals during operation of the device; and determining the mask placement status and occlusion status substantially simultaneously.

[0018] In some embodiments, the controller, upon determination of: the mask placement status as “mask on” based on the mask signal, and / or the occlusion status as “occluded” based on the occlusion signal, controls an output device to provide an audible and / or visible and / or tactile alert.

[0019] In some embodiments, the controller, upon determination of one or both of: the mask placement status as “mask on” based on the mask signal, and the occlusion status as “occluded” based on the occlusion signal, controls the flow modulator to provide the flow of gases comprising gases at a target pressure and / or target flow rate; or comprising gases at a flow rate of 0 L / min.

[0020] The target pressure may comprise a predetermined target pressure threshold value for a corresponding target flow rate, or a predetermined target pressure threshold value corresponding to a flow rate less than the target flow rate.

[0021] In some embodiments, when the controller drives the flow modulator at the target pressure, the flow of gases may be reduced to a flow rate which is: about 15L / min or less; or about 10L / min or less; or about 10L / min; or about 5L / min to about 10L / min or less than about 5L / min or OL / min.

[0022] The controller may be in operative communication with or comprises a memory component storing one or more of a function, a curve, a look up table or an algorithm providing a relationship between one or more pressure threshold values and corresponding flow rate values.

[0023] The relationship between the pressure threshold values and the corresponding flow rate values may be represented by a pressure limit curve or a function defining a curve having a sigmoidal shape.

[0024] The relationship between the pressure threshold values and corresponding flow rates may comprise a first pressure region, a second pressure region, and a transition region disposed between the first pressure region and the second pressure region.

[0025] The controller may control the flow modulator according to: values in the first pressure region when the occlusion signal corresponds to an occlusion status of “unoccluded”; and / or values in the second pressure region when the mask placement status is determined as “mask on”.

[0026] The transition region may comprise a gradient of a pressure limit curve corresponding to a maximum rate of change in the flow rate of respiratory gases.

[0027] In some embodiments, the controller may be configured to: receive a pause signal, and in response to the pause signal, control the flow modulator to reduce a flow rate of gas in the respiratory support to substantially 0 LPM.

[0028] Optionally, upon receiving the pause signal, the controller may control the flow modulator to reduce the flow rate of gas to substantially 0 LPM for: a predetermined duration stored in a memory component in operative communication with or forming part of the controller, or a duration requested by a user providing an input to a user interface in operative communication with the controller.

[0029] The pause signal may be triggered by the device, an anaesthesia machine or ventilator receiving a user input requesting to monitor a parameter of gases exiting the patient.

[0030] The parameter of gases exiting the patient may be monitored by the anaesthesia machine or ventilator or a sensor associated with the anaesthesia machine or ventilator.

[0031] The monitored parameter may comprise one or more of 02 concentration, CO2 concentration, anaesthetic gas concentration and one or more ventilation parameters including tidal volume, minute volume, airway pressure, and flow rate.

[0032] The monitored parameter may be monitored by a sensor located in or receiving gases from the mask.

[0033] The values corresponding to the monitored parameter may be presented on a display device. The display device may form part of the anaesthesia machine or ventilator, and / or part of the device, and / or a separate display device which is not part of the device or the anaesthesia machine or ventilator.

[0034] Optionally, the controller, upon receipt of a mask signal that corresponds to “mask off” mask placement status and / or that does not correspond to a “mask on” mask placement status; and an occlusion signal corresponding to an “unoccluded” occlusion status, controls the flow modulator to provide respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold.

[0035] In some embodiments, when the mask placement status is “mask on”, the controller determines the mask placement status as “mask off” upon receipt of an occlusion signal indicative of an “unoccluded” occlusion status, and controls the flow modulator to provide respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold.

[0036] In some embodiments, the device may be integrated with or forms part of an anaesthesia machine or ventilator. In some embodiments, the device may be communicatively couplable and / or physically couplable to an anaesthesia machine or ventilator.

[0037] The device may comprise or may be operable with a humidifier for warming and / or humidifying respiratory gases provided to the patient, such as gases in the respiratory support.

[0038] The humidifier may be in operable communication with the controller.

[0039] The device may be operable to provide respiratory support comprising a flow rate that is: selectable from an available range of about 20 LPM to about 100 LPM; and / or selectable from a plurality of available fixed flow rates including at least 0 LPM, 40 LPM and 70 LPM.

[0040] The device may be operable to provide respiratory support comprising one or both of 02 or air such as filtered air.

[0041] The device may be operable to provide the respiratory support comprising 02 at a concentration in a range of about 21% to 100%.

[0042] The controller may be configured to also control an anaesthesia machine or ventilator.

[0043] The controller may form part of the device, or part of an anaesthesia machine or ventilator, or part of a separate device not part of the device or the anaesthesia machine or ventilator.

[0044] The high flow patient interface may comprise a nasal cannula, such as a non-sealing nasal cannula.

[0045] The high flow patient interface may comprise a collapsible portion which is operable in a first configuration in which the collapsible portion is in a substantially open condition, and in a second configuration in which the collapsible portion is in a substantially closed condition.

[0046] The controller may be operatively configured to determine the occlusion status as “occluded” based on the occlusion signal when the high flow patient interface is operating in the second configuration.

[0047] In some embodiments, an occlusions status as “occluded” and a mask placement status as “mask on” may indicate that the high flow patient interface maybe operating in the second configuration and a face mask is placed over the patient interface.

[0048] In some embodiments, the controller determines that an occlusion status as “occluded” and a mask placement status as “mask off” may indicate that an accidental occlusion may be present in the flow path; and optionally, the controller controls the flow modulator to provide respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold that may be dynamically and temporarily increased by the controller while the “mask off” status remains .

[0049] In some embodiments, an occlusions status as “unoccluded” may indicate that the high flow patient interface is operating in the first configuration.

[0050] Viewed from another aspect, there is disclosed herein, a system for providing respiratory support to a patient, the system comprising first device operable to provide a first respiratory support via a first patient interface comprising a face mask; a second device operable to provide a second respiratory support via a second patient interface comprising a high flow interface; a first sensor providing a first signal indicative of mask placement status of the face mask relative to the patient; a second sensor providing a second signal indicative of occlusion status of a flow path providing the second respiratory support; and a controller configured to receive the first and second signals and control the second device according to the occlusion status and / or mask placement status.

[0051] The first device may comprise an anaesthesia machine or a ventilator. The second device may comprise a high flow device.

[0052] In some embodiments, the second device may comprise changing the flow of the second respiratory support from the second device when a change in mask placement status is determined based on the first signal and the second signal.

[0053] The first sensor may be located at, or samples gases from, the face mask in fluid communication with the first device. In some embodiments, the first sensor may sense gases: in an expiratory flow path between the first device and the face mask; or in an inspiratory flow path between the first device and the face mask; or in a sealing cuff of the face mask.

[0054] The first sensor may comprise one or more of a pressure, flow rate, gas composition (e.g. 02, CO2 or anaesthesia gas), temperature, optical and humidity sensor.

[0055] In some embodiments, the first signal may indicate a “mask on” mask placement status when the first sensor detects at least one of: in an expiratory flow path (e.g. inside and / or between the first device and the face mask): a flow of gas; a change in concentration of one or more of CO2, 02 and an anaesthetic agent, such as an increase in concentration; a gas pressure greater than or less than ambient atmospheric pressure; a change in temperature, such as in increase in temperature; a change in humidity, such as an increase in relative humidity; an increase in pressure and / or temperature in a sealing cuff of the face mask; a change emitted and / or detected light corresponding to the face mask being applied to the patient’s face; in an inspiratory flow path : a flow of gas; a change in flow rate of gas such as an increase in the flow rate; a change in concentration of CO2 and / or an anaesthetic agent, such as an increase in CO2 and / or an anaesthetic agent concentration; and a gas pressure greater than or less than ambient atmospheric pressure.

[0056] In some embodiments, the first signal may indicate a “mask off” mask placement status when the first sensor detects at least one of:in an expiratory flow path (e.g. inside and / or between the first device and the face mask): a change in flow rate of gas such as a decrease in the flow rate; a substantially zero flow rate; a change in CO2 concentration, such as a decrease in CO2 concentration; a change in 02 concentration such as an increase in 02 concentration,; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a decrease in system pressure; a gas pressure at or about ambient atmospheric pressure; a change in temperature, such as a decrease in temperature; a change in humidity, such as an increase in relative humidity; a decrease in pressure and / or temperature in a sealing cuff of the face mask; in an inspiratory flow path: a substantially zero flow rate; a gas pressure at or about ambient atmospheric pressure; a substantially zero C02 concentration; a change in C02 concentration, such as a decrease in C02 concentration; a change of 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a change in temperature, such as a decrease in temperature; a change in humidity, such as an decrease in relative humidity; and a change in emitted and / or detected light corresponding to the face mask being removed from the patient’s face.

[0057] The controller may be configured to receive the first signal substantially continuously or at regular intervals during use of the system.

[0058] Optionally, the second sensor may be provided in the second device. The second sensor may monitor pressure of gases provided via the second respiratory support.

[0059] In some embodiments, the controller, upon receiving the second signal may determine the occlusion status as: occluded when the monitored pressure meets or exceeds a predetermined occlusion pressure threshold; and unoccluded when the monitored pressure falls below the predetermined occlusion pressure threshold.

[0060] The controller may be configured to, upon receiving the second signal indicating an occlusion status which is “occluded”, determine the mask placement status based on the first signal.

[0061] In some embodiments, the controller, upon receipt of: a first signal that does not correspond to a “mask on” mask placement status, and a second signal corresponding to an “occluded” occlusion status, controls an output device to provide an audible and / or visible and / or tactile alert.

[0062] In some embodiments, the controller, upon receipt of: a first signal corresponding to a “mask on” mask placement status, and a second signal corresponding to an “occluded” occlusion status, controls the second device to provide the second respiratory support comprising gases at a target pressure and / or target flow rate.

[0063] The target pressure may comprise a predetermined target pressure threshold value for a corresponding target flow rate, or a predetermined target pressure threshold value corresponding to a flow rate less than the target flow rate.

[0064] In some embodiments, when the controller controls the second device to the target pressure, the second respiratory support may be reduced to a flow rate which is: about 15L / min or less; or about 10L / min or less; or about 10L / min; or about 5L / min to about 10L / min or less than about 5L / min or OL / min.

[0065] The controller may be in operative communication with or may comprise a memory component storing one or more of a function, a curve, a look up table or analgorithm providing a relationship between one or more pressure threshold values and corresponding flow rate values.

[0066] The relationship between the pressure threshold values and the corresponding flow rate values may be represented by a pressure limit curve or a function defining a curve having a sigmoidal shape.

[0067] The relationship between the pressure threshold values and corresponding flow rates may comprise a first pressure region, a second pressure region, and a transition region disposed between the first pressure region and the second pressure region.

[0068] The controller may control the second device according to: values in the first pressure region when the second signal corresponds to an occlusion status of “unoccluded”; and / or values in the second pressure region when the mask placement status is confirmed by the first and second signals as “mask on”.

[0069] The transition region may comprise a gradient of a pressure limit curve corresponding to a maximum rate of change in the flow rate of respiratory gases.

[0070] In some embodiments, the controller may be configured to: receive a pause signal, and in response to the pause signal, control the second device to reduce the flow rate of gas in the second respiratory support to substantially 0 LPM.

[0071] In some embodiments, upon receiving the pause signal, the controller may control the second device to reduce the flow rate of gas to substantially 0 LPM for: a predetermined duration stored in a memory component in operative communication with or forming part of the controller, or a duration requested by a user providing an input to a user interface in operative communication with the controller.

[0072] The pause signal may be triggered by the first device or second device receiving a user input requesting to monitor a parameter of gases exiting the patient.

[0073] The parameter of gases exiting the patient may be monitored by the first device or a sensor associated with the first device.

[0074] The monitored parameter may comprise one or more of 02 concentration, CO2 concentration, anaesthetic gas concentration and one or more ventilation parameters including tidal volume, minute volume, airway pressure, and flow rate.

[0075] The monitored parameter may be monitored by a sensor located in or receiving gases from the face mask.

[0076] Values corresponding to the monitored parameter may be presented on a display device. The display device may form part of the first device, and / or part of the second device, and / or a separate display device which is not part of the first device or the second device.

[0077] In some embodiments, the controller, upon receipt of a first signal that corresponds to “mask off” mask placement status and / or that does not correspond to a “mask on” mask placement status; and a second signal corresponding to an “unoccluded” occlusion status, controls the second device to provide the second respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold.

[0078] In some embodiments, when the mask placement status is “mask on”, the controller determines the mask placement status as “mask off” upon receipt of a second signal indicative of an “unoccluded” occlusion status, and controls the second device to provide the second respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold.

[0079] The second device may be integrated with or forms part of the first device.

[0080] The first device and the second device may be communicatively couplable and / or physically couplable.

[0081] The system may comprise or may be operable with a humidifier for warming and / or humidifying respiratory gases provided to the patient, such as gases in the second respiratory support.

[0082] The humidifier may be in operable communication with the controller.

[0083] The second device may be operable to provide the second respiratory support comprising a flow rate that is: selectable from an available range of about 20 LPM to about 100 LPM; and / or selectable from a plurality of available fixed flow rates including at least 0 LPM, 40 LPM and 70 LPM.

[0084] The second device may be operable to provide the second respiratory support comprising 02 or air such as filtered air, or a mixture of these.

[0085] The second device may be operable to provide the second respiratory support comprising 02 at a concentration in a range of about 21% to 100%.

[0086] The controller may be configured to also control the first device. In some embodiments, the controller may comprise part of the first device, or part of the second device or a separate device not part of the first device or the second device.

[0087] The second patient interface may comprise a nasal cannula, such as a non-sealing nasal cannula.

[0088] The second patient interface may comprise a collapsible portion which is operable in a first configuration in which the collapsible portion is in a substantially open condition, and in a second configuration in which the collapsible portion is in a substantially closed condition.

[0089] The controller may be operatively configured to determine the occlusion status as “occluded” based on the second signal when the patient interface is operating in the second configuration.

[0090] In some embodiments, an occlusions status as “occluded” and a mask placement status as “mask on” may indicate that the patient interface is operating in the second configuration and a face mask is placed over the patient interface.

[0091] In some embodiments, an occlusions status as “occluded” and a mask placement status as “mask off” may indicate that an accidental blockage may be present in the patient interface.

[0092] An occlusions status as “unoccluded” may indicate that the patient interface is operating in the first configuration.

[0093] In some embodiments, the controller may be configured to perform one or more of: upon receiving the second signal and determining the occlusion status as “occluded”, determine the mask placement status based on the mask signal; upon receiving the first signal and determining the mask placement status as “mask on”, determine the occlusion status based on the second signal; receiving the first signal and / or the second signal substantially continuously or at regular intervals during operation of the device; and determining the mask placement status and occlusion status substantially simultaneously

[0094] Viewed from a further aspect, there is disclosed herein a system for providing respiratory support to a patient, the system comprising: a first device comprising an anaesthesia machine or ventilator operable to provide a first respiratory support comprising an anaesthetic gas via a first patient interface comprising a face mask; a second device operable to provide a second respiratory support comprising a high flow of gas via a second patient interface comprising a high flow interface; a controller configured to receive an anaesthesia status input indicative of an anaesthetic gas delivery status of the first device; wherein the second patient interface is configured for the first patient interface to be placed over it when in use; and wherein the controller controls the second device in response to the received anaesthesia status input.

[0095] In some embodiments, controlling the second device in response to the received anaesthesia status input may comprise, when the anaesthesia status input corresponds to an active anaesthetic gas delivery status in which anaesthetic gas isbeing delivered to the patient, controlling the second device to reduce the flow rate of gases comprising the second respiratory support to 0 LPM.

[0096] The anaesthesia status input may be determined from one or more of: an anaesthesia agent flow rate provided by the first device; concentration of anaesthetic gas measured by a sensor in or sampling gas from an inspiratory flow path of the face mask; concentration of anaesthetic gas measured by a sensor in or sampling gas from an expiratory flow path of the face mask; a minimum alveolar concentration (MAC) number indicative of a presence of anaesthetic agent; a vaporizer signal indicating active or inactive status of an anaesthetic vaporizer of the first device.

[0097] In some embodiments, the controller may also be configured to receive a mask placement status input, and controlling the second device comprises, in response to the received anaesthesia status input corresponding to an anaesthetic gas delivery status in which anaesthetic gas is not being delivered to the patient and the received mask status input corresponding to a mask on status, controlling the second device to provide the second respiratory support at a reduced flow rate which is: about 15L / min or less; or about 10L / min or less; or about 10L / min; or about 5L / min to about 10L / min or less than about 5L / min or OL / min.

[0098] Controlling the second device may include controlling pressure in the second respiratory support to achieve the reduced flow rate.

[0099] In some embodiments, the system may comprise: a first sensor providing a first signal indicative of mask placement status of the face mask relative to the patient; a second sensor providing a second signal indicative of occlusion status of a flow path providing the second respiratory support; wherein the controller configured is to receive the first and second signals and control the second device according to the occlusion status and / or mask placement status.

[0100] In some embodiments, controlling the second device according to the received first and second signals may comprise changing the flow of gas via the second respiratory support from the second device when a change in mask placement relative to the patient is determined based on the first signal and / or the second signal.

[0101] The first sensor may be located at, or sample gases from, the face mask in fluid communication with the first device.

[0102] In some embodiments, the first sensor may sense gases: in an expiratory flow path between the first device and the face mask; or in an inspiratory flow path between the first device and the face mask; or in a sealing cuff of the face mask.

[0103] The first sensor may comprise one or more of a pressure, flow rate, gas composition (e.g. 02, CO2 or anaesthesia gas), temperature, optical and humidity sensor.

[0104] The first signal may indicate a “mask on” mask placement status when the first sensor detects at least one of: in an expiratory flow path (e.g. inside and / or between the first device and the face mask): a flow of gas; a change in concentration of one or more of CO2, 02 and an anaesthetic agent, such as an increase in concentration; a gas pressure greater than or less than ambient atmospheric pressure; a change in temperature, such as in increase in temperature; a change in humidity, such as an increase in relative humidity; an increase in pressure and / or temperature in a sealing cuff of the face mask; a change in emitted and / or detected light corresponding to the face mask being applied to the patient’s face; in an inspiratory flow path : a flow of gas; a change in flow rate of gas such as an increase in the flow rate;a change in concentration of CO2 and / or an anaesthetic agent, such as an increase or decrease in CO2 and / or an anaesthetic agent concentration; a gas pressure greater than or less than ambient atmospheric pressure.

[0105] The first signal may indicate a “mask off” mask placement status when the first sensor detects at least one of: in an expiratory flow path (e.g. inside and / or between the first device and the face mask): a change in flow rate of gas such as a decrease in the flow rate; a substantially zero flow rate; a change in CO2 concentration, such as a decrease in CO2 concentration; a change in 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a decrease in system pressure; a gas pressure at or about ambient atmospheric pressure; a change in temperature, such as a decrease in temperature; and / or a change in humidity, such as an increase in relative humidity; a decrease in pressure and / or temperature in a sealing cuff of the face mask; in an inspiratory flow path: a substantially zero flow rate; a gas pressure at or about ambient atmospheric pressure; a substantially zero CO2 concentration; a change in CO2 concentration, such as a decrease in CO2 concentration; a change of 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a change in temperature, such as a decrease in temperature; a change in humidity, such as an decrease in relative humidity; and a change in emitted and / or detected light corresponding to the face mask being removed from the patient’s face.

[0106] The controller may be configured to receive the first signal substantially continuously or at regular intervals during use of the system.

[0107] The second sensor may be provided in the second device. The second sensor may monitor pressure of gases comprising the second respiratory support provided to the patient.

[0108] In some embodiments, the controller, upon receiving the second signal may determine the occlusion status as: occluded when the monitored pressure meets or exceeds a predetermined occlusion pressure threshold; and unoccluded when the monitored pressure falls below the predetermined occlusion pressure threshold.

[0109] The controller may be configured to, upon receiving the second signal indicating an occlusion status which is “occluded”, determines the mask placement status based on the first signal.

[0110] In some embodiments, the controller, upon receipt of: a first signal that does not correspond to a “mask on” mask placement status, and a second signal corresponding to an “occluded” occlusion status, controls an output device to provide an audible and / or visible and / or tactile alert.

[0111] In some embodiments, the controller, upon receipt of: a first signal corresponding to a “mask on” mask placement status, and a second signal corresponding to an “occluded” occlusion status, controls the second device to provide the second respiratory support comprising gases at a target pressure and / or target flow rate.

[0112] Viewed from another aspect, there is also disclosed herein a system for providing respiratory support to a patient, comprising: a pressure valve; a venting sensor providing an indication of gas venting from the pressure valve; and a controller configured to receive a venting signal from the venting sensor; wherein the controlleris configured to cause activation of an alert upon receipt of the venting signal indicating venting from the pressure valve.

[0113] In some embodiments, the system may be configured to provide high flow respiratory support, or it may comprise part of a device providing high flow respiratory support. In some embodiments, the device may be couplable with or integrated into an anaesthesia machine or ventilator.

[0114] In some embodiments, the pressure valve is a pressure relief valve, such as a flow compensated pressure relief valve. The pressure valve may comprise one or more of: a mechanical valve component; and an electronic valve component.

[0115] In some embodiments, the controller may be configured to cause the alert to be presented on a user interface device. The user interface may comprise part of: an anaesthesia machine; and / or a ventilator; and / or a device providing high flow respiratory support.

[0116] The alert may comprise one or more of an audible, a visible and a tactile alert. The alert may comprise one or more of: a qualitative alert; and a quantitative alert.

[0117] In some embodiments, the venting sensor may comprise one or more of a flow sensor, a pressure sensor and a gas concentration sensor.

[0118] In some embodiments, the pressure valve may comprise a valve outlet through which gases are vented and a main outlet through which gases are provided for respiratory support to a patient. The venting sensor may be located at or downstream of the valve outlet. Alternatively, the venting sensor may be located at or downstream of the main outlet.

[0119] In some embodiments, the pressure valve may be integrated with or form part of an anaesthesia machine or a ventilator.

[0120] In some embodiments, the venting sensor may be integrated with or form part of an anaesthesia machine or ventilator.

[0121] The anaesthesia machine or ventilator may provide a vent path such as an exhaust port to atmosphere for gases vented from the pressure valve.

[0122] In some embodiments, the venting sensor may be external to an anaesthesia machine or ventilator.

[0123] In some embodiments, the controller may be configured to control a flow source providing a flow of respiratory gases comprising the respiratory support to the patient. In some embodiments, the flow source may be integrated with or form part of an anaesthesia machine or ventilator.

[0124] In some embodiments, the system may comprise or be operable with a humidifier for warming and / or humidifying respiratory gases provided to the patient. In some embodiments, the humidifier may be in operable communication with the controller.

[0015] In some embodiments, the system may comprise or be operable with a patient interface configured to provide a flow of respiratory gases comprising the respiratory support to the patient.

[0126] In some embodiments, the controller may, upon receipt of a venting signal providing an indication of gas venting from the pressure valve, be configured to cause activation of an alert which is indicative of an occlusion in a flow path configured to provide respiratory gases to a patient.

[0017] In some embodiments, the controller may be configured to cause activation of an I / O device to display the alert. In some embodiments, the alert may comprise a quantitative alert selected from the group comprising (but not limited to): venting flow rate based on the venting signal; actual flow rate delivered to the patient; and pre-set flow rate of the respiratory support.

[0128] In some embodiments, the system comprises a humidifier, and the controller is a humidifier controller. In some embodiments, the humidifier may comprise a sensor configured to measure the incoming flow rate of gases entering the humidifier, wherein the humidifier controller is configured to determine a pre-set flow rate of gases intended for respiratory support to the patient by summing the incoming flow rate with a venting flow rate determined from the venting signal. In some embodiments, the humidifier may comprise a humidifier I / O device and the alert and / or the pre-set flow rate may be displayed on the humidifier controller.

[0129] Viewed from another aspect, the present disclosure provides a device for providing respiratory support to a patient, the device comprising: a flow modulator operable to provide a high flow of gas via a high flow patient interface; and a controller controlling the flow modulator, the controller being operatively configured to: receive an occlusion signal and a command signal; determine an occlusion status of a flow path of the high flow of gas to the patient based on the occlusion signal; and control the flow modulator according to one or both of the occlusion status and the command signal; wherein the controller receives the command signal from a machine that is operatively coupled with the device.

[0130] Viewed from another aspect, the present disclosure provides a system for providing respiratory support to a patient, the system comprising: a first component operable to provide a first respiratory support via a first patient interface comprising a face mask; a second component comprising a device having a flow modulator and operable to provide a second respiratory support via a second patient interface comprising a high flow interface; a first sensor providing a mask signal indicative of mask placement status of the face mask relative to the patient; a second sensor providing an occlusion signal indicative of occlusion status of a flow path providing the second respiratory support; and a controller configured to receive the first and second signals and control the second component according to one or both of the occlusion status and / or mask placement status.

[0131] In some embodiments of the system, the controller may be configured to receive a command signal, and to control the second component according to the command signal, wherein the command signal is received from the first component or another component that is not the second component. In some embodiments of the system the controller may comprise part of the second component.

[0132] In some embodiments of the device or system the command signal comprises one or more of a pause signal, an anaesthesia status input and a mask placement status input.

[0133] In some embodiments of the device or system, upon receiving the pause signal, the controller controls the flow modulator to reduce the flow rate of gas to substantially 0 LPM for: a predetermined duration stored in a memory component inoperative communication with or forming part of the controller or the machine or the first component, or a duration requested by a user providing an input to a user interface in operative communication with the controller.

[0134] In some embodiments of the device or system, the user interface comprises part of the machine / first component, or a separate device.

[0135] In some embodiments of the device or system, the pause signal may be triggered by the machine / first component receiving a user input and optionally, wherein the user input comprises a request to monitor a parameter of gases exiting the patient. In some embodiments, the parameter of gases exiting the patient is monitored by the machine or the first component or a sensor associated with the machine or the first component. In some embodiments, the monitored parameter comprises one or more of 02 concentration, CO2 concentration, anaesthetic gas concentration and one or more ventilation parameters including tidal volume, minute volume, airway pressure, and flow rate. In some embodiments, the monitored parameter may be monitored by a sensor located in or receiving gases from mask in fluid communication with the machine or first component. Values corresponding to the monitored parameter may be presented on a display device. The display device may be part of the device or the second component, and / or a separate display device which is not part of the device or the machine, or the first component or the second component.

[0136] In some embodiments of the device or system, a mask placement status input may be based on a mask signal received from the machine or the first component, or a first sensor associated with the machine or the first component. In some embodiments, the first sensor is located at, or samples gases from, a face mask in fluid communication with the machine or the first component. The first sensor may sense gases in one or more of: an expiratory flow path of a face mask in fluid communication with the machine or first component; an inspiratory flow path of a face mask in fluid communication with the machine or first component; a sealing cuff of a face mask in fluid communication with the machine or first component. The first sensor may comprise one or more of e.g. a pressure, flow rate, gas composition (e.g. 02, CO2 or anaesthesia gas), temperature and humidity sensor.

[0137] In some embodiments of the device or system, the mask signal indicates a “mask on” mask placement status when the first sensor detects at least one of: in an expiratory flow path: a flow of gas; a change in concentration of one or more of CO2, 02 and an anaesthetic agent, such as an increase in concentration; a gas pressure greater than or less than ambient atmospheric pressure; a change in temperature, such as in increase in temperature; a change in humidity, such as an increase in relative humidity; an increase in pressure and / or temperature in the sealing cuff of the face mask; a change in emitted and / or detected light corresponding to the face mask being applied to the patient’s face; in an inspiratory flow path: a flow of gas; a change in flow rate of gas such as an increase in the flow rate; a change in concentration of CO2 and / or an anaesthetic agent, such as an increase in CO2 and / or anaesthetic agent concentration; and a gas pressure greater than or less than ambient atmospheric pressure.

[0138] In some embodiments of the device or system, the mask signal indicates a “mask off” mask placement status when the first sensor detects at least one of: in an expiratory flow path: a change in flow rate of gas such as a decrease in the flow rate; a substantially zero flow rate; a change in CO2 concentration, such as a decrease in CO2 concentration; a change on in 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a decrease in system pressure; a gas pressure at or about ambient atmospheric pressure; a change in temperature, such as a decrease in temperature; a change in humidity, such as an increase in relative humidity; a decrease in pressure and / or temperature in the sealing cuff of the face mask; in an inspiratory flow path: a substantially zero flow rate; a gas pressure at or about ambient atmospheric pressure; a substantially zero CO2 concentration; a change in CO2 concentration, such as a decrease in CO2 concentration; a change of 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a change in temperature, such as a decrease in temperature; a change in humidity, such as an decrease in relative humidity; and a change in emitted and / or detected light corresponding to the face mask being removed from the patient’s face.

[0139] In some embodiments of the device or system, the occlusion signal is received from an occlusion sensor. Optionally, the occlusion sensor may be providedin the device. In some embodiments, the occlusion sensor may comprise a pressure sensor for monitoring pressure of gasses provided by the respiratory support. In some embodiments, detection by the pressure sensor of: an increase in pressure to meet or exceed a predetermined occlusion pressure threshold causes the controller to determine the occlusion status as occluded; and a decrease in pressure to fall below the predetermined occlusion pressure threshold causes the controller to determine the occlusion status as unoccluded.

[0140] In some embodiments of the device or system, the controller may be configured to receive one or more of the pause signal, an anaesthesia status input and a mask placement status input substantially continuously or at regular intervals during operation of the device or system.

[0141] In some embodiments of the device or system, the controller may be configured to perform one or more of: upon receiving the occlusion signal and determining the occlusion status as “occluded”, determine the mask placement status based on the mask signal; upon receiving the mask signal and determining the mask placement status input as “mask on”, determine the occlusion status based on the occlusion signal; receiving the occlusion signal and / or the mask signal substantially simultaneously; and determine the mask placement status and occlusion status substantially simultaneously.

[0142] In some embodiments of the device or system, the controller, upon receiving mask placement status input corresponding to “mask on” and / or occlusion status corresponding to “occluded” and / or a control signal: controls an I / O device to provide an audible and / or visible and / or tactile alert; and / or controls the flow modulator to provide the flow of gases at a target pressure and / or target flow rate. In some embodiments, the target pressure comprises a predetermined target pressure threshold value for a corresponding target flow rate, or a predetermined target pressure threshold value corresponding to a flow rate less than the target flow rate.

[0143] In some embodiments of the device or system, when the controller drives the flow modulator at the target pressure, the flow of gases is reduced to a flow rate which is: about 15L / min or less; or about 10L / min or less; or about 10L / min; or about 5L / min to about 10L / min or less than about 5L / min or OL / min.

[0144] In some embodiments of the device or system, the controller is in operative communication with or comprises a memory component storing one or more of a function, a curve, a look up table or an algorithm providing a relationship between one or more pressure threshold values and corresponding flow rate values. In some embodiments, the relationship between the pressure threshold values and the corresponding flow rate values is represented by a pressure limit curve or a function defining a curve having a sigmoidal shape. In some embodiments, the relationship between the pressure threshold values and corresponding flow rates comprises a first pressure region, a second pressure region, and a transition region disposed between the first pressure region and the second pressure region. The transition region may comprise a gradient of a pressure limit curve corresponding to a maximum rate of change in the flow rate of respiratory gases. In some embodiments, the controller controls the flow modulator according to: values in the first pressure region when the occlusion signal corresponds to an occlusion status of “unoccluded”; and / or values in the second pressure region when the mask placement status is determined as “mask on”.

[0145] In some embodiments of the device or system, the controller controls the flow modulator to change the flow rate and / or pressure of the flow of gas upon receipt of a mask placement status input corresponding to a change in mask placement relative to the patient.

[0146] In some embodiments of the device or system, the device is physically couplable with the machine / first component.

[0147] In some embodiments of the device or system, the device is operable to provide the respiratory support comprising a flow rate that is selectable from an available range of about 20 LPM to about 100 LPM; and / or selectable from a plurality of available fixed flow rates including at least 0 LPM, 40 LPM and 70 LPM.

[0148] In some embodiments of the device or system, the machine or first component comprises an anaesthetic machine or a ventilator.

[0149] Viewed from another aspect, the present disclosure provides an anaesthesia machine comprising: a high flow module operable to provide a high flow of gas to a patient via a high flow patient interface, a flow compensated pressurerelief valve configured to provide gas venting of at least a portion of the high flow of gas delivered from the high flow module.

[0150] In some embodiments, the high flow module may be couplable with or integrated into the anaesthesia machine.

[0151] In some embodiments, the pressure relief valve comprises one or more of: a mechanical valve component; and an electronic valve component.

[0152] In some embodiments, the anaesthesia machine comprises a venting sensor providing an indication of gas venting from the pressure relief valve.

[0153] In some embodiments, the anaesthesia machine or the high flow module comprises a controller configured to receive a venting signal from the venting sensor, and cause activation of an alert upon receipt of the venting signal indicating venting from the pressure valve. The controller may be configured to cause the alert to be presented on a user interface device.

[0154] In some embodiments, the user interface comprises part of the anaesthesia machine; and / or the high flow module; and / or a ventilator; and / or a humidifier in operative communication with the high flow module. The alert may comprise one or more of an audible, a visible and a tactile alert. The alert may comprise one or more of: a quantitative alert; and a qualitative alert such as an alarm. In some embodiments, the quantitative alert is selected from the group comprising: venting flow rate based on the venting signal; actual flow rate delivered to the patient; and pre-set flow rate of the respiratory support.

[0155] In some embodiments, the venting sensor may comprise one or more of a flow sensor, a pressure sensor and a gas concentration sensor.

[0156] In some embodiments, the pressure relief valve may comprise a valve outlet through which gases are vented and a main outlet through which gases from the high flow module are provided for respiratory support to a patient, and wherein the venting sensor is located at or downstream of the valve outlet.

[0157] In some embodiments, the pressure relief valve comprises a valve outlet through which gases are vented and a main outlet through which gases are providedfor respiratory support to a patient, wherein the venting sensor is located at or downstream of the main outlet.

[0158] In some embodiments, the anaesthesia machine provides a vent path to atmosphere for gases vented from the pressure relief valve.

[0159] In some embodiments, the anaesthesia machine comprises or is operable with a humidifier for warming and / or humidifying respiratory gases provided to the patient.

[0160] In some embodiments, the high flow patient interface may comprise a nonsealing interface.

[0161] In various aspects and embodiments of the disclosure, a controller may dynamically alter the pressure threshold normally limiting the amount of pressure that may be provided in the high flow of gas provided to the patient by the high flow patient interface. For instance, if the controller determines there an “occluded” status with “mask off”, the controller may be determine there to be an accidental occlusion. In that case, the controller may increase the pressure threshold normally limiting the amount of pressure that can be provided to the high flow patient interface. In some examples, any dynamic increase may be limited by a safety limit that cannot be exceeded during use of the device or system. When the controller determines there to be an “unoccluded” or “mask on” or not “mask off” status, it may automatically return the pressure threshold to the normal limit. It will be appreciated that dynamic variation of the pressure threshold may be implemented by a controller independently of other actions that may otherwise occur to alter the gas flow to the high flow patient interface.

[0162] It is to be understood that in the various aspects and embodiments described herein, reference to a sensor, or a sensor signal, such as a first sensor or a first sensor signal, or a second sensor or a second sensor signal, is to be taken to include the possibility of more than one such sensor or signal. Thus, in the case of a first sensor, there may be more than one first sensor providing more than one first sensor signal used in the determination of a mask placement status. Similarly, there may be more than one second sensor providing more than one second sensor signal that may be used in the determination of an occlusion status.

[0163] It is to be understood each of the various aspects described herein may incorporate one or more features, modifications and alternatives described in the context of one or more other aspects and may include one or more features, modifications and alternatives of any of the embodiments described below, as appropriate. For efficiency, such features, modifications and alternatives have not been repetitiously disclosed for each and every aspect although one of skill in the art will appreciate that such combinations of features, modifications and alternatives disclosed for some aspects and embodiments apply similarly for other aspects and are within the scope of and form part of the subject matter of this disclosure.

[0164] To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

[0165] The disclosure consists in the foregoing and also envisages constructions of which the following gives examples only. Features disclosed herein may be combined into new embodiments of compatible components addressing the same or related inventive concepts.

[0166] In order that the invention may be more readily understood and put into practice, one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings.

[0167] It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.BRIEF DESCRIPTION OF THE DRAWINGS

[0168] Preferred embodiments of the disclosure will be described by way of example only and with reference to the following drawings.

[0169] 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:

[0170] Figure 1 A illustrates a high flow respiratory system.

[0171] Figure 1 B is a schematic representation of a pressure valve. (The embodiment in Figure 1 B illustrates a pressure relief valve (PRV) or more specifically a flow-controlled pressure relief valve (FCPRV)).

[0172] Figure 1 C is a perspective view of a FCPRV and adapter assembly according to one embodiment.

[0173] Figure 2 is a cross-sectional view of the FCPRV and adapter assembly shown in figure 1 C.

[0174] Figure 3 is a perspective view of the adapter in the assembly shown in Figure 2.

[0175] Figure 4 is a cross-sectional view of a FCPRV and adapter assembly according to another embodiment.

[0176] Figure 5 is a perspective view of the adapter in the assembly shown in Figure 4.

[0177] Figure 6A is a perspective cross-sectional view of a FCPRV and adapter assembly according to another embodiment.

[0178] Figure 6B is a cross-sectional view of a FCPRV and adapter assembly shown in Figure 6A.

[0179] Figure 7 is a perspective view of the adapter in the assembly of Figures 6A and 6B.

[0180] Figure 8 illustrates a tuning routine for a flow-compensated pressure relief valve (FCPRV).

[0181] Figure 9A is a perspective view of an adapter according to a further embodiment.

[0182] Figure 9B is a side view of the adapter of Figure 9A.

[0183] Figure 9C is a section view of the adapter of Figures 9A and 9B, taken through a centreline of the adapter.

[0184] Figure 10 illustrates respiratory system pressure and FCPRV relief pressure response curves with respect to changing input flow rate, wherein the flow rate is the flow rate of gases provided to a patient or from a main outlet of the FCPRV.

[0185] Figures 11 A and 11 B are schematic representations of an electromechanical FCPRV. Figure 11 A illustrates the FCPRV in a lower flow configuration and Figure 11 B higher flow configuration.

[0186] Figures 12A and 12B are schematic representations of another electromechanical FCPRV. Figure 12A illustrates the FCPRV in a lower flow configuration and Figure 12B higher flow configuration.

[0187] Figures 13A and 13B are schematic representations of another electromechanical FCPRV.

[0188] Figures 14 to 18 illustrate venting flow indicators that may be implemented in one or more of the PRV or FCPRV embodiments described. Figures 14 to 16 are cross sectional views of a portion of a FCPRV. Figures 17 and 18 are cross sectional views of a body of a FCPRV including a venting flow indicator.

[0189] Figure 19A illustrates an impeller flow indicator and Figure 19B illustrates a FCPRV comprising an impeller in an outlet to indicate flow from the outlet of the FCPRV.

[0190] Figure 20A illustrates a flap flow indicator. Figure 20B shows a FCPRV comprising a flap flow indicator not visible in a no-flow condition. Figure 20C illustrates the FCPRV of Figure 20B with a flow of gases from an outlet of the FCPRV indicated by the flap moved to a flow condition.

[0191] Figure 21 illustrates a FCPRV comprising a flow indicator comprising a guide tube and shuttle or plunger.

[0192] Figures 22A and 22B show a patient wearing a second patient interface (Figure 22A) and a first patient interface with a second patient interface (Figure 22B) for use with a respiratory system for providing respiratory gases to a patient according to an embodiment of the present disclosure;

[0193] Figures 23A and 23B provide schematic illustrations of the first and second configurations of a collapsible portion of the patient interface; Figure 23A shows the first configuration and Figure 23B shows the second configuration;

[0194] Figures 23C and 23D illustrates another configuration, in which a mask and nasal cannula can be used together;

[0195] Figures 24A to 24C are schematic diagrams of respiratory support systems for providing respiratory gases to a patient according to different embodiments;

[0196] Figure 24D is a graph illustrating a curve that represents a relationship between flow and pressure, used in controlling a flow of respiratory gases according to an embodiment;

[0197] Figure 24E is a graph illustrating a curve that represents a relationship between flow and pressure, used in controlling a flow of respiratory gases according to an embodiment;

[0198] Figure 24F is a graph illustrating another curve that represents a relationship between flow and pressure, used in controlling a flow of respiratory gases according to an embodiment;

[0199] Figure 24G is a graph illustrating that at zero flow the pressure curve can have a nominal pressure limit (curve R) or a zero pressure limit (curve S).

[0200] Figure 24H is a graph illustrating a curve that represents a relationship between flow and pressure offset, used in controlling a flow of respiratory gases according to an embodiment;

[0201] Figure 24I is a state diagram of the states of operation of a respiratory system according to an embodiment;

[0202] Figure 24J is a flow chart of operation of a respiratory system according to an embodiment;

[0203] Figures 25A and 25B are schematic illustrations of a system providing respiratory support to a patient and configured to sense gas venting from a pressure valve. In Figure 25A a sensor is provided downstream of the pressure valve (venting) outlet. In Figure 25B the sensor is provided downstream of the pressure valve main outlet.

[0204] Figure 26 is a schematic illustration showing a pressure valve operatively coupled with and external to an anaesthesia machine.

[0205] Figure 27 is a schematic illustration showing a pressure valve operatively coupled and integral with, or forming part of, an anaesthesia machine.

[0206] Figure 28 is a schematic illustration showing components of a device for providing respiratory gases which may be suitable for provision of high flow respiratory support.

[0207] Figure 29 is a schematic illustration of an anaesthesia machine and a high flow device interoperating via a coupling mechanism such as a dock.

[0208] Figure 30 is a schematic illustration of a system for providing respiratory support to a patient having a high flow module and humidifier integrated into a single device where information is communicated with the anaesthesia machine via the humidifier controller.

[0209] Figure 31 a schematic illustration of a system for providing respiratory support to a patient having a high flow module and humidifier integrated into a single device where information is communicated with the anaesthesia machine via the high flow module controller.

[0210] Figure 32 is a schematic illustration of a display view presented on an interface device of an anaesthesia machine.

[0211] Figure 33 is a schematic illustration of an enlarged display zone relating to high flow respiratory support parameters.

[0212] Figure 34 is a schematic illustration of a high flow module and an anaesthesia machine with which it may dock. Figure 35 shows the high flow module just prior to insertion into the docking bay of the anaesthesia machine. Figure 36 shows the high flow module docked in the docking bay of the anaesthesia machine.

[0213] Figures 37 and 38 are front and rear perspective views respectively, showing the high flow module of Figures 34 to 36 in more detail.

[0214] Figure 39 shows an example of a high flow module configured to be installed with or in an anaesthesia machine via an installation bay.

[0215] Figure 40 is a schematic side view of part of the high flow module of Figure 39.

[0216] Figure 41 shows an example of a high flow module incorporating or having an integrated humidifier and configured to dock with or in an anaesthesia machine.

[0217] Figure 42 is a schematic illustration of a system for providing respiratory support to a patient having a flow controller instead of a high flow module.

[0218] Figure 43 is a schematic illustration of a system for providing respiratory support to a patient, where the anaesthesia machine provides the high flow device.

[0219] Figure 44 is a schematic diagram of an anaesthesia machine.

[0220] Figure 45 is a reproduction of the curve in Figure 24E including annotations to indicate points of transition between flow rate guided control and pressure guided control of during high flow respiratory support. Figure 46 is an enlarged view of region A in Figure 45.

[0221] Figures 47 to 52 are process flow diagrams illustrating computerised methods executed by a controller to control operations of a high flow device based on occlusion and mask placement detection according to different embodiments.DETAILED DESCRIPTION

[0222] Various embodiments are described with reference to the figures. Throughout the figures and specification, similar reference numerals may be used to designate the same or similar components, and redundant descriptions thereof may be omitted.

[0223] In this specification, “high flow”, “high flows”, “high-flow” or other equivalent terminology means, without limitation, any gas flow with a flow rate that is higher than usual / normal, such as higher than the normal inspiration flow rate of a healthy patient. Alternatively, or additionally, it can be higher than some other threshold flow rate that is relevant to the context - for example, where providing a gas flow to a patient at a flow rate to meet or exceed inspiratory demand, that flow rate might be deemed “high flow” as it is higher than a nominal flow rate that might have otherwise been provided. “High flow” is therefore context dependent, and what constitutes “high flow” depends on many factors such as the health state of the patient, type of procedure / therapy / support being provided, the nature of the patient (big, small, adult, child) and the like. Those skilled in the art know from context what constitutes “high flow”. It is a magnitude of flow rate that is over and above a flow rate that might otherwise be provided.

[0224] But, without limitation, some indicative values of high flow can be as follows.

[0225] In some configurations, delivery of gases to a patient at a flow rate of greater than or equal to about 5 or 10 litres per minute (5 or 10 LPM or L / min).

[0226] In some configurations, delivery of gases to a patient at a flow rate of about 5 or 10 LPM to about 150 LPM, or about 15 LPM to about 95 LPM, or about 20 LPM to about 90 LPM, or about 25 LPM to about 85 LPM, or about 30 LPM to about 80 LPM, or about 35 LPM to about 75 LPM, or about 40 LPM to about 70 LPM, or about 45 LPM to about 65 LPM, or about 50 LPM to about 60 LPM. For example, according to those various embodiments and configurations described herein, a flow rate of gases supplied or provided to an interface via a system or from a flow source or flow modulator, may comprise, but is not limited to, flows of at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 1 10, 120, 130, 140, 150 LPM, or more, and useful ranges may be selected to be any of these values (for example, about 20 LPM to about 90 LPM,about 40 LPM to about 70 LPM, about 40 LPM to about 80 LPM, about 50 LPM to about 80 LPM, about 60 LPM to about 80 LPM, about 70 LPM to about 100 LPM, about 70 LPM to about 80 LPM).

[0227] In “high flow” the gas delivered will be chosen depending on for example the intended use of a therapy and / or respiratory support. Gases delivered may comprise a percentage of oxygen. In some configurations, the percentage of oxygen in the gases delivered may be about 15% to about 100%, about 20% to about 100%, or about 30% to about 100%, or about 40% to about 100%, or about 50% to about 100%, or about 60% to about 100%, or about 70% to about 100%, or about 80% to about 100%, or about 90% to about 100%, or about 100%, or 100%.

[0228] In some embodiments, gases delivered may comprise a percentage of carbon dioxide. In some configurations, the percentage of carbon dioxide in the gases delivered may be more than 0%, about 0.3% to about 100%, about 1% to about 100%, about 5% to about 100%, about 10% to about 100%, about 20% to about 100%, or about 30% to about 100%, or about 40% to about 100%, or about 50% to about 100%, or about 60% to about 100%, or about 70% to about 100%, or about 80% to about 100%, or about 90% to about 100%, or about 100%, or 100%.

[0229] Flow rates for “high flow” for premature / infants / paediatrics (with body mass in the range of about 1 to about 30 kg) can be different. The flow rate can be set to 0.4- 8 LPM / kg with a minimum of about 0.5 LPM and a maximum of about 70 LPM. For patients under 2 kg maximum flow may be set to 8 LPM.

[0230] High flow has been found effective in meeting or exceeding the patient’s normal real inspiratory flow, to increase oxygenation of the patient and / or reduce the work of breathing. Additionally, high flow therapy and / or respiratory support may generate a flushing effect in the nasopharynx such that the anatomical dead space of the upper airways is flushed by the high incoming gas flows. This creates a reservoir of fresh gas available of each and every breath, while minimising re-breathing of carbon dioxide, nitrogen, etc.

[0231] For example, a high flow respiratory system 10 is described below with reference to Figure 1 A. High flow may be used as a means to promote gas exchange and / or respiratory support through the delivery of oxygen and / or other gases, andthrough the removal of CO2 from the patient’s airways. As mentioned, high flow may be particularly useful prior to, during or after a medical and / or anaesthetic procedure such as a sedation or general anaesthesia procedure.

[0232] When used prior to a medical procedure, high gas flow can pre-load the patient with oxygen (i.e. increase the reservoir of oxygen in the blood) so that their blood oxygen saturation level and volume of oxygen in the lungs is higher than normal in order to provide an oxygen buffer while the patient is in an apnoeic phase during the medical procedure.

[0233] A continuous supply of oxygen is important to sustain healthy respiratory function during medical procedures (such as during anaesthesia) where respiratory function might be compromised (e.g. diminishes or stops). When this supply is compromised, conditions such as hypoxia and / or hypercapnia can occur. During medical procedures such as an anaesthetic procedure, patient breathing is monitored to detect if spontaneous breathing is diminished or ceases. If oxygen supply and / or CO2 removal is compromised, the clinician stops the medical procedure and facilitates oxygen supply and / or CO2 removal. This can be achieved for example by manually ventilating the patient for example through bag mask ventilation, or by providing a high flow of gases to the patient's airway using a high flow respiratory system. Further, it will be appreciated that a mask that is used for sedation / ventilation (not necessarily limited to a bag mask) may also be used for pre-oxygenation and also for monitoring patient parameters such as end tidal CO2, etc.

[0234] Further advantages of high gas flow can include that the high gas flow increases pressure in the airways of the patient, thereby providing pressure support that opens airways, the trachea, lungs / alveolar and bronchioles. The opening of these structures enhances oxygenation, and to some extent assists in removal of CO2 and / or can help support patients with collapsed areas of the lung.

[0235] When humidified, the high gas flow can also prevent airways from drying out, mitigating mucociliary damage, reducing risk of infection and reducing risk of laryngospasms and risks associated with airway drying such as nose bleeding, aspiration (as a result of nose bleeding), and airway obstruction, swelling and bleeding. Another advantage of high gas flow is that the flow can clear smoke created duringsurgery in the air passages. For example, smoke can be created by lasers and / or cauterizing devices.

[0236] The embodiments described herein may be particularly adapted for use in respiratory systems such as continuous positive airway pressure (CPAP) or high flow respiratory gas systems, for example a high flow respiratory support system for use in anaesthesia procedures. Respiratory systems in which the embodiments may be particularly useful are CPAP, Bilevel Positive Airway Pressure (BiPAP), high flow respiratory support, varying high flow respiratory support, low flow air, low flow O2 delivery, bubble CPAP, apnoeic high flow respiratory support (i.e. high flow to anaesthetized patients), invasive ventilation and non-invasive ventilation. Further, the embodiments described herein may be useful in systems other than respiratory systems. Some of the embodiments described herein are configured for use with a pressure relief or pressure regulating device.

[0237] Unless the context suggests otherwise, a flow source provides a flow of gases at a set flow rate. A set flow rate may be a constant flow rate, variable flow rate or may be an oscillating flow rate, for example a sinusoidal flow rate or a flow rate with a step or square wave profile. Unless the context suggests otherwise a pressure source provides a flow of gases at a set pressure. The set pressure may be a constant pressure, variable pressure or may be an oscillating pressure, for example a sinusoidal pressure or a pressure with a step or square wave profile.

[0238] With reference to Figure 1 A, the respiratory system 10 may comprise an integrated or separate component-based arrangement, generally shown in the dotted box 1 1 in Figure 1 A. In some configurations the system 10 could comprise a modular arrangement of components. The respiratory system 10 will be referred to herein as system, but this should not be considered limiting. The system 10 may include a flow source 12, such as an in-wall source of oxygen, an oxygen tank, a blower, a flow therapy apparatus, or any other source of oxygen or other gas.

[0239] In some embodiments, the flow source 12 comprises a flow modulator and in some embodiments, the flow modulator comprises a flow generator such as a blower, bellows, and / or pistons. In some embodiments, the flow modulator comprises a flow generator and a proportional valve which may function to control oxygen concentrationin a flow of blended gas such as air (preferably filtered air) and oxygen which is delivered to the patient. In some embodiments, the flow modulator comprises a proportional valve, and in such embodiments, the flow modulator may not comprise a flow generator. In other embodiments, the flow source 12 need not comprise a flow generator and in such embodiments, the flow source 12 may comprise an in-wall gas source and / or a blended gas or other gas supply. In some embodiments, the flow source 12 may comprise a compressed gas source (e.g. an in-wall gas source, an oxygen tank supply, etc.) and a blower.

[0240] In some embodiments, the flow source 12 comprises or is part of an anaesthesia machine. The system 10 may also comprise an additive gas source 12a, comprising one or more other gases that can be combined with the flow source 12. The flow source 12 can provide a pressurised high gas flow 13 that can be delivered to a patient 16 via a delivery conduit 14, and patient interface 15 (such as a nasal cannula). The flow of gas 13 may deliver a high flow to the patient, in the context described in the foregoing. A controller 19 controls the flow source 12 and additive gas source 12a through valves or the like to control flow rate and other characteristics such as any one or more of pressure, composition, concentration, volume of the high flow gas 13. A humidifier 17 is also optionally provided, which can humidify the gas under control of the controller and control the temperature of the gas. One or more sensors 18a, 18b, 18c, 18d, such as flow rate, oxygen, pressure, humidity, temperature or other sensors can be placed throughout the system and / or at, on or near the patient 16. The sensors can include a pulse oximeter 18d on the patient for determining the oxygen concentration in the blood.

[0241] The controller 19 may be operatively coupled with one or more components of system 10 by various means including wired or wireless coupling. For example, the controller 19 may be operatively coupled with one or more of the flow source 12, the additive gas source 12a, humidifier 17, sensors 18a-18d, and input / output (I / O) interface 20. By way of example, the controller 19 may be provided on or in a high flow apparatus, a separate component and / or incorporated into or utilised with another device such as an anaesthesia machine or a ventilator, or it may comprise part of system 10 and communicate with one or more separate controllers controlling operation of separate components used with system 10 for the provision of respiratory support to the patient. The controller may comprise a microcontroller, a PID (proportional-integral-derivative) controller or a variation of a PID controller where the proportional, integral and derivative elements of the controller can be turned on or off as needed (such as P, PI or I controllers), or some other architecture, configured to operate by an algorithm that is stored in a memory in communication with the controller to direct the operation of controllable components of the respiratory system. The controller 19 may thus control the flow source 12 and other components of or used with system 10 to provide the delivered flow of gas to the patient with certain characteristics such as a desired flow rate, pressure, composition (where more than one gas is being provided), volume and / or other parameters based on feedback from one or more sensors 18a-18d.

[0242] The controller 19 can also control any other suitable parameters of the flow source to meet oxygenation, airway pressure and / or flow rate requirements of the patient and / or system pressure and / or flow rate requirements of the system (for example pre-determined or set by a user through interface 20). The controller 19 can also control the humidifier 17 and this control may be based on feedback from one or more of the sensors 18a-18d. Using input from the sensors, the controller may determine operational changes required to meet oxygenation requirements and alter control parameters of the flow source 12 and / or humidifier 17 and / or other additive gas source 12A and / or other components of the system as required.

[0243] An input / output (I / O) interface 20 (such as a display and / or input device) may be provided. The interface 20 enables information and inputs (such as the required patient respiratory support parameters) to be received from a user (e.g. clinician or patient) that can be used for determining oxygenation, pressure, flow requirements and / or other system settings used in the control of one or more of the flow source 12, additive gas source 12A and other components of the system 10, to achieve a flow of gas 13 with the characteristics necessary to provide the required respiratory support.

[0244] The pressure may also be controlled. As noted above, the high gas flow (optionally humidified) can be delivered to the patient 16 via a delivery conduit 14 and the patient interface 15 or ‘interface’, such as a cannula, nasal mask, nasal interface, oral device or combination thereof. In some embodiments, the high gas flow (optionally humidified) can be delivered to the patient 16 for surgical uses, e.g. surgical insufflation. In these embodiments, the ‘interface’ could be a surgical cannula, trocar, or other suitable interface. The patient interface may seal, substantially seal, partially seal, benon-sealing, substantially non-sealing, or partially non-sealing with a patient's airways. A nasal interface as used herein is a device such as a cannula, a nasal mask, nasal pillows, or other type of nasal device or combinations thereof configured to direct a flow of gas into one or both nares of the patient. A nasal interface can also be used in combination with a mask or oral device (such as a tube inserted into the mouth) and / or a mask or oral device (such as a tube inserted into the mouth) that can be detached and / or attached to the nasal interface. A nasal cannula is a nasal interface that includes one or more prongs that are configured to be inserted into a patient’s nasal passages. A mask refers to an interface that covers a patient’s nasal passages and / or mouth and can also include devices in which portions of the mask that cover the patient’s mouth are removable. A nasal mask also refers to a nasal interface that includes nasal pillows that create a substantial seal with the patient’s nostrils.

[0245] A system 10 according to embodiments herein may include a pressure valve. A pressure valve may include a pressure regulating device, a pressure relief device, or pressure limiting device. In the specific embodiments described herein, the pressure valve may be a flow compensated pressure relief valve (or FCPRV) 100. The FCPRV 100 may be a valve having features described in WO2018 / 033863, the entirety of which is hereby incorporated by reference herein. It is to be understood that the terms “pressure valve”, “pressure relief valve”, “flow compensated pressure relief valve” and “FCPRV” may be used interchangeably in this disclosure. Furthermore, the term FCPRV is to be taken as broadly capturing the terms “pressure valve” and “pressure relief valve” except where a specific interpretation is necessitated by the context. The pressure valve (or FCPRV) may be placed anywhere in the system between the flow source 12 and the patient 16. In some examples, the FCPRV 100 is provided at an outlet of the flow source 12, or between the flow source 12 and the humidifier 17, for example near to an inlet of the humidifier 17. In some embodiments, the FCPRV 100 may be provided at an outlet of the humidifier 17 and / or an inlet to the conduit 14, or at any point along the conduit 14 through a suitable housing or coupling device. The FCPRV 100 may be located anywhere in the system, for example the FCPRV could be part of the patient interface 15.

[0246] A FCPRV 100 according to embodiments the present disclosure relieves pressure at an approximately consistent pressure across a given range of flow rates. The FCPRV 100 may be used to provide an upper limit for patient safety, and / or toprevent damage to system components caused by overpressure. For example, an occlusion in the system may cause a substantial back pressure in the system upstream of the occlusion, and the FCPRV may operate to ensure the back pressure does not increase above a limit to protect the patient and / or system components from damage. A blockage in the patient’s nares or exhaling conduit can result in an increased patient pressure. An occlusion in the system may be caused by, for example, inadvertent folding or crushing of the conduit 14, or may be caused deliberately, for example by occluding the conduit 14 (e.g. by pinching a portion of the conduit closed) to prevent a flow of gases from reaching the patient.

[0247] Figures 1 C and 2 show one embodiment of a FCPRV 100, which is illustrated schematically in Figure 1 B. The FCPRV 100 comprises an inlet 101 , an outlet chamber 102 with an outlet 103, a valve seat 104 between the inlet 101 and the outlet chamber 102, and a valve member 105 biased to seal against the valve seat 104. The valve member 105 is adapted to displace from the valve seat by pressure Pcat the FCPRV inlet 101 increasing above a pressure threshold. The pressure Pcacts on the valve member 105 to force the member away from the valve seat 104 once the pressure Pcreaches or exceeds the threshold. As the valve member 105 displaces from the valve seat 104, a flow of gases flows from the inlet 101 into the outlet chamber 102, and then from the outlet chamber 102 via the outlet 103 to ambient pressure / atmospheric pressure. The outlet from the chamber is configured so that the flow of gases through the outlet causes a (back) pressure Pb in the outlet chamber that acts on the valve member 105 to further displace the valve member 105 from the valve seat 104. As the valve member 105 is further displaced from the valve seat 104, a gap between the valve member 105 and valve seat 104 increases.

[0248] The FCPRV 100 further comprises a sensing mechanism 150 to dynamically adjust the pressure threshold at which the FCPRV 100 vents pressure based on the flow rate and / or pressure of the gases or a portion thereof, passing through the FCPRV or through the respiratory system. In certain embodiments, the FCPRV 100 comprises a sensing mechanism 150 to dynamically adjust the pressure threshold at which it vents pressure based on the flow rate of the gases or a portion thereof, passing through the FCPRV or through the respiratory system. In certain embodiments, the FCPRV 100 comprises a sensing mechanism 150 to dynamically adjust the pressure threshold at which it vents pressure based on the pressure of the gases or a portion thereof, passingthrough the FCPRV or through the respiratory system. An adapter 200 according to embodiments described herein can be used with the FCPRV 100.

[0249] Referring to figures 1 B and 2, features and functionality of the FCPRV will now be described. The FCPRV 100 comprises a body 1 10 defining a main inlet 151 and a main outlet 153. In the illustrated embodiment, the sensing mechanism 150 includes a flow restriction or flow constriction 152 between the main inlet 151 and main outlet 153 of the FCPRV. The main inlet 151 and / or main outlet 153 may be integral with or defined by the FCPRV body 110. In the embodiment of Figures 1 B and 2, the flow restriction 152 is part of the FCPRV body. In later described embodiments, the flow restriction is part of an adapter. For ease of reference, the term ‘flow restriction’ may be used herein to describe both a flow restriction such as an orifice plate and a flow constriction such as used in a venturi. In operation, the flow of gases in a respiratory system flow through the FCPRV 100 from the main inlet 151 to the main outlet 153. The sensing mechanism 150 senses the flow rate / pressure of gases flowing to the patient at or downstream of the flow restriction / constriction. In the embodiment shown, the inlet 101 is between the main inlet 151 and main outlet 153, and the flow restriction / constriction is downstream of the inlet 101 , but upstream of the main outlet 153. The sensing mechanism 150 senses the flow rate and / or pressure of gases flowing to the patient at or through the main outlet 153 of the valve.

[0250] The sensing mechanism 150 also includes a sensing chamber 154, and a sensing member 155 located in the sensing chamber 154. The sensing member 155 divides the sensing chamber 154 into a first chamber 154a and a second chamber 154b. The first chamber 154a is in fluid communication with the flow of gases upstream of the flow restriction 152, e.g. the first chamber 154a is in fluid communication with the main inlet 151 and the valve inlet 101 upstream of the restriction 152. The second chamber 154b is in fluid communication with the flow of gases at the flow constriction 152 or downstream of the flow restriction 152. In some embodiments, the device comprises a flow constriction configured as a venturi, with the second chamber 154b in fluid communication with the constriction via a pressure ‘tap’ or communication line 156 (Figure 1 B). However, in an alternative configuration the device may comprise a flow restriction 152, e.g. an orifice plate, and the first and second chambers may tap off either side of the orifice plate, for example via pressure ‘tap’ or communication line 111 shown in Figure 2. A pressure differential may be generated in any other suitable way,for example by a permeable membrane or a filter with a known pressure drop (a flow restriction).

[0251] A resulting pressure drop caused by the flow of gases that pass from the main inlet 151 to the main outlet 153 of the device, through the restriction 152 is therefore sensed by the sensing member 155 located within the sensing chamber 154.

[0252] In order to increase the flow rate through the respiratory system 100, the pressure provided by the flow source 12 is increased, increasing the pressure at the main inlet 151 and also in the first chamber 154a of the sensing chamber 154. As the flow rate through the FCPRV increases, a larger pressure drop is created by the restriction 152 due to an increased velocity of the gases passing through the restriction 152, and the pressure Pv in the second chamber 154b of the sensing chamber 154 decreases. Thus, an increasing flow rate through the FCPRV 100 from the main inlet 151 to the main outlet 153 results in an increasing differential pressure across the sensing member 155, with the first chamber 154a being a high (higher) pressure side of the sensing chamber 154 and the second chamber 154b being a low (lower) pressure side of the sensing chamber 154. This causes the sensing member 155 to move towards the low-pressure side of the sensing chamber 154, away from the valve member 105.

[0253] The sensing member 155 is mechanically coupled to the valve member 105 of the FCPRV 100, so that as the sensing member 155 moves towards the lower pressure side of the sensing chamber 154, the sensing member 155 pulls or biases the valve member 105 of the FCPRV against the valve seat 104. For a given flow rate setting, a higher flow rate causes a higher differential pressure across the sensing member 155, biasing the valve member 105 further towards the valve seat 104. This causes the pressure relief threshold for the FCPRV 100 to increase. If a flow restriction (e.g. squashed conduit 14 or blockage in patient’s nare) is introduced, the flow source 12 (rapidly) adjusts to increase pressure in the system to maintain the flow rate at a desired level. If the system pressure required to maintain the desired flow rate is above the relief pressure, the FCPRV begins to vent, with a portion of the flow provided to the main inlet 151 venting via the FCPRV valve member 105, and a portion of the flow passing through the restriction 152 and from the main outlet 153. The flow source 12 maintains a set flow rate to the main inlet 151 of the FCPRV 100. Thus, as the FCPRVbegins to vent, the flow rate through the constriction or restriction 152 decreases, and the pressure differential acting on the sensing member 155 decreases. This causes the bias provided by the sensing member 155 to the valve member 105 to decrease, and therefore the pressure relief threshold for the FCPRV 100 to decrease. In an ideal situation, an equilibrium state will be reached, whereby the patient receives as much flow as possible without exceeding the pressure relief threshold, or without exceeding a maximum delivered pressure at the patient interface.

[0254] If the flow restriction completely (or substantially completely) blocks the system, for example a conduit 14 is completely occluded (completely crushed or pinched closed) or a patient’s naris is completely blocked, all or substantially all flow delivered to the main inlet 151 of the FCPRV 100 is vented via the valve member 105.

[0255] Figure 1 B shows a body that provides or forms the outlet chamber 102 and the first chamber 154a of the sensing chamber 154. Those features are not shown in the other figures, but it will be appreciated that any of the embodiments of the FCPRV or adapter described herein may be used with a valve body having those features.

[0256] Figure 8 illustrates a tuning method for tuning the FCPRV 100. At step 160 the system 10 is pressure tested to determine a system flow (e.g. flow delivered to the patient) versus the overall pressure drop response curve for the system 10. In step 161 a desired relief pressure v flow curve is determined, for example by adding an offset pressure to the system pressure v flow curve. At step 162, the FCPRV 100 is installed in the system 10. At step 163, a flow restriction is then progressively added to the system downstream of the FCPRV 100, and the resulting relief pressure for a range of flow rates is determined to create a curve of measured pressure relief vs flow rate. At step 164, the actual pressure relief v flow curve is compared to the desired curve. At step 165, if the actual curve does not match the desired curve, the size of the flow restriction (Venturi throat or orifice) is adjusted and steps 163 and 164 are repeated again, until the desired pressure relief characteristic is achieved, at which point at step 166 the FCPRV 100 has been successfully tuned.

[0257] As illustrated in Figure 8, a gradient of the relief pressure response curve can be adjusted by altering the size of the flow restriction. A greater gradient indicates a higher rate of change in the FCPRV relief pressure with respect to increasing flowrate. By altering the gradient, the flow and pressure characteristics of a specific respiratory system can be tuned for optimal performance for a particular patient population. Accordingly, in some embodiments, the gradient can be altered for optimal performance in a particular respiratory system by adjusting the size of the flow restriction on the adapter.

[0258] Alternatively, or additionally the vent pressure threshold may be adjusted by adjusting any one or more of the other features of the FCPRV. For example, the tension in the valve membrane 105 may be adjusted by for example adjusting the relative position of the valve inlet 101 to the valve member 105, or the size of the vent outlet 103. In the FCPRV 100, the size of the vent outlets determines the shape of the pressure relief valve relief pressure v flow curve and therefore the vent pressure threshold over a range of flow rates. When the system is completely blocked / occluded, the sensing member may provide some additional bias to the valve member 105. Also, the biasing force provided to the valve member 105 by the sensing member 155 may be adjustable. For example, the length of the mechanical link 157 between the sensing and valve members may be adjustable, a shorter length link increasing the biasing force and therefore the vent pressure.

[0259] Four stages of operation of the FCPRV 100 will now be described with reference to Figure 10. In stage 1 , indicated by point 1 on curve 141 indicating pressure in the respiratory system 10, the respiratory system 10 is providing a flow of gases to a patient 16. All (or substantially all) of the flow provided from the flow source 12 to the main inlet 151 of the FCPRV 100 is delivered to the system 10 from the main outlet 153 of the FCPRV 100. At point 1 a very low or ambient pressure is being delivered to the patient 16 since all pressure is being dropped through the system 10. As the flow rate delivered to the patient 16 is adjusted up and down, for example by a user, the pressure relief threshold of the FCPRV 100 varies along the relief pressure v flow curve 142 - as the flow rate to the patient increases, the increasing differential pressure sensed by the sensing member 155 acts on the valve member 105 to increase the FCPRV vent threshold pressure as indicated by curve 142.

[0260] For a given flow rate setting (90L / min in Figure 10), in stage 2, in a situation where a flow restriction is introduced to the system 10, for example by the partial occlusion of a patient inspiratory conduit 14, or a squashed nasal prong of a nasalcannula patient interface 15, or a blockage at the patient, for example between a nasal prong and the patient's nares, the flow rate may instantaneously decrease. However, in a set flow system, the flow source 12 (rapidly) adjusts to increase pressure in the system to maintain the flow rate at a desired level. The drop in flow rate and then increase in pressure by the flow source response to maintain a set flow rate to the FCPRV may occur essentially instantaneously, i.e. very quickly, and is therefore negligible. As the flow is maintained, the differential pressure caused by the flow constriction or restriction 152 of the FCPRV remains constant, the bias provided to the valve member 105 by the sensing member 155 remains constant, and therefore the relief pressure threshold for the FCPRV 100 remains constant. However, as the system pressure has increased (for example due to an increased pressure in the patient's airway / nares), the pressure Pcacting on the valve member 105 (and the sensing member 155 on the high-pressure side of the sensing chamber 154) is increased towards the relief pressure of the FCPRV 100. This situation is represented by the vertical arrow 2 in Figure 10. If a partial occlusion was held and an equilibrium condition reached, a higher system pressure v flow curve indicated by curve 141 b in Figure 10 would result, with a smaller offset between the higher system pressure v flow curve 141 b and the FCPRV relief pressure v flow curve 142.

[0261] For example, for a partial blockage between a nasal prong and a patient's nare that results in an increased system pressure 141 b, the pressure generated in the patient's nare is the offset between curve 141 b and curve 141. In stage 3, the introduced flow restriction (e.g. squashed conduit 14 or blockage in patient's nare) is increased to a level whereby the system pressure required to maintain the desired flow rate is above the relief pressure 142 of the flow compensated relief valve for the given flow rate (about 90L / min in Figure 10). As the system pressure at the FCPRV (e.g. Pc) exceeds the flow compensated relief pressure 142, the FCPRV 100 begins to vent, with a portion of the flow provided to the main inlet 151 venting via the FCPRV 100 and a portion of the flow passing through the restriction 152 and from the main outlet 153. The flow source maintains a set flow rate to the main inlet of the FCPRV. Thus, as the FCPRV 100 begins to vent, the flow rate through the constriction or restriction 152 decreases, and the pressure differential acting on the sensing member 155 decreases. This causes the bias provided by the sensing member 155 to the valve member 105 via the mechanical link 157 to decrease, and therefore the pressure relief threshold forthe FCPRV 100 to decrease. This situation is represented by arrow 3 on the pressure relief v flow curve 142 in Figure 10. In an ideal situation, an equilibrium state will be reached, whereby the patient receives as much flow as possible without exceeding the pressure relief threshold, or without exceeding a maximum delivered pressure at the patient interface.

[0262] In stage 4, indicated by point 4 in Figure 10, the flow restriction introduced to the system may completely (or substantially completely) block the system, for example a conduit 14 is completely occluded (completely crushed or pinched closed) or a patient's nare is completely blocked. All flow delivered to the main inlet 151 is vented via the FCPRV 100. As there is no flow through the device 100 from the inlet 151 to the outlet 153, and therefore no flow through the constriction / restriction 152, the pressures in the first and second chambers 154a, 154b are equal and the sensing member 155 provides a minimum bias to the valve member 105. Changes in pressure Pc do not change the pressure differential across the sensing membrane 155.

[0263] Thus, in a situation whereby a patient's nares are blocked, the maximum pressure that the patient can receive is the offset between the relief pressure curve 142 and the system pressure drop curve 141 , protecting the patient against overpressure. For example, in Figure 10 this maximum patient pressure is 20cmH2O. Thus, the FCPRV provides a venting pressure threshold that is dependent on flowrate yet simultaneously sets an upper pressure limit that the patient will receive. The FCPRV must be capable of venting the maximum flow rate provided by the flow source 12, to ensure the FCPRV can vent the system along curve 142 back to zero flow to the patient, otherwise a higher patient pressure than the indicated offset pressure may eventuate.

[0264] The above-described operation of the FCPRV is for a system providing a flow of gases to a user via an unsealed or non-sealing patient interface, such as a nasal cannula that does not seal with the patient's nares. The flow source in such a system may be a compressed gas tank or a hospital wall flow meter supply, or a blower capable of providing sufficient flow rate, or other suitable sources that has the ability to provide a rapid response to variation in system resistance to maintain a set flow to the system. A system including a flow source 12 providing a set flow rate of gases to a patient via a FCPRV, humidifier 17, filter and a non-sealing nasal cannula 15 is illustrated in Figure 1 A. Such a system is particularly adapted for providing nasal high flow therapy.

[0265] Figures 2 and 3 show the FCPRV 100 with one embodiment of an adapter 200 for coupling the FCPRV to a conduit for the supply of gas to a patient. The embodiment of the adapter 200 shown in Figure 2 is a single part. The adapter 200 is a male adapter. The adapter 200 is configured for use with a connector associated with the outlet of the FCPRV 100 (also referred to herein as the ‘FCPRV connector’), which is a female connector provided by the FCPRV 100. An example of a female connector is the valve body 1 10 at the outlet 205, as shown in figures 1 C and 2.

[0266] Referring to Figures 2 and 3, features of one embodiment of the adapter 200 will now be described. The adapter 200 has a hollow body with an inlet 203 and an outlet 205. The inlet 203 and outlet 205 define a gas flow passage therebetween. In some embodiments, the gas flow passage is or comprises a pressure line. The gas flow passage is defined at least in part by a wall 207 of the adapter 200. The wall 207 provides an adapter that is a generally tubular component having a generally cylindrical body that may be tapered and / or vary in its cross-sectional area along the length of the adapter 200. In other embodiments, the adapter 200 comprises other cross-sectional shapes, e.g., elliptical, oval, obround, square and rectangle.

[0267] The body of the adapter 200 has an overlap portion 201 that is configured to overlap with a portion of the connector associated with the FCPRV 100, when connected thereto. The adapter 200 has an access passage, an access aperture, or an access hole, extending through the overlap portion 201 to the gas flow passage. The access passage fluidly communicates with the gas flow passage of the adapter to enable sensing of the pressure in the gas flow passage. In this embodiment, the access passage comprises an aperture 21 1. In the embodiment shown in figures 2 and 3, the aperture extends through the wall 207 of the adapter 200. This embodiment has a single aperture 21 1 . The aperture 21 1 has a similar size and shape to that of the bleed line 1 1 1. In alternative embodiments, there may be more than one aperture 211 extending through the wall 207. The adapter 200 may have alignment features (not shown) to guide the adapter towards the correct alignment position to ensure the two dimensional features such as text, symbols, and arrows. Other examples of alignment features include three dimensional features such as complementary protrusions and recesses. In various embodiments, the adapter 200 may have one or more alignment positions with respect to the main outlet 153 of the FCPRV 100, to facilitate obtaining or not obtaining a flow and / or pressure compensated response from valve 100 or notobtaining any pressure relief from valve 100. In a first configuration, the aperture 211 is not aligned with the bleed line 1 1 1 of the sensing mechanism and so there is no fluid communication between the gas flow passage through the adapter 200 and the sensing chamber 154 via the access passage 211 such that the valve 100 will not provide any pressure relief functionality but will still allow gases to flow through the flow passage between main inlet 151 and main outlet 153. In such a configuration, the valve does not function as a pressure relief valve. In a second configuration, the aperture 21 1 is aligned with the bleed line 1 1 1 such that there is fluid communication between the gas flow passage through the adapter 200 and the sensing chamber 154 via the bleed line 1 1 1 of the sensing mechanism and the access passage 21 1 . The FCPRV 100 thereby functions as a flow and / or pressure compensated pressure relief valve as described above.

[0268] External features of the adapter 200 may seal with internal features of the connector, for example, the main outlet 153 of the valve body 110. In this embodiment, a portion of the exterior surface of the adapter 200 is tapered. The surface is tapered inwardly towards the terminal end (inlet 203) of the adapter 200. The taper may be a constant taper. The adapter body tapers outwardly from the terminal end, from a smaller diameter to a larger diameter. In other embodiments, the adapter 200 may have a constant diameter.

[0269] The main outlet 153 of the valve body 1 10 has a complementary size and taper such that the components may seal when assembled. Further embodiments are described below in which the connection between the main outlet 153 and the adapter creates the effect of a low pass filter between the flow passage through the adapter and the sensing mechanism. In this embodiment, there is no low pass filter effect because a cavity is not formed between the walls of the main outlet 153 and the adapter 200, where the cavity is in fluid communication with the gas flow passage and bleed line 1 11.

[0270] The adapter 200 may comprise a stop. In the embodiment shown, the stop is a shoulder 209. The shoulder 209 is integral with the adapter body. The shoulder 209 is positioned to abut the terminal end of the FCPRV outlet 153 / connector when the adapter 200 is assembled with the FCPRV body, thereby preventing, or at least substantially inhibit the adapter 200 being over-inserted into the connector.

[0271] The adapter 200 may further comprise an engagement mechanism configured to couple the adapter to the FCPRV 100. In the embodiment shown in figures 2 and 3, the fit between the adapter 200 and the main outlet 153 of the valve body 1 10 acts as an engagement mechanism. That is, the adapter 200 is retained in place due to frictional forces between the internal walls of the connector / main outlet 153 and the external surface of the adapter 200.

[0272] Another (second) embodiment of the adapter will now be described with reference to figures 4 and 5. The adapter 400 has the same features and functionality as the first adapter 200, unless described below. Like numbers are used to indicate like parts with the adapter 200.

[0273] In this embodiment, the adapter has a cavity forming portion 413 and a sealing mechanism 415. When the adapter 400 and the valve 100 are assembled, the sealing mechanism 415 substantially pneumatically seals the adapter 400 and the main outlet 153 of the valve body 1 10. The cavity forming portion 413 and the main outlet 153 of the valve body 110 form a cavity.

[0274] The cavity forming portion 413 is a recess or change in a surface of the adapter body that faces away from the gas flow passage. The exterior surface of the cavity forming portion has a shape that is not complementary to the internal surface of the main outlet 153 of the FCPRV 100, such that when assembled, the surfaces may be configured (e.g., having converging, diverging and / or parallel portions) to form a cavity 414. In the embodiment, a recess is provided by a stepped portion of the adapter's outer surface, while the main outlet 153 of the valve body 110 does not have a complementary shape. Rather, the main outlet 153 of the valve body 1 10 has a gradual taper such that when assembled, the adapter 400 and main outlet 153 define a cavity 414 therebetween. In other configurations, the main outlet 153 of the valve body 1 10 may not have a taper. The cavity 414 is defined by an internal surface of the main outlet 153 of the valve body 110 and the cavity forming portion 413, when the adapter 400 is coupled to the main outlet 153. In addition to having a stepped portion, the cavity forming portion 413 comprises an arcuate (includes but is not limited to curved) surface, e.g. a radial surface. The arcuate surface is defined by the cylindrical adapter body.

[0275] When formed, the cavity 414 is in fluid communication with the bleed line 1 1 1. The formed cavity 414 is in fluid communication with the gas flow passage via the access passage 41 1 . The access passage comprises one or more apertures 41 1 . This arrangement allows the communication of pressure in the gas flow passage through the apertures 411 into the cavity 414 and then subsequently into the bleed line 1 1 1 and the second chamber 154b, which can create a pressure differential across the sensing member 155 in the sensing chamber 154 so that the FCPRV 100 can function as described above.

[0276] In the embodiment shown, the cavity forming portion 413 has a longitudinal dimension along a longitudinal axis that is substantially parallel to a direction of gas flow in the gas flow passage. In an alternative embodiment, the cavity forming portion 413 may not be substantially parallel to a direction of gas flow in the gas flow passage. In this embodiment, the one or more apertures 41 1 are arranged substantially parallel or substantially perpendicular to a direction of gas flow in the gas flow passage. The location and formation of the cavity 414 in relation to the bleed line 1 1 1 or opening of the bleed line 1 1 1 can vary, provided it is in fluid communication with the bleed line 1 1 1 via the apertures 41 1 .

[0277] In this embodiment, apertures 411 are arranged on the stepped portion / shoulder 412 formed between the cavity forming portion 413 and the sealing portion 415. This embodiment includes three apertures 411 that are radially arranged about the gas flow passage. There may be more apertures 41 1 , for example, four or five apertures 411 . There may be fewer apertures 41 1 , for example, one or two apertures.

[0278] At least one aperture 41 1 may be in fluid communication with the gas flow passage via another aperture, the apertures being connected and in fluid communication by a channel (for example, a port in the wall of the adapter that allows for downstream sampling).

[0279] Figures 4 and 5 show the inlet end (terminal end) of the adapter includes a wall 404 having an inlet aperture 403 that provides a flow restriction or an additional flow restriction. The inlet aperture 403 is also the inlet of the adapter 400. The wall 404 is spaced inwardly from the end of the adapter, forming a recess. The wall 404 is located slightly inwardly, spaced from the terminal end, which increases the stiffness ofthe terminal end. The inlet aperture 403 is a tuning aperture in conjunction with a radial clearance, as described below. In an alternative embodiment, the wall 404 and inlet aperture 403 may be arranged directly at the terminal end of the adapter 400. In another alternative embodiment, the aperture 403 may be absent, that is, the wall 404 is a continuous wall. In such an embodiment, all of the gas flows through the access passage apertures 41 1 .

[0280] The sealing mechanism 415 is configured to form a first seal with a portion of the main outlet 153 of the valve body 1 10. The sealing mechanism may comprise one or more of sealing mechanisms known in the art, e.g., a face seal, an O-ring, a lip seal, a wiper seal, or a sealing surface. In the embodiment shown in figures 4 and 5, the sealing mechanism is a sealing surface 415.

[0281] The cavity 414 is upstream of the sealing mechanism. In this case, the seal comprises an outer seal, that is, a seal that is proximate the terminal end of the main outlet 153 and / or proximate the collar 409 of the adapter of Figure 4, for the valve to function. Figure 4 shows an example of an embodiment with this outer seal, as the sealing surface, where the outer seal is formed by engagement or interaction of a portion of the exterior wall of the adapter 400 with a portion of the interior wall of the main outlet 153. It should be noted that other embodiments described with more than one seal could also be implemented with a single sealing surface. An outer seal can be defined as a seal that is downstream of the bleed line 1 1 1 and cavity 414 that is formed.

[0282] By providing a valve body 1 10, and a separate adapter 400, it is possible for the features of the valve body 1 10 to be set or fixed, while the pressure relief characteristics can be readily tuned by altering and / or adjusting the features of the adapter or changing the adapter used. Rather than providing a large number of different FCPRVs, it is possible to provide one design of a valve body and a variety of different adapters. Each adapter can be specifically tuned to provide the desired features, functionality and / or pressure relief characteristics, for example sealed and unsealed respiratory systems, and differentially sized patient interfaces (e.g. nasal cannulas), and different types of patients (e.g., adult patients or paediatric patients), as different flow rates and different system components (e.g. different patient interfaces) are typically required for patient populations. For example, at step 165 of the tuningprocess illustrated in Figure 8, the size of the flow restriction can be adjusted by changing the adapter to one having a different sized inlet 403.

[0283] As shown in Figures 6A and 6B, in some embodiments an additional inner seal 619 may be present. An inner seal 619, described further below, comprises a seal that is upstream of the bleed line 1 1 1 and cavity 614 that is formed. This inner seal may be proximate to the centre of the FCPRV when the adapter 600 is engaged with the main outlet 153.

[0284] In alternative embodiments, other configurations of the adapter and the valve body 1 10 may be used to form the cavity 414, 614. For example, the main outlet 153 of the valve body 1 10 may have a stepped portion and the adapter may have a gradual taper. In another alternative embodiment, the main outlet 153 of the valve may have a taper and the adapter may have a different taper. In another alternative embodiment, the main outlet 153 of the valve body 1 10 may have a stepped portion change and the adapter 400 may have a stepped portion change, where the stepped portion changes are offset in a direction that is parallel to the direction of gas flow, forming a cavity. Further, the shape of the adapter 400 and the shape of the main outlet 153 of the valve body 1 10 or other parts of the valve, together with the configuration of those components when assembled may be chosen or designed such that there is a tolerance and the components do not have to line up exactly to form a suitable cavity.

[0285] In the embodiment 400 of Figures 4 and 5, a radial clearance, at high fluid velocity, occurs. Flow accelerates through the apertures 41 1 and creates low pressure areas. In this embodiment there is an annular cavity 414 created that is sealed only at one end (outer seal). The size of the annular cavity 414 between the adapter 400 and the internal wall of the main outlet 153 of the valve body 1 10 where there is no seal will have to be taken into account so that venting occurs as desired. As the cavity is only sealed at one end, the other end is in fluid communication with the gas flow passage, which may make tuning of the valve more difficult. The valve tuning has to take into account the leak flow into the cavity 414 which can affect the pressure differential across the sensing member 155 in the sensing chamber 154. T uning the valve involves adjusting the size of the tuning aperture 403 or changing the diameter of the main outlet 153 and / or cavity forming portion 413 to change the size of the radial clearance to achieve a desired response. Changing the radial clearance will adjust the flow velocity.The relative sizes of the aperture 403 and the radial clearance will change the ratio of flow taking each path. This may be achieved by substituting a different adapter with differently dimensioned inlet aperture 403, outlet 153, and / or cavity forming portion 413.

[0286] The adapter may comprise a stop. In the embodiment shown, the stop is a collar 409. In the embodiment shown, the collar 409 is an annular collar. In alternative embodiments, the stop may be another feature that comprises the collar 409. The collar 409 is integral with the adapter body. In an alternative embodiment, the collar 409 may be a separate component that is assembled with the adapter body. A surface of the collar 409 may be configured to form a face seal with a surface of the FCPRV connector. In other configurations, the collar 409 may replace or aid the sealing mechanism 415. The collar 409 prevents, or at least substantially inhibits the adapter 400 from being over-inserted into the connector of the FCPRV.

[0287] Another (third) embodiment of the adapter will now be described with reference to Figures 6A, 6B and 7. The adapter 600 has the same features and functionality as the second adapter 400, unless described below. Like numbers are used to indicate like parts with the adapter 200.

[0288] In this embodiment, there is a first sealing mechanism 615 and a second sealing mechanism 619. Embodiments of the adapter having two sealing mechanisms facilitate tuning of the response of the FCPRV. The cavity forming portion 613 is between the first sealing mechanism 615 and the second sealing mechanism 619. The access passage is in fluid communication with the cavity 614. The access passage is also positioned between the first sealing mechanism 613 and the second sealing mechanism 615. In the embodiment of Figures 6 and 7, the cavity 614 that is formed between the first sealing mechanism 615 and the second sealing mechanism 619, when the adapter 600 is coupled to the main outlet 153, is an annular cavity. That is because the main outlet 153 of the valve body 1 10 has a radial bore and the adapter 600 has a radial outer surface.

[0289] In the embodiment shown in Figures 6A, 6B and 7, the second sealing mechanism 619 is a sealing surface. The first sealing mechanism 615 and the second sealing mechanism 619 are formed by the interference / friction fit of the external surfaces of the adapter 600 and the complementary inner surface(s) of the main outlet153 of the valve body 1 10 as shown. However, many other methods may be used to create seals and form a cavity. For example, O-rings, wiper seals, adhesives, foams or lip seals may be used at different locations on an adapter and seal with internal or external surfaces of the female connector (valve body 1 10) to form the cavity 614. Further, an internal interference fit may be used for one seal in conjunction with retention features such as a tab and clip or other external sealing method on the outside of the valve / connection assembly to create a cavity.

[0290] Figures 6A, 6B and 7 show an assembly, in which the overlap portion 601 includes the first sealing mechanism 615. The overlap portion 601 also comprises the second sealing mechanism 619. In an alternative embodiment, the overlap portion 601 may comprise only one of the sealing mechanisms.

[0291] Figure 6B shows the main outlet 153 of the valve body 1 10 has an internal, gradually tapered bore. This internal bore of the main outlet 153 of the valve body 1 10 has non-standard diameters. This is to avoid the connection of incorrect adapters with the main outlet 153. In this embodiment, the flow restriction is provided by the aperture 603 at the inlet to the adapter (rather than by the valve body). If an incorrect adapter is made that fits into the main outlet 153, the valve is unlikely to operate as a flow and / or pressure compensated valve or a valve that provides pressure relief because the valve and adapter would not have a flow restriction and / or an access passage with the main gas flow path to achieve the flow rate and / or pressure sensing as described in relation to the embodiments of the valve and adapter. In this case, if an incorrect adapter that does not have a flow restriction, but which provides fluid communication between the second sensing chamber and the main gas flow passage between main inlet 151 and main outlet 153, (e.g. via the communication line 11 1 ), is used with the FCPRV body, the pressure response of the valve 100 will match the response observed when the outlet 153 of the valve is blocked and gases are venting from the valve. That could include a substantially flat response of, for example, 20 cm H2O. If an incorrect adapter that does not provide fluid communication between the second sensing chamber and the main gas flow passage between main inlet 151 and main outlet 153 (i.e., the communication line 1 11 is blocked), is used with the FCPRV body, the valve 100 will not provide any pressure relief during use but gases are still able to flow through the main flow passage. As a result, the respiratory system may not be able to deliver all of the prescribed flow rates to the patient or the flow is limited.

[0292] The adapter and the main outlet 153 of the valve body 1 10 may be pneumatically sealed such that there is not a significant leak of gas to atmosphere. In some embodiments, if there is a known or expected leak, the flow restriction may be adjusted (for example by altering the size of the tuning orifice) based on this known or expected leak such that expected valve function is maintained.

[0293] Another embodiment of the adapter will now be described with reference to Figures 9A to 9C. The adapter 700 has similar features and functionality to the third embodiment adapter 600, unless described below. Like numbers are used to indicate like parts with the adapter 200.

[0294] In the adapter 700 of Figures 9A to 9C, the apertures 71 1 in the wall of the adapter for fluid communication with the FCPRV sensing mechanism 150, are provided in the cavity forming portion of the adapter 713. The apertures 71 1 are positioned adjacent to the shoulder 712 that is formed between the cavity forming portion 713 and the overlap portion 715. Fluid flow through the apertures 711 is substantially perpendicular to the main flow direction through the adapter 700 from the inlet aperture 703 to the outlet. In some embodiments, the apertures may be provided in the wall of the adapter at, or immediately adjacent and downstream of, the flow restriction.

[0295] A moulding notch 721 may be present at the upstream, inlet end of the adapter 700, for ease of manufacturing of the adapter, for example by injection moulding.

[0296] In some embodiments described herein, the cavity forming portion may be tapered relative to a direction of gas flow. An example is when the gas flow passage is or comprises a pressure line. The adapter may taper towards a terminal end, from a larger diameter to a smaller diameter.

[0297] In some embodiments, the adapter may be configured to be coupled to a pressure relief valve. In particular, the adapter may further comprise an engagement mechanism configured to couple the adapter to a pressure relief valve. Suitable engagement mechanisms include clips, complementary threaded portions, or press fits. In the embodiments shown, the engagement mechanism is a press fit.

[0298] In some embodiments, the pressure relief valve may be a flow and / or pressure compensated pressure relief valve. In some embodiments, the pressure relief valve may be a flow compensated pressure relief valve or a pressure compensated pressure relief valve. The pressure line may be in fluid communication with a sensing chamber of the pressure relief valve. The pressure relief valve may comprise a sensing member configured to sense a pressure differential between the sensing chamber and a main gas flow passage that provides gas flow to a patient. Movement of the sensing member changes the venting pressure of a valve member.

[0299] In some embodiments, the pressure line is a first pressure line and the adapter further comprises a second pressure line that is upstream of the first pressure line. The first pressure line and the second pressure line may each be coupled to a pressure sensing mechanism.

[0300] In some embodiments, the adapter may be configured to be coupled to a respiratory circuit component. For example, the adapter may comprise an engagement mechanism configured to engage the adapter with the respiratory circuit component. Suitable engagement mechanisms include clips, complementary threaded portions, or press fits.

[0301] Some of the described embodiments indicate a direction of flow. However, in all described assembly embodiments that the direction of gas flow can be either direction. The terms ‘upstream’ and ‘downstream’ used herein, are dependent on the direction of flow in for example the gas flow passage.

[0302] Any one of the adapters described herein may be releasably or permanently secured to, or integral with, the end of a conduit. An example of a conduit 900 is shown in Figure 6A. The adapter may be assembled with the conduit during manufacturing, or after manufacturing. The conduit may be any suitable conduit. The conduit will be chosen or designed depending on a variety of factors. Those factors include the location of the FCPRV in the circuit, and / or the location at which pressure sensing is desired.

[0303] The adapter may be configured to releasably attach to the end of an existing conduit to enable the existing conduit to be used with the pressure relief device described herein. The connection between the conduit 900 and the adapter 400 maybe by way of an interference fit, for example, where the conduit connecting portion 417 of the adapter is received by the conduit 900 and seals against the internal wall surface of the conduit 900. Alternatively, attachment portion 405 of the adapter 400 may receive the conduit and form an interference fit with the outer surface of the conduit.

[0304] This conduit 900 with the adapter 400 is then connected to the FCPRV body, forming a FCPRV and adapter assembly. In one example, the adapter is attached to the end of a conduit during manufacturing. The adapter and the conduit are then connected to the FCPRV by a user. The conduit 900 may be part of a circuit between a flow source and a humidifier or between a pressure relief valve and a humidifier. For example, the conduit may extend from a flow source to a humidifier. The conduit 900 may be referred to as a dry line when it connects an outlet of a flow source or a pressure relief valve to an inlet of a humidifier or humidification chamber, and the gases that it transports is not humidified. Furthermore, additional components may be included to modify the circuit (e.g., a gas flow modulator) and the dry line may extend from a flow source to one of these additional components or from the additional components to a humidifier or humidification chamber. In some embodiments, a gas flow modulator receives a gases flow from a flow source and the adapter and conduit are connected to an outlet of the gas flow modulator to deliver the gases flow from the gas flow modulator to a humidifier or humidification chamber for the gases flow to be humidified. A gas flow modulator may be a gas flow modulator having features described in WO201 7 / 187390, the entirety of which is hereby incorporated by reference herein.

[0305] The interaction between the adapter that is integral with or coupled to the dry line and the FCPRV connector may be an interference / friction fit. However, other methods may be employed such as a twist / screw attachment or an external engagement mechanism, e.g., adhesives (includes but not limited to glues, chemical bonding, etc), overmoulds and welds.

[0306] Each of the adapter described herein allows alterations or modifications to the tuning orifice to be readily made by changing the adapter rather than the entire valve. Further, the adapter described discourages connection of incorrect adapter to the FCPRV connector because the FCPRV will not function as desired unless the adapter is an adapter having the features and functionality of one of the embodimentsdescribed here, or unless the adapter is tuned appropriately (e.g. size of the flow restriction) for the resistance to desired flow of the circuit and patient interface.

[0307] In a further alternative embodiment, a FCPRV may comprise a sensing mechanism that is an electrical sensing device, comprising one or more electronic sensors to detect the flow rate (e.g. a pressure drop across a flow restriction or flow through the restriction) of gases flowing from the main inlet to the main outlet of the FCPRV (‘electronic FCPRV’). Some examples of sensors that may be suitable are hot film sensors or ultrasonic sensors, or any other suitable sensor, including the use of pressure sensors or a differential sensor to measure flow via an orifice or venturi. An electrical controller / processor that receives a signal from the sensor(s) may provide an output to drive an actuator to control a PRV of the FCPRV to adjust the relief pressure threshold of the PRV of the FCPRV. Examples are provided in Figures 11 A to 13B. For example, the actuator may compromise a servo that drives a member such as a link 157, 257 attached to a valve member 105, 2050 of the PRV to adjust an amount of bias of the member 105, 2050 towards a valve seat 104, 204 of the PRV. A solenoid may be controlled to move the valve member.

[0308] Various PRV and FCPRV embodiments have been illustrated with circular valves and sensing members. However, other shapes may be desirable to achieve desired characteristics.

[0309] FIGS. 11 A and 11 B illustrate a FCPRV 901 comprising an electrical sensing device. The electrical sensing device comprises a flow and / or pressure sensing arrangement, a processor or controller 951 (e.g. digital and / or analogue electronics and / or electro-mechanical devices) and an actuator 952. The sensing arrangement may comprise a venturi and first and second pressure sensors to measure the flow at the venturi throat and adjacent to the venturi throat, or may comprise an orifice with an upstream and a downstream pressure sensor, or any other flow sensing arrangement known in the art. The controller 951 receives a signal from the sensor 950 and controls the actuator 952 to vary an amount of force or load applied to the valve member 2050 (i.e. a plunger) against the valve seat 104, for example via a mechanical link 157 based on the flow rate of gases flowing through the main outlet 153. In the embodiment of FIGS. 11 A and 11 B, the valve member is a plunger adapted to bear against the valve seat 104. The actuator may be connectedto the valve member 2050 via a biasing member or element 953, for example a spring 953. The actuator may be driven by the controller to adjust the amount of bias provided by the biasing member 953 to adjust the pressure required to lift the valve member 2050 off the valve seat 104 depending on the flow rate determined by the controller from the signal provided by the sensor 950. FIG. 11 B illustrates the actuator driven to increase bias by elongating the biasing member 953, to increase the relief pressure of the PRV. The coupling member 157 may also be rigid, whereby the actuator directly opens and closes the valve member. In such an embodiment, the sensor measures both pressure and flowrate and opens the vent valve based on a relationship between pressure and flow rate; for a measured flow rate and measured pressure, the valve will open a predetermined amount, to control the pressure at the patient to achieve a characteristic illustrated in FIG. 10.

[0310] FIGS. 12A and 12B illustrate a FCPRV comprising an electrical sensing device. The electrical sensing device comprises a flow and / or pressure sensor 950, a processor or controller 951 (e.g. digital and / or analogue electronics) and an actuator 952. The controller 951 receives a signal from the sensor 950 and controls the actuator 952 to vary an amount of force or load applied to the valve member 105 against the valve seat 104, for example via a mechanical link 157. In the embodiment of FIGS. 12A and 12B, the valve member 104 is flexible diaphragm adapted to bear against the valve seat 104. The actuator may be driven to adjust the amount of force or load applied to the valve member to vary an amount of flex in the flexible diaphragm as it is pulled against the valve seat, to adjust the pressure required to lift the valve member 105 off the valve seat 104 depending on the flow rate determined by the controller from the signal provided by the sensor 950. Bias against the valve seat is provided by the resiliency of the flexible diaphragm. FIG. 12B illustrates the actuator driven to increase bias by pulling the diaphragm against the valve seat 104.

[0311] FIGS. 13A and 13B illustrate flow controlled pressure regulating devices that control the pressure at the patient to a safe level based on a relationship between pressure and flow rate provided to the patient. The devices each comprises an electrical sensing device. The electrical sensing device comprises a flow and / or pressure sensor(s) 950, a processor or controller 951 (e.g. digital and / or analogue electronics) and an actuator 952. The controller 951 receives a signal from the sensor 950 and controls the actuator 952 to vary the size of a restriction or opening / orifice toadjust the amount of flow to the patient. The sensor 950 is located downstream (i.e. on a patient side) of the variable flow restriction 954 (e.g. a valve), to provide an indication of pressure relative to the patient. Turbulence may occur after the variable restriction or valve 954. To reduce the effect of turbulence on the sensing device 950 baffles or vanes may be provided and / or the sensor may be located sufficiently downstream of the variable flow restriction / valve. In FIG. 13A the variable flow restriction 954 is in the main flow path from the main inlet 151 to the main outlet 153. If a flow restriction is introduced to the system downstream of the variable restriction 954 (or in the patient's nares for example), the controller senses an increased pressure for a given flow rate and may reduce the flow restriction 954 by moving the actuator 952 to increase the size of the orifice or opening 954 to maintain a set flow rate through the system (e.g. as indicated by the vertical line in the chart of FIG. 10). If a restriction to flow results in a pressure at the device reaching a pressure limit based on a pressure vs flow relationship (i.e. curve 142 in FIG. 10), the controller may then begin to increase the flow restriction 954 by moving the actuator 952 to decrease the size of the orifice or opening, to limit the pressure at the device and therefore the flow rate and pressure at the patient (i.e. the flow restriction controlled so that the pressure and flow at the device is at point 3 in FIG. 10). Thus the valve or variable flow restriction 954 is controlled based on a relationship between pressure and flow rate. An additional vent 955 may be used to reduce the pressure in the outlet tube in the case of a fast blockage to which the actuator cannot respond fast enough.

[0312] In FIG. 13B, the variable flow restriction 954 is in a vent path to vent a portion of flow from the system. If a flow restriction is introduced to the system downstream of the valve or variable restriction 954, the controller senses an increased pressure and reduces the flow restriction 954 by moving the actuator 952 to increase the size of the orifice or opening 954, to vent flow from the system, to maintain a maximum set pressure at the pressure regulating device and therefore the patient. Thus, the valve or variable flow restriction 954 is controlled based on a relationship between pressure and flow rate. In some embodiments, the device of FIG. 13A may comprise a second actuator and valve 954 to control a flow rate of gases venting from the aperture 955. For example, the vent aperture 955 in FIG. 13A may be controlled by a valve arrangement as shown in FIG. 13B. A controller may control the (first) actuator and valve to occlude the flow from the main inlet to the mainoutlet as shown in FIG. 13A, and the second actuator and valve to control a vent flow from the aperture 955 downstream of the first valve, as shown in FIG. 13B. The first valve may be controlled as described above, however, in an event the first valve is unable to respond to a quick pressure increase, the second valve can operate to vent flow and pressure.

[0313] In some embodiments the PRV (e.g. PRV 100) or FCPRV (e.g. FCPRV 800) comprises a vent indicator to indicate when flow is venting from the PRV or FCPRV via the outlet chamber 102 and outlet vents 103. A number of vent indicator embodiments are described below with reference to FIGS. 14 to 21 .

[0314] In some embodiments, as illustrated in FIG. 14, the FCPRV comprises a guide or sight tube 1001 and a shuttle 1002 that moves along the tube 1001 in response to a flow of gases exiting the outlet chamber 102. The tube 1001 may be aligned with outlet vent aperture 103. When the shuttle moves with flow through the vent aperture 103 the shuttle becomes visible from an outside of the housing 180, e.g. via a clear portion of the housing and / or sight tube.

[0315] In some embodiments, as illustrated in FIG. 15, the FCPRV comprises a flap 1003 that moves about a hinge axis in response to a flow of gases exiting the outlet chamber 102, e.g. in the direction indicated by arrow A. The flap 1003 is located adjacent to or in proximity to the outlet vent 103. The housing may have a sight aperture 1004 so that when the flap bends in response to flow from the vent 103 the flap covers the sight aperture such that it becomes visible from the outside of the housing. Through the aperture 1004 the flap shows as a coloured ‘dot’ when in the bending or venting configuration.

[0316] In some embodiments, as illustrated in FIG. 16, the FCPRV comprises a plunger or shuttle received in a guide to move in response to a flow of gases exiting the outlet chamber 102. The shuttle 1005 may comprise an annular portion or cuff received in the housing outlet 188, e.g. coaxially received in the housing outlet 188. The annular housing outlet 188 may guide the shuttle. In a venting configuration the shuttle moves to be visible from an outside of the housing, e.g. may extend externally from the housing, or may become visible through a clear portion of the housing. For example the housing outlet 188 may be clear. A remainder of the housing may beopaque. FIG. 17 illustrates a similar embodiment comprising a shuttle 1005 that moves in response to gases exiting the outlet chamber, In the embodiment of FIG. 17, the shuttle comprises a member received in the outlet chamber vent outlet 103, for example there are two elongated members 1006, each elongate member received in a respective vent outlet 103.

[0317] In some embodiments, as illustrated in FIG. 18, the FCPRV comprises a plunger or shuttle 1007 received in a guide, e.g. guide tube 1008, to move in response to a pressure in the outlet chamber. The pressure in the outlet chamber 102 is proportional to the flow of gases venting from the outlet chamber and is thus an indication of the rate of gases venting from the FCPRV. When the shuttle moves along the guide it becomes visible from an outside of the housing 180, e.g. via a clear portion of the housing and / or sight tube / guide 1008. The guide tube may be marked with a scale relating the position of the shuttle along the guide tube to a flow rate. An annular space may be formed between an outer surface of the shuttle and an inner surface of the guide 1008. Venting gases may enter the sight tube 1008 through the outlet vent 103 and travel along the guide and around the shuttle 1007 and exit the guide via an outlet end of the tube. A cap 1008a may be fitted to the outlet end of the tube, the cap comprising a hole or aperture 1008b. The hole may be smaller than the cross section of the guide 1008, and may be sized to calibrate the shuttle to indicate the flow rate of the venting gases.

[0318] The venting indicator arrangements described may provide a binary indication of a venting flow from the PRV / FCPRV, e.g. indicating venting or no venting (above a threshold). Such an arrangement may be described as a ‘pop-up’ indicator, comprising a member that ‘pops up’ to be visible from outside of the housing when flow is venting from the valve. Alternatively in some embodiments a venting indicator may provide a proportional indication of venting, indicative of the rate of flow of gases venting from the outlet chamber. For example the housing or shuttle guide 1001 , 1008 or portion of a housing 180 may comprise a marking or indicia indicating an amount of travel of the shuttle that is indicative of the venting flow rate.

[0319] In some embodiments a PRV or a FCPRV may comprise an indicator to indicate a flow of gases being provided from an outlet of the PRV / FCPRV to a patient or user. For example, with reference to FIGS. 19A and 19B, in some embodiments aflow indicator comprises an impeller 1009 to be located in an outlet 153 of the FCPRV. As a flow of gases passes along the outlet 153 the flow causes the impeller to spin to indicate the flow. The impeller may be visible from an end of the outlet 153 or the outlet 153 may be transparent so that the impeller is visible through a wall of the outlet. The impeller 1009 may be rotationally mounted in an impeller housing 1010, and the impeller housing 1010 may be received in the outlet 153.

[0320] With reference to FIGS. 20A to 20C, in some embodiments, a flow indicator may comprise a flap 101 1 to be located in the outlet 153 of the PRV. The flap is movable between a closed position at least partially occluding the outlet, and an open position. Flow causes the flap to move to the open position to provide an indication of flow through the outlet to the patient. The flap may be visible from an end of the outlet 153 or the outlet 153 may be transparent so that the flap is visible through a wall of the outlet. As shown in FIG. 21 , in some embodiments, a flow indicator may comprise a plunger or shuttle 1012 received in a guide tube 1008. An inlet end 1008 c of the guide tube may be in fluid communication with the inlet 151 of the FCPRV and an outlet end 1008 d may be in fluid communication with the outlet 153 of the FCPRV, such that the guide tube senses a pressure differential across the flow restriction 152 between the inlet 151 and the outlet 153 of the FCPRV. The shuttle 1012 is adapted to move within the guide tube in response to the pressure differential across the flow restriction 152 to provide an indication of the flow through the FCPRV to the patient. As shown in FIG. 21 , the guide tube may be marked with a scale relating the position of the shuttle along the guide tube to a flow rate. A spring (not shown in FIG. 21 ) may bias the shuttle or plunger against movement in response to increasing flow rate. In other words, a spring may bias the plunger or shuttle towards a zero flow indication. As the flow increases, the flow moves the shuttle or plunger against the bias of the spring to indicate a flow rate through the FCPRV.

[0321] FIGS. 22A and 22B show examples of a patient 16 wearing a patient interface 5200, for example the nasal cannula 15 of the respiratory system 10 of FIG. 1 , with a collapsible breathing conduit portion. The patient depicted is an adult. However, the patient may be an infant, child or adolescent.

[0322] The patient interface 5200 comprises a gas (delivery) conduit 5202. The gas conduit 5202 is adapted to receive gases from the respiratory system 10 of FIG. 1(for example, via the conduit 14 shown in FIG. 1 ) and direct the gases to the patient 16. The gas conduit 5202 may comprise a reinforcement element 5203 adapted to strengthen and / or add rigidity to the gas conduit to prevent deformation or collapse of the gas conduit 5202 arising due to the application of forces against the gas conduit 5202. The reinforcement element 5203 may include a number of structures, including but not limited to plastic or metallic reinforcing beads that lie in or on the wall of the gas conduit lumen 5202.

[0323] The patient interface 5200 may comprise a gases delivery side arm in fluid communication with the gas conduit 5202. The gas conduit 5202 is in pneumatic communication with a flow manifold 5206 which is provided at an end of the gases delivery side arm. The flow manifold 5206 receives gases from the gas conduit 5202 and provides passage to one or more nasal delivery elements 5208 (e.g. nasal prongs) extending from the manifold. The one or more nasal delivery elements 5208 extend outwardly from the flow manifold 5206. The one or more nasal delivery elements 5208 are adapted to be non-sealingly positioned in one or more nares of the patient 16. Patient interface 5200 is accordingly a non-sealing patient interface. As shown, the patient interface 5200 comprises two nasal prongs 5208 adapted to be positioned with one in each of the patient's nares. Each nasal prong 5208 may be shaped or angled such that it extends inwardly towards a septum of the patient's nose. Alternatively, the patient interface 5200 may be a sealing nasal interface.

[0324] In the embodiment shown in FIGS. 22A and 22B, the flow manifold 5206 receives flow from one lateral side of the flow manifold 5206 (e.g. with respect to an imaginary vertical plane bisecting the face of the patient P) and provides a passage for flow through to the manifold to each of the nasal prongs 5208. In some embodiments a conduit may extend from a single side of the manifold, for example from the left-hand side or from the right-hand side of the manifold. In some situations, providing the conduit on the left-hand side of the patient interface may be preferred for access by a clinician, for example for intubation. Alternatively, a conduit extending from the right-hand side may be preferred, for example in procedures such as endoscopies where the patient is typically lying on his or her left-hand side. In other configurations, the patient interface 5200 may comprise greater (for example, three or four) or fewer (for example, one) nasal delivery elements 5208. In other configurations, each of the nasal delivery elements 5208 can have differentproperties. For example, one of a pair of nasal delivery elements 5208 can be relatively long and the other nasal delivery elements 5208 can be relatively short.

[0325] In some configurations, the flow manifold 5206 may be configured to receive flow from two lateral sides of the flow manifold 5206 (e.g. from a ‘left’ and ‘right’ of the flow manifold 5206 instead of just the patient's right-hand side of the flow manifold 5206 as seen in FIGS. 22A and 22B). In some such configurations, multiple gas conduits may be used to provide for pneumatic communication between the flow manifold 5206 and the respiratory system 10. For example, the patient interface may comprise dual conduits, a first gas conduit 5202 extending from a first side of the interface (in the illustrated example the right-hand side of the patient) and a second gas conduit (not shown) extending from a second opposite side of the interface. In some configurations, the flow manifold 5206 may be configured to receive flow from a non-lateral side of the flow manifold 5206 (e.g. from a ‘bottom’ or ‘top’ of the flow manifold 5206 or both) or from a front face of the flow manifold 5206, opposite the patient 16.

[0326] The patient interface 5200 may further comprise mounts and / or supports, e.g., cheek supports 5210, for attaching and / or supporting the gas conduit 5202 or conduits on the patient's face. Alternatively, or additionally, the patient interface 5200 may be held in place via one or more head straps or headgear (not shown).

[0327] The gas conduit 5202 of the patient interface 5200 comprises a first portion 5204 configured to transition from a first configuration in which a first level of gases is able to pass through the first portion 5204 to a second configuration in which a second level of gases is able to pass through the first portion 5204.

[0328] FIG. 22B shows the patient 16 wearing the patient interface 5200 comprising two nasal prongs 5208 simultaneously underneath a face mask assembly 5300. In this arrangement, face mask assembly (first patient interface) 5300 is placed upon the patient interface (second patient interface) 5200 which is worn by patient 16. FIG. 22B schematically shows the face mask assembly 5300 as a transparent structure in order to illustrate the patient interface 5200 under it. The patient interface 5200 may be used with a respiratory support system 10 and the face mask assembly 5300 may be used together with another respiratory support system (not shown). Insome configurations, the respiratory support systems providing the patient interface 5200 and face mask assembly 5300 are the same system and / or the respiratory support systems comprise a common flow source despite the modes of respiratory support being provided by the respective respiratory support systems being different. In other configurations, the respiratory support systems are separate systems.

[0329] The configuration shown in FIG. 22B may be beneficial in the provision of selective delivery of separate therapies or modes of support to a patient using different patient interfaces, and / or in stopping or ceasing the delivery of a therapy from an interface and / or allowing gases provided by an interface to be sampled. For example, the configuration may find particular application in emergency resuscitation, around intubation of a patient receiving high flow therapy, ear, nose, and throat (ENT) surgery, in assisting with conditioning of a patient in a pre-operative state prior to administration of anaesthetics, and during post-extubation and recovery.

[0330] The face mask assembly 5300 may be used as or with a respiratory support system and / or to deliver one or more substances other than a substance delivered by the patient interface 5200. For example, for delivery of anaesthetic agents and / or oxygen, to the patient, or for delivery of the same substance as the patient interface 5200 but at different flow and / or pressure levels. Alternatively, the face mask assembly 5300 may be used to reduce or stop the delivery of therapy from the respiratory support system through the patient interface 5200. In some embodiments, the face mask assembly 5300 may also be adapted to measure respiratory gases, for example exhaled carbon dioxide from the patient, the measurements of which may otherwise be affected by flow from the patient interface 5200 and associated respiratory support system.

[0331] The configuration shown in FIG. 22B allows for the alternation between the two different respiratory support systems. Additionally, this configuration may allow the patient interface 5200 to be left on the patient throughout a medical procedure and / or into recovery (whether or not the patient continues to receive therapy through the patient interface 5200 throughout the procedure) without interfering with other clinical practices.

[0332] In the embodiment shown, the face mask assembly 5300 comprises a fullface mask 5302 configured to cover both the patient's nose and mouth. In other configurations, the face mask assembly 5300 may comprise a nasal mask which is placed over the patient interface 5200 to cover only the patient's nasal region.

[0333] As shown, the face mask 5302 comprises a seal region 5304 adapted to seal against the patient's face. The face mask assembly 5300 is connected to a gas source, for example via a filter element 5350, which supplies the one or more other gases to the patient via the face mask. In some configurations, the gas source supplying the face mask assembly 5300 is different from the source supplying gas (for example a supplementary gas source or flow generator) to the patient interface 5200. In some configurations, the gas source supplying the face mask assembly 5300 is the same as the source supplying gas to the patient interface 5200.

[0334] In some embodiments, the face mask assembly 5300 is connected to a flow source that is or comprises a separate gas source or a separate respiratory support system configured to provide respiratory support separate from any flow source, or respiratory support system delivering a flow of gas to the patient interface 5200. For example, the separate respiratory support system can be a ventilator or a CPAP device or a high flow therapy device or a manual resuscitator (for example a hand-held face mask with bag). Alternatively or additionally, the face mask assembly 5300 may be connected to a device for measuring a characteristic of respiratory gases.

[0335] Alternatively, the separate respiratory support system may be or comprise an anaesthetic device (e.g. an anaesthesia machine). The gas source supplying the face mask assembly 5300 may comprise an anaesthetic gas, or air, or oxygen, or a combination of gases, for delivery via the face mask 5302.

[0336] The configuration shown in FIG. 22B allows for the delivery of gas from multiple sources via at least two different respiratory support modes, and further allows a doctor, clinician or medical professional to quickly and easily change the type of respiratory support mode.

[0337] In one particular application, a patient undergoing an anaesthetic procedure may undergo pre-oxygenation by delivering a high flow of oxygen orhumidified gases or mixture of both, for example via a nasal cannula, when the patient is still spontaneously breathing and before the administration of anaesthetic agents. Pre-oxygenation increases the patient's oxygen reservoir prior to the anaesthetic procedure. The term “anaesthetic procedure” may refer, without limitation, to general anaesthesia, procedural sedation and regional / local anaesthesia. In some circumstances, anaesthetists managing the anaesthetic procedure of a patient may want to switch between delivery of gas flow from one patient interface (for example a nasal cannula 5200) and delivery of gas flow from another patient interface, such as via a face mask 5300.

[0338] Anaesthetists may also use a mask with a bag to oxygenate a patient, and in some instances find it more beneficial to use a bag mask if a patient's vital signs begin to drop for example to deliver more pressure to support the patient's airways, or to have greater manual control over the variation in delivered pressure. In some situations, a medical professional may wish to switch between different respiratory systems or support modes. In a first mode, respiratory support may be provided by first respiratory support system (for example via the patient interface 5200) and in a second mode respiratory support may be provided by a second respiratory support system (for example via the face mask assembly 5300), with the support from the first system reduced or stopped. For example, it may be desirable to stop high flow from a patient interface 5200 when delivering anaesthetic agents through the face mask assembly 5300 because a high flow from interface 5200 may modify the expected behaviour of the anaesthetic circuit provided by the face mask 5300 (which is typically a sealed circuit) and may dilute anaesthetic agents delivered by face mask assembly 5300. Thus, it may be advantageous to be able to stop the additional flow from the first respiratory system or substantially reduce it.

[0339] In some configurations, the switching between two respiratory support modes or subsystems may be facilitated by a structure of the first gas conduit 5202, which has first portion 5204 configured to transition between a first configuration in which a first level of gases is able to pass through the first portion 5204 and a second configuration in which a second level of gases is able to pass through the first portion 5204.

[0340] In some configurations, the first portion 5204 is configured to be more collapsible or otherwise better adapted for changing the flow of gas through the first portion 5204 (to reduce the flow of gas through the conduit and to the patient) than other portions of the conduit 5202, and / or allowing a seal of a mask to seal over the top of the conduit. In other configurations the entire conduit 5202 may be configured to be collapsible or otherwise better adapted for changing the flow of gas through conduit 5202. In some configurations a vent arrangement may be provided upstream of a collapsible portion, to vent gases from the conduit upstream of the collapsible portion 331 to atmosphere. In some embodiments, a pressure valve or an FCPRV, such as those described above, may comprise the vent arrangement.

[0341] In some embodiments, the first configuration is a fully or substantially open condition, and the second configuration is a fully or substantially closed condition. That is, the conduit 5202 is configured to be more collapsible, deformable or otherwise adapted to fully or substantially close off the flow at the first portion 5204 than at other portions of the conduit 5202, when in the second configuration. It will be understood that there may be one or more intermediate conditions between the first and second configurations, where these one or more intermediate conditions may be less open (or more closed) than the fully or substantially open condition (first configuration) but more open (or less closed) than the fully or substantially closed condition (second configuration).

[0342] FIGS. 23A and 23B provide schematic illustrations of the first and second configurations wherein FIG. 23A shows the first configuration (substantially open) and FIG. 23B shows the first portion 5204 in the second configuration (substantially closed) by application of the seal 5304 of face mask 5302 over the first portion 5204. In some embodiments, the first portion 5204 (i.e. the more collapsible or deformable section) of the first gas conduit 5202 should be of a length that is greater than a width of a section of a seal 5304 of the face mask 5302 that bears over the first portion 5204 of the first gas conduit 5202. This ensures the seal of the face mask 5302 does not bear over a non-collapsible section of the first gas conduit 5202. For example, the first portion 5204 may extend from a distance of 35 mm or less from the centre of a user's nose to at least 50 mm from the centre of a user's nose. The first portion 5204 may have a length of at least about 5 mm, about 1 mm to about 30 mm in length, or about 5 mm to about 15 mm in length, or about 10 mm in length. In someembodiments the length of the first portion may be at least 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm, 45 mm, 50 mm or greater.

[0343] The first portion 5204 may progress between the first and second configurations based on a relative level of force applied to a wall of the first portion 5204. For example, as shown in FIGS. 22 and 23, the force may be applied by the seal 5304 of face mask 5302. In this example, first portion 5204 is configured to be positioned under the seal 5304 of the face mask 5302.

[0344] Alternatively, the force may be applied to first portion 5204 by other means, e.g., clamps (not shown), or alternatively a medical practitioner may compress the conduit by pressing on the conduit wall with a finger or thumb.

[0345] In some embodiments, the seal of the face mask acting on the first portion 5204 of the gas conduit 5202 causes the first portion 5204 to form a seal or at least a partial seal between the nasal outlets of the patient interface 5200 and the flow source 12. Additionally, the seal of the face mask forms a seal or at least a partial seal over the first portion 5204 of the gas conduit 5202.

[0346] Switching between respiratory support therapies may therefore be achieved simply by applying a mask to the patient's face so that the seal of the mask collapses (partially or completely) the first portion 5204 of the gas conduit 5202 supplying the patient interface 5200 to reduce or stop the therapy supplied by the patient interface 5200. This also provides a seal between the face mask 5300 and the external surface of the first portion 5204 of the conduit 5202 such that respiratory support or therapy can be provided by the face mask 5300 where the respiratory support or therapy provided by the patient interface 5200 can be reduced or shut off. The patient interface 5200 with a collapsible conduit portion 5204 allows a user, e.g. an anaesthetist or a nurse or a clinician, to use a face mask assembly 5300 over the patient interface 5200 to select and control delivery of gases from multiple respiratory support systems to provide different therapies or modes of support. The patient interface 5200 may be structured to function in a manner that prevents the delivery of high flow and other respiratory therapy or anaesthetic agents through the patient interface 5200 when the first portion 5204 is in a second configuration. In someembodiments removal of the face mask assembly 5300 from the patient's face allows the first portion 5204 to return to its first configuration so that respiratory support or therapy supplied by the patient interface 5200 can recommence or return to operating in the conditions present prior to the change in configuration.

[0347] With reference to Figures 23C and 23D, another configuration of the user interface is shown. This configuration has a face mask 311 applied over the nasal cannula 301 and prongs 305 of the nasal cannula. The face mask 311 has a mask seal 330 which may have a compressed section 331 that can easily fit over the nasal cannula e.g. the nasal cannula gas conduit E.g. Figure 23D shows a cross-section through the mask seal 330 and nasal cannula 301 when the face mask 311 is applied over the nasal cannula 301 . The face mask 311 may clip onto the cannula 301 .

[0348] In some embodiments, the face mask 311 may be configured and adapted to allow intrusion of the gas conduit 302 into the interior volume of the face mask 311 , while maintaining a substantially gas tight seal between the face mask and the patient’s face. The gas conduit 302 may be the gas conduit of the nasal cannula 301 or may supply gases to the nasal cannula 301 .

[0349] The face mask 311 comprises one or more accommodation sites or portions 333 adapted to facilitate intrusion of the gas conduit 302 into the interior volume of the face mask while maintaining the seal between the interface and the patient’s face. The one or more accommodation sites or portions 333 is provided on or adjacent the face mask seal and / or the face mask body. In the embodiment shown, the accommodation site is provided as a cut-out in the seal. The cut-out has a profile which is similar, or slightly smaller in dimension than the cross-section of the gas conduit. This is so that the gas conduit can extend into or out of the interior volume of the body without leaving a gap between the seal and the user's face which could then compromise the seal between the face mask seal and the patient’s face.

[0350] The accommodation sites or portions of the interface may allow for the face mask to be used with the nasal cannula 301 .

[0351] The nasal cannula 301 is used to deliver a relatively high flow of oxygen or a high flow of blended gases or high flow of air (e.g. via a high flow device). The mask may be used for various other respiratory support or for anaesthetic delivery. Asmentioned above, the mask comprises a seal to seal against the patient’s face when in-use.

[0352] The accommodation sites or portions 333 allow for the nasal cannula to be used with the face mask interface without compromising or substantially affecting or interfering with the seal between the interface and the patient’s face. This may allow for a nasal cannula 301 which for example delivers high flow therapy to be used in combination with the face mask 31 1 which is used to provide other respiratory support. A medical practitioner can adjust or choose which respiratory support to be used on the user without irritating the user by constantly adding or removing the user interfaces, such as the mask and the nasal cannula.

[0353] As described above, in some embodiments, the respiratory support system includes a pressure valve or device. The system 10 may include such a pressure relief or regulating device, or pressure limiting device 100 (e.g. a pressure relief valve or PRV or FCPRV). This pressure limiting device 100 may be a valve having features described above and as described in WO2018 / 033863, the entirety of which is incorporated by reference herein. The pressure valve or FCPRV may activate in response to a restriction or occlusion in the conduit e.g. due to a face mask being placed over a collapsible conduit portion of a nasal cannula if pressure in the system rises accordingly. The pressure valve or FCPRV may vent or co-ordinate venting of flow when a pressure limit is reached. In some embodiments, the respiratory system does not include, or excludes a pressure relief valve or device. In some embodiments, the respiratory system does not include, or excludes a flow compensated pressure relief valve or device, for example, a flow compensated pressure relief valve having features as described in WO2018 / 033863.

[0354] Pressure relief and pressure control are particularly desirable for use in a respiratory support system such as a high flow system 10 comprising a non-sealing patient interface (such as a nasal cannula in patient interface 5200), to provide an upper limit on pressures that may be generated downstream from the flow source 12 which in turn can impact patient airway pressure (also referred to as patient pressure). Importantly, the upper pressure limit may be configured to provide a safety threshold, to ensure patient pressure safety, and / or to prevent damage to tubes, fluid connections, or other components in the system 10 due to over-pressure. Similarly, apressure relief or regulating device 100 may be used in a sealed system, such as CPAP (continuous positive airway pressure), BiPAP (bilevel positive airway pressure) and / or Bubble CPAP systems to regulate the pressure provided to the patient.

[0355] In some embodiments, the respiratory system does not include, or excludes a pressure relief valve or device. In some embodiments, the respiratory system does not include, or excludes a flow compensated pressure relief valve or device, for example, a flow compensated pressure relief valve having features as described in WO2018 / 033863. In some embodiments, the respiratory system includes a controller comprising a processor configured to execute instructions stored in memory, for controlling one or more devices providing a flow of gas to a patient to achieve pressure relief, or pressure guided respiratory support and / or flow rate guided respiratory support.Flow rate guided control and pressure guided control

[0356] A respiratory support system 22 for providing a flow of respiratory gases to a patient is shown in each of Figures 24A to 24C according to a different embodiment of the present disclosure. The respiratory support systems 22 may be high flow respiratory support systems 22, each incorporating a high flow device for providing a high flow of gas to a patient 16.

[0357] Figure 24A shows a respiratory support system 22 which may comprise a high flow device providing high flow respiratory support to a patient 16. The high flow device can include a controller 24 and a flow source 12 which may comprise a flow modulator configured to be controlled by the controller 24 to modulate a flow of respiratory gases to a patient 16. The controller may be configured to receive an input of a flow rate and a pressure of the flow of respiratory gases in the system, and be configured to control the flow source to provide the flow of respiratory gases at a target flow rate to a patient and control the flow modulator to modulate the flow of respiratory gases to a target pressure when the pressure of the flow of respiratory gases in the system meets or exceeds a pressure threshold value corresponding to that target flow rate. In some embodiments, the target pressure comprises the pressure threshold value corresponding to the target flow rate or a pressure threshold value corresponding to a flow rate less than the target flow rate. The pressurethreshold value corresponding to the target flow rate may be determined by the controller e.g. using a function stored in a memory component of or operatively coupled with the controller. A target pressure or pressure threshold may be defined as an absolute pressure value or a gauge pressure value.

[0358] Typically, the system 22 further comprises one or more sensors 28 configured to determine characteristics of the respiratory support system, for example characteristics of the flow of respiratory gases in the respiratory support system and / or being provided to the patient. Sensors 28 may be located internally or externally of the high flow device. The system 10 can use ultrasonic transducer(s), flow rate sensor(s) such as thermistor flow sensor(s), pressure sensor(s), temperature sensor(s), humidity sensor(s), or other sensors, in communication with the controller 24, to monitor characteristics of the system and / or operate the system 22 in a manner that provides suitable respiratory support. Such characteristics can include gases concentration, flow rate, pressure, temperature, humidity, or other characteristics. The sensors 28, such as pressure, temperature, humidity, and / or flow rate sensors, can be placed in various locations of the system 22 such as for example, inside a main housing containing components of system 22, the patient conduit 12, and / or the patient interface 5200. The controller 24 can receive signals from the sensors 28 providing controller inputs used in determining control of one or more components of the respiratory support system 22 in a manner that provides suitable respiratory support. For example, the controller 24 may use signals from one or more of the sensors 28 to determine a suitable target temperature, humidity, flow rate, and / or oxygen concentration of the gases flow, or suitable pressures that may be generated downstream from the flow source 12 within the system. Providing suitable respiratory support can include meeting a patient’s inspiratory demand.

[0359] In some embodiments, the sensors comprise flow rate sensors (such as e.g. ultrasonic, thermal based or other suitable flow rate sensors) configured to sense flow rate of the flow of gases provided to the patient 16, and the sensed flow rate is used by the controller 24 to determine a safe upper pressure limit (also referred to herein as a maximum or safety pressure threshold) for operation of the system 22 at the sensed flow rate. The controller 24 can then control operation of one or more components (e.g. actuators) of system 22 (or transmit a control signal to one or more components of the system) such as the flow source 12 to e.g. modify blower speed,so as to achieve a target flow rate stored in the controller, or a memory in operative communication with the controller or any other component of the system. The target flow rate may be a flow rate set point entered by a user of the system through I / O interface 20 or it may be determined or pre-programmed into the controller or associated memory / components. Modifying the flow rate may involve an increase or decrease in blower speed (and / or an increase or decrease in aperture size of a proportional valve), to achieve an increase or decrease in flow rate, respectively.

[0360] In some embodiments, when the system begins operation from an ‘off’ or dormant state, the controller is configured to monitor the flow rate of the flow of respiratory gases in the system and is configured to control the flow modulator to modulate the flow of respiratory gases to achieve the target flow rate. Ideally, the target flow rate changes over time to increase from a current value to a flow rate set point. The controller may also be configured to monitor the flow rate of the flow of respiratory gases to a new target flow rate in other circumstances, such as when a user changes the flow rate set point to which the system operates.

[0361] The controller 24 may receive inputs from one or more pressure sensors. The controller can measure or infer the pressure delivered to the patient from the pressure sensor inputs. The pressure sensors are located downstream of the flow source 12. For example, a pressure sensor can be located at or near the patient interface 5200. A pressure sensor can also be located directly after the flow source. The pressure delivered to the patient’s airways (patient pressure) can be determined by the controller calculating the difference between the ambient pressure and the absolute pressure downstream of the flow source. The patient pressure can be estimated by measuring the pressure in the main device housing downstream of the flow generator and calculating the pressure drop along the delivery conduit 5202. The pressure sensor(s) can also be located at other locations in the pneumatic circuit downstream of the flow source 12. The pressure sensor(s) can include one or more gauge pressure sensors, or alternatively one or more absolute pressure sensors. The gauge pressure sensor(s) can directly measure a difference between the absolute pressure downstream of the flow generator and the ambient pressure. In systems having two absolute pressure sensors, one sensor can be located downstream of the flow source to measure the absolute pressure downstream of the flow source and the other sensor can be located in a different location to measure the ambient pressure.The controller can determine the pressure delivered to the patient by determining the differences between the pressure measurements made by the two absolute pressure sensors.

[0362] Controller 24, in various embodiments, is configured to receive one or more signals directly from one or more pressure sensors, or through manual inputs provided to a user interface which is in operative communication with the controller, or derived values, which are indicative of system pressure in the pneumatic circuit downstream of the flow source 12 through which the flow of respiratory gases in the respiratory system 22 are delivered to patient 16. The controller 24 may convert the received signals to pressure values, and the controller may compare these values with pressure threshold values for corresponding flow rates as stored by the controller or a memory device or module in operative communication with the controller. Since the controller is required to know the flow rate of gases in the pneumatic circuit in order to ascertain if the system pressure meets or exceeds the pressure threshold for corresponding flow rates, the controller may also receive one or more signals directly from one or more flow rate sensors, or the controller may obtain flow values through manual inputs provided to a user interface in operative communication with the controller, or it may derive flow values e.g. by knowing the resistance to flow in the pneumatic components of the system 22, and calculating the flow from e.g. blower speed in the flow source 12.

[0363] Controller 24 may determine the system pressure continuously, or intermittently and there may be benefits associated with each. For example, continuous determination of system pressure provides for maximum responsiveness in terms of how fast the controller can detect a change in which system pressure meets or exceeds (or falls below) the pressure threshold for a corresponding flow rate, and respond quickly by controlling the flow source 12 e.g. to reduce blower speed (which may in turn reduce the flow of respiratory gases) in response to the pressure meeting or exceeding the pressure threshold values for the corresponding flow rates, and to control the flow source 12 to modulate the flow of respiratory gases in response to the pressure not meeting or exceeding the pressure threshold values for the corresponding flow rates. Alternatively, the controller 24 may sense or receive pressure inputs intermittently which provides for more economical operation, however the system may experience delays in responsiveness since the system pressure maychange sometime before the controller receives a pressure input, and so the modulating and / or control of the flow source 12 will not be as responsive.

[0364] The pressure threshold values for corresponding flow rates may be stored by a memory component of the controller 24 or a memory device or component external to and in operative communication with controller 24. The relationship between the pressure threshold values and the corresponding flow rates may be stored as one or more of a function, a curve, a lookup table, or a mathematical model or algorithm used by the controller to determine the particular pressure threshold value for a corresponding flow rate. In some embodiments, the relationship between the pressure threshold values and the corresponding flow rates as utilised by the controller 24 can be represented graphically and examples are shown in Figures 24D to 24H.

[0365] Figure 24B shows another embodiment of a respiratory support system 22 comprising a high flow device for providing high flow respiratory support to a patient 16. The high flow device can include a controller 24 and a flow source 12 configured to be controlled by the controller 24 to modulate a flow of respiratory gases to a patient 16 via a patient interface 5200 (as previously described with reference to Figures 22A to 23B), in fluid communication with the flow source 12 and configured to deliver the flow of respiratory gases to the patient 16. The respiratory system 22 also comprises one or more sensors 28 configured to determine system pressure downstream of the flow source 12, and / or the flow rate of the flow of respiratory gases in the respiratory support system providing the gases to the patient.

[0366] As previously described, the patient interface 5200 receives a flow of respiratory gases from the flow source 12 via a conduit 5202. Conduit 5202 comprises a first portion 5204 configured to operate in at least a first configuration and a second configuration.

[0367] The controller 24 in the embodiment shown in Figure 24B may be configured to receive inputs indicative of pressure and / or flow rate of the flow of respiratory gases in the respiratory support system 22 from the sensors 28, compare the sensed pressure with a pressure threshold, and control the flow source 12 to provide a first modulation of the flow of respiratory gases in response to the pressuremeeting or exceeding the pressure threshold. Further, the controller 24 can control the flow modulator to provide a second modulation of the flow of respiratory gases in response to the pressure not meeting or not exceeding the pressure threshold.

[0368] As mentioned, in some embodiments, the second modulation is different from the first modulation and the first modulation comprises maintaining the system pressure downstream of the flow source at a target pressure, for example at the pressure threshold and / or reducing the system pressure downstream of the flow source to a target pressure that is below the pressure threshold. The second modulation may comprise increasing, or decreasing the flow rate of respiratory gases to a target flow rate in response to the system pressure downstream of the flow source not meeting or not exceeding the pressure threshold.

[0369] A corresponding flow rate may be a flow rate of the flow of respiratory gases provided by a flow source, at or along a portion of the pneumatic circuit of respiratory system 22 providing the flow of gases to the patient interface 5200, at the patient interface 5200 and / or at the patient’s airways. As noted in the foregoing, the corresponding flow rate may be a flow rate obtained by one or more flow rate sensors providing input directly to controller 24, it may be entered by a user operating a user interface in operative communication with the controller, or it may be inferred from other factors such as e.g. blower speed of the flow source, if the resistance of the pneumatic components of the system 22 are known.

[0370] Figure 24C shows a respiratory system 22 according to another embodiment of the present disclosure. In this embodiment, the system 22 includes a high flow device including the controller 24 and the flow source, in the form of a flow modulator or a blower 27, configured to be controlled by the controller 24 to generate a flow of respiratory gases to a patient 16 via a delivery conduit 5202. Typically, the controller 24 and the blower 27 are contained within a common housing 33 (forming the high flow device) although it is contemplated that the controller could be located remotely from or in a separate housing to the blower 27 and other components of the respiratory support system. In some embodiments, the housing 33 also contains a humidifier comprising a humidification chamber through which a flow of gases from the blower is passed to humidify the gases provided to the patient by increasing the moisture content and in some cases, temperature. The humidified gases are thendelivered by delivery conduit 5202 (which may comprise a part of the delivery circuit 38 downstream of the humidifier and the patient breathing circuit 40) to the patient interface 5200. The respiratory support system 22 further includes a patient interface 5200 configured to receive a flow of gases through delivery conduit 5202 for delivery to the patient 16. The patient interface 5200 may comprise one or more nasal elements or a face mask assembly configured to provide gases to the patent’s nare(s) or mouth respectively or both. The patient interface 5200 receives a flow of respiratory gases from the blower 27 via a conduit 5202. Conduit 5202 comprises a collapsible first portion 5204 configured to operate in at least a first configuration and a second configuration as described elsewhere in the specification.

[0371] The collapsible portion 5204 is configured to operate in a first configuration (e.g. un-collapsed or fully or substantially open condition) and collapsible from the first configuration to a second configuration (e.g. collapsed or fully or substantially closed condition). It will be understood that there may be one or more intermediate conditions between the first and second configurations, where these one or more intermediate conditions may be less open (or more closed) than the fully or substantially open condition (first configuration) but more open (or less closed) than the fully or substantially closed condition (second configuration). As mentioned, controller 24 alters the operation of the flow source when the collapsible portion 5204 is in the second configuration compared to when the collapsible portion 5204 is in the first configuration. In some embodiments, this is achieved by modulating (e.g. reducing) the speed of the blower 27 which may in turn modulate (e.g. reduce) the flow of respiratory gases to a reduced flow rate in the system in response to the sensed system pressure meeting or exceeding the pressure threshold values for the corresponding flow rate of the flow of respiratory gases being provided to the patient. In some embodiments, the controller 24 alters the condition (e.g. extent of opening) of one or more proportional valves which may in turn modulate (e.g. reduce) the flow of respiratory gases to a reduced flow rate in the system in response to the sensed system pressure meeting or exceeding the pressure threshold values for the corresponding flow rates of the flow of respiratory gases being provided to the patient. In some embodiments, the controller 24 alters the operation and / or condition of both a blower and a proportional valve.

[0372] The respiratory system 22 shown in Figure 24C includes two types of sensors: flow rate sensor(s) 32 configured to sense flow rate of the flow of respiratory gases in the respiratory system 22; and pressure sensor(s) 29 configured to sense pressure in the respiratory system 22 downstream of the blower 27 including downstream of an outlet of the housing 33.

[0373] Flow rate sensor(s) 32 and pressure sensor(s) 29 are located downstream of the flow modulator, i.e. blower 27. The flow rate sensor(s) 32 and pressure sensor(s) 29 are configured to sense flow rate and pressure, respectively, downstream of the flow modulator and in the delivery conduit 5202. The controller 24, in this embodiment, is configured to receive data indicative of pressure and flow rate of the flow of respiratory gases in the delivery conduit 5202, from the pressure sensor(s) 29 and flow rate sensor(s) 32, and to compare the sensed pressure with pressure threshold values for corresponding flow rates as stored by the controller 24 or a memory component with which the controller is operatively coupled.

[0374] In some embodiments, one or more pressure sensors may be located downstream of blower 27 near the system outlet to which delivery conduit 5202 is coupled, to determine system outlet pressure. The pressure at the outlet can be used to infer patient pressure as discussed below. In some embodiments, a second pressure sensor 29 may be provided for redundancy, to provide a backup pressure input in the event that the primary pressure sensor fails. In some embodiments, the controller 24 may receive an input from an absolute (ambient) pressure sensor 29a to detect operating air pressure which may vary e.g. due to altitude, and can have a bearing on performance of the flow source and its components such as the blower. Gauge sensors, however, may have superior resolution and may be a preferred pressure sensor for many applications.

[0375] The patient interface 5200 has features as described above. Thus in some embodiments, patient interface 5200 is a nasal cannula, such as a non-sealing nasal canula, receiving a flow of respiratory gases from a conduit 5202 having a collapsible portion 5204 which is capable of transitioning between a first configuration (Figure 23A) and a second configuration (Figure 23B).

[0376] The patient interface 5200 will hereinafter be referred to as nasal cannula 5200 to provide more particular description of parts involved in the delivery of respiratory gases according to embodiments of the disclosure. In some embodiments, the collapsible portion 5204 is collapsed to the second configuration when a face mask assembly 5300 is applied to the patient 16 over the nasal cannula 5200. The face mask assembly 5300 may be referred to in short form as mask 5300. The delivery conduit 5202 is thus configured to deliver the flow of respiratory gases to the patient 16 through the collapsible portion 5204 when in the second configuration at a reduced flow rate compared to when the collapsible portion 5204 is in the first configuration. For example, the reduced flow rate may be less than about 15L / min, about 0-15L / min or about 5-15L / min or OL / min. The flow rate when the collapsible portion 5204 is in the first configuration is a high flow rate which may be more than about 20L / min, in the range of about 20-90L / min, or about 40-70L / min.

[0377] The delivery conduit 5202 may be considered to provide a delivery circuit 38 and a patient breathing circuit 40 disposed between the delivery circuit 38 and the patient interface 5200. The patient breathing circuit 40 is connected to the delivery circuit 38 via an outlet connector 34. In the embodiment of Figure 24C, the controller 24, blower 27, pressure sensor(s) 29, flow rate sensor(s) 32, and the delivery circuit 38 are housed within a housing 33. The outlet connector 34 may be mounted to or through the housing 33 to provide a physical coupling between the delivery circuit 38 inside the housing and the patient breathing circuit 40 outside the housing. It will be appreciated that the patient interface 5200 may be connected to the patient breathing circuit 40 via a connector that is not shown in this Figure. It will also be appreciated that the system 22 may further comprise one or more proportional valves, of the type described above, and this may also be housed within the housing 33. As will be appreciated, intentionally collapsing a portion of the patient interface 5200, or the collapsible portion 5204 from which the patient interface receives a flow of gas, introduces a restriction to flow in the respiratory system. When this occurs, in an example of the respiratory system 22 in use, the controller 24 detects the restriction to the flow by determining there has been an increase in system pressure, and may control the flow modulator (for example by changing the speed of the blower 27 and / or a size of a flow passage through a proportional valve) to modulate the system pressure. When the collapsible portion 5204 returns to the first configuration, thecontroller 24 detects the change by determining there has been a reduction of system pressure, and may control the blower 27 and / or the proportional valve to increase the flow of respiratory gases which may, in turn, increase the system pressure, while it remains below the pressure threshold corresponding to the flow rate at which the gases flow.

[0378] Respiratory support systems may be susceptible to accidental restrictions to flow, caused by e.g. snagging, folding, or crushing of the delivery conduit 5202. Another way flow may be restricted in such systems is when specific patient anatomy and / or airway features have higher resistances. These restrictions may create a substantial backpressure in the flow path upstream of the restriction. In some embodiments of the respiratory system 22, when these restrictions occur, the respiratory system may determine by operation of controller 24, that pressure in the delivery conduit 5202 exceeds the pressure threshold value for a corresponding flow rate and the controller 24 can control the blower 27 to reduce the flow of respiratory gases - thus reducing pressure in the system 22. When the accidental restriction is removed, the controller 24 may further control the blower 27 to increase the flow of respiratory gases - thus increasing pressure in the system 22. Alternatively or additionally the controller 24 may control proportional valve to open further, thereby increasing the flow of respiratory gas which may increase pressure in system 22.

[0379] Figures 24D to 24H are graphs illustrating curves that represent a relationship between flow and pressure, which are used in embodiments of the present disclosure in the control of components of a respiratory support system to deliver a flow of respiratory gases to a patient. As mentioned, the controller 24 is configured to control the flow modulator to increase, maintain or reduce the flow of respiratory gases. For example, the controller 24 is configured to control operation of the blower 27 to increase, maintain or reduce an angular velocity (i.e. speed) of the blower 27 by providing an electronic control signal, or by directly controlling the voltage or current supply to the blower, which in turn increases, maintains or reduces the flow of respiratory gases. The controller 24 determines the appropriate control for the flow modulator in response to the pressure not meeting or not exceeding, or meeting or exceeding, one or more pressure threshold values at corresponding flow rates, such as those represented in the curves of Figures 24D to 24H which may hereinafter be referred to as pressure limit curves C. In some embodiments, thecontroller 24 determines the appropriate control for the flow modulator in response to the system pressure being below or meeting or exceeding, a pressure threshold value at a corresponding flow rate. One or more pressure threshold values may be a predetermined pressure threshold value (also referred to herein as a predetermined occlusion pressure threshold). As mentioned, the pressure threshold values and corresponding flow rates may be stored in a memory component of or operatively coupled with controller 24. A pressure threshold value may be an occlusion pressure threshold for determining when an occlusion is present in a corresponding gas flow passage.

[0380] In some embodiments, the controller 24 is configured to control the flow modulator to modulate the flow of respiratory gases to the target pressure when the flow rate of the flow of respiratory gases is less than the target flow rate. This avoids a condition where the controller tries to increase flow to approach the target flow rate which may cause the system pressure to exceed the pressure threshold value for the current flow rate. Alternatively / additionally, the controller may be configured to control the flow modulator to modulate the flow of respiratory gases to the target flow rate when the flow rate of the flow of respiratory gases is above the target flow rate, i.e. to modulate flows down to the target flow rate when it has been exceeded, to avoid risk of harm to the patient. In some embodiments, the controller is configured to control the flow modulator to the target pressure when the pressure of the flow of respiratory gases exceeds the pressure threshold value corresponding to the target flow rate or a pressure threshold value corresponding to flow rates less than the target flow rate.

[0381] The pressure limit curves C have been determined by taking into account known resistances to flow of system components and known flow ranges to be delivered to a patient. It will be appreciated that the pressure limit curves C may be stored in a memory that is accessible by the controller 24 as discussed previously and which may include a computer-readable medium (e.g., a disk, hard drive, USB, optical drive or other data storage device) containing program instructions for causing the controller 24 to perform the necessary control as described herein.

[0382] In some embodiments, a pressure limit curve C provides a safety threshold (also referred to herein as a safety pressure threshold or maximum pressure threshold) corresponding to a safe patient pressure for a corresponding flow rate ofgases to the patient when there is restricted flow to the nasal cannula 5200, such as when collapsible portion 5204 is in the collapsed configuration and a mask 5300 is applied. This pressure threshold is applied to reduce risk of over-pressurising the patient, which may lead to barotrauma of the patient’s airways. Thus, in some embodiments, the controller 24 automatically reduces flow through the nasal cannula 5200 to the patient when there is a blockage in the delivery conduit 5202 such as an accidental blockage, or when the mask 5300 is used to ventilate the patient and is applied over the nasal cannula with a pressure sufficient to collapse the collapsible portion 5204 e.g. to the second configuration. When this occurs, the controller 24 may implement pressure-control of the system 22 by controlling operation of the blower 27 and / or other components such as a proportional valve to achieve a target pressure guided by pressure limit curve C. Further, controller 24 may automatically increase the flow of respiratory gases when the mask is removed enabling the collapsible portion 5204 to return to the first configuration.

[0383] In some embodiments, the controller 24 may be programmed to apply a further safety threshold being a pressure limit which, when reached at any flow rate, will trigger the controller 24 to substantially reduce or stop operation of the flow modulator, for example by turning off the blower 27 and / or closing off of the proportional valve. This safety threshold may be a value above about 20 cmb O such as for example about 30 cmF O, about 40 cmFkO, about 50 cmF O or about 60 cmFW or about 70 cmF . In some embodiments, a safety threshold of about 60 cmFW may be preferred, or a safety threshold calculated as a safe margin above the predetermined pressure threshold value for the corresponding flow rate may be used, or calculated as a safe margin above a normal expected region or range of system pressures.

[0384] The resistance to flow of system components may be measured, calculated and / or estimated, and may include the resistance of all components of the respiratory support system 22, optionally all components downstream of an outlet of the flow modulator. This requires carefully designed consumables of the system 22 to have tight tolerances for resistance to flow, or use of conservative assumptions to account for less strict manufacturing tolerances. Knowledge of the resistance of the system 22 enables the estimate of the pressure difference across the respiratory support system 22 to allow inference of patient pressure from system pressure. Therespiratory support system 22 may also determine a real time characterization of resistance in the delivery conduit 30 from the pressure sensors 29 and flow rate sensors 32, compare this to the known resistance to reduce expected variation in the patient pressure. Knowledge of the current patient pressure ensures pressure can be controlled according to the pressure limit curve C and, as a result, the respiratory system 22 can better control pressure / flow to the nasal cannula 31 . In practice, controller 24 operates the blower 27 and other components of system 22 to avoid or minimise operation of the system in the “over pressure” area corresponding to region 64 as discussed below.

[0385] During operation of the respiratory support system 22, the “normal” operating pressure values for corresponding flow rates are shown as being beneath the pressure limit curve C. More specifically, Figures 24D and 24E show an area 58 corresponding to Normal operating system pressures at corresponding flow rates. Advantageously, the Normal operating zone provides a range of safe system pressures for the corresponding flow rates and therefore provides a “safe” zone which in practice provides scope for a clinician to safely manipulate components of the system, such as the delivery conduit 5202, collapsible portion 5204, manifold 5206, cannula 5200 and other components required for delivery of gases to the patient, without risk of delivering excess pressure to the patient’s airways and risking barotrauma or other harm.

[0386] Figure 24E shows a restricted operating area 60 in which a pressure limit curve C may be defined for use in controlling operation of the system for delivery of respiratory gases to the patient. In some embodiments, the controller calculates the shape of curve C using a function stored in a memory component of or operatively coupled with the controller. Thus, upon receipt of a “set point flow rate” entered to the I / O interface 20 by a user, the controller defines the upper flow limit of the required curve C and, knowing the lower pressure limit (which may be defined by the manufacturer or the user as an operational constraint of the system), uses the function to fit the curve within the restricted operating area 60. When the controller 24 determines the system pressure to be within the restricted operating area 60 and under the curve C it may not immediately alter control of the system components to reduce flow rather, it may permit continued delivery of flow at the current control. The restricted operating area 60 may be desirable to avoid the controller 24 immediatelyreducing flow rate every time there is a bend in the tube which may be inadvertent, or may occur as clinicians are interacting with the patient and / or arranging various components of the respiratory support system including patient interfaces on the patient causing temporary or transient blockages or restrictions to flow. This area is absent from the embodiment shown in Figures 24D and 24F as the pressure limit curve C has been defined immediately next to the normal operating region and provides the pressure thresholds that may be used by the controller. The control parameters conveyed by embodiment of Figures 24D and 24F may be utilised in scenarios where it may be desirable to limit the extent of inadvertent (or deliberate) temporary blockages in the delivery conduit 5202 before flow rate is reduced.

[0387] The area below the pressure limit curve C and below the normal operating area is the incompatible area 62. Operation in this area might occur if the delivery conduit leaks or becomes disconnected from the flow generating components of the system, e.g. if it becomes decoupled from the housing 33. Flow rates and pressures in this incompatible area 62 may also occur if incompatible or unintended system components are used. This area may also include pressures for corresponding flow rates which may be undesired, such pressures that may not achieve adequate or intended respiratory support. In some embodiments, detection by controller 24 of pressures in the incompatible / disconnected zone 62 may result in controller 24 sounding an alarm or alert, which may be visible and / or audible, which communicates to system users that the system has detected an incompatible condition for example one that may signify a leakage or disconnection in the system 22.

[0388] The area above the pressure limit curve C, and above the restricted operating area 60 shown in Figure 24E, is referred to as the over pressure area 64. In embodiments that apply a safety threshold (Figure 24F), this limit may be located within the over pressure area 64 .When the controller 24 determines that the system pressure exceeds the threshold defined by pressure limit curve C, it may alter control of the blower 27 to reduce the blower speed in order to lower system pressure to a target pressure, for example a pressure at or below a pressure value defined by curve C at the corresponding flow rate. Alternatively / additionally, the controller 24 may control operation of a valve such as a proportional valve to lower pressure in the system. In some embodiments, the controller 24 may be configured to track time spent in the restricted operating area 60 and / or above the pressure limit curve C and,if the pressure in the respiratory system 22 remains in this area after a certain period of time, the controller 24 may trigger an audible and / or visible alarm to alert users to the possibility of a blockage in the gas delivery conduit or other components of the system.

[0389] Figure 24E also shows that the sigmoidal pressure limit curve C allows for an increase in pressure to occur (as long as the increase is below the pressure threshold or predetermined occlusion threshold) without that increase causing the controller to operate in pressure guided control mode (i.e. in which the controller causes a reduction in pressure and / or flow). That is, in use, in the first configuration of the collapsible portion 5204, a nominal (baseline) system pressure in the normal operating pressure area 58 is below the pressure limit curve C by a first pressure margin M1 or greater. In the second configuration of the collapsible portion 5204, a nominal (baseline) system pressure in the normal operating pressure area 58 is below the pressure limit curve C by a second pressure margin M2 or greater. The nominal (baseline) pressure may be an upper pressure limit of the normal operating pressure area 58. It can be seen in Figure 24E that the first pressure margin M1 is greater than the second pressure margin M2. That is, the system 22 provides an allowable deviation of pressure change in the system 22. When the system 22 is in the normal operating state 58, there is a larger margin of allowable deviation from normal system pressure at higher flows than when the flow is lower. The tight pressure margins at lower flows which may correspond to the collapsed state and the greater pressure margins at higher flows which may correspond to the uncollapsed state provide that in the absence of a significant pressure and / or flow rate change, the control of system 22 remains in those regions and in the “collapsed” or “uncollapsed” states respectively. Accordingly, the controller 24 requires pressure in the system to vary significantly before initiating a change in control (e.g. from a pressure control to flow control or vice versa) as may be required when the collapsible portion 5204 transitions from a second (collapsed) configuration to a first (uncollapsed) configuration or vice versa, ensuring that control is not altered until the blockage is substantially unblocked (triggering a shift to flow control) or until the blockage is more than transient (triggering a shift to pressure control).

[0390] Referring to the graph of Figure 24F, during operation of the respiratory support system 22 in the normal operating pressure region 58, the controller 24 isconfigured to control the flow modulator to provide a flow of respiratory gases at a target flow rate, for example a set point flow rate prescribed by the user such as the clinician using I / O interface 20. As long as the system pressure remains beneath the pressure value defined by pressure limit curve C at that target flow rate, in the normal operating area 58, the controller 24 controls the flow modulator to provide a flow of gases at that target flow rate. In such a situation, the controller may be considered to be in a first control mode which is a flow rate control mode (also referred to herein as flow guided control or flow guided control mode). According to the control illustrated in Figure 24F, when the controller 24 determines that the system pressure meets or exceeds the pressure value defined by the pressure limit curve C at that target flow rate (for example when an obstruction starts to occur), the controller 24 is configured to control the flow modulator to modulate the flow of respiratory gases to a target pressure which is at or below the pressure value defined by the pressure limit curve C. In such a situation, the controller may be considered to be in a second control mode which is a pressure control mode (also referred to herein as pressure guided control or pressure guided control mode). In the embodiment of Figure 24F, the target pressure comprises a pressure value along pressure limit curve C (also referred to herein as a predetermined occlusion pressure threshold). As the obstruction increases (for example collapsible portion 5204 becomes more collapsed), flow rate of the flow of respiratory gases in the system reduces and the corresponding target pressure at the reduced flow rate also reduces. Accordingly, the controller 24 controls the flow modulator to modulate the flow of respiratory gases downwards along pressure limit curve C when the amount of obstruction increases.

[0391] While the controller 24 may be configured to identify the system pressure as “meeting” the pressure limit curve C when the sensed pressure input value equates to the value of the curve for the corresponding flow rate, it is to be understood that the controller may also be programmed to activate a change in control when the sensed system pressure “approximates” or is very close to the value in the pressure limit curve C such as e.g. within up to about 10% of the curve value, or within up to about 5% of the curve value, or within up to about 3% of the curve value, or within up to about 2% of the curve value or within up to about 1% of the curve value. In some embodiments, the flow rate of the flow of respiratory gases may be reduced progressively and could eventually reach a very low flow rate approaching(or in some cases reaching) 0 L / min. This reduces pressure in the respiratory system 22 and may avoid pressure in the system 22 from meeting or exceeding the pressure limit curve C.

[0392] In some embodiments, the controller 24 controls the flow modulator to control the flow of respiratory gases to maintain the system pressure at or along the pressure limit curve C. If the system pressure falls below a pressure limit along the pressure limit curve C at a corresponding flow rate, the controller 24 may control the flow modulator to increase the flow of respiratory gases to achieve a target pressure. This target pressure may be a pressure value along pressure limit curve C. This target pressure may be a higher target pressure along pressure limit curve C. In other words, as an obstruction reduces or as the blower increases speed for a given system pressure, the flow rate of respiratory gases increases and the corresponding target pressure along pressure limit curve C increases, such that the controller controls the flow modulator to modulate the flow rate of respiratory gases upwards along the pressure limit curve C as the obstruction reduces, towards the flow rate set point. The control to a target pressure may be switched to a flow rate control when the target flow rate is met, optionally where the target flow rate is met and the system pressure is less than the pressure value along pressure limit curve C at that target flow rate. The increase and / or reduction in the flow of respiratory gases may be a continual increase and / or reduction or it may be a stepped increase and / or reduction.

[0393] The pressure limit curve C has been devised to provide guidance to the controller 24 to avoid or reduce the likelihood of restricted flow in the system 22 causing an over pressure event or condition which may deliver unsafe patient pressures or system pressures that could damage system components. As mentioned, the restriction may be caused intentionally by collapsing of the collapsible portion 5204 supplying or forming part of the nasal cannula 5200 with application of a mask 5300 or the restriction may be caused accidentally by, for example, snagging, kinking or bending a portion of the delivery conduit. The shape of the pressure limit curve C in Figure 24E and 24H has a sigmoidal or “S” shape. In embodiments utilising a sigmoidal pressure limit curve, the controller 24 may operate the flow modulator to modulate the flow rate of gases by a variable rate of increase or decrease. A sigmoidal pressure limit curve C allows for the controller 24 to control the flow modulator to provide or maintain a low system pressure at low flows. This may bebeneficial in enabling the collapsible portion 5204 to remain collapsed while also minimizing the chance of there being a pressure difference or significant pressure difference across the collapsible portion when in the second configuration which may otherwise drive residual flow through the collapsed portion 5204 to the patient, or make it difficult to apply a mask over a cannula for delivery of a required respiratory support. In some embodiments, the pressure limit curve C may be defined such that a known amount or range of amounts of residual flow across a collapsible portion 5204 in the second configuration is achieved. For example, by providing a certain amount of pressure differential across the collapsible portion 5204 in the second configuration to achieve a certain amount of residual flow. The smoothness of the pressure threshold curve C provides for smooth tactile feedback to the user who will be able to feel, through the mask 5300 if there is a force being applied by the system pressure, through the collapsible portion 5204 and the mask 5300.

[0394] It is to be understood that the pressure threshold curve C may have a variety of shapes however in all circumstances, it is shaped to direct control to achieve delivery of gases at or below a pressure limit for the corresponding flow rates, and is ideally relatively smooth to achieve smooth control (although stepped control arising from a stepped curve C may also be adopted in some embodiments however these may give rise to control instability between steps). The normal operating region 58 beneath the curve C may be determined by a resistance to flow of components within system 22, allowing for different manufacturing tolerances as discussed above. Parameters of curve C may be varied according to operational preferences. In some embodiments, a higher pressure limit at zero flow (y-intercept), may give rise to greater residual flows across the collapsible portion 5204 when in the second configuration. In other embodiments, the target pressure at zero flow may be close to or at 0 cmH20. Alternatively / additionally, a higher pressure limit at a high flow rate (i.e. a greater difference between the pressure limit curve C and a normal operating system pressure within region 58) may accommodate more variation in system condition (e.g. state of cannula collapse or blockage) before the controller 24 modulates control of the flow modulator to reduce pressure. This provides a greater tolerance for the system pressure to increase before the pressure limit value in the pressure limit curve C at a target flow rate is met or exceeded. In some embodiments, curve C could be or include a linear portion between the control end points defined bythe minimum and maximum operating pressures. However controlling to a linear curve C may give rise to an undesirable amount of residual flows across the collapsible portion 5204 when in the second condition at low flows.Alternati vely / additionally , curve C could be or include a quadratic portion however this may in some circumstances more easily give rise to accidental triggering of pressure threshold detection in cases where there is an inadvertent or temporary bend or kink or other condition causing a high system pressure. Thus, it has been determined that a sigmoidal or other s-shaped curve, in conjunction with a “restricted” operating area 60 may be preferred for guiding control in some embodiments.

[0395] Figure 24G is a graph provided to illustrate that at zero flow the pressure curve can have a nominal pressure limit (curve R) or a zero pressure limit (curve S). Zero pressure limit at zero flow theoretically gives zero residual flow when there is a blocked or collapsed condition in the system. The higher the nominal zero flow pressure limit (curve R), the more residual flow may occur when collapsed. In some embodiments, it may be desirable to operate the system 22 with a small amount of residual pressure at low or zero flow (e.g. when the collapsible portion 5204 is in the second condition). In such embodiments, the controller 24 controls and maintains operation of the flow modulator such that a small amount of system pressure is maintained at zero (or low) flow, for example, the blower 27 is maintained at very low angular velocity. This has the benefit of helping to restore flow within the system and to the patient when the collapsible portion 5204 changes towards the first configuration. In particular, when the collapsible portion 5204 changes from the second configuration to the first configuration (i.e. obstruction is being reduced), the flow rate of the flow of respiratory gases will increase and the system pressure will drop. The controller 24 will control the flow modulator to modulate the flow of respiratory gases to a new target pressure for that given increased flow rate. In trying to achieve that new target pressure, the flow rate of the flow of respiratory gases increases again which provides a new target pressure.

[0396] Accordingly, the controller 24 controls the flow modulator to modulate the flow of respiratory gases to a target pressure along pressure limit curve C until the flow rate set point is met, upon which the controller 24 switches to a flow rate control mode. However a small amount of system pressure at zero (or low flow) may cause a pressure differential across the collapsible portion 5204 which may result in a residualflow. In some applications, a residual flow is desirable. In other applications, a residual flow is undesirable and such residual flow may be stopped or substantially reduced by configuring the pressure limit curve to intersect the y-axis of the pressureflow graph at the origin (0,0), which would correspond to a complete shut off of the flow modulator. In such an embodiment, the absence of any flow in the system may make it impossible for the controller 24 to determine if there has been a change in pressure and / or flow in the system sufficient to operate the controller 24 in a pressure control (pressure-guided control) and / or flow control (flow-guided control) mode. Accordingly, the controller 24 may be configured to control the flow modulator to deliver short bursts or pulses of flow corresponding to a “test pulse” to determine if there has been a change in the system pressure indicating that the obstruction or blockage (e.g. arising due to the collapsible portion 5204 being in the second configuration) has been cleared. If the test pulses give rise only to an increase in system pressure (with negligible increase in flow rate), the controller determines that the obstruction or blockage remains and pressure-guided control (or deactivation of the flow modulator except for test pulse) should remain. The duration between test pulses may be pre-programmed and / or altered according to operational requirements, recognising that more regular (or longer) pulses may increase residual flows if the blockage has not been cleared. Conversely, if the duration between pulses is long, the residual flow may be reduced significantly however the controller may not be sufficiently responsive since a reduction in system pressure cannot be detected until a test pulse occurs. If the controller detects an increase in flow in response to a test pulse, it may determine that the blockage has been cleared and modulates control of the flow modulator to increase speed thereby increasing flow and / or pressure in the system.

[0397] In an example, the controller 24 continuously receives or periodically samples data indicative of pressure and / or flow rate of the flow of respiratory gases in the system 22 and compares the received data with the values obtained from pressure limit curve C. Ideally, the controller 24 seeks to achieve the target flow rate corresponding to the flow rate set point, subject to pressures in the system not exceeding a target pressure corresponding to values along curve C. The controller 24 may control the flow modulator according to the received pressure values. For example if the received pressure values indicate that the system pressure meets orexceeds the value in curve C for the corresponding flow rate, the controller 24 controls the system to achieve a system pressure which is at or below the value in curve C for the corresponding flow rate (i.e. pressure guided control). Alternatively, when the received pressure values indicate that the system pressure does not meet or exceed the value in curve C, the controller controls the system to achieve a target flow rate (i.e. flow rate guided control). By way of example, the controller 24 may modulate operation of the system 22 to reduce the flow of respiratory gases in response to the received pressure exceeding the value in pressure limit curve C for the corresponding flow rate by controlling the flow modulator to reduce or stop the flow of respiratory gases being provided to the patient. Alternatively or additionally, the controller may operate a proportional valve to reduce pressure in the system. Conversely, the controller may modulate operation of the system 22 to increase the flow of respiratory gases in response to the received pressure not exceeding the value in the pressure limit curve C for the corresponding flow rates by controlling the flow modulator (and optionally, a proportional valve) to increase the flow of respiratory gases in response to the pressure not exceeding the pressure limit curve C for corresponding flow rates.

[0398] Figure 24H shows an example of a sigmoidal pressure limit curve C in an offset pressure characterisation for improved clarity. It shows the normalised system pressure and how the pressure threshold value at low flows (e.g. 1 cmH20) differs from the pressure threshold value at high flows (e.g. 20 cmF O). The sigmoidal shaped pressure limit curve C has a first pressure region 66 corresponding to the normal state of the nasal cannula 31 , a second pressure region 68 corresponding to the collapsed state of the nasal cannula 31 , or some other restriction of flow in the system 22 or delivery conduit 30. The sigmoidal shaped pressure limit curve C has a transition region designated by broken line 69 which is disposed between first pressure region 66 and the second pressure region 68. The first pressure region 66 is substantially parallel to the second pressure region 68 of the pressure limit curve C. The first pressure region 66 and the second pressure region 68 correspond to pressure thresholds for corresponding flow rates in the respective regions. The transition region may be determined according to required operational parameters, and is typically dictated by a trade-off between whether it is preferred to enjoy the benefit of low pressure threshold values at a wider range of low flows, or the benefit ofhigher pressure threshold values at a wider range of high flows. Being joined by a smooth “S” shaped transition provides for smoother control, avoiding oscillations and / or instability that may arise in the system if the pressure transition was an instantaneous step. While two pressure regions have been described in relation to the pressure limit curve C, it is to be understand that additional pressure regions may be provided.

[0399] The transition region 69 of the pressure limit curve represents a maximum rate of increase / decrease in the control of the flow of respiratory gases and is centred about a transition flow rate that is less than the flow rate set point (i.e. target flow rate) during normal operation. That is, the controller 24 is configured to control the flow modulator to reduce the flow of respiratory gases at the maximum rate of decrease when the sensed pressure and flow rate is in the transition region 69 of the pressure limit curve and the sensed pressure exceeds the pressure limit curve C for the corresponding flow rate. In an example, the system 22, when in this transition region 69, prevents patient airway pressure from exceeding safe limits and reduces flow (ideally down to near zero) when, for example, the nasal cannula 5200 has been collapsed for bag mask ventilation.

[0400] As mentioned, the difference between the flow rate at the transition region and target flow rates allows for a temporary increase in system pressure enabling the controller 24 to reduce the flow of respiratory gases at an initial minimum rate of decrease until the transition flow rate is approached in case the cause of the pressure increase is a temporary restriction and the temporary pressure increase is quickly removed.

[0401] As mentioned, Figure 24E shows a restricted area 60 where the sigmoidal pressure limit curve C may be defined, and where a temporary increase in pressure may be permitted to occur before controller 24 alters control of the flow modulator. This temporary increase in pressure may occur, for example, due to an inadvertent bending of a tube of the respiratory system 22. In some embodiments, the pressure limit curve C may be set to be as close as possible to the expected normal pressure to minimise flow at lower pressures and allow for movement of mask 5300 over the nasal cannula 5200 without rapidly ramping up flow to the flow rate set point.

[0402] It will be appreciated that the pressure limit curve C is not limited to a sigmoidal shape. The sigmoidal shape, however, allows for a quick transition in pressure between two pressure regions without an instantaneous jump between the two regions. An instantaneous jump may not be ideal as this discontinuity could lead to instability in the control of the respiratory system 22. For example, the output (e.g. blower speed control parameter) from controller 24 would change by large amounts that correspond with the instantaneous rate of change of pressures and flows in the transition region, and this instantaneous rate of change in the controller output will lead to instability.

[0403] Referring again to Figure 24H, while the respiratory system 22 is operable in normal operating region 66, when operating closer to the transition region 69 of the sigmodal pressure limit curve C, the respiratory system 22 may more quickly transition between pressure states (i.e. higher pressure offset vs lower pressure offset relative to normal operating pressure). As alluded to previously, curves of different overall shapes are envisaged, such as a “Z” shaped curve, which still allows for a quick transition in pressure. The “Z” shaped curve allows for the pressure limit curve to be ‘flat’ (steady at the pressure limit) in the non-collapsed state and the collapsed states.

[0404] Figure 24I is a state diagram of the states of operation of the respiratory system 22 with reference to the pressure limit curves of Figures 24D to 24H. From the normal state of operation of the respiratory system 22, the normal state may transition to the incompatible / disconnected state. In the incompatible / disconnected state, the controller may increase the flow of respiratory gases to approach a target flow rate / set point, but the sensed pressure will not meet expected values, so controller 24 may trigger an alarm to a user of the respiratory system 22 and / or the controller may operate the flow modulator or a proportional valve to reduce or stop the flow.

[0405] The normal state may also transition to a restricted state at which system pressure for example meets (but does not exceed) the pressure limit curve C for the corresponding flow rate. That is, in some embodiments, when sensed pressure is at the pressure limit curve C for a given flow rate, the controller initiates pressure-guided control to stay at or return below the pressure limit. In other embodiments, the controller may reduce the speed of a blower or lower the degree of openness of aproportional valve of the flow modulator when the sensed pressure meets or exceeds the pressure limit curve C. Alternatively, the controller 24 may remain in pressure- guided control but alter the target flow rate to a lower set point. For example, when pressure meets or exceeds the pressure limit curve, the controller may override the target flow rate of e.g. 70 L / min prescribed by the operator and set a new target flow rate at a lower set point of e.g. 20 L / min. When controller 24 determines the system pressure to have dropped below the pressure limit, the controller may then switch to flow-guided control and increase the speed of a blower or increase the degree of openness of a proportional valve of the flow modulator in order to (gradually) meet the flow rate set point. The controller 24 may check system pressure periodically or continuously and, if the system pressure has not reduced below the pressure limit, maintain or further decrease the flow modulator parameters discussed above. A reduced blower speed may be achieved by e.g. reducing a control signal or supply current (or voltage) to the flow modulator to cause decreasing angular velocity of the blower. Alternati vely / additionally the controller may control operation of a proportional valve to decrease flows. In other embodiments, the controller 24 may be configured to determine current system pressure only once the flow rate inputs have established that the system is operating at the lower flow rate set point, rather than periodically or continuously determining system pressure.

[0406] In the normal state, the controller may control flow modulator to deliver a target flow rate (also referred to as set point flow rate) through the nasal cannula 5200 to the patient. The controller 24 may control the respiratory system 22 to allow operation in the restricted state without switching between flow-guided and pressure- guided control to minimise accidental or unnecessary pressure and / or flow limiting events occurring in response to transient or temporary changes in system pressure. This allows users of the respiratory system 22 more freedom to work normally with the respiratory system 22, by allowing moving / bending of circuits, checking if a patient is breathing, moving their head, possibly awakening the patient, conducting nasal fibre optic intubation, etc without causing a transition to the over pressure state described elsewhere. The pressure limit curve C is in some embodiments set to be as high as possible while ensuring the patient is safe.

[0407] When the sensed pressure increases to cross pressure limit curve C at a corresponding flow rate, the restricted state transitions to the over pressure state. Inthe over pressure state, the controller 24 is configured to control the flow modulator or a proportional valve to reduce or stop the flow of respiratory gases as described above and / or to initiate an audible and / or visible an alarm if this state occurs for an extended time period. Ideally transition to the over-pressure state causes the controller to transition to pressure-guided control and in some embodiments, the controller may be configured to sound an alert while the controller is in pressure- guided control mode, or if pressure-guided control persists for longer than a preprogrammed time duration, or a pre-programmed proportion of a time period over which respiratory support has been provided to the patient. Triggering of one or more alerts or alarms while in the over-pressure state may also be contingent on other parameters such as whether there is flow delivered to the patient and / or what proportion (e.g. 90%) of the target flow rate is being achieved.

[0408] Blocked is a further state of the respiratory system 22 which may be transitioned to from the normal or restricted states. The blocked state is transitioned from the restricted or normal states when the sensed flow rate reaches a threshold of, for example, 2 L / min or reaches 0 L / min and when the system pressure is at or beyond the pressure limit curve C for a corresponding flow rate. In some embodiments, when in the blocked state, the controller 24 controls the flow modulator to modulate the flow of respiratory gases (which may be 0 L / min) to a target pressure above 0 cmFhO (which is where pressure limit curve C intersects the y-intercept). Hence in such embodiments, there will be a system pressure at zero or substantially low flow rates. When an obstruction or blockage in the system is removed, the system pressure will decrease and the flow rate of the flow of respiratory gases will increase. The controller 24 will therefore control the flow modulator to modulate the flow of respiratory gases to a new higher target pressure that corresponds to the higher flow rate. As the flow modulator increases the pressure of the flow of respiratory gases, the flow rate will accordingly increase and result in a new higher flow rate that establishes a new target pressure that corresponds to the new higher flow rate.Accordingly, the flow modulator is controlled to modulate the flow of respiratory gases to an increasing target pressure until the flow rate set point is met following which the controller 24 switches to flow-guided control. In addition, or in an alternative, the controller 24 determines whether the sensed pressure and flow rate corresponds to pressure waveforms that match when the nasal cannula 31 is collapsed indicatingthat bag mask ventilation has occurred. If this is not determined, the controller 24 may continue to increase flow and return to the first configuration.

[0409] Figure 24J is a high-level schematic representation of operation control of the respiratory system 22 according to an example of the present disclosure. In the example shown, the controller 24 may be considered to provide a flow rate controller providing flow rate control output and a pressure controller providing a pressure control output, operating as separate modules of the controller 24. The flow rate controller uses the flow set point (which may be the target flow rate) and the sensed flow rate (flow measurement) as inputs and the pressure controller uses a pressure set point calculated from the pressure limit curve C for corresponding measured flow rates and the sensed pressure (pressure measurement) as input. The controller 24, implementing these pressure and flow rate controllers concurrently, is thus able to provide pressure-guided control and flow-guided control to the respiratory system 22. Changes in control, in either pressure-guided or flow-guided control mode, may be achieved by altering control of the flow modulator e.g. to achieve a change in blower angular velocity and / or altering control of the proportional valve by changing supply current or voltage to achieve a required increase or decrease in flow rate. As mentioned, the predetermined pressure threshold values and corresponding flow rates represented by curve C may be stored in a memory component of or operatively coupled with controller 24 and represented in any suitable form such as one or more of a function, a curve, a look up table or algorithm or the like. To implement control, the controller 24 selects the minimum control value determined by the flow control system and the pressure control system, for control of the flow modulator / blower or proportional valve.

[0410] Further detail regarding the flow control system and pressure control system are described in WO2022 / 130306, the entire contents of which are incorporated herein by reference.Respiratory support systems incorporating PRV

[0411] In some embodiments, the PRV (e.g. PRV 100 or FCPRV 800) may form part of or be operatively coupled with, a system for providing respiratory support to a patient, with a sensor to provide an indication of gas venting from the PRV orpressure valve. Gas venting occurs when there is a partial or total occlusion in the system, as may be caused by, for example, inadvertent folding or crushing of the conduit 14, or may be caused deliberately, for example by occluding the conduit 14 (e.g. by pinching a portion of the conduit closed) to prevent a flow of gases from reaching the patient. A number of embodiments directed to sensing gas venting are disclosed with reference to the schematic drawings in Figures 25A to 27. Sensing of gas venting may be useful in order to understand the nature of the occlusion that has led to the gas venting through pressure valve 100. This may have particular use in applications utilising a patient interface comprising a collapsible portion as discussed with reference to Figures 22A, 22B, 23A and 23B, wherein an alert indicating when the pressure valve is venting may be relied upon by a user to determine e.g. when a seal of a face mask 5300 has formed a good seal over the top of (and occluding) the collapsible portion.

[0412] In some embodiments, as illustrated in Figures 25A and 25B, a system such as respiratory system 10 of Figure 1 , provides respiratory support to a patient. The system may be configured to provide, incorporate or comprise part of a device providing high flow respiratory support to a patient. The high flow device may be coupled with or form part of an anaesthesia machine or ventilator as will be described. A pressure valve 100, such as pressure relief valve described in the foregoing, receives a flow of gases via main inlet 151 , and provides a flow of gases through main outlet 153. As disclosed above, a sensing mechanism within the pressure valve 100 senses the flow rate and / or pressure of gases flowing to the patient at or through the main outlet 153 of the valve. In the event of a partial or total occlusion of the flow path downstream of the main outlet 153 for example conduit 14 providing a flow of gases to a patient interface 15 becomes completely occluded (completely crushed, pinched closed, or occluded by application of a face mask over a collapsible portion) or a patient’s naris is completely blocked, all or substantially all flow delivered to the main inlet 151 of the pressure valve 100 is vented via valve outlet 103, and is not delivered to the patient. The pressure valve may comprise a flow compensated pressure relief valve (FCPRV) as disclosed in the foregoing. The pressure valve may comprise one or more of a mechanical valve and an electronic valve (or components thereof) as disclosed in relation to Figures 2 to 10, and Figures 11 to 13 respectively. In some examples, the gases may be humidified to a desired dew point and / ortemperature by humidifier 17 before being provided to a patient via conduit 14 and patient interface 15. In order to provide an indication of when gas venting by pressure valve 100 occurs, an indicator may be provided as disclosed in relation to Figures 14 to 21 . Alternatively or additionally, a sensor 500 may be provided to indicate that there is gas venting by pressure valve 100. The output of the sensor 500 may be determined according to operation of the indicator (e.g. by the sensor sensing a change in the indicator), or by sensing a property of a flow of gases to determine that there is gas venting.

[0413] In the example of Figure 25A, sensor 500 is provided at or downstream of the valve outlet 103 and is in fluid communication with an exhaust 510 to atmosphere / ambient. During provision of gas to the patient, sensor 500 receives substantially no flow. However, when gases are vented through valve outlet 103, sensor 500 detects one or more gas parameters of the vented gas flow and provides a venting signal to a controller (e.g. controller 19). The sensor may comprise one or more of e.g. a flow sensor, a pressure sensor a gas concentration sensor or another type of sensor that can determine when there is gas venting by the pressure valve 100. For example, an increase in gas flow rate and / or gas pressure and / or e.g. oxygen concentration at the sensor 500 corresponds to a venting signal indicative of gas venting by the pressure valve 100. Upon receipt of a venting signal, the controller 19 causes activation of an alert to a user. Such an alert may be provided on one or more user interfaces such as I / O interface 20 which is in operative communication with the controller.

[0414] In some examples, the humidifier 17 may comprise the controller 19 or a separate controller module. Humidifier 17 may be configured to receive a venting signal from sensor 500. Alternatively or additionally the humidifier 17 itself may comprise a sensor configured to determine characteristics of the flow of gases downstream of the PRV. The humidifier controller may cause an associated I / O device to display the venting flow rate measured by the sensor 500, and / or the actual flow rate measured by the humidifier sensor. In some examples, the humidifier 17 may be communicatively coupled with a controller of the respiratory support system such that it may, in some examples, display on an associated I / O device the pre-set flow rate for the respiratory support.

[0415] An alternative arrangement is provided in Figure 25B, in which sensor 500 is located at or downstream of the main outlet 153 of the pressure valve 100. Pressure valve outlet 103 is in fluid communication with an exhaust 510 to atmosphere / ambient. During provision of gas to the patient, sensor 500 receives a flow of gas and may sense parameters that are consistent with pre-set values according to the respiratory support provided. The sensor 500 may comprise one or more of e.g. a flow sensor, a pressure sensor, a gas concentration sensor or another type of sensor that can determine when there is gas venting by the pressure valve, by determining a change in the gas parameters away from the pre-set values for the respiratory support provided. For example, a decrease in gas flow rate and / or gas pressure and / or e.g. oxygen concentration at the sensor 500 causes a venting signal indicative of gas venting by the pressure valve 100. Upon receipt of a venting signal, the controller causes activation of an alert to a user. Such an alert may be provided on one or more user interfaces such as I / O interface 20 which is in operative communication with the controller. The controller 19 may comprise part of a high flow device, or an anaesthesia machine, or ventilator, or humidifier. The I / O interface 20 may comprise part of a high flow device, or an anaesthesia machine or ventilator, or humidifier, or a separate system. The controller 19 and the I / O interface 20 need not form part of the same device and may be operatively coupled together in order to achieve the activation of one or more alerts upon receipt by the controller of a venting signal. The operative coupling may comprise wired or wireless communication infrastructure between the components. Although the sensor 500 is shown downstream of the PRV 100, it is to be understood that the sensor 500 may comprise part of the PRV. For example, PRV sensor 950 may provide the dual function of sensor 500 as described with reference to Figure 25 and sensor 950 as described with reference to Figures 11 A, 11 B and 12A, 12B. Thus, the signal from sensor 950 forming part of PRV 100 may be used as a venting signal by controller 19 to activate one or more alerts. Although the sensor 500 is shown downstream of the PRV 100 and before the humidifier 17 in Figure 25B, in other embodiments sensor 500 may be provided at other locations downstream of PRV 100 such as at the humidifier 17, or between the humidifier 17 and the patient interface 15.

[0416] In some examples the system for sensing gas venting is couplable with or may be integrated into an anaesthesia machine or ventilator. The controller receivingthe venting signal may be operatively coupled with a user interface device, such as an I / O device 20, that is part of an anaesthesia machine, or a ventilator, or a device providing high flow respiratory support or a humidifier. In some examples, the controller may be operatively coupled with more than one such user interface device. The alert activated by the controller may comprise an audible alert such as a single or multiple tone audible alert or an audible message such as “GASES VENTING” “OCCLUSION DETECTED” pronounced by a loudspeaker of the user interface. Alternatively or additionally, the alert may comprise a visible alert comprising a visible representation on a display of the user interface device such as a colour change in part of all of the display view and / or presentation of alphabetical and / or numeric text. Alternatively or additionally, the alert may comprise a tactile alert comprising a vibration or haptic feedback provided to a user wearing or operating a device having a haptic actuator in operative communication with the controller. The alert may be qualitative, simply indicating the presence of gas venting or an occlusion that has given rise to the gas venting. Alternatively or additionally, the alert may provide a quantitative indication of the duration of the gas venting / occlusion and / or the extent of gas venting / occlusion as may be represented by one or more values corresponding to the pressure, flow rate and / or gas composition detected by the sensor. In the case of sensor 500 in Figure 25A, a lower flow rate and / or pressure and / or oxygen concentration corresponds to a venting signal which, when received by the controller, indicates incomplete occlusion. Conversely, flow rate and / or pressure and / or oxygen concentration values which are higher and may be similar to parameters of the flow intended for the patient correspond to a venting signal which, when received by the controller, indicates complete or near complete occlusion.

[0417] The venting signal from the sensor 500 may itself be qualitative or quantitative. In examples where the venting signal is qualitative, a change in or the mere generation of the signal may be used by the controller 19 to provide an alert that there is gas venting. For example, a sensor 500 may provide a venting signal triggered by a non-zero flow rate / pressure (with respect to ambient pressure) or nonambient 02 concentration. In another example, a sensor 500 may provide a venting signal triggered by a measured parameter meeting or exceeding a threshold, such as a flow rate above 5 L / min, a pressure above 2cmH2O or an 02 concentration above 30%. In some examples, the sensor 500 may comprise a comparator and generate aventing signal when the difference between the pre-set flow rate for the respiratory support (communicated from the controller 19) and the measured venting flow rate is greater than zero. In examples where the venting signal is quantitative, a characteristic of the venting signal such as the amplitude or frequency, or a value encoded on the signal, may be used by the controller 19 to determine one or more qualitative alerts. The venting signal may correspond to a value that may be used by the controller to cause the I / O device 20 to present an alert that displays the flow rate of the vented gases and / or the actual flow rate of gases being delivered to the patient. The controller 19 may be configured to calculate the actual flow rate being delivered to the patient by subtracting the flow rate of vented gases (from the venting signal) from the pre-set flow rate for the respiratory support being provided. In one example relating to Figure 25A, if the sensor 500 provides a venting signal corresponding to a venting flow rate of 60 L / min and the pre-set flow rate is 70 L / min, the controller 19 calculates the actual flow rate provided to the patient as the difference between these values, i.e. 10 L / min. This actual flow rate may be presented on the I / O device 20. Alternatively or additionally the venting flow rate may be presented on the I / O device 20. These values may be presented visibly, audibly or both. The audible element of the alert may comprise an alarm sound, or an audible mention of the actual and / or venting flow rate.

[0418] In some examples, the humidifier 17 may comprise a controller configured to control the humidifier and receive signals from devices other than the humidifier 17. The humidifier controller may be associated with an I / O device which may be part of the humidifier, or another device. The humidifier controller may be configured to cause the associated I / O device to provide an alert when inputs to the humidifier controller indicate that there is venting. The alert may be qualitative or quantitative. In some examples the humidifier controller is configured to cause an alert when a sensor signal received by the humidifier controller indicates that an exhaust threshold is met. In some examples, the exhaust threshold corresponds to a predetermined flow rate being measured at the sensor 500, for example 5 L / min. In another example the exhaust threshold corresponds to percentage of the pre-set flow rate for the respiratory support. The humidifier may comprise a sensor such as a flow sensor. The humidifier controller can calculate the pre-set flow rate by measuring the flow rate of gas at the humidifier sensor and summing this with the venting flow rate ascertainedfrom the venting signal from sensor 500. The exhaust threshold can be calculated as a percentage of the calculated pre-set flow rate. The I / O device associated with the humidifier may display the venting flow rate and / or the pre-set flow rate and / or the actual flow rate provided to the patient.

[0419] Advantageously, displaying the venting flow rate and / or the actual flow rate of gas delivered to the patient can provide clinicians with a more accurate representation of the actual respiratory support being provided, as compared to the pre-set flow rate values which will become less accurate as the PRV vents gases in response to an occlusion. Providing the venting flow rate gives clinicians a quantitative guide as to the extent to which there is an occlusion in the flow path to the patient interface. In situations where there is an intentional occlusion (e.g. when a mask is applied over a collapsible cannula), the qualitative alerts can provide confirmation or guidance as to whether or not the clinician’s action has achieved the desired effect. For example, a clinician will have a greater degree of confidence that there is full occlusion where the displayed venting flow rate approximates or equates to the pre-set flow rate of the respiratory support, and / or when the displayed actual flow rate delivered to the patient approaches or equals 0 L / min. One or more of these values presented by the I / O device can also provide better visibility to the clinician of occlusions that might otherwise go unnoticed or undetected and unresolved. The actual flow rate of gases provided to the patient is also useful for clinicians to understand the extent of dilution of gases measured in an expired gas flow. For example, if the actual flow provided to the patient is 0 L / min then there will be no dilution, whereas if the actual flow provided to the patient is 10 L / min then there may be around 50% dilution of the expired gases.

[0420] In some embodiments, the pressure valve 100 may be external from and operatively coupled with an anaesthesia machine 3100 as shown in Figure 26. Alternatively, the pressure valve 100 may be integrated with or form part of an anaesthesia machine 3100 as shown in Figure 27. For simplicity, the common features of an anaesthesia machine such as a vaporizer, CO2 absorber, pressure relief valves, rebreathing components and the like are omitted from the figures. Although not shown, the pressure valve may similarly be integrated with or form part of a ventilator or other respiratory support device, or be located externally of and operatively coupled with a ventilator or other respiratory support device.

[0421] Anaesthesia machine 3100 may comprise a power module 3110 for powering powered components of the anaesthesia machine such as bellows and flow generators, controller 19 and / or I / O device 20 which may provide an alert to a user as described above. However, it is to be noted that the controller 19 and / or I / O device 20 need not form part of the anaesthesia machine 3100, and may instead (or additionally) be incorporated into a standalone controller and / or I / O device, and / or a High Flow (HF) device 4200. The high flow device 4200 may be provided separately from the anaesthesia machine 3100, or it may be integrated with or into the anaesthesia machine as schematically shown. In some examples, high flow device 4200 may be powered by power module 3110.

[0422] In some examples, high flow device 4200 may have features as described with reference to the device 2100 in Figure 28 and / or the components described with reference to the dotted box 11 in Figure 1 . The high flow device 4200 may comprise a flow generator or blower for generating high flows of gasses. Alternatively or additionally the high flow device 4200 may receive a supply of compressed 02 3122 and compressed air 3124, and the flow rates controlled by one or more proportional valves 4202, 4204, under the control of a controller such as controller 19 forming part of the high flow device 4200 or the anaesthesia machine 3100. In some examples, the high flow device 4200 may receive only a flow of oxygen e.g. from a supply of compressed 02 3122. In some examples, the high flow device 4200 may be a high flow (HF) module configured to removably cooperate with and add functionality to an anaesthesia machine 3100 enabling the additional functionality of providing high flow respiratory support, as well as anaesthesia. An example of such a high flow module 4200 is described below with reference to Figures 29 to 38. In some examples, a high flow module 4200 can be configured to operate as a standalone device.

[0423] In Figure 26, the anaesthesia machine 3100 comprising the high flow device 4200 provides a flow of gases to a high flow gases outlet 3153 of the anaesthesia machine which may comprise a coupling for connecting with a conduit 900 (which may be referred to as a dry line) providing a flow path between outlet 3153 and the PRV 100 externally of the anaesthesia machine. In other examples where the high flow device 4200 is separate from but coupled with an anaesthesia machine 3100, a high flow of gases may be provided from an outlet of the high flow device 4200 which may comprise a coupling for connecting with conduit 900. Notably, thePRV may be a FCPRV in some examples. In some embodiments, a further conduit may be provided to an additional component such as a humidifier 17, before the flow of gases is provided to the patient interface 15. Alternatively, the PRV 100 may couple to the outlet 3153 and the conduit 900 may be provided between the PRV 100 and the humidifier 17. In some examples, the humidifier 17 may be in operative communication with the controller 19 and may comprise one or more sensors providing a signal corresponding to parameters of the gas flow provided to the humidifier 17 or the patient interface 15 (such as flow rate, pressure, gas composition, temperature and humidity) which may be used in the control of one or more other components in the high flow device 4200 and / or anaesthesia machine 3100 (or ventilator). In some examples, the humidifier 17 may comprise one or more sensors that are operable to provide a venting signal as described above. This is similar to Figure 25B but with sensor 500 forming part of humidifier 17.

[0424] In the example shown in Figure 26, sensor 500 is provided as part of the anaesthesia machine 3100 (or ventilator) and receives a flow of gases from the valve outlet 103 or from a flow path in fluid communication with the valve outlet 103. Sensor 500 provides a venting signal to the controller 19 which may cause activation of an alert on I / O device 20 in a manner similar to that described for Figure 25A. Anaesthesia machine 3100 also provides an exhaust outlet 510 providing a vent path to atmosphere / ambient for the vented gases diverted from the PRV 100. Alternatively, both sensor 500 and / or exhaust outlet 510 may be provided externally of the anaesthesia machine. In such an embodiment, a venting signal from sensor 500 can still be provided to the controller 19 which may cause activation of an alert on I / O device 20 in a manner similar to that described for Figure 25A. However, it is to be understood that in another example, the sensor 500 may be located downstream of the outlet 153 of the PRV 100. In such an example, sensor 500 provides a venting signal to the controller 19 which may cause activation of an alert on I / O device 20 in a manner similar to that described for Figures 25A and 25B.

[0425] In Figure 27, the anaesthesia machine 3100 comprising the high flow device 4200 also comprises a PRV 100 and sensor 500 internally of the machine. Notably, the PRV may be a FCPRV in some examples. In some examples, the PRV may be provided as part of the high flow device 4200 in anaesthesia machine 3100. In the example shown in Figure 27, sensor 500 receives a flow of gases from thevalve outlet 103 internally of the machine. The PRV 100 provides a flow of gases to an outlet 3153 of the anaesthesia machine or to a flow of gas in fluid communication with the outlet 3153. The outlet 3153 may comprise a coupling for connecting with a conduit 900 providing a flow path between outlet 3153 and patient interface 15, optionally via the humidifier 17 as shown. However, it is to be understood that in another example, the sensor 500 may be located between the patient interface 15 and the outlet 3153, such as between the humidifier 17 and the outlet 3153. Sensor 500 provides a venting signal to the controller 19 which may cause activation of an alert on I / O device 20 in a manner similar to that described for Figures 25A and 25B. The controller 19 and I / O device 20 may comprise part of the anaesthesia device as shown. In some embodiments, a further conduit may be provided to an additional component such as a humidifier 17, before the flow of gases is provided to the patient interface 15. In some examples, the humidifier 17 may be in operative communication with the controller 19 and may comprise one or more sensors providing a signal corresponding to parameters of the gas flow (such as flow rate, pressure, gas composition, temperature and humidity) which may be used in the control of one or more other components in the high flow device 4200 and / or anaesthesia machine 3100 (or ventilator). In some examples, the controller 19 and / or I / O device 20 may comprise part of the humidifier 17. Anaesthesia machine 3100 also provides an exhaust outlet 510 providing a vent path to atmosphere / ambient for the vented gases diverted from the PRV 100.

[0426] An advantage of locating the sensor 500 within anaesthesia machine 3100 as shown in Figures 26 and 27 is that it may be powered by power module 3110 without requiring a separate power supply, and may be communicatively coupled with the controller 19 via circuitry within the machine. However it is to be understood that this need not be the case, and the sensor 500 may be located externally of the anaesthesia machine 3100 (or ventilator). In some examples, the sensor may be provided with or incorporated into the PRV 100. Thus, the sensor may communicate wirelessly with the controller 19 from within or outside the anaesthesia machine 3100 (or ventilator) and may comprise a separate power supply, such as a battery or a power supply of e.g. the high flow module 4200 or the humidifier 17.

[0427] In addition to providing an alert, which is indicative of gas venting from the pressure valve 100 and draws the attention of a user to the presence of a likelyocclusion, in some examples the venting signal from the sensor 500 may also be used in the control of one or more of a high flow device 4200 (or high flow module), the anaesthesia machine or a ventilator. For example, the venting signal may be used by a controller to reduce the flow rate of gases from a flow source such as the high flow device 4200 while there is a partial or complete occlusion in the system. In addition to protecting the patient and / or system components from damage due to overpressure, reducing the flow rate of gases may reduce wastage of e.g. compressed air 3122 or compressed oxygen 3124 which would otherwise be vented to atmosphere via exhaust outlet 510. This may also reduce dilution of e.g. anaesthetic gases provided to the patient via a face mask applied over a nasal cannula with a collapsible portion, as described with reference to Figures 22A, 22B and Figures 23A, 23B. Alternatively or additionally, the venting signal may be used by a controller to prompt or initiate delivery of anaesthetic agents from an anaesthesia machine 3100 based on a venting signal, e.g. when the venting signal indicates an occlusion or collapsed cannula as described with reference to Figures 22A and 22B.

[0428] In some embodiments, the present disclosure provides a device comprised of mechanical, electrical and electronic components arranged to provide a flow of gases that delivers the required respiratory support safely, and / or efficiently. Figure 28 is a schematic drawing showing components of a device 2100 for providing respiratory gases according to embodiments of the present disclosure. In some embodiments, device 2100 provides respiratory gases suitable for provision of high flow respiratory support. The device 2100 comprises an 02 flow path 2200, air flow path 2300 and a mixed gases flow path 2400. Mixed gases flow path 2400 may terminate in an outlet configured to couple with a conduit for provision of high flow gases to a patient via a patient interface. 02 flow path 2200 is in fluid communication with an 02 supply 2210 which may be a high pressure 02 supply. Device 2100 may be considered representative of flow source 12 of Fig. 1 . In an example, the flow source 12 may also include 02 supply 2210. The flow rate of gases in the 02 flow path 2200 is controlled by a proportional valve 2212 which is operatively coupled with controller 19 Air flow path 2300 may have a blower 2310 which draws ambient air from air intake 2314. The flow rate of gases in the air flow path 2300 is controlled by the blower 2310 which is operatively coupled with controller 19. Air from air intake 2314 may be filtered by air filter 2316 to remove particulates. Similarly, a filter 2216may be provided to filter small particles (e.g. <100um) from the 02 supply 2210. This filter may be placed inside an 02 connector that is coupled with the inlet of the 02 supply 2210. 02 is mixed with air downstream of blower 2310 to form a mixed gas flow in mixed gas flow path 2400 which is delivered as a flow of respiratory gases to the patient. A flow conditioner may be provided downstream of the proportional valve 2212 and upstream of 02 flow sensor 2218. A cooling fan or ventilating blower 231 OA may be provided, inside the device housing 2900 but outside the gas delivery flow paths, to cool components inside the device 2100.

[0429] Various sensors may also be provided such as 02 pressure sensor 2214 which is configured to sense 02 pressure in the 02 flow path (e.g. to determine that there is a flow of 02 entering the 02 flow path), 02 flow sensor 2218 which is configured to sense flow rate in the 02 flow path 2200, air flow sensor 2318 which is configured to sense flow rate in the air flow path 2300, and mixed gas flow sensor 2418 which is configured to sense flow rate in the mixed gas flow path 2400 which is delivered to the patient. Additionally, one or more gauge pressure sensors 2414 may be provided in the mixed gas flow path 2400 and one or more ambient pressure sensors 2114 may be provided to sense ambient air pressure. The gauge pressure sensor(s) 2414 may take reference from one or more ambient pressure sensors 2114 to measure the pressure in the mixed gas flow path 2400. The flow rate and pressure of mixed gases in the mixed gas flow path 2400 may be controlled by operation of the blower 2310 and / or proportional valve 2212.

[0430] Mixing of gases from the 02 flow path 2200 and air flow path 2300 occurs in a mixing chamber 2500 shown in broken lines in Figure 28, where gases from the 02 flow path 2200 enter the mixing chamber through an 02 outlet 2220 and gases from the air flow path 2300 enter the mixing chamber through an air outlet 2320. As will become apparent below, owing to the physical arrangement of the blower 2310 in the air flow path 2300 in some preferred embodiments, air outlet 2320 may in some embodiments be referred to as blower outlet 2320. The mixing chamber 2500 may be circular in cross section, such as e.g. cylindrical or spheroid, or may have an oval or obround cross section such that flow of gases in the mixing chamber may be minimally interrupted or disturbed by corners or other internal features of the mixing chamber. Mixing chamber 2500 has a mixed gases inlet 2510 through which mixed gases from the mixing chamber flow to the mixed gases flow path 2400 as describedfurther in WO2023 / 119240, the entirety of which is incorporated herein by this reference.

[0431] Device 2100 may be provided in a housing 2900 which may further comprise a ventilating blower 2650 to improve safe operation of the device as will be described in further detail below. Not shown in the schematic layout of Figure 28 is the electrical input to the device 2100 which supplies each of the electrically powered components. Electrical input to the device 2100 is by an IEC connector. The IEC connector may be connected to an IEC retainer. Both the IEC connector and the IEC retainer are of the type known to persons skilled in the art.

[0432] As shown in the schematic drawing of Figure 28, the 02 flow path 2200 and the air flow path 2300 are represented as parallel flow paths. Relevantly, when the schematic representation of device 2100 of Figure 28 is manifested in a mechanical device 2100, it may also be desirable in some embodiments, for the 02 flow path 2200 and the mixed gas flow path 2400 to be arranged in the device such that at least part of those flow paths are arranged in a parallel configuration, as will be described below.

[0433] In some embodiments, the 02 flow path 2200 and the air flow path 2300 and particularly the 02 outlet 2220 the air outlet 2320 are arranged relative to one another to reduce or prevent flow from entering the 02 path in a reverse flow direction (i.e. against the direction of bulk flow of 02 entering the 02 flow path from 02 source 2210). It is desirable to reduce or prevent reverse flow from entering the 02 path as this could affect the accuracy of sensing by 02 flow sensor 2218. Inaccurate sensing of 02 flow can affect the control signal provided to proportional valve 2212 which can in turn have negative consequences on the accuracy and safety of respiratory gases provided to the patient.

[0434] For example in the embodiment of Figure 28 where the 02 concentration in a flow delivered to the patient is calculated based on the flow sensors 2218, 2318 and the concentration of 02 in the 02 flow path (e.g. 100% 02) and 02 in the air flow path (which is at 21%), when a user provides an input to I / O interface 20 to supply a delivered gas flow with a 21% fraction of 02 to the patient, there should be zero to low flow in the 02 flow path since 21% 02 is largely representative of ambient air.However if an undesirable flow occurs in the 02 flow path 2200, the flow sensor 2218 may register a negative or positive flow reading which could cause controller 19 to register that there is less or more than 21% 02 in the delivered gas flow. This could cause the controller to, in the case of less than 21% 02 in the delivered flow, open proportional valve 2212 to allow more 02 to flow to the patient, or in the case of more than 21% 02 in the delivered flow, to close the proportional valve 2212 further or register an error if the proportional valve 2212 cannot be closed further. Additional 02 may not be desirable in some applications, for example when 02 supply is limited. Embodiments of the device 2100 seek to mitigate such issues by careful placement of the blower outlet 2320 relative to the 02 outlet 2220, and may utilise a plurality of flow sensors, such as flow sensors 2218, 2318, 2418 to accurately monitor and control the fraction of 02 in the mixed gas flow path 2400. The risk of this error occurring could also be reduced by adding an 02 concentration sensor into one or more flow paths, for example the 02 flow path 2200 or the mixed gas flow path 2300.

[0435] In some embodiments, it may be desirable to deliver respiratory gases containing 100% 02. In such a scenario, the user would enter this 02 concentration set point into I / O interface 20. The controller 19 then controls proportional valve 2212 to open sufficiently (e.g. by increasing supply current) to allow enough 02 into the flow of respiratory gases to meet the 02 concentration set point. This may create a pressure downstream of the blower 2310, such that only 02 is delivered to the patient; the blower 2310 will still be operating to provide flow and pressure under control of controller 19 however the proportional valve 2212 acts to prevent dilution of the 02 by air from airflow path 2300. In other words, in an embodiment where the device is set to output 100% FiO2, (wherein FiO2 is the fraction of oxygen supplied to the patient) the controller 19 adjusts both the amount of opening of the proportional valve 2212 and the speed of the blower 2310 to meet the flow rate requirement set by the user. The blower 2310 maintains a pressure to limit 02 exiting through the air inlet. For example, if the set points are at 70LPM and 100% FiO2 and the 02 flow sensor records 72LPM, the speed of blower 2310 and size of proportional valve 2212 opening may be reduced. Thus, the blower 2310 still controls the flow to the patient.Flow module

[0436] In some embodiments, the present disclosure relates to interoperability between a device providing high flow support and an anaesthesia machine or ventilator as may be achieved by sharing of venting signals from venting sensor 500 with a controller of one or both of a high flow device and an anaesthesia machine or ventilator. In some examples, venting signals may be shared with a controller of a humidifier (humidifier controller). In some embodiments, interoperability may be achieved by a flow device that can be releasably coupled with the anaesthesia machine or ventilator. Additionally or alternatively, the coupling may be communicative, in that it provides for exchange of sensor and / or control signals, and / or data, between respective components of the device(s), and / or the coupling may be operative in that it provides for flow of gases between the respective components. Alternatively or additionally the coupling may be energetic in that it provides for supply of power from one of the components to another coupled component. A number of examples relating to coupling between an anaesthesia machine or ventilator and a high flow device are described with reference to Figures 25A to 27 which also provide for sensing when a pressure valve releases gases through an exhaust port in response to an occlusion in the system. Figures 29 to 38 relate to further examples of arrangements and components for interoperability between a high flow device and an anaesthesia machine or ventilator according to embodiments of the disclosure.

[0437] Figure 29 is a schematic illustration of an anaesthesia machine 3100 and a high flow (HF) device 4200 in the form of a high flow (HF) module interoperating via a dock 3140. The dock illustrated in Figure 29 is representative of any coupling mechanism that may be deployed between an anaesthesia machine 3100 and a high flow module 4200. The dock need not be a physical dock although a specific example of a physical dock is provided herein. Rather, dock 3140 is to be interpreted as a collective term to describe any mechanism / s for connecting one or more of the fluid lines, control modules and / or power modules of the anaesthesia machine and the high flow module in order to integrate one or more aspects of their functionality.

[0438] Anaesthesia machine 3100 may comprise features as described with reference to Figures 26 and 27. Anaesthesia machine 3100 may comprise a power module 3110 which may power components of the anaesthetic machine and / or the high flow device from a battery or mains power connection (e.g. IEC connector). Insome examples, as shown in the schematic drawing of Figure 29 a data bus 3118 may be configured to permit communication of data (including sharing of venting signals) between the high flow module controller 4219 and the anaesthesia machine controller 3119. Communication may be via a physical communication link provided by the dock 3140 and the data bus 3118, and / or a wireless link utilising transceivers and communication protocols implemented in the respective components. A physical interface in the form of a dock 3140 on the anaesthesia machine 3100 or ventilator may in some examples be configured to interconnect with a corresponding part on the high flow module 4200. The high flow module 4200 is detachable from the anaesthesia machine 3100 or ventilator. The high flow module 4200 may be docked in the anaesthesia machine 3100 or ventilator in order to add functionality that permits provision of high flow respiratory support, in addition to the anaesthetic agent delivery and / or ventilation that is normally provided on the anaesthesia machine or ventilator workstation. In some examples, the high flow module 4200 may operate to provide high flow respiratory support independently of the anaesthesia machine 3100. In other examples, the high flow module 4200 may be powered by the power module 3110 of the anaesthesia machine. Power to the high flow module 4200 may be supplied via the dock 3140 by a physical or electromagnetic transfer.

[0439] The high flow module 4200 comprises a high flow module controller 4219 configured to control provision of high flow respiratory support through a conduit 900 connected at gas outlet 4253 of the high flow module. The high flow module receives a flow of gases such as air and 02 from the anaesthesia machine 3100 via the dock 3140 which may contain pneumatic couplings for connecting a gas flow path within the anaesthesia machine with a corresponding gas flow path within the high flow module, high flow module 4200 may comprise a blower 4210 for generating a high flow rate of gases when the supply of air is non-pressurised, such as room air. Alternatively or additionally a supply of compressed air 3124 may be provided via the anaesthesia machine 3100 (which also receives and provides to the high flow module a supply of compressed 02 3122) and the flow rate controlled using one or more proportional valves (e.g. 4202) under control of the HF module controller 4219. In some examples, the high flow module 4200 may receive only a flow of oxygen from the anaesthesia machine 3100 e.g. from a supply of compressed 02 3122.

[0440] In some examples, the high flow module may comprise various features and functionality described with reference to the device 2100 in Figure 28. In some examples, the high flow module 4200 may include an I / O device 4220. However, in some examples it may be preferred that when the high flow module 4200 is docked with the anaesthesia machine 3100, the I / O device 3120 of the anaesthesia machine (AM) becomes the interface used for displaying parameters of the high flow respiratory support. This may be irrespective of whether or not a HF I / O device 4220 is provided on the high flow module 4200. The AM I / O device 3120 may also be used to select and control parameters of the HF support provided through high flow module 4200, with the input selections received from a user through AM I / O device being communicated by anaesthesia (AM) controller 3119 to high flow module controller 4219 for control of the blower 4210 and / or proportional valve(s) (when provided).

[0441] In examples where the high flow module 4200 is docked with the anaesthesia machine 3100, the I / O device 3120 of the anaesthesia machine (AM) may become the interface used for displaying alerts relating to the high flow respiratory support. In some examples, when a humidifier 17 is in use, the humidifier controller may be in operative communication with the HF Module controller 4129 such that parameters and alerts relating to the operation of the humidifier may be displayed on the HF I / O device 4220. Alternatively or additionally, the I / O device 3120 of the anaesthesia machine (AM) may become the interface used for displaying parameters and alerts relating to operation of the humidifier 17. This may occur by direct operative communication between the humidifier controller and the AM controller 3119, or by operative communication via the HF Module controller 4219. Examples of parameters relating to operation of the HF Module 4200 may include flow rate and gas composition. Examples of alerts relating to operation of the HF Module 4200 may include pressure threshold alerts arising when there is total or partial occlusion of an associated patient interface or supply conduit as described below, and alerts triggered by a venting signal as described above. Examples of parameters relating to operation of the humidifier 17 may include humidity parameters, gas flow rate, pressure and / or composition parameters as described below. Examples of alerts relating to operation of the humidifier 17 may relate to humidifier water level and / or signals indicative of a disconnection of a conduit at the input or output side of the humidifier as described below.

[0442] The high flow module 4200 may receive power from the power module 3110 of anaesthesia machine 3100 via the dock 3140. Power transmission may be via electrical (e.g. wired) and / or electromagnetic energetic transfer. Alternatively or additionally, high flow module 4200 may comprise a separate power supply in the form of battery 4240. Battery 4240 may be rechargeable or replaceable. In some embodiments, the anaesthesia machine 3100 may include a charging circuit to charge and recharge the battery 4240 when the battery is inserted into the dock 3140. In some examples, high flow module 4200 may be configured to receive electrical input by an IEC connector of the type known to persons skilled in the art permitting standalone use of the high flow module in the provision of high flow respiratory support, even without a battery.

[0443] In some embodiments, turning on anaesthesia machine 3100 may cause the humidifier 17 and / or the high flow device or high flow module 4200 also to turn on. This may occur when the anaesthesia machine 3100 is turned on or when a start-up mode of the anaesthesia machine 3100 is initiated by a user. For example, a user may turn on the anaesthesia machine 3100 by providing a user input through e.g. I / O device 3120. This user input may turn on or wake up the anaesthesia machine controller 3119, which then sends ‘on’ or ‘wake up’ signals to activate one or both of the high flow module control 4219 (or the high flow device) and the humidifier 17. The signal may be sent via dock 3140 or by other suitable wired or wireless communication means. Moreover, the high flow module 4219 may activate the humidifier 17, or vice versa, after being activated by the anaesthesia machine 3100 controller, or in response to being sent the ‘on’ or ‘wake up’ signal from the anaesthesia machine controller 3119.

[0444] Activating the anaesthesia machine 3100, high flow module 4200 or high flow device, and the humidifier 17 via a single user input streamlines processes and enables the devices 3100, 4200, 17 to activate together. In this manner, when the anaesthesia machine 3100 is turned on, the high flow module 4200 or high flow device may automatically turn on and transition to a default display screen where a user can provide further input, and / or a humidifier may automatically turn on and start running e.g. begin heating or transitioning to a default display screen where a user can provide further input.

[0445] In one example, when the high flow module 4200 or high flow device is turned on and activated in this manner, gas flow provision of the high flow module 4200 or high flow device may also be activated to a default setting. The default setting may include a default flow rate being provided via the high flow module 4200 or high flow device. In one example, the default flow rate may be 10 L / min. Such a flow rate may assist with a start up procedure of the humidifier 17.

[0446] Similarly, turning off the anaesthesia machine 3100 may cause the humidifier 17 and / or the high flow module 4200 or high flow device to also turn off. In one example, instead of turning off the high flow module 4200 or high flow device, turning off the anaesthesia machine 3100 may cause the oxygen delivery provided by the high flow module 4200 or high flow device to turn off.

[0447] In some embodiments, the anaesthesia machine 3100 or a ventilator may be configured for communication between AM controller 3119 and a remote system 5000 such as a remote patient record management system for generating and / or storing electronic medical records (EMRs). EMRs may be generated by the AM controller 3119 according to applicable standards and stored locally in a memory device on the anaesthesia machine 3100 or ventilator before being communicated to the remote system 5000. Such communications may occur via a wired or wireless communication network. Alternatively or additionally, the high flow module 4200 may be configured for communications between high flow module controller 4219 and a remote system 5000. Alternatively or additionally, the humidifier 17 may be configured for communications between the humidifier controller and a remote system 5000. EMRs may be generated by the high flow module controller 4219 and / or the humidifier controller according to applicable standards and stored locally in a memory device on the high flow module 4200 or humidifier 17 before being communicated to the remote system either directly or via the AM controller 3119.

[0448] In some examples, high flow module 4200 and / or humidifier 17 may be provided externally of the anaesthesia machine 3100. High flow module 4200 and humidifier 17 may be separate devices operating together as a high flow system. Alternatively, high flow module 4200 and humidifier 17 may be integrated into a single device as shown in Figure 30 and Figure 31 . In some examples, when the high flow module 4200 and humidifier 17 are integrated into a single device there is asingle controller for both the humidification and high flow gas function of the combined device. In some embodiments, anaesthesia machine 3100 may provide a physical structure on which one, or both, of the high flow module 4200 and humidifier 17 (when separate or integrated into a single device) may be supported or mounted. The physical structure may comprise e.g. a mounting arm 3900 that may be adjustable to optimise the location and / or orientation of the high flow module 4200 and / or humidifier 17. The high flow module 4200 may receive a supply of gases for the respiratory support from a gases source that is not the anaesthesia machine 3100. For example, high flow module 4200 may receive a supply of gases from a wall outlet and / or bottles. A splitter or separate wall outlet may be used to supply gases separately to the anaesthesia machine 3100. The humidifier 17 receives a flow of gases from the high flow module 4200.

[0449] The high flow module 4200 and humidifier 17 may be in operative communication with each other via an associated HF Module Controller 4219 and humidifier controller. Alternatively or additionally, high flow module 4200 and / or humidifier 17 may be in operative communication directly with AM controller 3119 via their respective controllers. Alternatively, communication with the AM controller 3119 may be via the humidifier controller which relays data from the HF Module Controller 4219 as in Figure 30. In another example, communication with the AM controller 3119 may be via the HF Module Controller which relays data from the humidifier controller as shown in Figure 31 . Alternatively, as mentioned above, there may be a single controller for both the humidifier 17 and high flow module 4200 as described above, which communicates with the AM controller 3119. Figure 30 and Figure 31 show the humidifier 17 as integrated into the HF Module 4200. However it is to be understood that this need not be the case, and as mentioned above, the humidifier and HF Module may be separate devices.

[0450] In some examples, parameters for operation of the HF module 4200 and / or the humidifier 17 may be received from an operator by the AM I / O device 3120 which conveys control signals to the HF Module controller 4219 and / or humidifier controller respectively, or to a single combined controller when the HF module and humidifier are integrated. In some examples the AM controller 3119 and / or the HF Module controller 4219 and / or the humidifier controller may communicate directly or indirectly (i.e. via other operatively coupled device controllers) with a remote system 5000 suchas a remote patient record management system for generating and / or storing EMRs. In an example shown in Figure 30 both the humidifier 17 and the anaesthesia machine 3100 are in operative communication with remote system 5000. Data from the HF module 4200 may be transmitted to the remote system 5000 via the humidifier 17 (and optionally further via the anaesthesia machine 3100). In another example shown in Figure 31 , both the high flow module 4200 and the anaesthesia machine 3100 are in operative communication with the remote system 5000. Data from the humidifier 17 may be transmitted to the remote system 5000 via the HF module 4200 (and optionally further via the anaesthesia machine 3100). Alternatively, when the high flow module 4200 and the humidifier 17 are integrated, there may be a single controller configured to transmit data to the remote system 5000.lt is to be appreciated that parameters for operation of the HF module 4200 which may be entered by a user via an AM I / O device 3210 may include but are not limited to e.g. power up and power down (switching on / off) of the HF Module 4200, user selected parameters for provision of respiratory support such as pre-set flow rate, pre-set gas composition (e.g. shown as FiO2) as well as humidifier control parameters such as temperature and dew point. Measured parameters that may be presented on the AM I / O device 3210 may include but are not limited to e.g. pre-set flow rate, pre-set gas composition, measured flow rate (e.g. downstream of the HF Module), measured gas composition (e.g. FiO2). Alerts that may be presented on the AM I / O device 3210 may include but are not limited to e.g. occlusion alerts, over pressure alerts, and humidifier alerts such as water level alerts and alerts that a conduit is not connected. These parameters and alerts may be presented on the AM I / O device 3210 in addition to parameters relating to operation of the anaesthesia machine 3100. These parameters may relate to e.g. flow rate in an expiratory limb, composition of anaesthetic gas and the like. It will be appreciated that while these examples are described in the context of an anaesthesia machine, such a machine may instead be a ventilator.

[0451] In some examples, the high flow module 4200 may be controlled to provide a flow of gases according to parameters set by a user making selections using the AM I / O Device 3120. In some examples, upon receiving the high flow module 4200 in the dock 3140, the AM Controller 3119 detects connection of the high flow module and in response, modifies the display view presented on a screen or monitor of the AM I / O Device 3120 to include a display zone that relates to operation of the high flowmodule, as an alternative or in addition to a display zone that relates to operation of the anaesthesia machine 3100. This is achieved under control of AM controller 3119 which is in operative communication with high flow module controller 4219. An example of such display zones is provided in relation to Figures 32 and 33.

[0452] Figure 32 is a schematic illustration of a display view 3400 presented on AM I / O device 3120 which includes an AM display zone 3410 and a HF display zone 3420 which may become visible automatically following connection of the high flow module 4200 with the anaesthesia machine 3100. The connection may be physical connection as described above with reference to Figure 30 and Figure 31 , or via a docking station as described with reference to Figures 34 to 38. For simplicity the detailed parameters typically represented on a display of an anaesthesia machine (e.g. patient blood gas parameters, heart rate, blood pressure, electrocardiographic activity, and the like) are omitted from the illustrated AM display zone 3410 however it is to be understood that this display zone may be configured according to the needs of the anaesthetist etc. In some examples, during use the AM I / O device 3120 comprises one or more regions that are user selectable, either by incorporating a touch screen into the AM I / O device or by providing a selector tool such as a mouse or track ball that can be used to move a selector across a display to permit selection of different visible features such as, tiles, buttons and / or icons that upon selection, can be utilised to change the view and / or parameters of operation of the anaesthesia machine.

[0453] In some examples, HF display zone 3420 may convey to a user that a high flow module 4200 is connected and / or high flow support is being provided e.g. by being illuminated, coloured, flashing and / or showing the letters HF or other meaningful content corresponding to the provision of high flow respiratory support. In some examples, HF display zone 3420 may be selectable and once selected, may enlarge the HF display zone to present more detail about the parameters of the high flow respiratory support. An example of an enlarged HF display zone is provided in Figure 33. In some examples, it may be possible to toggle between the simple (Figure 32) and enlarged (Figure 33) HF display zone 3420 by selection of a tile or icon on the display view 3400. In other examples, only a detailed HF display zone corresponding to Figure 33 may be presented on the display view 3400 upon connection of the high flow module 4200 to the anaesthesia machine 3100.

[0454] In the example of Figure 33, the enlarged HF display zone 3420 may include flow rate display zone 3426 for displaying the selected flow rate to be provided and / or the actual flow rate in the flow of gases, as may be determined e.g. by one or more sensors in the high flow module 4200 or downstream of the gases outlet 4253 e.g. at the humidifier 17 or the patient interface 15. In some examples, the HF display zone 3420 may include an oxygen concentration display zone 3422 for displaying the selected oxygen concentration (which may be identified as FiO2) to be provided and / or the actual concentration of oxygen (e.g. FiO2) in the flow of gases, as may be determined e.g. by one more sensors in the high flow module 4200 or downstream of the gases outlet 4253 e.g. at the humidifier 17 or the patient interface 15. In some examples, although not necessarily part of the high flow module 4200 per se, the HF display zone 3420 may include a humidification display zone 3428 which may display a humidity parameter such as the temperature and / or dew point selected for humidification and warming of gases from the high flow module by the humidifier 17. Alternatively, a separate and optionally selectable humidification display zone may be provided elsewhere on the display view 3400. Although humidifier 17 is shown as a separate component that may be operatively coupled with one or both of the anaesthesia machine 3100 and the high flow module 4200, in some embodiments the humidifier may be integrated with or incorporated into the high flow device or anaesthesia machine.

[0455] Advantageously, various embodiments disclosed herein provide for activation of alerts which are presented on an I / O device to provide clinicians with important information about the respiratory support that is provided to the patient. Various examples of alerts are discussed throughout this disclosure, including qualitative alerts that provide coarser information such alarm states relating to an occlusion in a gas flow path or disconnection of a conduit, and quantitative alerts that provide measured parameter values, such as actual flow rates, venting flow rate, FiO2 and the like. In some examples, the AM controller 3119 may cause activation of an alert on AM I / O device 3120 upon receipt of a signal that indicates a pressure threshold has been exceeded in the gas flow system and particularly the gas flow path down stream of the high flow module 4200. A pressure threshold may be exceeded when there is a partial or complete occlusion in the system as may occur e.g. when the patient interface 15 (or conduit 900) becomes crushed or pinchedclosed or the patient interface becomes occluded by application of a face mask over a collapsible portion. Activation of an alert may follow receipt by AM controller 3119 (or high flow module controller 4219) of a signal indicative of such an over pressure or occlusion. Such a signal may comprise a venting signal from a sensor 500 providing an indication of gas venting from e.g. a pressure relief valve as discussed in relation to Figures 25A to 27. Alternatively or additionally, such a signal may comprise a signal from a dedicated pressure sensor in the flow path downstream of the blower 4210 (or proportional valve, when provided). Alternatively or additionally such an alert may be activated on HF I / O device 4210, by the HF control module 4219 receiving one or more signals indicative of an over pressure, either from the sensors themselves or via AM controller 3119.

[0456] In some examples, an over pressure in the system may cause AM controller 3119 to alarm. In some examples as disclosed herein, a pressure relief valve 100 may be provided to respond to such over pressure by venting excess pressure to atmosphere. In some examples, in response to system pressure exceeding a safe threshold, high flow module controller 4219 may alter control of the blower 4210 to reduce the blower speed in order to lower system pressure to an acceptable or safe target pressure. Alternatively / additionally, the controller 4219 may control operation of a valve such as a proportional valve to lower pressure in the system. In some embodiments, the controller 4219 (or controller 3219) may be configured to track time spent in over-pressure and, if the pressure in the system remains over pressure after a certain period of time, the controller 4219 (or controller 3219) may trigger an audible and / or visible alarm on the HF I / O device 4120 and / or the AM I / O device 3120 to alert users to the possibility of a blockage in the gas delivery conduit or other components of the system. Delaying the alert for a certain time period may reduce alarms arising from pressure spikes that are not sustained, as may arise due to temporary occlusions from e.g. brief crushing or kinking of a conduit that is not sustained. Alternatively or additionally, when the venting signal is obtained from a sensor downstream of the main outlet 153, that signal may be used to monitor gas flow parameters that enable the controller 4219 (or controller 3219) to track time spent in under-pressure (e.g. to track time when flow is venting and thus, pressure in the system is less than expected) and, if the pressure in the system remains under pressure aft...

Claims

CLAIMS:1 . A device for providing respiratory support to a patient, the device comprising: a flow modulator operable to provide a high flow of gas via a high flow patient interface; and a controller controlling the flow modulator, the controller being operatively configured to: receive one or both of an occlusion signal and a mask signal; determine an occlusion status of a flow path of the high flow of gas to the patient based on the occlusion signal; and / or determine a mask placement status based on the mask signal; and control the flow modulator according to the occlusion status and / or mask placement status.

2. The device according to claim 1 , wherein the controller controls the flow modulator to change the flow of gases when a change in mask placement status is determined based on the occlusion signal and the mask signal.

3. The device according to any one of the preceding claims, wherein the mask signal is received from an anaesthesia machine or ventilator, or a first sensor associated with an anaesthesia machine or ventilator.

4. The device according to claim 1 or 2, wherein the mask signal is provided by a first sensor located at, or sampling gases from, a face mask in fluid communication with an anaesthesia machine or ventilator.

5. The device according to claim 3 or claim 4, wherein the first sensor senses gases: in an expiratory flow path of a face mask in fluid communication with the anaesthesia machine or ventilator; or in an inspiratory flow path of a face mask in fluid communication with the anaesthesia machine or ventilator; orin a sealing cuff of a face mask in fluid communication with the anaesthesia machine or ventilator.

6. The device according to any one of claims 3 to 5, wherein the mask signal is provided by the first sensor, the first sensor comprising one or more of a pressure, flow rate, gas composition (e.g. 02, CO2 or anaesthesia gas), temperature and humidity sensor.

7. The device according to claim 5, wherein the mask signal indicates a “mask on” mask placement status when the first sensor detects at least one of: in the expiratory flow path: a flow of gas; a change in concentration of one or more of CO2, 02 and an anaesthetic agent, such as an increase in concentration; a gas pressure greater than or less than ambient atmospheric pressure; a change in temperature, such as in increase in temperature; a change in humidity, such as an increase in relative humidity; an increase in pressure and / or temperature in the sealing cuff of the face mask; a change in emitted and / or detected light corresponding to the face mask being applied to the patient’s face; in an inspiratory flow path: a flow of gas; a change in flow rate of gas such as an increase in the flow rate; a change in concentration of C02 and / or an anaesthetic agent, such as an increase in C02 and / or anaesthetic agent concentration; and a gas pressure greater than or less than ambient atmospheric pressure.

8. The system according to claim 5, wherein the mask signal indicates a “mask off” mask placement status when the first sensor detects at least one of: in an expiratory flow path: a change in flow rate of gas such as a decrease in the flow rate; a substantially zero flow rate; a change in CO2 concentration, such as a decrease in CO2concentration; a change in 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a decrease in system pressure; a gas pressure at or about ambient atmospheric pressure; a change in temperature, such as a decrease in temperature; a change in humidity, such as an increase in relative humidity; a decrease in pressure and / or temperature in the sealing cuff of the face mask; in an inspiratory flow path: a substantially zero flow rate; a gas pressure at or about ambient atmospheric pressure; a substantially zero C02 concentration; a change in C02 concentration, such as a decrease in C02 concentration; a change of 02 concentration such as an increase in 02 concentration; a change in anaesthetic agent concentration, such as a decrease in anaesthetic agent concentration; a change in temperature, such as a decrease in temperature; a change in humidity, such as an decrease in relative humidity; and a change in emitted and / or detected light corresponding to the face mask being removed from the patient’s face.

9. The device according to any one of the preceding claims, wherein the occlusion signal is received from an occlusion sensor.

10. The device of claim 9, wherein the device comprises the occlusion sensor.11 . The device according to claim 9 or 10, wherein the occlusion sensor comprises a pressure sensor for monitoring pressure of gasses provided by the flow modulator.

12. The device according to claim 11 , wherein detection by the pressure sensor of: an increase in pressure to meet or exceed a predetermined occlusion pressure threshold causes the controller to determine the occlusion status asoccluded; and a decrease in pressure to fall below the predetermined occlusion pressure threshold causes the controller to determine the occlusion status as unoccluded.

13. The device according to any one of the preceding claims, wherein the controller is configurable to control the flow modulator based on receiving the mask signal in the absence of the occlusion signal.

14. The device according to any one of the preceding claims, wherein the controller is configured to perform one or more of:- upon receiving the occlusion signal and determining the occlusion status as “occluded”, determine the mask placement status based on the mask signal;- upon receiving the mask signal and determining the mask placement status as “mask on”, determine the occlusion status based on the occlusion signal;- receiving the occlusion signal and / or the mask signal substantially continuously or at regular intervals during operation of the device; and- determining the mask placement status and occlusion status substantially simultaneously.

15. The device according to any one of the preceding clams, wherein the controller, upon determination of: the mask placement status as “mask on” based on the mask signal, and / or the occlusion status as “occluded” based on the occlusion signal, controls an output device to provide an audible and / or visible and / or tactile alert.

16. The device according to any one of preceding clams, wherein the controller, upon determination of one or both of: the mask placement status as “mask on” based on the mask signal, and the occlusion status as “occluded” based on the occlusion signal, controls the flow modulator to provide the flow of gases at a target pressure and / or target flow rate, or at a flow rate of 0 L / min.

17. The device according to claim 16, wherein the target pressure comprises a predetermined target pressure threshold value for a corresponding target flow rate, ora predetermined target pressure threshold value corresponding to a flow rate less than the target flow rate.

18. The device according to claim 16 or 17, wherein, when the controller drives the flow modulator at the target pressure, the flow of gases is reduced to a flow rate which is: about 15L / min or less; or about 10L / min or less; or about 10L / min; or about 5L / min to about 10L / min or less than about 5L / min or OL / min.

19. The device according to any one of claims 16 to 18, wherein the controller is in operative communication with or comprises a memory component storing one or more of a function, a curve, a look up table or an algorithm providing a relationship between one or more pressure threshold values and corresponding flow rate values.

20. The device according to claim 19, wherein the relationship between the pressure threshold values and the corresponding flow rate values is represented by a pressure limit curve or a function defining a curve having a sigmoidal shape.21 . The device according to claim 19 or 20, wherein the relationship between the pressure threshold values and corresponding flow rates comprises a first pressure region, a second pressure region, and a transition region disposed between the first pressure region and the second pressure region.

22. The device according to claim 21 , wherein the controller controls the flow modulator according to: values in the first pressure region when the occlusion signal corresponds to an occlusion status of “unoccluded”; and / or values in the second pressure region when the mask placement status is determined as “mask on”.

23. The device according to claim 21 or 22, wherein the transition region comprises a gradient of a pressure limit curve corresponding to a maximum rate of change in the flow rate of respiratory gases.

24. The device according to any one of the preceding claims, wherein the controller is configured to: receive a pause signal, andin response to the pause signal, control the flow modulator to reduce a flow rate of gas in the respiratory support to substantially 0 LPM.

25. The device according to claim 24, wherein upon receiving the pause signal, the controller controls the flow modulator to reduce the flow rate of gas to substantially 0 LPM for: a predetermined duration stored in a memory component in operative communication with or forming part of the controller, or a duration requested by a user providing an input to a user interface in operative communication with the controller.

26. The device according to claim 24 or 25, wherein the pause signal is triggered by the device, an anaesthesia machine or ventilator receiving a user input requesting to monitor a parameter of gases exiting the patient.

27. The device according to claim 26, wherein the parameter of gases exiting the patient is monitored by the anaesthesia machine or ventilator or a sensor associated with the anaesthesia machine or ventilator.

28. The device according to claim 26 or 27, wherein the monitored parameter comprises one or more of 02 concentration, C02 concentration, anaesthetic gas concentration and one or more ventilation parameters including tidal volume, minute volume, airway pressure, and flow rate.

29. The device according to any one of claims 26 to 28, wherein the monitored parameter is monitored by a sensor located in or receiving gases from the mask.

30. The device according to any one of claims 26 to 29, wherein values corresponding to the monitored parameter are presented on a display device.31 . The device according to claim 30, wherein the display device forms part of the anaesthesia machine or ventilator, and / or part of the device, and / or a separate display device which is not part of the device or the anaesthesia machine or ventilator.

32. The device according to any one of the preceding claims, wherein the controller, upon receipt of- a mask signal that corresponds to “mask off’ mask placement status and / or that does not correspond to a “mask on” mask placement status; and- an occlusion signal corresponding to an “unoccluded” occlusion status, controls the flow modulator to provide respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold.

33. The device according to any one of the preceding claims, wherein when the mask placement status is “mask on”, the controller determines the mask placement status as “mask off” upon receipt of an occlusion signal indicative of an “unoccluded” occlusion status, and controls the flow modulator to provide respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold.

34. The device according to any one of the preceding claims, wherein the device is integrated with or forms part of an anaesthesia machine or ventilator.

35. The device according to claims 1 to 33, wherein the device is communicatively couplable and / or physically couplable to an anaesthesia machine or ventilator.

36. The device according to any one of claims 1 to 33, wherein the device comprises or is operable with a humidifier for warming and / or humidifying respiratory gases provided to the patient, such as gases in the respiratory support.

37. The device according to claim 36, wherein the humidifier is in operable communication with the controller.

38. The device according to any one of the preceding claims 1 to 35, wherein the device is operable to provide respiratory support comprising a flow rate that is: selectable from an available range of about 20 LPM to about 100 LPM; and / or selectable from a plurality of available fixed flow rates including at least 0 LPM,40 LPM and 70 LPM.

39. The device according to any one of the preceding claims, wherein the device is operable to provide respiratory support comprising one or both of 02 or air such as filtered air.

40. The device according to any one of the preceding claims, wherein the device is operable to provide the respiratory support comprising 02 at a concentration in a range of about 21 % to 100%.41 . The device according to any one of the preceding claims, wherein the controller is configured to also control an anaesthesia machine or ventilator.

42. The device according to any one of the preceding claims, wherein the controller forms part of the device, or part of an anaesthesia machine or ventilator, or part of a separate device not part of the device or the anaesthesia machine or ventilator.

43. The device according to any one of the preceding claims, wherein the high flow patient interface comprises a nasal cannula, such as a non-sealing nasal cannula.

44. The device according to any one the preceding claims, wherein the high flow patient interface comprises a collapsible portion which is operable in a first configuration in which the collapsible portion is in a substantially open condition, and in a second configuration in which the collapsible portion is in a substantially closed condition.

45. The device of claim 44, wherein controller is operatively configured to determine the occlusion status as “occluded” based on the occlusion signal when the high flow patient interface is operating in the second configuration.

46. The device of claim 44 or 45, wherein an occlusions status as “occluded” and a mask placement status as “mask on” indicates that the high flow patient interface is operating in the second configuration and a face mask is placed over the patient interface.

47. The device of any one of the preceding claims, wherein the controller determines that an occlusions status as “occluded” and a mask placement status as “mask off” indicates that an accidental occlusion may be present in the flow path; andoptionally, the controller controls the flow modulator to provide respiratory support comprising gases at a flow rate set point and / or a gas pressure less than or about equal to a predetermined occlusion pressure threshold that may be dynamically and temporarily increased by the controller while the “mask off” status remains.

48. The device of any one of claims 44 to 46, wherein an occlusions status as “unoccluded” indicates that the high flow patient interface is operating in the first configuration.

49. A system for providing respiratory support to a patient, the system comprising: first device operable to provide a first respiratory support via a first patient interface comprising a face mask; a second device operable to provide a second respiratory support via a second patient interface comprising a high flow interface; a first sensor providing a first signal indicative of mask placement status of the face mask relative to the patient; a second sensor providing a second signal indicative of occlusion status of a flow path providing the second respiratory support; and a controller configured to receive the first and second signals and control the second device according to the occlusion status and / or mask placement status.

50. A system for providing respiratory support to a patient, comprising: a pressure valve; a venting sensor providing an indication of gas venting from the pressure valve; and a controller configured to receive a venting signal from the venting sensor; wherein the controller is configured to cause activation of an alert upon receipt of the venting signal indicating venting from the pressure valve.51 .The system according to claim 50, wherein the system is configured to provide high flow respiratory support.

52. The system according to claim 50, wherein the system comprises part of a device providing high flow respiratory support.

53. The system according to claim 52, wherein the device is couplable with or integrated into an anaesthesia machine or ventilator.

54. The system according to any one of claims 50 to 53, wherein the pressure valve is a pressure relief valve, preferably a flow compensated pressure relief valve.

55. The system according to any one of claims 50 to 54, wherein the pressure valve comprises one or more of: a mechanical valve component; and an electronic valve component.

56. The system according to any one of claims 50 to 55, wherein the controller is configured to cause the alert to be presented on a user interface device.

57. The system according to claim 56, wherein the user interface comprises part of: an anaesthesia machine; and / or a ventilator; and / or a device providing high flow respiratory support.

58. The system according to any one of claims 50 to 57, wherein the alert comprises one or more of an audible, a visible and a tactile alert.

59. The system according to any one of claims 50 to 58, wherein the alert comprises one or more of: a qualitative alert; and a quantitative alert.

60. The system according to any one of claims 50 to 59, wherein the venting sensor comprises one or more of a flow sensor, a pressure sensor and a gas concentration sensor.61 .The system according to any one of claims 50 to 60, wherein the pressure valve comprises a valve outlet through which gases are vented and a main outlet through which gases are provided for respiratory support to a patient, and wherein the venting sensor is located at or downstream of the valve outlet.

62. The system according to any one of claims 50 to 60, wherein the pressure valve comprises a valve outlet through which gases are vented and a main outlet through which gases are provided for respiratory support to a patient, wherein the venting sensor is located at or downstream of the main outlet.

63. The system according to any one of claims 50 to 62, wherein the pressure valve is integrated with or forms part of an anaesthesia machine or a ventilator.

64. The system according to any one of claims 50 to 63, wherein the venting sensor is integrated with or forms part of an anaesthesia machine or ventilator.

65. The system according to claim 64, wherein the anaesthesia machine or ventilator provides a vent path to atmosphere for gases vented from the pressure valve.

66. The system according to any one of claims 50 to 65, wherein the venting sensor is external to an anaesthesia machine or ventilator.

67. The system according to any one of claims 50 to 66, wherein the controller is configured to control a flow source providing a flow of respiratory gases comprising the respiratory support to the patient.

68. The system according to claim 67, wherein the flow source is integrated with or forms part of an anaesthesia machine or ventilator.

69. The system according to any one of claims 50 to 68, wherein the system comprises or is operable with a humidifier for warming and / or humidifying respiratory gases provided to the patient.

70. The system according to claim 69, wherein the humidifier is in operable communication with the controller.71 .The system according to any one of claims 50 to 70, comprising or operable with a patient interface configured to provide a flow of respiratory gases comprising the respiratory support to the patient.

72. The system according to any one of claims 50 to 71 , wherein the controller, upon receipt of a venting signal providing an indication of gas venting from the pressure valve, is configured to cause activation of an alert indicative of an occlusion in a flow path configured to provide respiratory gases to a patient.

73. The system according to any one of claims 50 to 72, wherein the controller is configured to cause activation of an I / O device to display the alert.

74. The system according to any one of claims 50 to 73, wherein the alert comprises a quantitative alert selected from the group comprising:- venting flow rate based on the venting signal;- actual flow rate delivered to the patient; and - pre-set flow rate of the respiratory support.

75. The system according to any one of the claims 50 to 74, comprising a humidifier, and wherein the controller is a humidifier controller.

76. The system according to claim 75, wherein the humidifier comprises a sensor configured to measure the incoming flow rate of gases entering the humidifier, and wherein the humidifier controller is configured to determine a pre-set flow rate of gases intended for respiratory support to the patient by summing the incoming flow rate with a venting flow rate determined from the venting signal.

77. The system according to claim 76, wherein the humidifier comprises a humidifier I / O device and the alert and / or the pre-set flow rate are displayed on the humidifier controller.

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