PATIENT INTERFACE

FIELD OF THE INVENTION

Present invention relates to a patient interface for delivering respiratory gas to a patient. In particular, the present invention relates to a non-invasive patient interface.

BACKGROUND

One current treatment for obstructive respiration diseases, such as chronic obstructive pulmonary disease (COPD - which includes emphysema, refractory asthma and Chronic bronchitis), is non-invasive ventilation (NIV). This treatment applies a positive airway pressure to the lungs throughout the inhalation and exhalation cycle so as to splint the airways open. This improves the flow of respiratory gas into and out of the lungs.

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

The NIV treatment gives rise to two challenges, namely compliance (the extent to which patients are willing to submit to the treatment) and pressure sores. In addition to these challenges, a further challenge for patients with obstructive respiration diseases is flushing carbon dioxide out of anatomical dead space. Specifically, the end of the exhalation cycle is characterised by a reduction in pressure of the exhaled respiratory gas. This means that the carbon dioxide-loaded respiratory gas remains in the throat, nose and mouth of the patient and is pulled back into the lungs at the commencement of the inhalation cycle. Replacing the carbon dioxide-loaded respiratory gas in these regions with respiratory gas that includes oxygen in suitable concentrations for treating obstructive respiration diseases therefore assists patients.

It is desirable to provide a patient interface that improves patient comfort and that reduces pressure sores.

It is also desirable to provide a patient interface that assists with flushing anatomical dead space.

SUMMARY OF THE INVENTION

The present invention will now be described by way of a set of embodiments in which the invention may be defined by the features of each embodiment exclusively. However, it will also be appreciated that the invention may be defined by the features of two or more of the embodiments.

According to a first aspect, there is provided a non-invasive patient interface having a seal member which is shaped to encompass a mouth and nares of a patient, the interface defining :

(a) a primary flow path to communicate respiratory gas from a gas source to each of the mouth and the nares separately, and

(b) a flushing flow path to communicate respiratory gas from the primary flow path and/or from the gas source to the nares.

The primary flow path may include a primary flow cavity having one or more primary flow inlets for respiratory gas and having one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares.

The primary flow path may include a primary flow cavity having one or more primary flow inlets for respiratory gas and having one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares separately.

The flushing flow path may include a flushing flow cavity having one or more flushing flow inlets for respiratory gas and one or more flushing flow outlets to deliver the respiratory gas to the nares of a patient.

The interface may include a mask housing and wherein at least one of the one or more primary flow inlets is in the housing.

The primary flow cavity may be formed by the seal member and the housing.

At least one of the one or more primary flow inlets may be formed in the mask housing.

The patient interface may include one or more of the flushing flow inlets in the seal member.

The interface may include one or more of the flushing flow inlets in the mask housing.

The flushing flow cavity may be a bifurcated cavity having one flushing fluid inlet, two passages downstream of a bifurcation and respective flushing flow outlets at a downstream end of each of the passages.

The flushing flow cavity may be integrally formed with the seal member.

The flushing flow outlets may be flush with primary flow outlets to the nares.

The flushing flow outlets may be recessed within the primary flow cavity from the one or more primary flow outlets to the nares.

The flushing flow cavity may be shaped to direct respiratory gas into the nares.

The flushing flow cavity may be shaped to accelerate respiratory gases into the nares.

The flushing flow cavity may be defined by a cavity wall extending between the one or more flushing flow inlets and the one or more flushing flow outlets.

The flushing flow cavity may be defined by the cavity wall and the outer wall of the seal member.

The flushing flow cavity may be configured to accelerate the respiratory gas. The acceleration of the respiratory gas is an increase in the velocity of the respiratory gas. References, throughout this specification and the claims, to acceleration of the respiratory gas are taken to have the same meaning, unless indicated otherwise.

The seal member may have a first primary flow outlet defined by a first portion of the mask seal which forms a seal or substantially forms a seal surrounding the mouth of the patient and a second primary flow outlet defined by a second portion of the mask seal which forms a seal or substantially forms a seal around the nares of the patient.

The seal member may be a resilient material and may be connected to the mask housing to form a unitary structure.

The seal member may be a resilient material and may be mechanically locked to the mask housing to form a unitary structure.

The seal member may be over moulded onto the mask housing to mechanically lock with the mask housing.

The interface may include a mask frame that has one or more respiratory gas flow channels that enable respiratory gas flow from a gas source to the one or more primary flow inlets and to the one or more flushing flow inlets.

The mask frame may have a single respiratory gas flow channel.

The mask frame may have separate flow channels for delivering respiratory gas to the one or more primary flow inlets and to the one or more flushing flow inlets, and wherein the flow channel or channels for delivering respiratory gas to the one or more flushing flow inlets is configured to accelerate the respiratory gas.

The mask frame may be removably connectable to the mask housing.

The mask frame may be removably connectable by co-operable snap-fit formations on the mask housing and on the mask frame.

The mask frame may be permanently connectable to the housing by co-operable formations on the mask housing and the mask frame.

The mask frame and the housing may be integrally formed.

The interface includes vent holes to allow gas, including exhaled gas, to escape the primary flow cavity.

The vent holes may be in the mask housing.

The seal member has one or more primary flow outlets that direct respiratory gas into the nares and one or more flushing flow outlets that direct respiratory gas into the nares and wherein the primary flow outlets and the flushing flow outlets may be arranged to collectively form a nasal aperture.

The cavity wall may extend along an outer wall of the seal member so that the flushing flow cavity is defined by the cavity wall and the outer wall.

The flushing flow cavity may be a single passage from the one or more flushing flow inlets to the one or more flushing flow outlets.

The cavity wall of the flushing flow cavity may separate the one or more flushing flow outlets from the one or more primary flow outlets which direct respiratory gas to the nares.

The one or more flushing flow outlets may have a predetermined shape.

The cavity wall may include a tether that links to a rim of the nasal aperture and that resists deformation of the one or more flushing flow outlets from the predetermined shape.

The interface includes two flushing flow outlets which may be separated by the tether so that the flushing flow outlets are substantially aligned with the nares.

The tether may be substantially aligned with the septum of a patient when in use.

The predetermined shape may be an hourglass or lemniscate or hippopede shape.

The predetermined shape may be figure-eight shaped.

The tether and an outlet end of the cavity wall may be flush with the primary flow outlets which direct respiratory gas into the nares.

The tether may be recessed into the primary flow cavity to avoid contact with the patient when the interface is fitted to the patient.

The cavity wall may be recessed into the primary flow cavity to avoid contact with the patient when the interface is fitted to the patient.

The cavity wall may be recessed from the nasal aperture to avoid contact with the patient when the interface is fitted to the patient.

The flushing flow cavity may have higher resistance to gas flow than compared to the resistance to gas flow of the primary flow cavity and wherein the shape of the flushing flow cavity is selected to accelerate the gas flow sufficiently to cause flushing of anatomical dead space.

The mask frame may have a primary flow channel and a flushing flow channel that communicate respectively with the one or more primary flow inlets and the one or more flushing flow inlets.

The flushing flow channel may have internal dimensions that permit a lower volumetric flow rate of respiratory gas than the volumetric flow rate of respiratory gas permitted by the primary flow channel at the same temperature and pressure.

The interface may include a flow splitter that has a single inlet which is connectable to a single gas source and has two outlets that are connectable respectively to the primary flow channel and to the flushing flow channel of the mask frame.

The one or more primary flow inlets and the one or more flushing flow inlets may be in the mask housing.

The one or more primary flow inlets may be in the mask housing and the one or more flushing flow inlets may be in the seal member.

The flushing flow path may include a flushing flow cavity which has at least one outlet that is separate from the seal member such that the seal member and the outlet can move independently of each other.

The interface may include one primary flow inlet and one flushing flow inlet and wherein the interface further includes a mask frame that has a first respiratory gas flow channel that enables respiratory gas to flow from a gas source to the primary flow inlet and a second respiratory gas flow channel that enables respiratory gas to flow from the gas source to the flushing flow inlet.

The flushing flow cavity may be formed as a conduit which is separate of the seal member and wherein the conduit has a distal end connected to the second respiratory gas flow channel and a proximal end that terminates at or adjacent to the nasal aperture.

The proximal end of the conduit terminates at a location that may be recessed from the nasal aperture.

The conduit may be surrounded by the primary flow cavity.

The conduit may be formed of resilient material.

The conduit may be linked to the seal member such that the flushing flow outlet tracks the nasal aperture during seal deformation.

The conduit may be linked to the seal member by one or more web members.

The location and shape of the web members may be selected to substantially retain the flexibility of the seal member without the web members.

The one or more web members may be linked to the seal member at locations that cause the one or more web members to impart a force on the conduit when the seal member is deformed by the patient's nose during fitting or adjustment.

The one or more web members may link the proximal end of the conduit to the seal member at a location adjacent to or at a rim of the nasal aperture.

The one or more web members may extend from a position intermediate the proximal and distal ends of the conduit to link with the seal member at a location remote from the nasal aperture.

At least one web member may be a partition wall in a plane of symmetry of the seal member.

One or more web members may have a constant cross-section throughout their length.

One or more web members may have a cross-section that tapers.

The cross-section may taper outwardly toward ends of the web member from a point intermediate the ends.

The seal member may include flexible regions which adapt to the shape of a patient's face and relatively inflexible structural regions that support the flexible regions and wherein the one or more web members are linked to the structural regions.

The structural regions may coincide with a perimeter of the mask frame

The structural regions may comprise a portion of the seal member that attaches to the mask housing via over-moulding.

The seal member may include flexible regions which adapt to the shape of a patient's face and relatively inflexible structural regions that support the flexible regions and wherein the one or more web members are linked to the flexible regions.

The conduit and the second respiratory gas flow channel may have co-operable formations that enable the conduit to be fitted to the second respiratory gas flow channel such that the flushing flow outlet is aligned to direct respiratory gas into nares of a patient when the interface is fitted to a patient.

The co-operable formations may comprise a flange about an outlet of the second respiratory gas flow channel and a flange-receiving groove in an inner wall of the conduit.

The groove may be shaped to limit the extent to which the conduit can be fitted onto the second respiratory gas flow channel, thereby ensuring proper alignment of the conduit to direct respiratory gas into nares of a patient when the interface is fitted to a patient.

The shape of the groove may complement the shape of the flange.

The co-operable formations may comprise a flange portion extending at least partly about an outlet of the secondary respiratory gas channel, a recess which is adjacent and distal to the flange and a flange-receiving groove in an inner wall of the conduit which defines an inwardly directed lip, wherein the lip latches into the recess when the flange portion is seated in the groove, thereby ensuring proper alignment of the conduit to direct respiratory gas into nares of a patient when the interface is fitted to a patient.

The inner wall of the conduit may be flush with the inner wall of the secondary

respiratory gas channel at the point where the conduit connects to the secondary respiratory gas channel.

The conduit may have one or more preferential deformation zones remote from the flushing flow outlet to enable the conduit to track movement of the nasal aperture whilst substantially maintaining the shape of the flushing flow outlet.

The one or more deformation zones may have reduced wall thickness compared to the wall thickness of adjacent areas.

The one or more deformation zones may comprise bands.

The bands may have a curved profile or a square profile.

The deformation zones may be formed in an outer wall of the conduit to maintain a low resistance flow path in the flushing flow cavity.

According to a second aspect, there is provided a non-invasive patient interface having a seal-forming seal member which is shaped to encompass a mouth and nares of a patient, the interface defining :

(a) a primary flow cavity to communicate respiratory gas from a gas source to each of the mouth and the nares separately,

(b) a flushing flow cavity to communicate respiratory gas from the gas source to the nares; and

wherein the primary flow cavity and the flushing flow cavity are separated by a cavity wall that forms a partition between inlets to the primary flow cavity and to the flushing flow cavity.

The primary flow cavity may have one or more primary flow inlets for respiratory gas and may have one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares.

The primary flow cavity may have one or more primary flow inlets for respiratory gas and may have one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares separately.

The flushing flow cavity may have one or more flushing flow inlets for respiratory gas and may have one or more flushing flow outlets to deliver the respiratory gas to the nares of a patient.

The interface may include a housing and wherein at least one of the one or more primary flow inlets is in the housing.

The primary flow cavity may be formed by the seal member and the housing.

The mask housing includes an opening that is partitioned by the cavity wall to define the primary flow inlet and the flushing flow inlet.

The flushing flow cavity may be integrally formed with the seal member.

The flushing flow cavity may be shaped to direct respiratory gas into the nares.

The flushing flow cavity may have a shape that accelerates the respiratory gas as it flows from the flushing flow inlet to the one or more flushing flow outlets.

The seal member may have a first primary flow outlet defined by a first portion of the mask seal which forms a seal or substantially forms a seal surrounding the mouth of the patient and a second primary flow outlet defined by a second portion of the mask seal which forms a seal or substantially forms a seal with nares of the patient.

The flushing flow outlets may be flush with a primary flow outlet to the nares.

The seal member may be a resilient material and may be connected to the mask housing to form a unitary structure.

The seal member may be a resilient material and is mechanically locked to the mask housing to form a unitary structure.

The seal member may be over-moulded onto the mask housing to mechanically lock with the mask housing.

The interface may include a mask frame that has one or more respiratory gas flow channels that enable respiratory gas flow from a gas source to the one or more primary flow inlets and to the one or more flushing flow inlets.

The mask frame may have a single respiratory gas flow channel that communicates respiratory gas to the opening that defines the primary flow inlet and the flushing flow inlet.

The mask frame may have separate flow channels for delivering respiratory gas to the one or more primary flow inlets and to the one or more flushing flow inlets, and wherein the flow channel or channels for delivering respiratory gas to the one or more flushing flow inlets is configured to accelerate the respiratory gas.

The mask frame may be removably connectable to the mask housing.

The mask frame may be removably connectable by co-operable snap-fit formations on the mask housing and on the mask frame.

The mask frame may be removably connectable by co-operable formations on the mask housing and on the mask frame.

The mask frame and the housing may be integrally formed.

The interface may include vent holes to allow gas, including exhale gas, to escape the primary flow cavity.

The vent holes may be in the mask housing.

The interface may include an exhaust cavity that enables exhaled respiratory gas to be vented externally of the interface.

The exhaust cavity may be defined in part by an exhaust cavity wall which separates the exhaust cavity from the flushing flow cavity

The exhaust cavity may be defined by the exhaust cavity wall and the outer wall of the seal member.

The exhaust cavity may have at least one exhaust gas inlet to receive exhaled gas from the nares and has an exhaust outlet in the seal member that vents the exhaled gas externally of the interface.

The at least one exhaust gas inlet may be adjacent to the flushing flow outlet.

The at least one exhaust gas inlet may be in the exhaust cavity wall

The at least one exhaust gas inlet may be in the outer wall adjacent the one or more flushing flow outlets so that the nares overlap the at least one exhaust gas inlet and the one or more flushing flow outlets when the interface is fitted to a patient.

According to a third aspect, there is provided, a non-invasive patient interface having a seal-forming seal member which is shaped to encompass a mouth and nares of a patient, the interface defining :

(a) a primary flow path to communicate respiratory gas from a gas source to each of the mouth and the nares separately, and

(b) a flushing flow path to communicate respiratory gas from the primary flow path and/or from the gas source to the nares; and

wherein the primary flow path includes a primary flow cavity having a primary flow inlet and the flushing flow path includes a flushing flow cavity having a flushing flow inlet and wherein the primary flow inlet and the flushing flow inlet are formed by the seal member.

The primary flow cavity may have one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares.

The primary flow cavity may have one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares separately.

The flushing flow cavity may have one or more flushing flow outlets to deliver the respiratory gas to the nares of a patient.

The interface may include a housing fixed to the seal member such that the primary flow cavity is formed by the seal member and the housing.

The flushing flow cavity may be integrally formed with the seal member.

The one or more flushing flow outlets may be flush with a primary flow outlet to the nares.

The flushing flow cavity may be shaped to direct respiratory gas into the nares.

The flushing flow cavity may be defined by a cavity wall extending between the one or more flushing flow inlets and the one or more flushing flow outlets.

The cavity wall may extend along an outer wall of the seal member so that the flushing flow cavity is defined by the cavity wall and the outer wall.

The flushing flow cavity may be configured to accelerate the respiratory gas.

The seal member may have a first primary flow outlet defined by a first portion of the mask seal which forms a seal or substantially forms a seal surrounding the mouth of the patient and a second primary flow outlet defined by a second portion of the mask seal which forms a seal or substantially forms a seal with nostrils of the patient.

The seal member may be a resilient material and may be connected to the mask housing to form a unitary structure.

The seal member may be a resilient material and is mechanically locked to the mask housing to form a unitary structure.

The seal member may be over moulded onto the mask housing to mechanically lock with the mask housing.

The interface may include a mask frame that has a respiratory gas flow channel that enables respiratory gas to flow from a gas source to the primary flow inlet and to the flushing flow inlet.

The mask frame may be removably connectable to the mask housing.

The mask frame may be removably connectable by co-operable snap-fit formations on the mask housing and on the mask frame.

The mask frame may be removably connectable by co-operable formations on the mask housing and on the mask frame.

The mask frame and the housing may be integrally formed.

The interface may include vent holes to allow gas, including exhale gas, to escape the primary flow cavity.

The vent holes may be in the mask housing.

The shapes of the primary flow cavity and the flushing flow cavity may be selected to provide a resistance to gas flow which enables the delivery of respiratory gas through the primary flow cavity to provide pressure support therapy and which delivers respiratory gas flow through the flushing flow cavity to provide flushing of anatomical dead space.

The seal member may include a nasal aperture which is a combination of the flushing flow outlet and the primary flow outlet that delivers respiratory gas to the nares, each of these two outlets contributes a cross-sectional area to an overall cross-sectional area of the nasal aperture and wherein a ratio of the cross-sectional area of the flushing flow outlet to the cross-sectional area of the primary flow outlet that delivers respiratory gas to the nares is selected to provide a desired resistance to flow of respiratory gas through the primary flow cavity and through the flushing flow cavity.

The cavity wall may be connected to the seal member so that the ratio remains substantially the same when the interface is fitted to a patient.

The cavity wall may be connected to a rim of the nasal aperture such that the cavity wall partitions the nasal aperture.

The flushing flow cavity may have higher resistance to gas flow compared to the resistance to gas flow of the primary flow cavity and wherein the shape of the flushing flow cavity is selected to accelerate the gas flow sufficiently to cause flushing of anatomical dead space.

The mask housing may have a generally U-shaped form.

The primary flow inlet and the flushing flow inlet may have a combined cross-sectional area that enables mould tool cores, used to form the flushing flow cavity and the primary flow cavity when moulding the seal member to the mask housing, to be removed through the primary flow inlet and the flushing flow inlet.

According to a fourth aspect, there is provided a non-invasive patient interface having a seal-forming seal member which is shaped to encompass a mouth and nares of a patient, the interface defining :

(a) a primary flow cavity having one or more primary flow inlets for respiratory gas and having one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares separately; and

(b) a flushing flow cavity having one or more flushing flow inlets for respiratory gas and one or more flushing flow outlets to deliver the respiratory gas to the nares of a patient; and

wherein the primary flow cavity and the flushing flow cavity are separated by a cavity wall and the primary flow outlet to the nares and the flushing flow outlet to the nares are adjacent each other and the cavity wall is located to enable respiratory gas from the flushing flow cavity to enter the nares and to enable exhaled gas to exit the nares into the primary flow cavity.

The cavity wall includes one or more preferential deformation regions which

accommodate deformation of the cavity wall without occluding the flushing flow cavity.

In a fifth aspect, there is provided a non-invasive patient interface that forms a seal or substantially forms a seal about the mouth and nares of a patient, the interface defining :

(a) a primary flow cavity having one or more primary flow inlets for respiratory gas and having one or more primary flow outlets to deliver the respiratory gas to each of the mouth and the nares separately; and

(b) a flushing flow cavity having one or more flushing flow inlets for respiratory gas and one or more flushing flow outlets to deliver the respiratory gas to the nares of a patient; and

wherein the primary flow cavity and the flushing flow cavity are separated by a cavity wall and cavity wall includes one or more preferential deformation regions which accommodate deformation of the cavity wall without occluding the flushing flow cavity.

The interface may include a seal member and a mask housing and wherein the interface includes one primary flow inlet and one flushing flow inlet and both are located in the seal member.

The flushing flow cavity may be integrally formed with the seal member.

The flushing flow outlets may be flush with a primary flow outlet to the nares.

The flushing flow cavity may be shaped to direct respiratory gas into the nares.

The flushing flow cavity may be defined by a cavity wall extending between the one or more flushing flow inlets and the one or more flushing flow outlets.

The cavity wall may extend along the inside of an outer wall of the seal member so that the flushing flow cavity is defined by the cavity wall and the outer wall.

The flushing flow cavity may be configured to accelerate the respiratory gas.

The seal member may have a first primary flow outlet defined by a first portion of the mask seal which forms a seal or substantially forms a seal surrounding the mouth of the patient and a second primary flow outlet defined by a second portion of the mask seal which forms a seal or substantially forms a seal with nostrils of the patient.

The seal member may be a resilient material and may be connected to the mask housing to form a unitary structure.

The seal member may be a resilient material and is mechanically locked to the mask housing to form a unitary structure.

The seal member may be over-moulded onto the mask housing to mechanically lock with the mask housing.

The interface may include a mask frame that has first and second respiratory gas flow channels that enable respiratory gas flow from a gas source to the flushing flow inlet and to the primary flow inlet respectively.

The first respiratory gas flow channel may have a first inlet and the second respiratory gas flow channel has a second inlet and wherein the cross-sectional areas of the first and second inlets are selected to provide a desired resistance to flow through the first and second respiratory gas flow channels.

The cross-sectional area of the first inlet may be greater than the cross-sectional area of the second inlet such that the first respiratory gas flow channel has a lower resistance to flow than the resistance to flow of the second respiratory gas flow channel.

The interface may include one or more pressure ports for monitoring pressure within the patient interface.

The mask frame may be removably connectable to the mask housing.

The mask frame and the housing may be integrally formed.

The mask frame may be removably connectable by co-operable snap-fit formations on the mask housing and on the mask frame.

The mask frame may be removably connectable by co-operable formations on the mask housing and on the mask frame.

The interface may include vent holes to allow gas, including exhaled gas, to escape the primary flow cavity.

The vent holes may be in the mask housing.

The mask seal may have one or more primary flow outlets that direct respiratory gas into the nares and one or more flushing flow outlets that direct respiratory gas into the nares and wherein the primary flow outlets and the flushing flow outlets are arranged side-by-side to form a nasal aperture.

The flushing flow cavity may be a single passage from the one or more flushing flow inlets to the one or more flushing flow outlets.

The cavity wall of the flushing flow cavity may separate the one or more flushing flow outlets from the one or more primary flow outlets which direct respiratory gas to the nares.

The one or more flushing flow outlets may have a predetermined shape.

The cavity wall may include a tether that links to a rim of the nasal aperture and that retains the one or more flushing flow outlets in the predetermined shape.

The interfaces may include two flushing flow outlets which are separated by the tether so that the flushing flow outlets are aligned with the nares.

The tether may be configured to be aligned with a patient's septum when the mask is in use.

The seal member may be formed so that the cavity wall does not come into contact with the patient.

The cavity wall may be recessed from the nasal aperture.

The cavity wall may be linked to a rim of the nasal aperture or is linked to the seal member adjacent to the rim by a tether which is recessed from the nasal aperture to avoid contact with the patient.

The deformation region may decouple one portion of the cavity wall from another portion of the cavity wall such that a force applied to one portion is not transferred to the other portion.

The deformation region may decouple one portion of the cavity wall from another portion of the cavity wall such that the two portions can move relative to each other.

The deformation region may be shaped to roll over one portion of the cavity wall when the two portions of the cavity wall translate with respect to one another.

The deformation region may have a wall thickness that is less than the wall thickness of the two portions such that the deformation region is more flexible than each of the two portions.

The cavity wall may have upper and lower cavity wall portions which are linked by the deformation region such that the upper cavity wall portion translates with respect to the lower cavity wall portion.

The two portions of the cavity wall may be each shaped to resist deformation due to forces on the seal by engagement with the user's face.

The upper and lower cavity wall portions may be inclined relative to each other and are connected by the deformation region which enables relative shear movement between the portions.

The upper cavity wall portion may have an inclined valley shape with sides that curve upwardly and the lower cavity wall portion may be a curved wall with sides that curve outwardly in a rearward direction and the deformation region links the upper cavity wall portion and the lower cavity wall portion.

The deformation region may have a curved profile. Optionally, the deformation region may be a U-shaped wall.

The lower cavity wall portion may terminate in a rim that is recessed from the nasal aperture such that the tether and the deformation region co-operate to retain the rim at a location recessed from the nasal aperture when a deformation force is applied to the seal member.

The shapes of the upper cavity wall portion and the lower cavity wall portion may be selected to avoid occlusion of the primary flow cavity and the flushing flow cavity when they are deformed.

The tether may be recessed from the nasal aperture so that the tether does not contact the patient when the interface is fitted to the patient.

The cavity wall may be connected to a rim of the nasal aperture so that the nasal aperture remains in the same relative position to the rim of the cavity wall.

The cavity wall may be connected to a rim of the nasal aperture to define cross-sectional areas of the flushing flow outlet and the primary flow outlet to the nares and to resist changing the cross-sectional areas of the flushing flow outlet and the primary flow outlet when the seal member is deformed.

The seal member may include deformation resistant regions that translate deformation forces into the deformation regions such that deformation of the cavity wall is

substantially confined to the one or more preferential deformation regions.

The seal member may include a bead surrounding the rim of the nasal aperture wherein the bead has a wall thickness that is greater than the wall thickness of the surrounding seal member such that the bead is less flexible than the surrounding seal member and, therefore, resists occlusion of the nasal aperture.

The tether may be connected to the bead so that deformation forces are transmitted through the bead, to the tether, to one or both of the two cavity wall portions and then to the one or more preferential deformation regions.

The tether may contribute to resisting deformation of the nasal aperture.

According to a sixth aspect, there is provided a non-invasive patient interface having a seal-forming seal member which is shaped to encompass a mouth and nares of a patient, the interface defining :

(a) a primary flow cavity to communicate respiratory gas to each of the mouth and the nares separately, and

(b) an exhaust flow cavity to communicate exhaled gas from the mouth and nares and to communicate excess respiratory gas from the primary flow cavity or both to externally of the interface; and

wherein the seal member includes a cavity wall that separates the primary flow cavity from the exhaust flow cavity and includes a nasal aperture that enables respiratory gas to flow into and from the nares and wherein the cavity wall and the nasal aperture are arranged to enable respiratory gas from the primary flow cavity to flow to the nares via the nasal aperture and enable exhaled respiratory gas from the nares, the primary flow cavity, or from both to flow to the exhaust cavity via the nasal aperture.

The primary flow cavity may have one or more primary flow inlets for respiratory gas and have one or more first primary flow outlets to deliver the respiratory gas to the mouth and one or more second primary flow outlets to deliver the respiratory gas to the nares.

The seal member may include the nasal aperture and an oral aperture that enables respiratory gas to flow into and from the mouth via the primary flow cavity.

The interface may include an exhaust vent to communicate exhaled gas and excess respiratory gas from the exhaust flow cavity to a location external of the interface.

An exhaust vent is used to exhaust respiratory gas from the cushion module. An exhaust vent may comprise a single aperture or a group of apertures. The terms "vents", "vent holes", "bias vents", "bias vent apertures", "vent apertures" and "exhaust vent" are used throughout the specification to describe an exhaust vent.

The patient interface may include a mask housing and wherein the interface includes one primary flow inlet and one exhaust flow outlet and both are located in the seal member.

The exhaust flow cavity may be integrally formed with the seal member.

The exhaust flow inlets may be flush with the primary flow outlet to the nares.

The seal member may be a resilient material and may be connected to the mask housing to form a unitary structure.

The seal member may be a resilient material and may be mechanically locked to the mask housing to form a unitary structure.

The seal member may be over-moulded onto the mask housing to mechanically lock with the mask housing.

The interface may include a mask frame that includes the exhaust vent.

The interface may include one or more pressure ports for monitoring pressure within the interface.

The mask frame may be removably connectable to the mask housing.

The mask frame may be removably connectable by co-operable snap-fit formations on the mask housing and on the mask frame.

The mask frame may be removably connectable by co-operable formations on the mask housing and on the mask frame.

The seal member may have one or more second primary flow outlets that direct respiratory gas into the nares and one or more exhaust flow inlets that receive gas flow from the nares and from the primary flow cavity and wherein the second primary flow outlets and the exhaust flow inlets are adjacent to form the nasal aperture.

The seal member may be formed so that the cavity wall does not come into contact with the patient.

The cavity wall may be recessed from the nasal aperture.

The cavity wall may be linked to a rim of the nasal aperture or is linked to the seal member adjacent to the rim by a tether which is recessed from the nasal aperture to avoid contact with the patient.

The cavity wall may be recessed from the rim of the nasal aperture by an extent that permits gas from the primary flow cavity to flow into the exhaust flow cavity.

The cavity wall may be recessed from the rim of the nasal aperture by an extent that, in use of the patient interface, permits gas from the primary flow cavity to flow into the exhaust flow cavity.

The nasal aperture may comprise a volume between the rim of the nasal aperture and an end of the cavity wall recessed from the rim.

The cavity wall may include one or more preferential deformation regions which accommodate deformation of the exhaust flow cavity without occluding the exhaust flow cavity.

The deformation region may decouple one portion of the cavity wall from another portion of the cavity wall such that a force applied to one portion is not transferred to the other portion.

The deformation region may decouple one portion of the cavity wall from another portion of the cavity wall such that the two portions can move relative to each other.

The two portions of the cavity wall may be shaped to resist deformation.

The seal member may include deformation resistant regions that translate deformation forces into the deformation regions such that deformation of the seal member is substantially confined to the deformation regions.

The seal member may include a bead surrounding the rim of the nasal aperture wherein the bead has a wall thickness that is greater than the wall thickness of the surrounding seal member such that the bead is less flexible than the surrounding seal member and, therefore, resists occlusion of the nasal aperture.

The tether may be connected to the bead so that deformation forces are transmitted through the bead, to the tether, to one or both of the two cavity wall portions and then to the one or more preferential deformation regions.

The tether contributes to resisting deformation of the nasal aperture.

The mask frame may be co-operable with the seal member to separate the primary flow path from the exhaust flow path.

The mask frame may include a dividing wall which is co-operable with the cavity wall to separate the primary flow path from the exhaust flow path.

The mask frame may include a gas inlet that is opposite or substantially opposite the one or more first primary flow outlets such that the primary flow path is generally linear.

The mask frame may include a gas inlet arranged relative to the first primary flow outlets such that the respiratory gas undergoes small (0 to 5°) changes in direction between the gas inlet and the first primary flow outlets.

The mask frame may include a gas inlet arranged relative to the first primary flow outlet such that the primary flow path has a low resistance to gas flow. The first primary flow outlet may be opposite the gas inlet to define a primary flow path that is substantially straight.

The cavity wall may contact the mask housing.

The mask housing may include the exhaust vent and the cavity wall may be associated with the housing so that the exhaust cavity communicates with the exhaust vent.

The cavity wall may contact the mask housing so that the exhaust cavity communicates with the exhaust vent.

The exhaust vent may comprise a series of apertures in the cushion module arranged in a grouping.

The series of apertures may be in the mask housing.

The cavity wall may contact the mask housing to form a seal separating the exhaust cavity from the primary flow cavity.

The cavity wall may connect to the mask housing by over-moulding the cavity wall with the mask housing.

The mask housing may include a series of openings through which the cavity wall is able to be over-moulded to connect the cavity wall to the mask housing.

The series of openings may be disposed between a primary flow inlet and the exhaust vent in the mask housing.

The series of openings may form a U-shaped curve.

The series of openings may form a curved shape.

The seal member may be adapted to maintain a spaced relationship between the cavity wall and the nasal aperture when a deformation force is applied to the seal member.

The spaced relationship may be retained by linking a face-contacting portion of the seal member with the cavity wall.

The seal member may include a linking member extending from the face-contacting wall portion of the seal member to the cavity wall so that at least some of a deformation force applied to the face-contacting wall portion is directed to the cavity wall.

The face-contacting wall portion of the seal member may be a first wall portion between the nasal aperture and the oral aperture so that forces applied to the first wall portion are transferred to the cavity wall.

The face-contacting wall portion of the seal member may be a second wall portion of the seal member located between the nasal aperture and the exhaust vent so that forces applied to the second wall portion are transferred to the cavity wall.

The linking member may be connected to the first wall portion along a line of connection.

The line of connection may comprise at least 10% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

The line of connection may comprise at least 20% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

The linking member may be connected to the second wall portion along a line of connection.

The linking member may be connected to the cavity wall along a line of connection.

The one or more lines of connection may terminate at a location or at respective locations spaced from the rim of the nasal aperture.

The location or the respective locations may be spaced from the bead.

The linking member may be recessed from the nasal aperture.

The linking member may be recessed from the nasal aperture so that it does not contact the bead of the nasal aperture.

The deformation region may be interposed between first and second resilient regions.

The deformation region may comprise first and second resilient regions and a

deformation panel disposed between the regions.

The deformation panel may have a thickness that is less than the thickness of the first and second resilient regions.

The deformation panel may comprise a first wall projecting from the first resilient region and a second wall connecting the first wall with the second resilient region.

The first and second resilient regions of the cavity wall may have a thickness that is at least three times the thickness of the first wall.

The second wall may have a curved profile from the first wall to the second resilient region to induce a rolling movement in the second wall to accommodate deformation in the deformation region.

The second wall may increase in thickness from the first wall to the second resilient region to cause initial folding of the first wall during deformation and subsequent rolling in the second wall starting from an intersection between the second wall and the first wall.

The intersection between the second wall and the first wall is configured to cause deformation to occur along the intersection.

The linking member may be connected with the second resilient region to direct deformation forces into the deformation region.

A notional line extending from an intersection line between the first resilient region and the first wall may converge at a pivot point with another notional line extending along the intersection line between the first wall and the second wall.

The first wall may project from the first resilient region to the intersection with the second wall by a distance in the range of 1 to 10 mm. The distance may in the range of 2 to 5 mm. The distance may be 3 mm.

The second wall may project from the second deformation resistant region by a distance in the range of 2 to 15 mm. The distance may be in the range of 2 to 10 mm.

The first resilient region may comprise a first thickened region of the cavity wall.

The first thickened region may comprise a rim adjoining the deformation region and a terminal panel extending from the rim and connected to the mask housing.

The terminal panel may have a thickness that is at least double the thickness of the first wall. The terminal panel may have a thickness that is in the range of 0.5 to 3 mm.

The second resilient region may comprise a load-spreading member which joins to a side of the deformation region opposite to the side that the first resilient region joins.

The load-spreading member may comprise a second thickened region of the cavity wall .

The load-spreading member may be formed as a rib along one side of the deformation region and may be connected to the linking member such that forces imparted on the face -contacting wall portion of the seal member are directed into the deformation region.

The second resilient region may extend laterally across the cavity wall at least the same distance as the width of the nasal aperture. Alternatively, the second resilient region may extend across the entire width of the cavity wall.

The second resilient region may taper to the same thickness of the surrounding cavity wall.

The second resilient region may taper at lateral ends to the same thickness of the surrounding cavity wall.

The cavity wall may be configured to channel respiratory gas from the primary flow cavity into the nasal aperture.

The cavity wall may include a deflector panel which is recessed from the rim of the nasal aperture and which forms a channel for the flow of respiratory gas from the primary flow cavity to the nasal aperture.

The linking member may connect the face-contacting wall portion with the deflector panel to direct forces into the deformation region.

The deflector panel may abut the second resilient region such that forces imparted on the linking member are transferred to the second deformation resistant region.

The deflector panel may connect with an inner wall of the seal member remote from the rim of the nasal aperture.

The deflector panel may connect with an inner wall of the seal member remote from the bead surrounding the rim of the nasal aperture.

The primary flow inlet of the mask housing may have one or more key formations.

The patient interface may include a socket insert with a formation that is complimentary to the one or more key formations of the mask housing to restrict rotation movement of the socket insert relative to the mask housing.

The socket insert may include a connecting portion that is configured to connect the socket insert with an inlet on the housing and with an outlet portion of a conduit connecting elbow.

The mask housing may include headgear connectors.

Alternatively, the patient interface may include a frame that includes headgear connectors.

The frame may further include a formation that is configured to interact with the formation of the socket insert to rotationally lock the frame relative to the housing when the frame and socket insert are assembled with the housing.

The socket insert may include opposing formations between which the frame and the housing may be retained together.

The frame and the housing may be retained together in compression between the formations of the socket insert when assembled.

The frame may include an aperture which is configured to align with the exhaust vent of the mask housing to permit venting of respiratory gas through the frame to ambient environment.

The frame may be fastened to the mask housing. The frame may be fastened to the housing by gluing or by welding.

The cavity wall may be formed according to the twelfth aspect.

The primary flow cavity and the exhaust flow cavity may be within a cushion module formed by the seal member and a housing.

The cavity wall may be positioned relative to the nasal aperture and an oral aperture of the primary flow cavity to enable respiratory gas to flow from the primary flow cavity to the nares via the nasal aperture.

The cavity wall may be positioned relative to the nasal aperture and the oral aperture to enable exhaled respiratory gas from the mouth and nares to flow into the exhaust flow cavity.

The cavity wall may be at a recessed position relative to a rim of the nasal aperture.

The cavity wall may be positioned relative to the nasal aperture such that the primary flow and exhaust flow cavities are in communication with the nasal aperture.

An outlet of the primary flow cavity and an inlet of the exhaust flow cavity may be in communication with the nasal aperture.

The cavity wall may be configured so that the linking member directs forces imparted on the face-contacting wall portion into the deformation region of the cavity wall.

The exhaust vent may be formed as a series of apertures in the mask housing which are arranged in two or more separate groupings.

In one embodiment, the mask housing includes a cluster or grouping on each lateral side of the primary flow inlet and includes a series of openings extending about each grouping.

The series of openings may be arranged to form a V-shape or U-shape about each grouping.

The series of openings may form a W-shape.

According to a seventh aspect, there is provided a mask frame that is co-operable with a cushion module to form a pressurisable patient interface, the cushion module having a primary flow cavity for delivering respiratory gas to the mouth and nares of a patient and an exhaust flow cavity for transmitting exhaled respiratory gas from the patient interface and wherein the mask frame includes a respiratory gas inlet that is

substantially aligned with a primary flow outlet of the cushion module which delivers respiratory gas to a mouth of the patient.

The mask frame may include a dividing wall that is co-operable with the cushion module to define separate primary flow and exhaust flow paths through an assembled patient interface.

The mask frame further may include vent holes to communicate exhaled gas from the exhaust cavity to the exterior of the mask frame.

In an eighth aspect, there is provided a mask frame for a patient interface, wherein the mask frame includes first and second respiratory gas flow channels that enable respiratory gas to flow from a gas source to a cushion module of a patient interface and includes a flow transfer valve that enables:

(a) respiratory gas to flow from the first respiratory gas flow channel to the second respiratory gas flow channel; or

(b) respiratory gas to flow from the second respiratory gas flow channel to the first respiratory gas flow channel; or

(c) respiratory gas to flow from the first respiratory gas flow channel to the second respiratory gas flow channel and from the second respiratory gas flow channel to the first respiratory gas flow channel.

The flow transfer valve may operate when the gas pressure in the first respiratory gas flow channel or the second respiratory gas flow channel exceeds a threshold gas pressure.

The threshold gas pressure may be the gas pressure in the first respiratory gas flow channel or the second respiratory gas flow channel when there is a full or partial obstruction of the first respiratory gas flow channel, the second respiratory gas flow channel, the flushing flow cavity or the nasal aperture.

The flow transfer valve may include an opening which is sealed by a resilient cover and the elasticity of the resilient cover is selected such that the resilient cover is deformable by gas pressure exceeding the threshold gas pressure to allow respiratory gas to pass through the opening when the gas pressure exceeds the threshold gas pressure.

The resilient cover may be a poppet valve.

The flow transfer valve may be incorporated into the mask frames that include at least first and second respiratory gas flow channels.

In an alternative form, the flow transfer valve may be incorporated into the dividing wall of a housing in a patient interface.

In a ninth aspect there is provided a patient-interface housing that comprises a transverse member with lateral sections which are spaced apart and which define a spacing that opens outwardly on at least one side.

The housing, according to this aspect, may be U-shaped, inverted U-shaped, V-shaped or H-shaped.

The housing may have a perimeter formation that permits fixing or connection of a resilient seal-forming seal member to form a cushion module that incorporates the housing.

The perimeter formation may comprise a series of holes which are dimensioned to permit fixing or connection of the resilient seal-forming seal member by over-moulding.

In a tenth aspect, there is provided a patient interface that includes a cushion module which comprises a housing according to the aspect disclosed above and a resilient seal forming seal member that contacts the patient's face.

The resilient seal-forming seal member may be formed in accordance with any aspect disclosed above.

An eleventh aspect provides a cushion module for a patient interface, the cushion module comprising a first cavity, a second cavity, a nasal aperture and an oral aperture and wherein:

a. the first and second cavities are separated by a cavity wall that enables

respiratory gas to flow within the cushion module between the first and second cavities when in use;

b. the first cavity is configured to communicate respiratory gas to both the mouth and the nares of a patient via the oral aperture and the nasal aperture respectively;

c. the cushion module comprises an exhaust vent to communicate respiratory gas from within the cushion module to externally of the cushion module; and d. the second cavity is in communication with the exhaust vent.

The first cavity may be a primary flow cavity and the second cavity may be an exhaust cavity.

The cushion module may be configured to accelerate respiratory gas through the first cavity into the nares.

The first cavity may be configured to accelerate respiratory gas and to direct the accelerated respiratory gas toward the nasal aperture.

The first cavity may be configured with a taper that narrows toward the nasal aperture.

The taper may be formed between the cavity wall and a face-contacting wall portion that may be disposed between the oral aperture and the nasal aperture.

The cavity wall comprises a deformation region which preferentially deforms with respect to the remainder of the cavity wall when a deformation force is applied to the cavity wall.

The deformation region comprises a deformation panel that may be less resilient than the remainder of the deformation region such that the deformation panel preferentially deforms when a deformation force is applied to the seal member.

The deformation region further may comprise first and second resilient regions between which the deformation panel is disposed and wherein the resilient regions may direct a deformation force into the deformation panel to cause preferential deformation of the deformation panel.

The deformation of the deformation region may involve a reduction in the spacing between the first and second resilient regions and an associated deformation of the deformation panel to accommodate the reduction in spacing.

The deformation panel may include first and second walls that are adapted to deform in a predetermined sequence.

The predetermined sequence may include the deformation panel rolling over itself.

The predetermined sequence may include the second wall rolling over the first wall.

The first wall may project from the first resilient region in a first direction, the second wall projects from the second resilient region in a second direction different from the first direction and the first wall meets the second wall, and wherein the predetermined sequence may include the first wall being folded against the first resilient region.

The second wall may be configured to induce rolling of the second wall over the first wall.

The second wall may have a curved profile from the first wall to the second resilient region to induce a rolling movement in the second wall.

The second wall may increase in thickness from the first wall to the second resilient region to cause initial folding of the first wall during deformation and may cause subsequent rolling in the second wall starting from an intersection between the second wall and the first wall.

The deformation panel may have a wall thickness that is selected to induce deformation of the deformation panel in preference to the first and second resilient regions.

The first and second resilient regions may have a wall thickness that is at least three times the wall thickness of the deformation panel.

The cushion module may comprise a housing and a flexible seal member connected with a perimeter of the housing and wherein the seal member includes the cavity wall.

The cavity wall may connect with the housing interiorly of the connection between the perimeter of the seal member and the perimeter of the housing.

The housing may include the exhaust vent.

The cavity wall connection with the housing extends at least partially around the exhaust vent.

The exhaust vent may be bound by the cavity wall connection with the housing and a connection between the perimeter of the seal and the perimeter of the housing.

The seal member may be adapted to maintain a spaced relationship between the cavity wall and the nasal aperture when a deformation force is applied to the seal member.

The spaced relationship may comprise the cavity wall being recessed from a rim the nasal aperture.

The spaced relationship may further comprise the cavity wall being located such that first and second cavities open to the nasal aperture.

The seal member may be configured to direct at least some of a deformation force into the deformation region.

The cavity wall may be linked to the face-contacting portion of the seal member to maintain the spaced relationship between the cavity wall and the nasal aperture when a deformation force is applied to the seal member.

The seal member may include a linking member which connects the deformation region to a face-contacting portion of the seal member such that at least some of a deformation force applied to the face-contacting portion is directed to the deformation region.

The cavity wall may comprise a deflector panel adjacent to the nasal aperture, a main panel associate with the housing and the deformation region between the deflector panel and the main panel.

The deflector panel may be recessed from the rim of the nasal aperture and the linking member connects the face-contacting wall portion with the deflector panel to direct a deformation force into the deformation region.

An outlet from the first cavity to the nares and an inlet to the second cavity may form the nasal aperture.

The first cavity may be a lower cavity and the second cavity may be a upper cavity disposed above the first cavity.

The nasal aperture may be in communication with an outlet of the first cavity outlet and an inlet of the second cavity inlet.

In a twelfth aspect, there is provided a cavity wall for separating first and second cavities in a cushion module of a patient interface, the cavity wall having a deformation region that is adapted to preferentially deform under a deformation force applied to the cushion module.

The deformation region may comprise a deformation panel that deforms under a deformation force.

The deformation region may further comprise first and second resilient regions between which the deformation panel is disposed and wherein the resilient regions direct a deformation force into the deformation panel to cause preferential deformation of the deformation panel.

The deformation of the deformation region may involve a reduction in the spacing between the first and second resilient regions and an associated deformation of the deformation panel to accommodate the reduction in spacing.

The deformation panel may include first and second walls that are adapted to deform in a predetermined sequence.

The first wall may project from the first resilient region in a first direction, the second wall projects from the second resilient region in a second direction different from the first direction and the first and second walls have a connecting portion between them, and wherein the predetermined sequence may include the first wall being folded against the first resilient region.

The predetermined sequence may include the second wall buckling to accommodate the reduction in spacing between the first and second resilient regions.

The second wall may be configured to induce the buckling when the distance between the second resilient region and the connection portion is less than length of the second wall.

The second wall may have a curved profile from the connecting portion to the second resilient region to induce buckling of the second wall.

The second wall may increase in thickness from the connecting portion to the second resilient region to cause initial folding of the first wall during deformation and

subsequent buckling in the second wall.

The deformation panel may have a wall thickness that is selected to induce deformation of the deformation panel in preference to the first and second resilient regions.

The first and second resilient regions may have a wall thickness that is at least three times the wall thickness of the deformation panel.

A thirteenth aspect provides a non-invasive patient interface that is configured to deliver pressurized respiratory gas to the mouth and nares of a patient, the patient interface having a cushion module that has first and second cavities with respective nasal and oral apertures which are configured to communicate respiratory gas with the mouth and nares respectively of a patient and wherein:

(a) the first and second cavities are separated by a cavity wall that enables

respiratory gas to flow within the cushion module between the first and second cavities when in use; and

(b) the cavity wall is formed according to the twelfth aspect and is configured to direct external deformation forces on a face-contacting portion of the cushion module into the deformation region so that the cavity wall preferentially deforms in the deformation region.

The first cavity may be adapted to receive respiratory gas from a source and the second cavity may be adapted to vent respiratory gas from within the cushion module.

The cavity wall may be positioned relative to the nasal aperture and the oral aperture to enable respiratory gas to flow from the first cavity to the nares through the nasal aperture.

The cavity wall may be positioned relative to the nasal aperture and the oral aperture to enable exhaled respiratory gas from the mouth and nares to flow into the second cavity.

The cavity wall may be at a recessed position relative to a rim of the nasal aperture.

The cavity wall may be positioned relative to the nasal aperture such that the first and second cavities are in communication with the nasal aperture.

An outlet of the first cavity and an inlet of the second cavity may be in communication with the nasal aperture.

The cushion module may include a linking member extending from the face-contacting wall portion to the cavity wall so that at least some of the deformation force applied to the face-contacting wall portion is directed into the cavity wall.

The cavity wall may be configured so that the linking member directs forces imparted on the face-contacting wall portion into the deformation region of the cavity wall.

The linking member may be connected to the cavity wall along a first line of connection.

The linking member may be recessed from the nasal aperture

The face-contacting wall portion of the seal member may be a first wall portion between the nasal aperture and the oral aperture so that at least some of the forces applied to the first wall portion are directed into the cavity wall.

The linking member may be connected to the first wall portion along a second line of connection.

The second line of connection comprises at least 10% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

The second line of connection comprises at least 20% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

The face-contacting wall portion of the seal member may be a second wall portion of the seal member located between the nasal aperture and the exhaust vent so that forces applied to the second wall portion are transferred to the cavity wall.

The linking member is connected to the second wall portion along a third line of connection.

The second and/or third lines of connection may terminate at a location or at respective locations spaced from the rim of the nasal aperture.

The location or the respective locations may be spaced from a bead surrounding a rim of the nasal aperture.

The first cavity may be a lower cavity which is configured to communicate respiratory gas to both the mouth and the nares.

CLAIMS :

1. A cushion module for a patient interface, the cushion module comprising a first cavity, a second cavity, a nasal aperture and an oral aperture and wherein:

(a) the first and second cavities are separated by a cavity wall that enables

respiratory gas to flow within the cushion module between the first and second cavities when in use;

(b) the first cavity is configured to communicate respiratory gas to both the mouth and the nares of a patient via the oral aperture and the nasal aperture respectively;

(c) the cushion module comprises an exhaust vent to communicate respiratory gas from within the cushion module to externally of the cushion module; and

(d) the second cavity is in communication with the exhaust vent.

2. The cushion module as claimed in claim 1, wherein the first cavity is a primary flow cavity and the second cavity is an exhaust cavity.

3. The cushion module as claimed in claim 1 or claim 2, wherein the cushion module is configured to accelerate respiratory gas through the first cavity into the nares.

4. The cushion module as claimed in any one of the preceding claims, wherein the first cavity is configured to accelerate respiratory gas and to direct the accelerated respiratory gas toward the nasal aperture.

5. The cushion module as claimed in claim 4, wherein the first cavity is configured with a taper that narrows toward the nasal aperture.

6. The cushion module as claimed in claim 5, wherein the taper is formed between the cavity wall and a face-contacting wall portion disposed between the oral aperture and the nasal aperture.

7. The cushion module as claimed in any one of the preceding claims, wherein the cavity wall comprises a deformation region which preferentially deforms with respect to the remainder of the cavity wall when a deformation force is applied to the cavity wall.

8. The cushion module as claimed in claim 7, wherein the deformation region comprises a deformation panel that is less resilient than the remainder of the deformation region such that the deformation panel preferentially deforms when a deformation force is applied to the seal member.

9. The cushion module as claimed in claim 8, wherein the deformation region further comprises first and second resilient regions between which the deformation panel is disposed and wherein the resilient regions direct a deformation force into the deformation panel to cause preferential deformation of the deformation panel.

10. The cushion module as claimed in claim 9, wherein the deformation of the

deformation region involves a reduction in the spacing between the first and second resilient regions and an associated deformation of the deformation panel to accommodate the reduction in spacing.

11. The cushion module as claimed in any one of claims 8 to 10, wherein the

deformation panel includes first and second walls that are adapted to deform in a predetermined sequence.

12. The cushion module as claimed in claim 11, wherein the predetermined sequence includes the deformation panel rolling over itself.

13. The cushion module as claimed in claim 11 or claim 12, wherein the predetermined sequence includes the second wall rolling over the first wall.

14. The cushion module as claimed in any one of claims 11 to 13, wherein the first wall projects from the first resilient region in a first direction, the second wall projects from the second resilient region in a second direction different from the first direction and the first wall meets the second wall, and wherein the predetermined sequence includes the first wall being folded against the first resilient region.

15. The cushion module as claimed in any one of claims 11 to 14, wherein the second wall is configured to induce rolling of the second wall over the first wall.

16. The cushion module as claimed in claim 15, wherein the second wall has a curved profile from the first wall to the second resilient region to induce a rolling movement in the second wall.

17. The cushion module as claimed in claim 15 or claim 16, wherein the second wall increases in thickness from the first wall to the second resilient region to cause initial folding of the first wall during deformation and cause subsequent rolling in the second wall starting from an intersection between the second wall and the first wall.

18. The cushion module as claimed in any one of claims 9 to 17, wherein the

deformation panel has a wall thickness that is selected to induce deformation of the deformation panel in preference to the first and second resilient regions.

19. The cushion module as claimed in claim 18, wherein the first and second resilient regions have a wall thickness that is at least three times the wall thickness of the deformation panel.

20. The cushion module as claimed in any one of claims 7 to 19, wherein the

deformation region is part of the cavity wall.

21. The cushion module as claimed in claim 20, wherein the cushion module comprises a housing and a flexible seal member connected with a perimeter of the housing and wherein the seal member includes the cavity wall.

22. The cushion module as claimed in claim 21, wherein the cavity wall connects with the housing interiorly of the connection between the perimeter of the seal member and the perimeter of the housing.

23. The cushion module as claimed in claim 22, wherein the housing includes the

exhaust vent.

24. The cushion module as claimed in claim 23, wherein the cavity wall connection with the housing extends at least partially around the exhaust vent.

25. The cushion module as claimed in claim 24, wherein the exhaust vent is bound by the cavity wall connection with the housing and a connection between the perimeter of the seal and the perimeter of the housing.

26. The cushion module as claimed in any one of claims 21 to claim 25, wherein the seal member is adapted to maintain a spaced relationship between the cavity wall and the nasal aperture when a deformation force is applied to the seal member.

27. The cushion module as claimed in claim 26, wherein the spaced relationship comprises the cavity wall being recessed from a rim the nasal aperture.

28. The cushion module as claimed in claim 27, wherein the spaced relationship further comprises the cavity wall being located such that first and second cavities open to the nasal aperture.

29. The cushion module as claimed in any one of claims 21 to 28, wherein the seal member is configured to direct at least some of a deformation force into the deformation region.

30. The cushion module as claimed in claim 29, wherein the cavity wall is linked to the face-contacting portion of the seal member to maintain the spaced relationship between the cavity wall and the nasal aperture when a deformation force is applied to the seal member.

31. The cushion module as claimed in any one of claims 21 to 30, wherein the seal member includes a linking member which connects the deformation region to a face-contacting portion of the seal member such that at least some of a

deformation force applied to the face-contacting portion is directed to the deformation region.

32. The cushion module as claimed in any one of claims 21 to 28 when dependent on claim 20, wherein the cavity wall comprises a deflector panel adjacent to the nasal aperture, a main panel associate with the housing and the deformation region between the deflector panel and the main panel.

33. The cushion module as claimed in claim 32, wherein the deflector panel is recessed from the rim of the nasal aperture and the linking member connects the face contacting wall portion with the deflector panel to direct a deformation force into the deformation region.

34. The cushion module as claimed in any one of the preceding claims, wherein an outlet from the first cavity to the nares and an inlet to the second cavity form the nasal aperture.

35. The cushion module as claimed in any one of the preceding claims, wherein the first cavity is a lower cavity and the second cavity is an upper cavity disposed above the first cavity.

36. The cushion module as claimed in any one of the preceding claims, wherein the nasal aperture is in communication with an outlet of the first cavity outlet and an inlet of the second cavity inlet.

37. A cavity wall for separating first and second cavities in a cushion module of a

patient interface, the cavity wall having a deformation region that is adapted to preferentially deform under a deformation force applied to the cushion module.

38. The cavity wall as claimed in claim 37, wherein the deformation region comprises a deformation panel that deforms under a deformation force.

39. The cavity wall as claimed in claim 38, wherein the deformation region further comprises first and second resilient regions between which the deformation panel is disposed and wherein the resilient regions direct a deformation force into the deformation panel to cause preferential deformation of the deformation panel.

40. The cavity wall as claimed in claim 39, wherein the deformation of the deformation region involves a reduction in the spacing between the first and second resilient regions and an associated deformation of the deformation panel to accommodate the reduction in spacing.

41. The cavity wall as claimed in claim 40, wherein the deformation panel includes first and second walls that are adapted to deform in a predetermined sequence.

42. The cavity wall as claimed in claim 41, wherein the first wall projects from the first resilient region in a first direction, the second wall projects from the second resilient region in a second direction different from the first direction and the first and second walls have a connecting portion between them, and wherein the predetermined sequence includes the first wall being folded against the first resilient region.

43. The cavity wall as claimed in claim 42, wherein the predetermined sequence

includes the second wall buckling to accommodate the reduction in spacing between the first and second resilient regions.

44. The cavity wall as claimed in claim 43, wherein the second wall is configured to induce the buckling when the distance between the second resilient region and the connection portion is less than length of the second wall.

45. The cavity wall as claimed in claim 44, wherein the second wall has a curved profile from the connecting portion to the second resilient region to induce buckling of the second wall.

46. The cavity wall as claimed in claim 44 or claim 45, wherein the second wall

increases in thickness from the connecting portion to the second resilient region to cause initial folding of the first wall during deformation and subsequent buckling in the second wall.

47. The cavity wall as claimed in any one of claims 40 to 46, wherein the deformation panel has a wall thickness that is selected to induce deformation of the deformation panel in preference to the first and second resilient regions.

48. The cavity wall as claimed in claim 47, wherein the first and second resilient

regions have a wall thickness that is at least three times the wall thickness of the deformation panel.

49. A non-invasive patient interface that is configured to deliver pressurized respiratory gas to the mouth and nares of a patient, the patient interface having a cushion module that has first and second cavities with respective nasal and oral apertures which are configured to communicate respiratory gas with the mouth and nares respectively of a patient and wherein:

(a) the first and second cavities are separated by a cavity wall that enables

respiratory gas to flow within the cushion module between the first and second cavities when in use; and

(b) the cavity wall is formed according to any one of claims 37 to 48 and is

configured to direct external deformation forces on a face-contacting portion of the cushion module into the deformation region so that the cavity wall preferentially deforms in the deformation region.

50. The patient interface as claimed in claim 49, wherein the first cavity is adapted to receive respiratory gas from a source and the second cavity is adapted to vent respiratory gas from within the cushion module.

51. The patient interface as claimed in claim 49 or claim 50, wherein the cavity wall is positioned relative to the nasal aperture and the oral aperture to enable respiratory gas to flow from the first cavity to the nares through the nasal aperture.

52. The patient interface as claimed in any one of claims 49 to 51, wherein the cavity wall is positioned relative to the nasal aperture and the oral aperture to enable exhaled respiratory gas from the mouth and nares to flow into the second cavity.

53. The patient interface as claimed in any one of claims 49 to 52, wherein the cavity wall is at a recessed position relative to a rim of the nasal aperture.

54. The patient interface as claimed in any one of claims 48 to 53, wherein the cavity wall is positioned relative to the nasal aperture such that the first and second cavities are in communication with the nasal aperture.

55. The patient interface as claimed in claim 54, wherein an outlet of the first cavity and an inlet of the second cavity are in communication with the nasal aperture.

56. The patient interface as claimed in any one of claims 49 to 55, wherein the cushion module includes a linking member extending from the face-contacting wall portion to the cavity wall so that at least some of the deformation force applied to the face-contacting wall portion is directed to the cavity wall.

57. The patient interface as claimed in claim 56, wherein the cavity wall is configured so that the linking member directs forces imparted on the face-contacting wall portion into the deformation region of the cavity wall.

58. The patient interface as claimed in claim 56 or claim 57, wherein the linking

member is connected to the cavity wall along a first line of connection.

59. The patient interface as claimed in any one of claims 56 to 58, wherein the linking member is recessed from the nasal aperture

60. The patient interface as claimed in any one of claims 56 to 59, wherein the face contacting wall portion of the seal member is a first wall portion between the nasal aperture and the oral aperture so that at least some of the forces applied to the first wall portion are directed to the cavity wall.

61. The patient interface as claimed in claim 60, wherein the linking member is

connected to the first wall portion along a second line of connection.

62. The patient interface as claimed in claim 61, wherein the second line of connection comprises at least 10% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

63. The patient interface as claimed in claim 61, wherein the second line of connection comprises at least 20% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

64. The patient interface as claimed in any one of claims 49 to 59, wherein the face contacting wall portion of the seal member is a second wall portion of the seal member located between the nasal aperture and the exhaust vent so that forces applied to the second wall portion are transferred to the cavity wall.

65. The patient interface as claimed in claim 64, wherein the linking member is

connected to the second wall portion along a third line of connection.

66. The patient interface as claimed in claim 61 or claim 65, wherein the second and/or third lines of connection terminate at a location or at respective locations spaced from the rim of the nasal aperture.

67. The patient interface as claimed in claim 66, wherein the location or the respective locations are spaced from a bead surrounding a rim of the nasal aperture.

68. The patient interface as claimed in any one of claims 49 to 67, wherein the first cavity is a lower cavity which is configured to communicate respiratory gas to both the mouth and the nares.

69. The patient interface as claimed in any one of claims 49 to 68, wherein the cushion module further comprises an exhaust vent to communicate respiratory gas from within the cushion module to externally of the cushion module

70. The patient interface as claimed in claim 69, wherein the second cavity is an upper cavity disposed above the first cavity and is in communication with the exhaust vent.

71. The patient interface as claimed in claim 70, wherein the cushion module

comprises a housing and a seal member and the cavity wall connects with the housing.

72. The patient interface as claimed in claim 71, wherein the housing includes the

exhaust vent.

73. The patient interface as claimed in claim 71 or claim 72, wherein the cavity wall connection with the housing at least partially surrounds the exhaust vent.

74. The patient interface as claimed in any one of claims 71 to 73, wherein the exhaust vent is bound by the cavity wall connection with the housing and a connection between the perimeter of the seal and the perimeter of the housing.

75. The patient interface as claimed in any one of claims 71 to 74, wherein the cavity wall further comprises a main panel which connects the housing to the first resilient region.

76. The patient interface as claimed in claim 75, wherein the cavity wall further

comprises a deflector panel which is recessed from the rim of the nasal aperture and which forms a channel for the flow of respiratory gas from the first cavity to the nasal aperture.

77. The patient interface as claimed in claim 76, wherein the deflector panel abuts the second resilient region such that deformation forces are directed to the second resilient region.

78. The patient interface as claimed in claim 76 or claim 77, wherein the deformation region is arranged to structurally decouple the deflector panel from the main panel.

79. A non-invasive patient interface that is configured to deliver pressurized respiratory gas to the mouth and nares of a patient, the patient interface comprising a cushion module which comprises:

(a) a seal for sealing around the mouth and nares of the patient;

(b) a housing connected to the seal;

(c) an interior volume as claimed by the seal and the housing; and

(d) the seal comprises a cavity wall located within the interior volume so as to define first and second cavities within the interior volume of the cushion module.

80. The patient interface as claimed in claim 79, wherein the cushion module further comprises a preferential deformation region that comprises a deformation panel.

81. The patient interface as claimed in claim 80, wherein the deformation region

further comprises first and second resilient regions between which the deformation panel is disposed.

82. The patient interface as claimed in claim 81, wherein deformation of the

deformation region involves a reduction in the spacing between the first and second resilient regions and an associated deformation of the deformation panel to accommodate the reduction in spacing.

83. The patient interface as claimed in claim 81, wherein the deformation panel

includes first and second walls and a connecting portion between the first and second walls.

84. The patient interface as claimed in claim 83, wherein the first wall projects from the first resilient region in a first direction, the second wall projects from the second resilient region in a second direction different from the first direction.

85. The patient interface as claimed in claim 84, wherein the second direction is

inclined downwardly from a plane intersecting the second resilient region and the connecting portion.

86. The patient interface as claimed in claim 84, wherein the connecting portion has a bend profile which, at rest, aligns with the first direction of the first wall and aligns with an end of the second wall remote from the second resilient region.

87. The patient interface as as claimed in claim 84 or claim 85, wherein the second wall has a curved profile from the connecting portion to the second resilient region.

88. The patient interface as as claimed in any one of claims 84 to 86, wherein the second wall increases in thickness from the connecting portion to the second resilient region.

89. The patient interface as as claimed in any one of claims 80 to 87, wherein the

deformation panel has a wall thickness that is less than the wall thickness of the first and second resilient regions.

90. The patient interface as as claimed in claim 88, wherein the first and second

resilient regions have a wall thickness that is at least three times the wall thickness of the deformation panel.

91. The patient interface as claimed in any one of claims 80 to 90, wherein the

deformation region is part of the cavity wall.

92. The patient interface as claimed in claim 91, wherein the cavity wall further

comprises a main panel which connects the housing to the first resilient region.

93. The patient interface as claimed in claim 92, wherein the cavity wall further

comprises a deflector panel which is recessed from a rim of the nasal aperture and which forms a channel configured to direct respiratory gas from the first cavity to the nasal aperture.

94. The patient interface as claimed in claim 93, wherein the deflector panel abuts the second resilient region.

95. The patient interface as claimed in claim 93 or claim 94, wherein the deformation region is arranged to structurally decouple the deflector panel from the main panel.

96. The patient interface as claimed in any one of claims 80 to 95, wherein the cavity wall is positioned relative to the nasal aperture and the oral aperture to enable respiratory gas to flow from the first cavity to the nares through the nasal aperture.

97. The patient interface as claimed in any one of claims 80 to 96, wherein the cavity wall is positioned relative to the nasal aperture and the oral aperture to enable exhaled respiratory gas from the mouth and nares to flow into the second cavity.

98. The patient interface as claimed in any one of claims 80 to 97, wherein the nasal aperture is defined at the seal by a rim and the cavity wall is recessed within the cushion module relative to the rim.

99. The patient interface as claimed in any one of claims 80 to 98, wherein the cavity wall is positioned relative to the nasal aperture to enable the first and second cavities to communicate respiratory gas with the nasal aperture.

100. The patient interface as claimed in claim 99, wherein an outlet of the first cavity and an inlet of the second cavity are in communication with the nasal aperture.

101. The patient interface as claimed in any one of claims 80 to 100, wherein the

cushion module further comprises (a) a face-contacting wall portion of the seal and (b) a linking member extending from the face-contacting wall portion to the cavity wall.

102. The patient interface as claimed in claim 101, wherein the linking member braces the cavity wall in position relative to the nasal aperture and the face-contacting wall portion.

103. The patient interface as claimed in claim 101 or claim 102, wherein the linking member is connected to the cavity wall along a first line of connection.

104. The patient interface as claimed in any one of claims 100 to 103, wherein the

linking member is recessed from the nasal aperture

105. The patient interface as claimed in any one of claims 101 to 59, wherein the face contacting wall portion is a first wall portion between the nasal aperture and the oral aperture.

106. The patient interface as claimed in claim 105, wherein the linking member is

connected to the first wall portion along a second line of connection.

107. The patient interface as claimed in claim 106, wherein the second line of

connection comprises at least 10% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

108. The patient interface as claimed in claim 106, wherein the second line of connection comprises at least 20% of the first wall portion distance measured between the nasal aperture and the oral aperture on the exterior of the seal member.

109. The patient interface as claimed in any one of claims 49 to 59, wherein the face contacting wall portion of the seal member is a second wall portion of the seal member located on an opposite side of the nasal aperture to the face contacting wall portion.

110. The patient interface as claimed in claim 64, wherein the linking member is

connected to the second wall portion along a third line of connection.

111. The patient interface as claimed in claim 106 or claim 110, wherein the second and/or third lines of connection terminate at a location or at respective locations spaced from the rim of the nasal aperture.

112. The patient interface as claimed in claim 111, wherein the location or the

respective locations are spaced from a bead surrounding a rim of the nasal aperture.

113. The patient interface as claimed in any one of claims 80 to 112, wherein the first cavity is a lower cavity which is configured to communicate respiratory gas to both the mouth and the nares.

114. The patient interface as claimed in any one of claims 80 to 113, wherein the

cushion module further comprises an exhaust vent to communicate respiratory gas from within the cushion module to externally of the cushion module.

115. The patient interface as claimed in claim 114, wherein the second cavity is an upper cavity disposed above the first cavity and is in communication with the exhaust vent.

116. The patient interface as claimed in claim 115, wherein the housing includes the exhaust vent and the cavity wall connection with the housing at least partially surrounds the exhaust vent.

117. The patient interface as claimed in claim 116, wherein the exhaust vent is bound by the cavity wall connection with the housing and a connection between the perimeter of the seal and the perimeter of the housing.

118. The patient interface as claimed in claim 117, wherein the exhaust vent comprises one or more groups of apertures.

119. A non-invasive patient interface having a seal-forming seal member which is

shaped to encompass a mouth and nares of a patient, the interface comprising :

(a) a primary flow cavity to communicate respiratory gas to each of the mouth and the nares separately, and

(b) an exhaust flow cavity to communicate exhaled gas from the mouth and nares and to communicate excess respiratory gas from the primary flow cavity or both to externally of the interface; and

wherein the seal member includes a cavity wall that separates the primary flow cavity from the exhaust flow cavity and includes a nasal aperture that enables respiratory gas to flow into and from the nares and wherein the cavity wall and the nasal aperture are arranged to enable fresh respiratory gas from the primary flow cavity to flow to the nares via the nasal aperture and enable exhaled respiratory gas from the nares, the primary flow cavity or from both to flow to the exhaust cavity via the nasal aperture.

120. The patient interface as claimed in claim 119, wherein the cavity wall is formed according to any one of claims 37 to 48.

121. The patient interface as claimed in claim 119 or claim 120, wherein the primary flow cavity and the exhaust flow cavity are within a cushion module formed by the seal member and a housing.

122. The patient interface as claimed in any one of claims 119 to 121, wherein the

cavity wall is positioned relative to the nasal aperture and an oral aperture of the primary flow cavity to enable respiratory gas to flow from the primary flow cavity to the nares via the nasal aperture.

123. The patient interface as claimed in claim 122, wherein the cavity wall is positioned relative to the nasal aperture and the oral aperture to enable exhaled respiratory gas from the mouth and nares to flow into the exhaust flow cavity.

124. The patient interface as claimed in any one of claims 119 to 123, wherein the cavity wall is at a recessed position relative to a rim of the nasal aperture.

125. The patient interface as claimed in any one of claims 119 to 124, wherein the

cavity wall is positioned relative to the nasal aperture such that the primary flow and exhaust flow cavities are in communication with the nasal aperture.

126. The patient interface as claimed in claim 125, wherein an outlet of the primary flow cavity and an inlet of the exhaust flow cavity are in communication with the nasal aperture.

127. The patient interface as claimed in any one of claims 119 to 126, wherein the

cushion module includes a linking member extending from a face-contacting wall portion to the cavity wall so that at least some of a deformation force applied to the face-contacting wall portion is directed to the cavity wall.

128. The patient interface as claimed in claim 127, wherein the cavity wall is configured so that the linking member directs forces imparted on the face-contacting wall portion into the deformation region of the cavity wall.

129. A method of delivering respiratory gas to a patient comprising :

delivering respiratory gas at an elevated pressure to a first cavity in a cushion module of a patient interface to supply pressurised respiratory gas to the mouth and nares of the patient from the first cavity; and

accelerating respiratory gas flow through a portion of the first cavity to deliver an accelerated respiratory gas flow to the nares of the patient.

130. The method as claimed in claim 129, further comprising exhausting respiratory gas from a second cavity in the cushion module, the second cavity being in fluid communication with the first cavity.