Patent Description:
It is known to provide a flow of respiratory gases to a user via an interface such as a face mask to relieve a number of ailments - for example sleep apnea or snoring. One problem with supplying a flow of gases to a user via an interface such as a face mask is that it can be difficult to form a good seal between the mask and the face. The mask is often held in place against the user's face by head gear worn on the user's head. In use, the head gear may be over tightened so that the mask is pressed uncomfortably onto the user's face. Alternatively the headgear may be under tightened or applied to the user's head too loosely, preventing the formation of an effective seal between the mask and user's face.

Prior art face masks have attempted to improve the seal between the user's face and the mask and make the sealing interface with the user more comfortable. <CIT> (<CIT>) describes a mask assembly having a seal outer sheath and inner cushion. The inner cushion has a raised nasal bridge portion which results in a more flexible seal contact on the bridge of the user's nose. The raised nasal bridge portion is formed by a cut out portion of the inner cushion, the cut-out being on a mask body side of the cushion.

<CIT> describes a nasal mask cushion for sealing a nasal mask to a user's face. The cushion has a first membrane and a second membrane. The second membrane contacts a user's face when in use. The second membrane is thinner than the first membrane and is spaced apart from the first membrane when the mask is not in use. The second membrane is spaced from the first membrane by a greater distance in the nasal bridge region than in the cheek region.

It is an object of the present invention to provide an improved patient sealing interface, or to at least provide the industry or the public with a useful choice.

The present invention provides a sealing interface according to the claims.

Disclosed herein, but not independently claimed, is a sealing interface for use as part of an apparatus for supplying a flow of respiratory gases to a user comprising:.

According to a further aspect the hinged region is coupled to each said cheek region by a hinging portion.

According to a further aspect the nasal bridge region is the hinged region.

According to a further aspect the chin region is the hinged region.

According to a further aspect the hinged region is biased towards the outer sheath, in use said inner cushion hinged region substantially contacting said outer sheath.

According to a further aspect in use said sealing interface is coupled with a body that receives said gases, and
a gap is provided between the body and the cushion in the hinged region, said gap providing a space for said inner cushion hinged region to flex independently of said cushion cheek regions.

According to a further aspect each said hinging portion is a narrow necked section formed between said inner cushion hinged region and a corresponding said cheek region, said inner cushion hinged region and cheek regions being integrally formed.

According to a further aspect the gap is a valley in the inner cushion nasal bridge region, the valley being in a side of the inner cushion facing said body in use.

According to a further aspect the valley extends the full perimeter of the hinged region, a first end of the valley being adjacent one check region and a second end of the valley being adjacent the other cheek region.

According to a further aspect each narrow necked portion is formed by a notch aligned with a said first or second end of said valley, the notch being formed in a side of the inner cushion facing a user's face in use.

According to a further aspect each narrow necked portion is formed by a slit aligned with a said first or second end of said valley, the slit being formed in a side of the inner cushion facing a user's face in use.

According to a further aspect each said hinging portion biases said inner cushion nasal region towards the outer sheath, in use said inner cushion hinged region substantially contacting said outer sheath.

According to a further aspect said narrow necked section is formed by a first notch formed in a side of the inner cushion that faces the user's face in use, and a second notch formed in the side of the inner cushion that faces the mask body in use, said first and second notches being aligned to form said narrow necked section.

According to a further aspect said narrow necked section is formed by a slit formed in a side of the of the inner cushion that faces the user's face in use, and a notch formed in the side of the inner cushion that faces the mask body in use, said slit and said notch being aligned to form said narrow necked section.

According to a further aspect said narrow necked section is formed by a notch formed in a side of the of the inner cushion that faces the user's face in use.

According to a further aspect said narrow necked section is formed by a notch formed in the side of the inner cushion that faces the mask body in use.

According to a further aspect the hinged region of the cushion flexes, pivots or bends at the hinged portions.

According to a further aspect wherein the hinged region of the cushion flexes, pivots or bends at the hinged portions at a rate of defection, the rate of deflection being <NUM>. 04N/mm ± <NUM>%.

According to a further aspect the rate of deflection is <NUM>. 04N/mm ± <NUM>%.

According to a further aspect the inner cushion and the outer sheath are separately formed.

According to a further aspect the inner cushion and the outer sheath are integrally formed.

Disclosed herein, but not independently claimed, is a patient interface for use as part of an apparatus for supplying a flow of respiratory gases to a user comprising:.

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

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

Preferred embodiments will be described by way of example only and with reference to the drawings.

The sealing interface of the preferred and alternative forms described herein provides improvements in the delivery of CPAP therapy. In particular a sealing interface is described which may allow a reduced pressure of the mask on the user's face and reduces leakage when compared with the prior art. It will be appreciated that the sealing interfaces as described can be used in respiratory care generally or with a ventilator but will be described for illustration with reference to use in a humidified CPAP system. It will also be appreciated that the preferred and alternative forms described can be applied to any form of patient interface including, but not limited to, full face masks sealing around the user's nose and mouth, and nasal masks sealing around the user's nose.

With reference to <FIG> a humidified Continuous Positive Airway Pressure (CPAP) system is shown in which a patient <NUM> is receiving humidified and pressurised gases through a patient interface <NUM> connected to a humidified gases transportation pathway or inspiratory conduit <NUM>. It should be understood that delivery systems could also be VPAP (Variable Positive Airway Pressure) and BiPAP (Bi-level Positive Airway Pressure) or numerous other forms of respiratory therapy.

Inspiratory conduit <NUM> is connected to the outlet <NUM> of a humidification chamber <NUM> which contains a volume of water <NUM>. Inspiratory conduit <NUM> may contain heating means or heater wires (not shown) which heat the walls of the conduit to reduce condensation of humidified gases within the conduit. Humidification chamber <NUM> is preferably formed from a plastics material and may have a highly heat conductive base (for example an aluminium base) which is in direct contact with a heater plate <NUM> of humidifier <NUM>. Humidifier <NUM> is provided with control means or electronic controller <NUM> which may comprise a microprocessor based controller executing computer software commands stored in associated memory.

Controller <NUM> receives input from sources such as a user input interface or dial <NUM> through which a user of the device may, for example, set a predetermined required value (preset value) of humidity or temperature of the gases supplied to patient <NUM>. The controller may also receive input from other sources, for example temperature and/or flow velocity sensors <NUM> and <NUM> through connector <NUM> and heater plate temperature sensor <NUM>. In response to the user set humidity or temperature value input via dial <NUM> and the other inputs, controller <NUM> determines when (or to what level) to energise heater plate <NUM> to heat the water <NUM> within humidification chamber <NUM>. As the volume of water <NUM> within humidification chamber <NUM> is heated, water vapour begins to fill the volume of the chamber above the water's surface and is passed out of the humidification chamber <NUM> outlet <NUM> with the flow of gases (for example air) provided from a gases supply or blower <NUM> which enters the chamber through inlet <NUM>. Exhaled gases from the patient's mouth are passed directly to ambient surroundings in <FIG>.

Blower <NUM> is provided with a variable pressure regulator or with a variable speed fan <NUM> which draws air or other gases through blower inlet <NUM>. The speed of variable speed fan <NUM> is controlled by electronic controller <NUM> (or alternatively the function of controller <NUM> could carried out by controller <NUM>). The controller may control the fan speed or regulated pressure according to any useful criteria. For example the controller may respond to inputs from controller <NUM> and a user set predetermined required value (preset value) of pressure or fan speed via dial <NUM>.

A typical patient interface in the form of a nasal mask is shown in <FIG>. The mask includes a hollow body <NUM> with an inlet <NUM> connected to the inspiratory conduit <NUM>. The mask <NUM> is positioned around the nose of the user <NUM> with the headgear <NUM> secured around the back of the head of the patient <NUM>. The restraining force from the headgear <NUM> on the hollow body <NUM> and the forehead rest <NUM> ensures enough compressive force on a mask seal <NUM>, to provide an effective seal against the patient's face.

The hollow body <NUM> is constructed of a relatively inflexible material. For example, the hollow body <NUM> may be formed from polycarbonate plastic. Such a material would provide the requisite rigidity as well as being transparent and a relatively good insulator. The expiratory gases can be expelled through a valve in the mask, a further expiratory conduit, vent paths through the mask, or any other suitable method.

The mask seal <NUM> is provided around the periphery of the mask body <NUM> to provide an effective seal onto the face of the user to prevent leakage. The mask seal <NUM> is shaped to approximately follow the contours of a patient's face. The seal is contoured to approximately match the facial contours of a user around the user's nose, from the bridge of the nose, continuing down the cheek regions adjacent each side of the user's nose and across the user's philtrum area. Similarly, if the seal was applied to a full face mask covering a user's nose and mouth, the face seal would be shaped to approximate the facial contours of the user's chin and wider cheek regions. The mask seal <NUM> will deform when pressure is applied by the headgear <NUM> to adapt to the individual contours of any particular user.

A prior art nasal mask assembly for sealing around a user's nose is shown in <FIG>. The mask seal <NUM> is composed of an inner cushion <NUM> covered by an outer sealing sheath <NUM>. The inner cushion <NUM> is constructed of a resilient material, for example polyurethane foam, to distribute the pressure along the seal around the user's face. In other forms the cushion <NUM> may be formed of other appropriate material, such as gel, silicone, or other composite materials.

A face side <NUM> of the inner cushion is shaped to approximately match the shape of the user's face. As shown in <FIG>, there is an indented section <NUM> intended to fit over the bridge of the patient's nose, a cheek contour <NUM> on each side to follow the cartilage extending from the middle of the user's nose, and an indented section <NUM> to seal across the area of the user's face between the user's nose and upper lip. An opposite side of the cushion <NUM> is shaped to match and interface to the mask body.

The inner cushion may include a raised bridge <NUM> in the nasal bridge region. The raised bridge <NUM> can also be described as a cut out or valley <NUM> formed in the cushion on the mask body side <NUM> of the cushion. As the raised bridge <NUM> is unsupported by the mask body <NUM>, it is much more flexible and results in less pressure on the nasal bridge of the patient.

In other forms, the cushion may have other bridge portions, so that in these bridging areas the cushion is more flexible. For example the inner cushion may include a valley <NUM> formed in the region intended to seal between the nose and upper lip area of a user.

Again with reference to <FIG>, the inner cushion <NUM> is located around an inner periphery <NUM> of an open face <NUM> of the hollow body <NUM>, contacting the mask body except for in any raised bridge portions such as the raised nasal bridge <NUM>. The cushion is located in a cavity <NUM> extending around the inner periphery <NUM> of the body <NUM>, terminating at each side of the raised nasal bridge region <NUM> of the mask, where the raised bridge portion <NUM> of the cushion does not contact the mask body <NUM>. The cavity <NUM> is generally formed by two spaced apart walls <NUM> and <NUM> extending around the inner periphery of the mask. The walls are arranged such that the cavity has generally triangular cross section, as shown in <FIG>.

Similarly the outer sheath <NUM> is attached to an outer periphery of the mask body <NUM>, either directly to the body <NUM> in a push fit arrangement (not shown), or indirectly via a relatively inflexible seal clip <NUM> as shown in <FIG>. A mask body side of the outer sheath <NUM> is attached to the seal clip. The seal clip interfaces to the mask body <NUM>. The clip provides a releasable rigid or semi rigid interface, to allow the sealing interface to be easily attached and detached from the mask body many times. The outer sheath <NUM> surrounds and loosely covers over the top of the inner cushion <NUM>.

One side of the outer sheath is also shaped to match the facial contours of a user's face, and closely matches the shape of the side of the cushion adjacent a user's face in use.

In the prior art mask assembly of <FIG>, the cushion <NUM> is a separate item, with the outer sheath <NUM> fitting in place over the cushion <NUM>. The outer sheath holds the cushion in place within the mask assembly <NUM>. In other forms, the cushion may be permanently or releasably attached to the outer sheath. Alternatively, the cushion may be permanently or releasably attached to the mask body <NUM>, or the outer sheath and inner cushion may be integrally formed. For example, an alternative prior art sealing interface <NUM> comprising an integrally formed inner cushion <NUM> and outer sheath <NUM> is shown in cross section in <FIG>. The sealing interface of <FIG> is usually integrally formed in silicone.

A sealing interface as described herein may be introduced into a prior art mask, such as the mask of <FIG>. For example, a sealing interface <NUM> as described herein could be substituted for the sealing interface <NUM> of the prior art mask of <FIG>. The preferred and alternative embodiments will be described in relation to a sealing interface intended to be incorporated into the nasal mask of <FIG>. However, the sealing arrangement described herein may be incorporated into other mask assemblies, such as full face masks that seal around a user's nose and mouth.

A sealing interface that includes a mask inner cushion that has a hinged region is described. The hinged region is preferably attached to the inner cushion cheek regions by hinging portions. The hinging portions allow the hinged region of the inner cushion to flex independently of the cheek regions of the cushion. With a hinged region that flexes independently of the remainder of the inner cushion, the force applied by the mask seal interface <NUM> to a user's face in the hinged region can be independently reduced, without reducing the force applied in other regions of the mask seal.

A common cause for discomfort among users is the pressure applied by the mask seal <NUM> against the bridge of the user's nose during prolonged use. In extreme cases, prior art sealing interfaces may cause cuts or breakage of the user's skin in the nasal bridge region. A reduction in pressure, or force, applied by the mask sealing interface in the nasal bridge region, while maintaining an effective seal against the user's face, is a significant advantage achieved with the sealing interfaces of the preferred and alterative forms described.

In a preferred embodiment, the nasal bridge region of the inner cushion is the hinged region of the inner cushion. The hinged nasal bridge region is preferably attached or coupled to the inner cushion cheek regions by hinging portions. The hinged nasal bridge region allows the nasal bridge region of the inner cushion to flex independently of the cheek regions and chin or upper lip region of the cushion. With a nasal bridge region that flexes independently of the remainder of the inner cushion, the force applied by the mask seal interface <NUM> to a user's face in the nasal bridge region can be independently reduced, without reducing the force applied in other regions of the mask seal.

A preferred embodiment of the sealing interface <NUM> is described with reference to <FIG>. The inner cushion <NUM> generally comprises four regions, a nasal bridge region <NUM> corresponding with the nasal bridge region of a user, two cheek regions <NUM> corresponding with the left and right cheeks of a user, and an upper lip region <NUM> corresponding with a user's philtrum area. The nasal bridge region generally extends from the top of a user's nose and down each side of the user's nose to approximately where the sides of the user's nose meets the user's cheeks.

The nasal bridge region <NUM> is attached to each cheek region <NUM> by a hinging portion <NUM>. The hinging portions allow the nasal bridge region <NUM> to flex substantially independently of the remainder of the inner cushion.

Preferably each hinging portion is a narrow necked section <NUM> formed between the inner cushion nasal region and a corresponding cheek region. Preferably the inner cushion nasal region, cheek regions and chin or upper lip region are integrally formed.

The narrow necked portion <NUM> allows the nasal bridge region to flex substantially independently of the cheek regions. The raised nasal bridge region bends easily at the narrow necked portions. Any pressure or force applied to the nasal bridge region is effectively isolated from the remaining portions of the inner cushion. In use, the nasal bridge region may bend substantially out of the way of the nasal bridge region of the user's face to provide reduced pressure against the user's nasal bridge, while still providing support to the outer sheath in this area. Support of the outer sheath around substantially the full perimeter of the outer sheath is desirable for creating an effective seal between the mask seal <NUM> and the user's face. Ideally, a mask seal provides uniform pressure to the user's face around the perimeter of the seal.

The shape of the nasal bridge region differs significantly between users. Where a user has a prominent nose and nasal bridge region, excess pressure is generated in the nasal bridge region of the mask as the mask is tightened to achieve an effective seal in other positions of the seal. A mask seal incorporating a hinged nasal bridge region reduces the pressure in the nasal bridge region for a range of users who suffer from over pressure in the nasal bridge region when using prior art masks.

In the embodiment of <FIG>, the cushion <NUM> has a valley <NUM> on the side of the cushion that in use faces or couples to the mask body <NUM>, the valley being in the nasal bridge region <NUM> as described with reference to the prior art. Preferably the valley <NUM> extends substantially the full perimeter of the nasal bridge region, from one cheek region <NUM> to the other cheek region <NUM>, a first end <NUM> of the valley <NUM> being adjacent one check region <NUM> and a second end <NUM> of the valley <NUM> being adjacent the other cheek region <NUM>.

In the embodiment of <FIG>, each narrow necked portion <NUM> is formed by a notch <NUM> formed in the side of the inner cushion that faces the user's face in use, this notch being aligned with an end <NUM> of the valley <NUM>.

The preferred inner cushion may include other valley or other bridge portions as described with reference to the prior art. For example, the preferred inner cushion has a valley <NUM> the region of the cushion corresponding with the upper lip region of the user.

<FIG> indicates how the nasal bridge region <NUM> can flex substantially independently of the rest of the inner cushion. With force applied to the apex of the nasal bridge region in the direction of arrow B, notch <NUM> opens up, and the opposite side of the inner cushion, at an end <NUM> of the valley <NUM>, compresses. The nasal bridge region of the cushion flexes or bends at the narrow neck section <NUM>, substantially independently of the rest of the inner cushion.

As shown in <FIG>, the narrow necked portion <NUM> may be formed by a first notch <NUM> formed in the side of the inner cushion that faces the user's face in use, and a second notch <NUM> formed in the side of the inner cushion that faces the mask body in use, the first and second notches being aligned to form the narrow necked portion.

Alternatively, the narrow necked portion <NUM> may be formed by a slit <NUM> or cut formed in the side of the inner cushion that faces the user's face in use, and a notch <NUM> formed in the side of the inner cushion that faces the mask body in use, the slit and notch being aligned to form the narrow necked portion.

Alternatively, as shown in <FIG>, each narrow necked portion <NUM> may be formed by a slit <NUM> formed in the side of the inner cushion that faces the user's face in use, this slit being aligned with an end <NUM> of the valley <NUM>.

Alternatively, as shown in <FIG>, the narrow necked portion <NUM> may be formed by a notch <NUM> formed in the side of the inner cushion that faces the user's face in use, the notch extending across a substantial portion of the width of the cushion. Alternatively, as shown in <FIG>, the narrow necked portion may be formed by a notch <NUM> formed in the side of the inner cushion that faces the mask body in use, the notch extending across a substantial portion of the width of the cushion. In a further alternative embodiment, the narrow necked portion may be formed by a slit formed in the side of the inner cushion that faces the user's face in use, the slit extending across a substantial portion of the width of the cushion.

One advantage of the embodiment of <FIG> is the inner cushion is adapted to provide a continuous contact with the outer sheath around the perimeter of the seal. The notch <NUM>, <NUM> or slit <NUM> in the user's face side of the inner cushion in the other embodiments result in a discontinuous contact with the outer sheath which is less desirable.

In the further alternative embodiment of <FIG>, a plurality of slits <NUM> are arranged to create the narrow necked portion <NUM>. In use, as the nasal bridge region of the inner cushion flexes or bends at the hinged portion <NUM>, as shown in <FIG> due to a force applied to the apex of the nasal bridge region in the direction of arrow C. The fingers <NUM> of material between slits <NUM> provide bridging contact points <NUM> with the outer sheath to assist with support of the sheath at the narrow necked position of the seal.

The thickness of the cushion around the perimeter of the mask seal is typically around <NUM>, to provide support to the outer sheath in use. The thickness of the cushion is best shown in <FIG> as item <NUM>. For a foam cushion with a thickness of around <NUM>, the width <NUM> of the cushion across the narrow necked portion <NUM>, as indicated in <FIG>, is preferably approximately <NUM>. For a width <NUM> in the narrow necked portion <NUM> substantially greater than <NUM>, the nasal bridge region <NUM> will not deflect or bend substantially independently of the remainder of the inner cushion <NUM>. For a width substantially greater than <NUM>, the pressure in the nasal bridge region is not sufficiently reduced when compared to the prior art cushion.

Conversely, for a width <NUM> in the narrow necked portion <NUM> substantially less than <NUM>, the nasal bridge region <NUM> will flex too easily, and will not provide sufficient support to the outer sheath in use. If the narrow necked portion is too narrow, the effectiveness of the seal is compromised as the cushion does not provide sufficient support to the outer sheath in the nasal bridge region.

Preferably the width of the narrow necked portion is in the range of <NUM> - <NUM>.

The inner cushion may be made from other materials, such as gel, silicon or other composite materials. For different materials and different perimeter thicknesses, the width <NUM> of the narrow necked portion may need to change from the preferred dimensions described previously in order to achieve a cushion comprising a nasal bridge region that bends or flexes substantially independently of the remainder of the cushion.

The valley <NUM> provides a gap or space between the body and the inner cushion into which the nasal bridge region <NUM> may flex independently of the inner cushion cheek regions. Alternatively, the body may have a cavity or open area in the inner periphery of the mask body <NUM> into which the nasal region may flex. In this alternative embodiment, the inner cushion may or may not have a valley <NUM> formed in the nasal bridge region on the side of the cushion that in use faces or couples to the mask body <NUM>. An example of such an embodiment is shown in <FIG>.

The preferred and alternative forms may also be incorporated into an integrated inner cushion and outer sheath type sealing interface. Examples of an integrated inner cushion and outer sheath type sealing interface <NUM> are provided in <FIG>.

In the embodiment of <FIG>, each narrow necked portion <NUM> is formed by a notch <NUM> formed in the side of the inner cushion <NUM>. Notch <NUM> is substantially on the side of the inner cushion that faces the user's face in use. A notch or valley <NUM> is formed in a rearward portion of the inner cushion to provide a space <NUM> in which the nasal bridge region <NUM> of the inner cushion can flex into, substantially independently of the remaining regions of the inner cushion <NUM>.

<FIG> indicates how the nasal bridge region <NUM> can flex substantially independently of the rest of the inner cushion. With force applied to the apex of the nasal bridge region in the direction of arrow D, notch <NUM> opens up, and the opposite side of the inner cushion compresses. The nasal bridge region of the cushion flexes or bends at the narrow neck section <NUM>, substantially independently of the rest of the inner cushion. For clarity, the outer sheath is not shown deformed, however, in use, the outer sheath will deform together with the inner cushion as the inner cushion deflects, the outer sheath maintaining substantial contact with the inner cushion.

A further alternative embodiment is illustrated in <FIG>. The narrow necked section is formed by the valley or notch <NUM> in a rearward portion of the nasal bridge region <NUM> of the inner cushion <NUM>, without a notch in the forward side of the inner cushion.

Further alternative embodiments are shown incorporated into an integrated inner cushion and outer sheath sealing interface which include arrangements similar to those described previously in relation to a sealing interface comprising a separate inner cushion and outer sheath. For example, the narrow necked portion <NUM> of <FIG> may be formed by a slit instead of notch <NUM>.

In the preferred embodiment, the inner cushion hinged region is biased towards the outer sheath, so that in use the hinged region substantially contacts the outer sheath. In the embodiment of <FIG>, the nasal region is biased to the sheath contact position because the inner cushion is formed in this shape. The inner cushion nasal bridge region is substantially in contact with the outer sheath when in an un-stressed or un-deflected state. To deflect the nasal bridge region towards the mask body <NUM>, it is necessary to deform the inner cushion nasal bridge region. A high proportion of the stress induced in the inner cushion by a force applied to the nasal bridge region is concentrated in the narrow neck section of the cushion. This achieves deflection of the nasal bridge region substantially independently of the other cushion regions. As a result, the force required to deflect or deform the nasal bridge region is substantially reduced. This provides a more comfortable fit against the user's face compared to prior art mask sealing interfaces, while maintaining an effective seal.

When a force is applied to the nasal bridge region of the inner cushion of the embodiment of <FIG>, the nasal bridge region twists or bends at the narrow neck sections <NUM>. The narrow neck, or hinging portions <NUM> bias the inner cushion nasal region towards the outer sheath.

A mask which incorporates the preferred and alternative arrangements as described in this specification provides an improved fit against a range of user's facial contours. The hinged region flexes easily away from, for example, a user's nasal bridge region, while still providing a supporting member for the outer sheath in this region of the seal. In use, gases provided at typical CPAP pressures to the mask interior may cause some inflation of the outer sheath against the user's face. In the sealing interface as described, the outer sheath in contact with the user's face is effectively sandwiched between the inner cushion and the user's face, including in the hinged region of the cushion. This arrangement provides a secure seal against the user's face.

In alternative forms, the sealing interface may be implemented with an inner cushion comprising mechanical hinged portions. For example, the hinged portion may comprise a bracket including two halves connected together via a pivot pin. One bracket half is connected to the hinged region, for example the nasal bridge region, adjacent a cheek region, and the other bracket half is connected to the cheek region adjacent one side of the nasal bridge region. One hinged portion, or both hinged portions may include a biasing mechanism, such as a resilient member, to bias the nasal bridge region to an un-deflected state, as described previously in relation to the preferred embodiment. One or both hinged portions may include an end stop to define the un-deflected state.

Alternatively, a biasing means or resilient member such as a spring may be located in the gap between the raised nasal bridge region and the mask body <NUM>.

In a further alternative form, the hinged region may be separate from the other cushion regions. For example, the nasal bridge region may be pivotally attached to the mask body via two pivot points, the pivot points sharing a common pivot axis, the remaining portions of the inner cushion being attached or coupled to the mask body. Each pivot point may include a pivot pin and a pivot pin receiving portion. One or both pivot points may include a resilient member to bias the inner cushion nasal bridge region to an un-deflected state. In the un-deflected state, the nasal bridge region is substantially in contact with the outer sheath. Alternatively, a biasing means or resilient member such as a spring may be located in the gap between the raised nasal bridge region and the mask body <NUM>, to bias the nasal bridge region of the inner cushion to the un-deflected state.

A significant reduction in force required to deflect the hinged region of the inner cushion has been achieved with the sealing interface of the preferred and alternative forms as described. For example, <FIG> is a chart showing the force (Newton) required to deflect the hinged nasal bridge region of the embodiment of <FIG> by a distance (mm) compared to the force required to deflect the nasal bridge portion of a prior art seal. <FIG> shows that the force <NUM> required to deflect the nasal bridge region is approximately half the force <NUM> required to deflect the nasal bridge region of a prior art sealing interface.

The preferred and alternative forms as described herein allow the hinged region of the cushion to flex, pivot or bend about the hinged portions at a preferred rate of defection. For example, where the nasal bridge region of a cushion incorporating the preferred form is the hinged region of the cushion, preferably the hinged nasal bridge region deflects at a rate of <NUM>. 04N/mm ± <NUM>% when a force is applied to an apex area of the cushion, as indicated by arrow B in <FIG>. Preferably the rate of deflection is <NUM>. 04N/mm ± <NUM>%. Most preferably the rate of deflection is <NUM>. 04N/mm± <NUM>%.

Another problematic area for face or nasal mask sealing interfaces is the chin or upper lip region. For example, the shape of the chin region differs significantly between users. Where a user has a prominent chin, excess pressure is generated in the chin region of the mask seal as the mask is tightened onto the face of a user to achieve an effective seal in other positions of the seal.

The preferred and alternative forms may be applied to a mask seal to achieve reduced force or pressure in the chin or upper lip region. As illustrated in <FIG>, the inner cushion <NUM> for a full face mask incorporates a hinging portion <NUM> in the area between the chin region <NUM> and the cheek region <NUM>. The hinging portion <NUM>, in this example being a narrow necked portion <NUM>, allows the chin region <NUM> to flex or bend at the hinging portion <NUM> substantially independently of the remainder of the inner cushion <NUM>. The mask seal reduces the pressure in the chin region for a range of users who suffer from over pressure in the chin region when using prior art masks.

The hinging portion <NUM> between the chin region <NUM> and the cheek regions <NUM> may be formed in the same way as any one of the examples described previously in relation to the hinging portion <NUM> between the nasal bridge region and the cheek regions. For example, the hinged region <NUM> may be formed as any one of the narrow necked portion embodiments described previously in relation to the independently flexing nasal bridge region. Alternatively, hinging portion <NUM> may be a mechanical hinge, the chin region being coupled to the cheek regions by the mechanical hinge. One hinged portion, or both hinged portions may include a biasing means, such as a resilient member, to bias the nasal bridge region to an un-deflected state, as described previously in relation to the hinged nasal bridge region. One or both hinged portions may include an end stop to define the un-deflected state. Alternatively, a biasing means or resilient member such as a spring may be located in a gap between the chin region and the mask body <NUM>.

In a further alternative form, the chin region may be separate from the other cushion regions. The chin region may be pivotally attached to the mask body via two pivot points, the pivot points sharing a common pivot axis, the remaining portions of the inner cushion being attached or coupled to the mask body. Each pivot point may include a pivot pin and a pivot pin receiving portion. One or both pivot points may include a resilient member to bias the inner cushion chin region to an un-deflected state. In the un-deflected state, the chin region is substantially in contact with the outer sheath. Alternatively, a biasing means or resilient member such as a spring may be located in the gap between the chin region and the mask body <NUM>, to bias the chin region of the inner cushion to the un-deflected state.

To allow the chin region to flex, a preferred embodiment includes a valley on the side of the cushion that in use faces or couples to the mask body <NUM>, the valley being in the chin region of the cushion. The valley provides a gap or space between the body and the inner cushion into which the chin region <NUM> may flex independently of the inner cushion cheek regions <NUM>. Alternatively, the body may have a cavity or open area in the inner periphery of the mask body <NUM> into which the chin region may flex. In this alternative embodiment, the inner cushion may or may not have a valley formed in the chin region on the side of the cushion that in use faces or couples to the mask body <NUM>.

Claim 1:
A sealing interface (<NUM>) that includes an inner cushion (<NUM>, <NUM>), wherein
the inner cushion (<NUM>, <NUM>) comprises:
a hinged region (<NUM>); and
a cheek region (<NUM>),
wherein the hinged region (<NUM>) comprises hinging portions (<NUM>) that attach the hinged region (<NUM>) of the inner cushion (<NUM>) to the cheek region (<NUM>) of the inner cushion (<NUM>), and wherein the hinging portions (<NUM>) are adapted to allow the hinged region (<NUM>) of the inner cushion (<NUM>) to flex independently of the cheek regions (<NUM>) of the cushion (<NUM>, <NUM>); and wherein each hinging portion (<NUM>) is a narrow necked section (<NUM>) formed between the hinged region (<NUM>) and the corresponding cheek region (<NUM>).