WO2022192935A1

WO2022192935A1 - Nasal cpap mask and system thereof

Info

Publication number: WO2022192935A1
Application number: PCT/AU2022/050190
Authority: WO
Inventors: Philip Kwok; John Hilton; Christopher Dodds; Damian Peter Francis SAVIO; Fay Kooyakhi; Eric Siu; Richard Sokolov; Doug Cusack
Original assignee: Bespoke Medical Innovations Pty Ltd
Priority date: 2021-03-18
Filing date: 2022-03-08
Publication date: 2022-09-22

Abstract

A nasal mask for a patient comprises a rigid contoured nasal seal structure, a bellows, and a rigid mask frame. The rigid contoured nasal seal structure is adapted to sealably engage a nose of a patient. The bellows has a front end and a rear end where the rear end is a nearest end to a face of the patient. The rigid mask frame has an opening for receiving an air supply tube. The front end of the bellows is connected to the rigid frame and the rear end of the bellows is connected to the seal structure. When the nasal mask is in use, the bellows is adapted to balance the alignment of the seal structure and the rigid mask frame.

Description

Nasal CPAP Mask and System thereof

TECHNICAL FIELD

[0001] The present invention relates to a nasal continuous positive airway pressure (CPAP) mask and corresponding system thereof. In particular, the present invention relates to an improved bellows, mask frame, and headgear of a nasal continuous positive airway pressure mask system for treating sleep disordered breathing (SDB).

BACKGROUND.

[0002] Sleep apnoea is a subtype of SDB and is commonly treated with the equipment providing continuous positive airway pressure (CPAP), typically between 4 and 20 cm H O air pressure, to the nasal passage of the patient via a patient interface that forms a seal against the patient's face. The air pressure may be higher than 20 cm H O for bi-level positive airway pressure. CPAP acts as a pneumatic splint and may prevent upper airway occlusion by pushing the soft palate and tongue forward and away from the posterior oropharyngeal wall.

[0003] The application of a supply of air at positive pressure to the entrance of the airways of a patient is facilitated by the use of a patient interface, such as a nasal mask, full-face mask or nasal pillows. A range of patient interface devices with deformable seal-forming structures made from silicone, gel, and foam suffer from being one or more of obtrusive, aesthetically undesirable, poorly fitting, difficult to use and uncomfortable especially when worn for long periods of time or when a patient is unfamiliar with a system. Masks designed solely for aviators, as part of personal protection equipment or for the administration of anaesthetics may be tolerable for their original application, but nevertheless be undesirably uncomfortable to be worn for extended periods, for example, while sleeping.

[0004] The mask force and the pressurized air force combine to push the seal structure onto the patient's face and the skin force being equal and opposite to oppose this push. The 3D axis of the opposing force from the patient's skin determines the ideal axis from which the pressurized air and skin contact cross-section areas are calculated.

[0005] For a patient interface where the seal-forming structure is a flexible mask cushion, the combined push vector may be calculated as the largest pressurized air cross-section multiplied by the air pressure. Prior masks with a flexible and deformable mask cushion have used increased air pressure to produce a stronger push onto a stiffer peripheral wall portion or rim of the flexible mask cushion to provide a stronger sealing force with higher air pressures. One drawback is that such a flexible mask cushion is bulky, is not visually aesthetic, and obstructs a relatively large portion of the patient's face. Alternate prior masks have large skin contact areas and/or require a high level of headgear tension for their mask straps and therefore very uncomfortable for patients because CPAP therapy is typically required for a prolonged duration.

[0006] Prior masks with a flexible and deformable mask cushion require headgear straps to be highly tensioned until a perimeter seal is achieved by the mask cushion. Areas of interference are further compressed. These prior masks attempt to make these areas of interference flex more to accommodate population variation of facial anthropometric differences. A rigid seal-forming structure results in minimal or nominal concentrated facial compression because the seal-forming structure is personalised or customised for an individual patient without high or low gaps between the seal-forming structure and the patient's face.

[0007] Therefore, headgear tension used for a rigid seal-forming structure may be lower relative to prior masks with deformable or soft mask cushions, resulting in high levels of comfort and less likelihood of ulcer for the patient.

[0008] The use of a rigid seal-forming structure requires a number of supporting structures to achieve superior comfort and sealing. Many prior art products concentrated on creating a personalised interface to retrofit with an existing mask frame. There is a need to provide a flexible and modular supporting mask structure for interfacing with a personalised rigid nasal seal-for the CPAP mask system. [0009] US Patent Application No. 20180043122 discloses a CPAP mask with a customised interface. The CPAP mask of this prior art includes off-the-shelf components of current CPAP systems. The CPAP mask includes a customised CPAP interface attached to a tube frame. The tube frame is attached to a tube gasket and the tube gasket is connected to a ventilated elbow of an air supply tube on one end with an adapter on the other end. This configuration does not support a CPAP mask seal with a rigid structure sealing against the patient's face and as such the seal will not perform well as the patient moves around.

[0010] Published PCT Application No. WO2016154676 discloses a CPAP mask with a customised patient interface. The patient interface of this prior art includes a flexible nose engaging portion which adds complexity to the overall design and manufacturing. Also, the flexible nose engaging portion may lead to difficulties in properly and sealably fitting the mask to a patient.

PROBLEMS TO BE SOLVED

[0011] The inventive concept arises from a recognition that a seal structure may be comfortable for a patient and sealed against the patient face.

[0012] The present invention relates to a nasal continuous positive airway pressure mask and system thereof.

[0013] It may be advantageous to provide a fully integrated and optimised CPAP nasal mask that maximises the benefits of a customised nasal seal solution.

[0014] It may be advantageous to provide a nasal CPAP mask system that can be easy to use and promotes the advantages of superior comfort and sealing.

[0015] It may be advantageous to provide a nasal CPAP mask system that encourages patient compliance and satisfaction [0016] It may be advantageous to provide a bellows, a mask frame, and a headgear adapted to engage with a customised nasal seal solution to promote superior comfort and sealing.

[0017] Other objects and advantages will become apparent when taken into consideration with the following specification and drawing.

[0018] It may be an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

SUMMARY

[0019] In a first aspect of the present invention, there is provided a nasal mask for a patient comprising a rigid contoured nasal seal structure for sealably engaging a nose of the patient, a bellows having a front end and a rear end where the rear end is a nearest end to a face of the patient; a rigid mask frame having an opening for receiving an air supply tube, and wherein the front end of the bellows is connected to the rigid frame and the rear end of the bellows is connected to the seal structure, such that the bellows is adapted to balance a tension between the seal structure and the rigid mask frame, when in use.

[0020] Preferably, the bellows comprises a bellows retainer ring for receiving one end of the rigid mask frame.

[0021] Preferably, the bellows retainer ring comprises a snap-fit connector to releasably engage with a complimentary snap-fit connector of the rigid mask frame. [0022] Preferably, the bellows retainer ring comprises a snap-fit connector to releasably engage with a complimentary snap-fit connector of the rigid mask frame.

[0023] Preferably, the bellows retainer ring comprises a visual cue for aligning with the rigid mask frame.

[0024] Preferably, the bellows is over-moulded onto the bellows retainer ring.

[0025] Preferably, the bellows retainer ring is made of a rigid material including polycarbonate or nylon.

[0026] Preferably, the bellows has a spherical leading profile and a toroidal rear profile such that the rigid personalised nasal seal structure is allowed to move towards inside the bellows.

[0027] Preferably, the bellows comprises a pliable wall with a thickness greater in the spherical leading profile than the toroidal rear profile

[0028] Preferably, the bellows comprises a plurality of vent holes disposed on the wall of the spherical leading profile.

[0029] Preferably, the bellows comprises a rear aperture for receiving the rigid personalised nasal seal.

[0030] Preferably, the wall around the rear aperture has a locally thick section.

[0031] Preferably, the rear aperture has a diameter smaller than that of an engaging groove on a bellows connector of the rigid personalised nasal seal structure such that an air-tight seal is formed between the bellows and the rigid personalised nasal seal structure when fitted together. [0032] Preferably, headgear comprises at least two clips for connecting to the rigid mask frame, wherein one of the clips conforms to a profile of a left cheek of the patient and another clip conforms to a profile of a right cheek of the patient.

[0033] Preferably, each clip has a mask frame connector on one end to releasably secure the clip to the rigid mask frame.

[0034] Preferably, the mask frame connector is a snap-fit connector.

[0035] Preferably, the mask frame connector is adapted to allow the clip to pivot above the mask frame connector when connected to the mask frame connector.

[0036] Preferably, each of the clips has an arm comprising a buckle to connect to a tension strap of the headgear.

[0037] Preferably, the arm extends toward an upper region of an auricle and under the infraorbital margin of the patient when in use.

[0038] Preferably, each of the clips has a second arm comprising a buckle to connect to a supporting strap of the headgear.

[0039] Preferably, the second arm is removably connected to the clip.

[0040] Preferably, the nasal seal structure has a fixed distance between a nose tip of the patient and an end plane of the nasal seal structure.

[0041] Preferably, the nasal seal structure comprises a seal inlet having an angle between 0 to 30 degrees from a nasion line of a patient.

[0042] In a second aspect of the present invention, there is provided a bellows for a CPAP mask of a patient comprising a hemispherical body having a front aperture for receiving a mask frame and a rear aperture for receiving a personalised nasal seal; and an inward folding bloat around the rear aperture, wherein inward folding bloat is adapted to move the personalised nasal seal structure into the hemispherical body.

[0043] In a third aspect of the present invention, there is provide an arm for joining a mask frame of a CPAP mask of a patient to a headgear comprises an elongate body conforming to a profile of a cheek a patient, a buckle at one end of the elongate body for adjustable attached to a strap of the headgear; and a connection at another end of the elongate body for attaching to the mask frame.

BRIEF DESCRIPTION OF THE FIGURES

[0044] Fig. 1 shows an exploded view of a nasal mask of a preferred embodiment of the present invention;

[0045] Fig. 2 shows a schematic diagram explaining the positions of a personalised nasal seal structure of the nasal mask of Fig. 1;

[0046] Fig. 3 shows a schematic diagram showing a position of a personalised nasal seal structure of the nasal mask of Fig. 1;

[0047] Fig. 4 shows a perspective sectional view of part of a bellows and mask frame of the nasal mask of Fig. 1;

[0048] Fig. 5 shows a side sectional view of part of a bellows and mask frame of the nasal mask of Fig. 1;

[0049] Fig. 6 shows an exploded view of part of a bellows and mask frame of the nasal mask of Fig. 1; [0050] Fig. 7 shows a perspective view of a bellows retainer ring of the nasal mask of Fig. 1;

[0051] Fig. 8 shows another perspective sectional view of part of a bellows, bellows retainer ring, and nasal seal structure of the nasal mask of Fig. 1;

[0052] Fig. 9 shows another side section view of a bellows, bellows retainer ring, and nasal seal structure of the nasal mask of Fig. 1;

[0053] Fig. 10 shows an exploded view of part of a mask frame and a tube connector of the nasal mask of Fig. 1;

[0054] Fig. 11 shows a side section view of part of a mask frame and a tube connector of the nasal mask of Fig. 1;

[0055] Fig. 12 shows another exploded view of part of a mask frame and a tube connector of the nasal mask of Fig. 1;

[0056] Fig. 13A and Fig. 13B show a front and a back perspective view of a clip for connecting a headgear and a mask frame of the nasal mask of Fig. 1;

[0057] Fig. 14A and Fig. 14B show a front and a back perspective view of another clip for connecting a headgear and a mask frame of the nasal mask of Fig. 1;

[0058] Fig. 15A and Fig. 15B show a side section view of two embodiments of a clip connector for connecting a headgear and a mask frame of the nasal mask of Fig. 1;

[0059] Fig. 16A and Fig. 16B shows a side and a perspective view of each of the two embodiments of the bellows of a nasal mask of Fig. 1;

[0060] Fig. 17 shows a perspective view of a nasal mask of another preferred embodiment of the present invention; [0061] Fig. 18 shows a perspective of a nasal mask of yet another preferred embodiment of the present invention;

[0062] Fig. 19 shows a perspective of a nasal mask of another preferred embodiment of the present invention;

[0063] Fig. 20 shows a schematic diagram of the rigid mask frame and arm geometry of a nasal mask of the preferred embodiments of the present invention;

[0064] Fig. 21 shows a schematic diagram of a clip of a nasal mask of a preferred embodiment of the present invention; and

[0065] Fig. 22 shows a perspective of a nasal mask of yet another preferred embodiment of the present invention.

DESCRIPTION OF THE INVENTION

[0066] The present invention is herein described in reference to a series of preferred embodiments. The first preferred embodiment is depicted in Fig. 1. Referring to Fig. 1, there is provided a nasal mask 10 for a patient comprising a rigid personalised nasal seal or a rigid contoured nasal seal structure 12 for sealably engaging a nose of the patient, a bellows 100 having a front end 103 and a rear end 107; a rigid mask frame 300 having an opening 302 for receiving one end of an air supply tube 400, and a headgear 530 comprising one or more straps 532 for connecting to the rigid mask frame. In one embodiment, the air supply tube 400 is a swivel tube. The front end 103 of the bellows 100 in this specification refers to the distal end of the bellows relative to the face and the rear end 107 refers to the proximal end of the bellows relative to the face.

[0067] The front end 103 of the bellows 100 is connected to the rigid mask frame 300 and the rear proximal end 107 of the bellows is connected to a rigid contoured nasal seal structure 12, such that the bellows is adapted to balance the alignment of the seal structure and the rigid mask frame when in use, or to neutralise the pressure or tension between the rigid personalised nasal seal structure and the rigid mask frame. In other words, the bellows 100 is adapted to provide just enough seal pressure to the nasal seal structure 12 on a patient face while not exerting excessive force to cause local pressure ulcers.

[0068] One embodiment of the invention resides in the use of a relatively rigid nasal seal structure 12 that may be applied to a sleep apnoea treatment apparatus. This apparatus comprises a CPAP machine, an attached air delivery line and a nasal mask adapted to deliver the air to a patient's nostrils, in the form of a nasal mask adaptor that delivers air from the air-line to the patient's nostrils in a more comfortable and efficient manner that known in the prior art.

[0069] In one embodiment, the nasal seal structure 12 which is a three- dimensional (3D) seal or apnoea nasal seal structure is shaped to fit snugly to the patient's nose on one side, and adapted to fit on to the bellows 100.

[0070] In an embodiment, the nasal mask interface geometry is shaped so as to maintain an airtight seal over as wide a range of movement as possible of the mask body in relation to the adapter and so provide a robust seal as dislodging forces act on the mask body. A suitable retaining lip may be provided at the opening of the nasal mask interface to conveniently prevent the adapter from falling out of the mask whenever the mask is taken off the face. During night-time movement, the silicone skirt typically does not slide on the adapter but rather tends to freely roll over the surface.

[0071] In one preferred embodiment, the relatively rigid skin contact portion or nasal seal structure 12 is connected to the mask frame 300 or rigid mask platform with a flexible tube-like member or bellows 100 securely attached to both the nasal seal structure 12 and the mask frame 300. The rigid mask frame can move around due to dislodging forces from the straps and the air supply tube 400 while the air pressure and the spring-like nature of the flexible bellows keep the relatively rigid skin contact member in place on the patient's face. [0072] To achieve a relatively rigid skin contact portion, the nasal seal structure 12 is created in accordance with the contour of the patient face, and in particular, the nasal region from around the tip of the nose to the bridge of the lip. As such, the nasal seal structure 12 is a unique fit for every patient. In the preferred embodiment, the skin contact surface extends 15mm above the tip of the nose, at least halfway down the top lip, and fully encompasses the alar.

[0073] Referring to Fig. 2, the nasion-alar line is constructed from a profile view, from the most anterior point in the depression at the top of the nose, tangential to the alar. The nose tip is defined as the furthest point on the nose from this nasion-alar line. The angle of the seal inlet is chosen, and a projection plane is created at this angle to the nasion-alar line. The skin contact surface is projected to this plane, normal to the plane. The centroid of the projected skin contact surface is determined, and the inlet port is positioned such that the axis of the port runs through the centroid.

[0074] Reference is now made to Fig. 3. In the preferred embodiment, the angle between the seal inlet and the nasion-alar line is 10 degrees, and the inlet port is positioned as close as possible to the face without interfering. In one embodiment, the nasal seal structure 12 has a fixed distance between the nose tip and the nasal seal structure's end plane 32. In one embodiment the angle between the seal inlet and the nasion-alar line is between 0 and 30 degrees.

[0075] The joint between the nasal seal structure and bellows 100 has a unique positioning of the nasal seal structure within the bellows relative to frame and attachment points to provide common placement for all patients. It is also adapted to provide an optimal angle and alignment to the facial plane. The bellows 100 is designed to provide just enough seal pressure to seal the nasal seal structure 12 on a patient face while not exerting excessive force to cause local pressure ulcers.

[0076] Referring to Figs. 4 to 6, the nasal seal structure in the bellows 100 comprising a body 102, a front end 103, and a rear end 107, all of which are integrated into a single unit with a pliable wall having has a generally trapezoidal cross-section profile. In one embodiment the bellows 100 comprising a front end 103 with a hemispherical or dome shaped profile. The front end 103 comprises a frame receiving aperture 104 adapted to receive a rigid mask frame 300. The rear end 107 of the bellows is folded inwardly forming a bloated bottom skirt 106 defining a nasal seal aperture 108 adapted to receive the nasal seal or nasal seal structure 12. In one embodiment, the bloated bottom skirt 106 has a toroidal profile or concertina profile such that the nasal seal structure 12 may roll into the body 102 of the bellows 100.

[0077] In one embodiment, the bellows 100 has a unique 'marshmallow cushion' or "mushroom" shape and as sub-assembly with frame 300. The bellows can be functioned as an airbag to allow rolling and articulation.

[0078] In one embodiment, the bellows 100 has a thinner pliable wall at the rear end 107 and a thicker wall on the front end 103. As such, the bellows 100 is adapted to move towards the rear side. The static suspension of the nasal seal aperture 108 to make fitting easier, and its unique shape and size to optimise the nasal seal structure 12 contact force onto face, determination of wall sections; decouples frame interfering with bedding not transferring forces to the nasal seal structure.

[0079] When in use, the bellows may inflate slightly to allow the application of pressure to be applied to the rigid nasal seal structure 12. This application of pressure by the bellows to seal structure may improve the sealing properties of the seal structure against the contours of the face of the patient or user. Generally, the pressure may be applied in a direction towards the face of the patient or approximately transverse to the length axis of the patient's face. Another improvement involves the adjustment of the angle of the applied pressure from the bellows to an angle of about 10-20 degrees upward from the transverse of the length axis of the patient's face as depicted in Figs 2 and 3.

[0080] The designed wall thickness difference between the top and bottom of the bellows also allows side to side movement. The bellows 100 does not just allow lateral movement to face as it can roll or pivot about the face. Strap tension and precision of strap adjustments become less of a priority making the fitting very straightforward and without need for flow generator "mask fit" function.

[0081] Preferably, the bellows 100 has a complementary profile of nasal seal structure 12 such that compression does not increase the overall size (nasal seal structure moves into the bellows) in order to keep profile as low as practical and the nasal seal structure 12 is inherently low profile since it closely follows the facial profile with minimal dead space.

[0082] Preferably, as shown in Fig. 16A and Fig. 16B, the bellows 100 comprises integral vent holes 140 at the top side of the pliable wall near the front of the bellows. In one embodiment the top side of the pliable wall is thicker than the pliable wall of the lower side. For example, the pliable wall of the upper side may be 1.5mm while the thickness of the pliable wall of other area is 1mm. In one embodiment, the top side of the bellow comprises a rib to increase the wall thickness and provide a platform for the vent holes 140. The rib is less flexible and less pliable such that the region and vent holes 140 thereon are less likely to deform. The vent holes 140 may have a single line configuration or multiple lines configuration as shown in Fig. 16A and Fig. 16B. In one embodiment, the pliable wall has a thickness of 0.8 mm at the rear end 107; 1.25mm at the front end 103, and 2.5mm around the vent holes.

[0083] The enhanced thickness of the top front side wall of the bellows 100 makes the compression or displacement only occur towards the rear and the bottom side rather than the front or the top side to avoid significant deformation of the air vent holes 140. The position and direction of the vent holes allow air to vent away from eyes and not to direct sound waves onto bedding material especially when laying on the side. Fig. 16A also shows an example of the cross-section of a vent hole having an inner aperture bigger than that of the outer aperture. Preferably, this shaping of the apertures forming vent holes 140 may reduce the overall noise profile of the mask when in use. [0084] Preferably, the bellows 100 is moulded with a single parting line near the rear side. The pliable wall around the nasal seal aperture 108 has a locally thick section. In one preferred embodiment, the pliable wall is made of silicone, or a 3D printed elastomer.

[0085] In one embodiment, the nasal seal structure 12 in the bellows 100 provides a complementary 'nesting' shape of nasal seal structure's generally tapered base moving inside of the bellows taper shape retains consistent overall size and low profile; overall width of the bellows is substantially comparable to the overall width of the nasal seal structure. This will minimise obtrusiveness of the mask so that the overall size of the bellows 100 does not need to be significantly larger than the face contacting portion of the nasal seal structure 12. Unlike prior art bellows, the bellows 100 of the present invention has a unique bellows performance and remains as compact as possible that allows low strap tension whilst providing adequate seal force under pressure. The surface area acting on the nasal seal structure 12 is within the overall width of the nasal seal structure. The low profile of the bellows 100 is preferable to make the user feel the mask is unobtrusive.

[0086] In one embodiment, the nasal mask 10 comprises a bellows retainer ring 110 for attaching to the rigid mask frame receiving aperture 102 of the bellows 100. The bellows retainer ring 110 is a rigid structure to allow a firm grab on the bellows 110 since the bellows is made of flexible and pliable material. Engaging and disengaging the rigid mask frame 300 directly with the bellows will cause the pliable material of the bellows 100 fatigue and tear. A bellows retainer ring 110 is therefore provided for engaging directly with the bellows 100 such that the rigid mask frame 300 can be attached and detached from the bellows retainer ring 110.

[0087] Fig. 5 shows a bellows retainer ring 110 of a preferred embodiment of the present invention comprising a key feature 122 to allow visual cue for aligning the rigid mask frame 300 in relation to the bellows 100. The bellows retainer ring 110 has a controlled surface 124 to restrict airflow and limit air pressure drop. The bellows retainer ring 110 also has point retention features 126, preferable one on top and another at the bottom of the bellows retainer ring, to secure the rigid mask frame BOO to the bellows retainer ring. The bellows retainer ring 100 also has point lead guides 128, preferably one on the left side and another on the right side of the bellows retainer ring, for guiding the joint of the rigid mask frame into the bellows 100.

[0088] Reference is now made to Fig. 7 showing a bellows retainer ring 110 of a preferred embodiment of the present invention. The key feature 122 is a protrusion extending from the upper portion of the rim of the bellows retainer ring 110. The key feature has a locally thick section. In one preferred embodiment, the bellows retainer ring 110 may be moulded with a single parting line inside. Around the upper portion of the bellows retainer ring 100, there is provide a plurality of anchors 134 around the rim to increase the over-moulding contact surface.

[0089] In one embodiment, bellows 100 is over-moulded to the retainer ring 110. The bellows retainer ring 100 preferably comprises a stepped profile which increases the surface area for bonding and hence the bonding strength between the bellows 100 and the bellows retainer ring.

[0090] Preferably, the bellows retainer ring is made of PEEK, polycarbonate, polystyrene, or similar rigid material.

[0091] In one embodiment as shown in Figs. 8 and 9, the nasal seal structure or apnoea nasal seal structure 12 comprises a snap-fit connection 20 for securing to the nasal seal aperture 108. Preferably, the snap-fit joint 20 is an annular snap-fit connection having a tapered leading rim 22. The snap-fit connection 20 comprises a retention groove 24 for retaining the fringe 109 of the pliable wall around the nasal seal aperture 108. The nasal seal aperture 108 has a circumference less than that of the retention groove 24. As such, the circumference stress of the pliable wall around the nasal seal aperture exerted to the snap-fit connection 20 is adapted to provide an air-tight seal and avoid leaking. [0092] The bellows 100 of the present invention differentiates to traditional bellows where common overtightening of headgear results in bellows becoming fully compressed to point of not functioning as intended as experienced in the prior art. The bellows 100 of the present invention makes fitting much easier and intuitive. Users do not require precision to set bellows in the correct positions.

[0093] Reference is now made to Figs. 10 to 12 showing the rigid mask frame 300 for connecting the bellows 100 and the swivel tube or air supply 400. In one preferred embodiment, the swivel tube 400 comprises a bayonet attachment for securing the swivel tube to the rigid mask frame 300. In one embodiment, the rigid mask frame 300 is made of polycarbonate, polystyrene, or similar rigid material. The rigid mask frame 300 may be moulded with a single parting line.

[0094] In one embodiment the bayonet attachment comprises a male connector 402 for engaging with the female connector 404. Preferably, the male connector is secured to one end of the swivel tube 400 and the rigid mask frame 300 has an opening 302 comprises the female connector 404. In one embodiment, the male connector 402 comprises a plurality of bayonet teeth 412. Each of the bayonet teeth 412 is disposed on a spring arm 414. Preferably, the male connector 402 comprises one or more visual cues 416 to assist aligning the male connector 402 with the female connector 404. The female connectors 404 comprises a plurality of slots 422 equal to the number of bayonet teeth 412. Each of the slots comprises a locking feature 424 to retain the bayonet teeth 412 therein. When the male connector 402 is secured to the female connector 404, the engaging surfaces are adapted to restrict airflow and limit leaking as shown in Fig. 11.

[0095] In one embodiment, the male connector 402 and the female connector 404 of the bayonet attachment is made of polypropylene or similar material. The male connector 402 may be moulded with a single parting line.

[0096] Reference is now made to Figs. 13A to 15B showing the clips 500 connecting to the rigid mask frame 300 of the nasal mask. In one embodiment the clip 500 is connected to the rigid mask frame 300 with a releasable snap-fit connector 510. Preferably, the releasable snap-fit connector 510 is a cantilever snap-fit connector having a release button 522. In one embodiment, the clip 500 comprises a male part of the snap-fit connector 510 and the rigid maskframe comprises a female part of the snap-fit connector, or vice versa. A guide rail is provided on the male part of the snap-fit connector 510 to lead a clip mechanism 512 to a recess 514 on the female part of the snap-fit connector. Alternatively, the guide rail may also be provided on the female part to lead the clip mechanism to the male part. The clip mechanism 512 may be released from the recess 514 by pushing the release button 522 for disengaging the male part from the female part of the snap-fit connector.

[0097] In one embodiment, each of the clips 500 comprises two arms 502 and each of the arms is adapted to engage with a strap of the headgear 530. In one embodiment, the clips 500 are made of polycarbonate, polystyrene, or similar rigid material. The clips 500 may be moulded with a single parting line.

[0098] Reference is now made to Figs. 17 to 19 showing the headgear 530 of the nasal mask of an embodiment of the present invention. Fig. 20 shows the rigid mask frame 300 and clips 500 geometry from an elevation view.

[0099] In one embodiment, it is estimated that the bizygomatic width of minimum and maximum users face is between 129mm to 154mm. The arms width of the clips will affect the pressure exerted on the face of the patient. Therefore, the clips 500 are preferably customised to conform to the facial contour of the patient. In one embodiment, the arms width of the clips is about 140mm at 68mm from nasal seal structure end plane 32. This will allow the clips 500 to stretch outwards on wider users and be pulled in on narrower users as shown in Figs. 15A and 15B.

[0100] In another embodiment, the nasal seal structure 12 has a connection to the bellows 100 brought as close to the nose of the patient as possible to allow most intimate fit and optimisation of bellows compression. This also allows more users fitting within medium or small arm size range to reduce production costs. [0101] In one embodiment of the present invention, the headgear is convertible to allow two or more types of headgear with minimal reconfiguration - for example, the standard headgear as shown in Fig. 19 and the compact headgear as shown in Fig. 18.

[0102] In one embodiment as shown in Fig. 20, the arms of different sizes will have a 7 mm increment from 31.75mm to 45.75mm. The theoretical contact point is at 75mm across the face. The bellows 100 is allowed to have a 6mm compression. The 7mm arm increments allow a lower profile mask that can fit across a bigger range of people. It is also a better fit for some people without nasal seal structure adjustment.

[0103] In another embodiment, the clips 500 of different sizes will have a 10 mm increment from 31.75mm to 45.75mm. The 10mm arm increments as used in testing allows a larger range to be covered, e.g. from 31.75mm to 51.75 mm. Some adjustments to sizing are required by moving the nasal seal structure's position.

[0104] Referring to Fig. 21, the clip 500 has a preferable a side routing close to but away from the user's eyes. The clips 500 should be at the same angle as the nasal seal structure end plane (around 10°) to allow the arms sitting at 0° to face. In one of the embodiments, each of the clips 500 has an arm 502a extending toward an upper region of an auricle and under the infraorbital margin of the patient when in use.

[0105] As illustrated in Figs. 17 to 19, the headgear 530 is connected to a rigid mask frame 300 of a preferred embodiment of the present invention. The non floating aspect of the rigid mask frame 300 including facial support from clips 500 substantially reduces the 'piston' moving effect of a bellows. The nasal seal structure 12, bellows 100, frame 300, clips 500, and headgear 530 work mutually to eliminate the need for rotational adjustment between the rigid mask frame and the arm. This allows the alignment of an average sealing vector to provide a balanced position of the nasal seal structure 12 against the face of a patient. Therefore, balancing adjustments like traditional 4 strap masks (e.g. needing to tighten top or bottom strap to pull in at top or bottom to achieve seal) is not necessarily required. All four major components work cohesively to optimally position the nasal seal structure 12 over the nose with controlled compression of the bellows 100. As such, the clips 500 may have a single arm 502 for two-strap headgear or dual arms for four-strap headgear.

[0106] Preferably, each of the clips 500 comprises a strap adjustable buckle 505 or ladder lock at a distal end of an arm 502 for connecting a strap 532 of the headgear 530. The adjustable buckle 505 or ladder lock may shorten or release the length of the headgear strap span to suit different head sizes.

[0107] In the embodiment where the headgear 300 comprises four straps, where the lower strap 532b serves a support strap rather than one that requires tensioning. The lower strap 532b is not a tensioning strap, more of a tether to stop the mask tilting up especially with tubing over the head.

[0108] In another embodiment as shown in Fig. 22, there is provided a headgear clip integral arm 550 adapted to provide standard or other variants to accommodate the user preference. The headgear clip integral arm 550 is customised to accommodate the user's face shape and has a predominantly shape-forming around sides of the cheeks of a patient. However, the headgear clip integral arm 550 does not yield upon the cheek bones into directions of the face such that the rigid mask frame does not move excessively towards face thus negatively collapsing the bellows 100.

[0109] Reference is now made to Figs. 22 showing the clips 500 connecting to the rigid mask frame 300 of the nasal mask. In one embodiment the clip 500 is connected to the rigid mask frame 300 with an adjustable snap-fit connector 560. Preferably, the adjustable snap-fit connector 560 allows the clips 500 to pivot about the joint 562. In one embodiment, the joint is a circular joint. The joint 562 may be a bayonet connector or a snap-fit connector. In another embodiment, the joint 562 has an integrated rotation mechanism that uses friction for angle adjustment. The angular adjustment of the clips 500 allows each user to find the most comfortable position. [0110] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms, in keeping with the broad principles and the spirit of the invention described herein.

[0111] The present invention and the described preferred embodiments specifically include at least one feature that is industrially applicable.

Claims

1. A nasal mask for a patient comprising: a rigid contoured nasal seal structure for sealably engaging a nose of a patient, a bellows having a front end and a rear end where the rear end is a nearest end to a face of the patient; a rigid mask frame having an opening for receiving an air supply tube, and wherein the front end of the bellows is connected to the rigid frame and the rear end of the bellows is connected to the seal structure, such that the bellows is adapted to balance the alignment of the seal structure and the rigid mask frame, when in use.

2. A nasal mask according to claim 1, the bellows comprises a bellows retainer ring for receiving one end of the rigid mask frame.

3. A nasal mask according to claim 2, wherein the bellows retainer ring comprises a snap-fit connector to releasably engage with a complimentary snap-fit connector of the rigid mask frame.

4. A nasal mask according to claim 2, wherein the bellows retainer ring comprises a visual cue for aligning with the rigid mask frame.

5. A nasal mask according to claim 2, wherein the bellows is over-moulded onto the bellows retainer ring.

6. A nasal mask according to claim 2, wherein the bellows retainer ring is made of a rigid material including polycarbonate or nylon.

7. A nasal mask according to claim 2, wherein the bellows has a spherical leading profile and a toroidal rear profile such that the seal structure is adapted to allow movement towards inside the bellows.

8. A nasal mask according to claim 2, wherein the bellows comprises a pliable wall with a thickness greater in the spherical leading profile than the toroidal rear profile.

9. A nasal mask according to claim 2, wherein the bellows comprises a plurality of vent holes disposed on the wall of the spherical leading profile.

10. A nasal mask according to claim 2, wherein the bellows comprises a rear aperture for receiving the rigid personalised nasal seal structure.

11. A nasal mask according to claim 10, wherein the wall around the rear aperture has a locally thick section.

12. A nasal mask according to claim 10, wherein the rear aperture has a diameter smaller than that of an engaging groove on a bellows connector of the rigid personalised nasal seal structure such that an air-tight seal is formed between the bellows and the seal structure when engaged.

13. A nasal mask according to claim 1, wherein headgear comprises at least two clips for connecting to the rigid mask frame, wherein at least one of the clips conforms to a profile of a left cheek of the patient and at least one other clip conforms to a profile of a right cheek of the patient.

14. A nasal mask according to claim 13, wherein each of the clips has a mask frame connector on one end to releasably secure the clip to the rigid mask frame.

15. A nasal mask according to claim 14, wherein the mask frame connector is a snap-fit connector.

16. A nasal mask according to claim 14, wherein the mask frame connector is adapted to allow the clip to pivot above the mask frame connector when connected to the mask frame connector.

17. A nasal mask according to claim IB, wherein each of the clips has an arm comprising a buckle to connect to a tension strap of the headgear.

18. A nasal mask according to claim 17, wherein the arm extends toward an upper region of an auricle and under the infraorbital margin of the patient when in use.

19. A nasal mask according to claim 17, wherein each of the clips has a second arm comprising a buckle to connect to a supporting strap of the headgear.

20. A nasal mask according to claim 17, wherein the second arm is removably connected to the clip.

21. A nasal mask according to claim 1, wherein the nasal seal structure 12 has a fixed distance between a nose tip of the patient and an end plane of the nasal seal structure.

22. A nasal mask according to claim 21, wherein the nasal seal structure comprises a seal inlet having an angle between 0 to 30 degrees from a nasion line of a patient.