Breathing assistance device

Abstract

A breathing assistance device to assist in preventing obstructive sleep apnea, the breathing device comprising: a body having: a mouth locator to locate and hold the body within a desired location within the mouth of a user; one or more inlet valves operatively attached to the mouth locator, the one or more valves allowing air to pass through the one or more valves from a lip side of the mouth locator to a lung side of the mouth locator but prevent air from passing through the one or more valves from the lung side of the mouth locator to the lip side of the mouth locator; and one or exit passageways operatively attached to the mouth locator, the one or more exit apertures allow air to pass from the lung side of the mouth locator to the lip side of the mouth locator.

Description

"BREATHING ASSISTANCE DEVICE"FIELD OF THE INVENTION

[0001] This invention relates to a breathing assistance device. In particular, the invention relates to a breathing assistance device to assist in preventing obstructive sleep apnea.BACKGROUND OF THE INVENTION

[0002] Obstructive sleep apnea (OSA) is characterized by repetitive occlusions of the upper airway during sleep, resulting in sleep fragmentation and oxygen desaturations. The prevalence of OSA is reported to be 34% in men and 17% in women, whereas OSA accompanied by symptoms of sleepiness is reported to occur in 14% of men and 5% of women between 30-70 years old. OSA is an important contributor to cardiovascular disease, stroke and depression and is a recognized risk factor for motor vehicle accidents, workplace injuries, and loss of productivity.

[0003] Although continuous positive airway pressure (CPAP) remains the treatment of choice for OSA, custom-fit oral appliances that advance the mandible — a mandibular advancement device (MAD) — are emerging as an alternative treatment option. These devices are used primarily in patients with mild to moderate OSA, CPAP intolerant OSA, and primary snorers. Studies consistently demonstrate that CPAP reduces the apnea-hypopnea index (AHI) further than oral appliances; however, CPAP efficacy is likely to be offset by reductions in usage and adherence.

[0004] In support of this, recent studies have demonstrated that the health outcomes in patients with moderate to severe OSA after treatment with CPAP and MAD are similar. Patients with high nasal resistance may have difficulty in using both CPAP and traditional oral appliances, with studies reporting high nasal resistance being associated with both CPAP and oral appliance intolerance. High nasal resistance is an indication of reversible or irreversible nasal obstruction and its prevalence is highin OSA.

[0005] In order to address this issue, an oral appliance was developed incorporating both mandibular advancement to reduce pharyngeal collapsibility and an enclosed airway that allows airflow through the device to circumvent nasopharyngeal obstruction. Clinical evidence showed good efficacy in line with other oral appliances and importantly, showed efficacy, response and compliance were not reduced by the presence of nasal obstruction. In addition to the integrated airway the development of an oral positive end expiratory pressure (PEEP) valve was shown to further enhance efficacy. A PEEP valve is designed to produce expired positive airway pressure (EPAP). It uses resistance on exhalation to create “back pressure” to further stabilise the airway. Hence low resistance through the oral breathing pathway on inhalation and increased resistance on exhalation was shown to increase efficacy compared to a standard oral appliance. Even with this clinical evidence this technology was not widely adopted.

[0006] The primary reason was the belief that the presence of a low resistance pathway on inhalation that was continuously open to atmospheric air would encourage the utilization of the oral breathing pathway over the nasal breathing pathway. The fact that the airway extended beyond the lips meant that air might enter preferentially through the mouth. This was viewed as an issue, as nasal breathing is preferred to mouth breathing for a myriad of clinical and physiological reasons.OBJECT OF THE INVENTION

[0007] It is an object of the invention to overcome and / or alleviate the abovementioned problems and / or provide the consumer with a useful or commercial choice.SUMMARY OF THE INVENTION

[0008] In one form, although not necessarily the only or broadest form, the invention resides in a breathing assistance device to assist in preventing obstructive sleep apnea, the breathing device comprising:a body having: a mouth locator to locate and hold the body within a desired location within the mouth of a user; one or more inlet valves operatively attached to the mouth locator, the one or more valves allowing air to pass through the one or more valves from a lip side of the mouth locator to a lung side of the mouth locator but prevent air from passing through the one or more valves from the lung side of the mouth locator to the lip side of the mouth locator; and one or more exit passageways operatively attached to the mouth locator, the one or more exit passageways allowing air to pass from the lung side of the mouth locator to the lip side of the mouth locator.

[0009] The body is typically integrally formed. The body may be made from any suitable material such as acrylonitrile butadiene styrene (ABS), nylon, high-density polyethylene, low-density polyethylene (LDPE), polycarbonate (PC), polyoxymethylene (POM), acrylic poly (Methyl Methacrylate) (PMMA) or thermoplastic polyurethane (TPU). The body may be moulded or 3D printed.

[0010] The mouth locator may include one or more lip shields. The mouth locator may include one or more teeth landing platforms. Typically, there is a single lip shield. The lip shield may extend along the front of the body. The teeth landing may be located between the front of the teeth and lips of a user’s mouth. The lip shield may be contoured to the shape of a user’s teeth.

[0011] The lip shield may be arcuate in shape. The lip shield may at least partially cover the top teeth, the bottom teeth or both the top teeth and the bottom teeth.

[0012] One or more lip shield extenders may extend outwardly from the lip shield. The extenders may assist in holding the lip shield in a desired position to cover the top teeth, the bottom teeth or both the top teeth and the bottom teeth. The one or more lip shield extenders may extend outwardly from a top of the lip shield. The one or more lip shield extenders may extend outwardly from a bottom of the lip shield. The one or more lip shield extenders may extend outwardly from a top and a bottom of the lip shield.

[0013] The one or more landing platforms may be used to engage the tips of teeth. There may be one landing platform to engage the tips of the top teeth. There may be a landing to engage the tips of the bottom teeth. Preferably there are two landing platforms to engage the tips of the top teeth and the tips of the bottom teeth. The one or more landing platforms may be contoured to the shape of a user’s teeth.

[0014] The one or more landing platforms may be located on the lung side of the lip shield. The one or more landing platforms may be attached to the lip shield.

[0015] The one or more landing platforms may be located adjacent the one or more inlet valves. The one or more landing platforms may form part of the one or more inlet valves.

[0016] The one or more inlet valves may be located on the lung side of the lip shield. The one or more inlet valve may be movable between an open position to allow air to pass through the one or more inlet valves and a closed position to prevent air passing through the one or more inlet values. The one or more inlet valves may be biased toward the closed position.

[0017] Typically, there is a single inlet valve. The inlet valve may be in the form of a duckbill valve. The duckbill valve may have a fixed open end and a moveable end connected by one or more sidewalls, the fixed end being formed within the lip shield.

[0018] The inlet valve may be in the form of a flap valve. The flap valve may be connected to the lip shield. The flap valve may be connected to a top of the lip shield. Alternatively, the lip shield may be connected to a bottom of the lip shield. The flap valve may include a flap that is pivotally moveable between an open position that allows air to flow through the valve and a closed position that prevents air from flowing through the valve.

[0019] The one or more passageways may limit the exhalation speed of a user to create positive pressure within the mouth of a user. The one or more exit passageways may be any shape. The passageways may be permanently open.Alternatively, one or more of the one or more passageways may include a one-way valve.

[0020] The one or more passageways may be located on one or more of the inlet valves. When the one or more valves are a single duckbill vale, the one or more passageways may be located on the sidewalls of the duckbill valve.

[0021] When the one or more valves are one or more flap valves, the one or more passageways may be located on a flap of the one or more flap valves. Alternatively, when the one or more valves are one or more flap valves, the one or more passageways may be located adjacent one or more sides of a flap of the one or more flap valves.

[0022] In another form, the invention resides in a method of operating a breathing assistance device, the method including the steps of: locating a breathing assistance device entirely within the mouth of a user so that the breathing assistance device allows a user to inhale freely but restricts exhalation of the user to thereby cause oral positive end expiratory pressure in the oral cavity of a user.

[0023] The breathing assistance device may provide no or limited resistance to airflow when a user inhales. The breathing assistance device may provide resistance to airflow when a user exhales.

[0024] The breathing assistance device may use one or more inlet valves to allowing air to pass through the one or more valves from when a user inhales but prevent air from passing through the valves when a user exhales.

[0025] The breathing device may include one or more exit passageways that are one or more exit apertures allowing air to pass from the lung side of the mouth locator to the lip side of the mouth locator.

[0026] The airflow during exhalation may be restricted by the size of one or more exit passageways. Alternatively, airflow during exhalation may be restricted by one ormore valves located within exit passageways.

[0027] The breathing assistance device may be located within the mouth of a user using the teeth of a user. Alternatively, the breathing assistance device may be located within the mouth of a user between the teeth and the lips. The front and / or tips of the teeth may be used to position the breathing assistance device. Normally at least the teeth between the incisors are used. The breathing assistance apparatus may use a mouth locator for this purpose.

[0028] The breathing assistance apparatus may include one or more of the features mentioned above.

[0029] Further features of the invention will become apparent from the detailed description below.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Embodiments of the invention will be described, by way of example only, with reference to the accompanying figures in which:

[0031] FIG. 1 is a front perspective view of a breathing assistance device according to a first embodiment of the invention;

[0032] FIG. 2 is a rear perspective view of a breathing assistance device as shown FIG.1 with an inlet valve in an open position;

[0033] FIG. 3 is a rear perspective view of a breathing assistance device as shown FIG.1 with an inlet valve in a closed position;

[0034] FIG. 4 is a rear perspective view of a breathing assistance device showing air flow when a user is inhaling, as shown FIG. 2;

[0035] FIG. 5 is a rear perspective view of a breathing assistance device showing air flow when a user is inhaling, as shown FIG. 3;

[0036] FIG. 6 is a front perspective view of a breathing assistance device according to a second embodiment of the invention; and

[0037] FIG. 7 is a rear perspective view of a breathing assistance device as shown FIG.1 with an inlet valve in an open position.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] FIGS 1 to 3 show a first embodiment of a breathing assistance device 10 to assist in preventing obstructive sleep apnea 10. The breathing assistance device 10 includes a body 11 which has a mouth locator 20, an inlet valve 30 and four exit passageways 40.

[0039] The mouth locator 20 is used to position the breathing assistance device 10 in a desired location within the mouth so that the inlet valve 30 and exit passageways 40 are in an optimal position. The mouth locator 20 is formed from a lip shield 21 and two teeth landing platforms 22.

[0040] The lip shield 21 is used to position the mouth locator 20 adjacent the front teeth and shield the tips of the teeth. The lip shield 21 is arcuate in shape and is dimensioned to extend over both the top and bottom front teeth between the incisors. The lip shield 21 may be shaped to replicate the front contours of the top and bottom front teeth. The lip shield 21 is sized fit in the mouth but not small enough such that it could be inhaled.

[0041] The two landing platforms 22 are used to hold the tips of both the top front teeth and bottom front teeth. The landing platforms 22 connected to the lip shield 21 on a lung side of the lip shield 21. The landing platforms are also located on the inlet valve 30 adjacent the lip shield 21. A single landing platform 22 is located on the top and the bottom of the inlet valve 30. The landing platforms 22 are shaped to match the contours of the tips of the top and bottom front teeth.

[0042] The inlet valve 30 and exit passageways 40 are used to help control the flow of air through the breathing assistance device 10 when a user breathes. The inlet valve 30 in this embodiment is in the form of a duckbill valve 31. The duckbill valve 31 is formed from a fixed open end 32 and a movable end 33 that are connected by side walls 34. The fixed open end 32 is located within the lip shield 21 whilst the moveable end 33 is spaced away from the lip shield 21 toward the lung side of the month when in use. The moveable end 33 is movable between an open position, as shown in FIG. 2, and a closed position shown in FIG. 3 with the movable end 33 biased toward the closed position.

[0043] The two landing platforms 22 are positioned on side walls 34 of the duckbill valve 30 adjacent the lip shield 30. A top landing platform 22 is located on a top side wall 34 of the duckbill valve 31 whilst a bottom landing platform 22 is located on a bottom side wall 34 of the duckbill valve 31.

[0044] The exit passageways 40 are also located on the side walls 34 of the duckbill valve 31 . Two top exit passageways 40 are located on a top side wall 34 of the duckbill valve 31 whilst two bottom exit passageways 40 are located on a bottom side wall 34 of the duckbill valve 31. The exit passageways 40 are in the form of circular holes.

[0045] To locate the breathing assistance device 10 entirely within the mouth of a user, a user positions the breathing assistance device 10 in the user’s mouth by opening their jaw. The breathing assistance device 10 is positioned between the top teeth and bottom teeth. The user’s jaw is the closed so that the tips of the top front teeth and bottom front teeth are located on their respective landing platform 22. This also ensures that the lip shield 21 is located adjacent the front of the top front teeth and bottom front teeth. In this position, the entire breathing assistance device 10 is located within the mouth of a user.

[0046] The breathing assistance device 10 is only used when a user switches to mouth breathing. The switch to mouth breathing is the end result of a cascade of events starting with increasing nasal resistance, which generates negative pressures in the oropharyngeal airway, which then triggers a switch to mouth breathing. During inhalation, air passes through the mouth which then passes through the lip shield 21via the inlet valve 30. Inhalation causes airflow into the oropharyngeal airway to move the moveable end 33 of the duckbill valve 31 from its closed position to its open position. It would also be appreciated that air will also pass through the holes forming outlet passageway 40 as the holes are open.

[0047] When inhalation ceases and exhalation commences, the moveable end 33 of the duckbill valve 31 moves from its open position to its closed position. This prevents airflow through the inlet valve 30 upon exhalation. The only way air is able to pass through the breathing assistance device 10 during exhalation is via the holes of the outlet passageway 40. The holes of the outlet passageway are sized to restrict the flow of air through the mouth to cause positive pressure in the oropharyngeal airway. As the pressure increases it will reach a point where the resistance in the oral pathway on exhalation is higher than the resistance in the nasal pathway and excess air will pass out through the nasal pathway expanding the nasal pathway increasing the likelihood that on the next inhalation there will be more air passing through the nose.

[0048] It is known that mouth breathing is a physiologic response to increasing nasal resistance. This means that patients will breathe through the nose to the extent that they can. As nasal resistance increases beyond a certain point, a switch to mouth breathing occurs. The breathing assistance device 10 is therefore not needed while the patient is breathing through the nose. It is only required when the switch to mouth breathing occurs. For this reason, breathing assistance device 10 is contained within the oral cavity, overcoming the risk that continuous communication between the oropharynx and atmospheric air encourages mouth breathing as found with other prior art devices. The breathing assistance device 10 allows a user to breathe normally through the nose to the extent that they can. When nasal resistance increases to the point that a switch to mouth breathing occurs, the breathing assistance device 10 becomes available, as and when needed. Thus, while a breathing assistance device 10 might appear to have no effect on the surface, it reduces the risk of mouth breathing when the patient can breathe normally through the nose and delivers the benefit of the oral expiratory positive airway pressure when the switch to mouth breathing would normally lead to the related detrimental clinical outcomes.

[0049] FIG. 6 and 7 show a second embodiment of a breathing assistance device110 that operates in a similar manner the breathing device 10 shown in FIGS 1 to 3. The breathing assistance device 110 includes a body 111 which has a mouth locator 120, an inlet valve 130 and four exit passageways 140.

[0050] The mouth locator 120 is used to position the breathing assistance device 110 in a desired location within the mouth so that the inlet valve 130 and exit passageways 140 are in an optimal position. The mouth locator 120 is formed from a lip shield 121 and four lip shield extenders 122.

[0051] The lip shield 121 is used to position the mouth locator 120 adjacent the front teeth and shield the lips from the teeth. The lip shield 121 is arcuate in shape and is dimensioned to extend over both the top and bottom front teeth between the incisors. The lip shield 121 may be shaped to replicate the front contours of the top and bottom front teeth. The lip shield 121 is sized fit in the mouth but not small enough such that it could be inhaled.

[0052] The four lip shield extenders 123 are used to assist in holding the lip shield in position 121. The four lip shield extenders 123 extend outwardly from the lip shield 121. The direction in which each four lip shield extenders 123 extend are different. The lip shield extenders 123 extend to the top right, top left, bottom right and bottom left with respect to lip shield 121 when in place in the mouth. The lip shield extenders 123 are normally positioned between the cheeks and the gums.

[0053] The inlet valve 130 and exit passageways 140 are still used to help control the flow of air through the breathing assistance device 110 when a user breathes. The inlet valve 130 in this embodiment is in the form of a flap valve 131. The flap valve 131 is formed from a pivotally movable flap 132. One fixed end 133 of flap 132 is connected to a top of the lip shield 121 whilst the other movable end 134 is located near the bottom of the lip shield 121. A top shelf 135 is used to connect the fixed end 133 of the flap 132 to the top of the lip shield 121. A bottom shelf 136 is connected to the bottom of the lip shield 121 and is located adjacent to the movable end 134 of the flap 132.

[0054] The exit passageways 140 are located on the flap 132 of the flap valve 131and to the sides of the flap 132 of the flap valve 131. The exit passageways 140 are in the form of circular holes on the flap. The exit passageways 140 adjacent the sides of the flap valve 131 are rectangular apertures.

[0055] To locate the breathing assistance device 110 entirely within the mouth of a user, a user positions the breathing assistance device 110 in the user’s mouth by opening their mouth. The breathing assistance device 110 is positioned inside the lips but in front of the teeth. The breathing assistance device 110 is attached to an upper and / or lower retainer engaged with the upper and / or lower teeth using lip shield extenders 123 that provide loops. This also ensures that the lip shield 121 is located adjacent the front of the top front teeth and bottom front teeth. In this position, the entire breathing assistance device 110 is located within the mouth of a user. When the user’s mouth is the closed the tips of the top front teeth and bottom front teeth are located on the top shelf 135 and bottom shelf 136 respectively. That is, the top shelf 135 and bottom shelf 136 act as landing platforms 122.

[0056] The breathing assistance device 110 is only used when a user switches to mouth breathing. The switch to mouth breathing is the end result of a cascade of events starting with increasing nasal resistance, which reduces airflow and generates negative pressures in the oropharyngeal airway, which then triggers a switch to mouth breathing. This may also be combined with obstructions of the airway by the soft palate, lateral walls and / or tongue. During inhalation, air passes through the mouth after passing through the lip shield 121 via the inlet valve 130. Inhalation causes airflow into the oropharyngeal airway to move the flap 132 from its closed position to its open position. It would also be appreciated that air will also pass through the circular holes and the rectangular apertures forming outlet passageway 140 as the holes and apertures are open .

[0057] When inhalation ceases and exhalation commences, the flap 132 of the flap valve 131 moves from its open position to its closed position. This prevents airflow through the inlet valve 130 upon exhalation. The only way air is able to pass through the breathing assistance device 110 during exhalation is via the circular holes and / or rectangular apertures of the outlet passageway 140. The circular holes and rectangular apertures of the outlet passageway 140 are sized to restrict the flow of airthrough the mouth to cause positive pressure in the oropharyngeal airway. As the pressure increases, it will reach a point where the resistance in the oral pathway on exhalation is higher than the resistance in the nasal pathway, and excess air will pass out through the nasal pathway, expanding the nasal pathway increasing the likelihood that on the next inhalation there will be more air passing through the nose. It would be appreciated by a person skilled in the art that the circular holes or rectangular apertures may be made larger and the other of the circular holes or rectangular apertures could be removed from the breathing assistance device 110.

[0058] In this specification, terms such as upward, downward, horizontal and vertical, and their grammatical derivatives, are used to describe the invention in its normal orientation and are not to be construed to limit the invention to any particular orientation.

[0059] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

[0060] It should be appreciated that various other changes and modifications may be made to the embodiments described without departing from the spirit or scope of the invention.

Claims

CLAIMS:1 . A breathing assistance device to assist in preventing obstructive sleep apnea, the breathing device comprising: a body having: a mouth locator to locate and hold the body within a desired location within the mouth of a user; one or more inlet valves operatively attached to the mouth locator, the one or more valves allowing air to pass through the one or more valves from a lip side of the mouth locator to a lung side of the mouth locator but prevent air from passing through the one or more valves from the lung side of the mouth locator to the lip side of the mouth locator; and one or exit passageways operatively attached to the mouth locator, the one or more exit apertures allow air to pass from the lung side of the mouth locator to the lip side of the mouth locator.

2. The breathing assistance device of claim 1 wherein the body is integrally formed.

3. The breathing device of claim 1 or claim 2 wherein the mouth locator includes a lip shield.

4. The breathing device of any one of the preceding claims wherein the mouth locator has one or more teeth landing platforms.

5. The breathing device of claim 3 or 4 wherein the lip shield is contoured to the shape of a user’s teeth.

6. The breathing device of any one of claims 3 to 5 wherein the lip shield may be arcuate in shape.

7. The breathing device of any one of claims 3 to 6 wherein one or more lip shield extenders outwardly from the lip shield.

8. The breathing device of any one of the preceding claims wherein the one or more landing platforms are used to engage the tips of teeth.

9. The breathing device of claim 8 wherein the one or more landing platforms are contoured to the shape of a user’s teeth.

10. The breathing device of claim 8 or 9 wherein the one or more landing platforms are located on the lung side of the lip shield.

11. The breathing device of any one of claims 8 to 10 wherein the one or more landing platforms are attached to the lip shield.

12. The breathing device of any one of claims 8 to 11 wherein the one or more landing platforms are located adjacent the one or more inlet valves.

13. The breathing device of any one of claims 8 to 11 wherein the one or more landing platforms may form part of the one or more inlet valves.

14. The breathing device of any one of claims 3 to 13 wherein the one or more inlet valves may be located on the lung side of the lip shield.

15. The breathing device of any one of the preceding claims wherein the one or more inlet valves are movable between an open position to allow air to pass through the one or more inlet valves and a closed position to prevent air passing through the one or more inlet values.

16. The breathing device of claim 15 wherein the one or more inlet valves are biased toward the closed position.

17. The breathing device of any one of the preceding claims wherein there is a single inlet valve.

18. The breathing device of any one of the preceding claims wherein the inlet valve is in the form of a duckbill valve.

19. The breathing device of claim 18 wherein the duckbill valve has a fixed open end and a moveable end connected by one or more sidewalls, the fixed end being formed within the lip shield.

20. The breathing device of any one of claims 1 to 18 wherein the inlet valve is in the form of a flap valve.

21. The breathing device of claim 20 wherein the flap is connected to the lip shield.

22. The breathing device of claim 20 or 21 the flap valve includes a flap that is pivotally moveable between an open position that allows air to flow through the valve and a closed position that prevents air from flowing through the valve.

23. The breathing device of any one of the preceding claims wherein the passageways may be permanently open.

24. The breathing device of any one of the preceding claims wherein the one or more passageways are located on one or more of the inlet valves.

25. The breathing device of any one of claims 1 to 19 wherein when the one or more valves are a single duckbill vale, the one or more passageways may be located on the sidewalls of the duckbill valve.

26. The breathing device of any one of claims 1 to 17 wherein when the one or more valves are one or more flap valves, the one or more passageways may be located on a flap of the one or more flap valves.

27. The breathing device of any one of claims 1 to 17 wherein when the one or more valves are one or more flap valves, the one or more passageways may be located adjacent one or more sides of a flap of the one or more flap valves.

28. A method of operating a breathing assistance device, the method including the steps of:locating a breathing assistance device entirely within the mouth of a user so that the breathing assistance device allows a user to inhale freely but restricts exhalation of the user to thereby cause oral positive end expiratory pressure in the oral cavity of a user.

29. The method of claim 28 wherein the breathing assistance device provides no or limited resistance to airflow when a user inhales.

30. The method of claim 28 or 29 wherein the breathing assistance device provides resistance to airflow when a user exhales.

31. The method of any one of claims 28 to 30 wherein the breathing assistance device uses one or more inlet valves to allow air to pass through the one or more valves from when a user inhales but prevents air from passing through the valves when a user exhales.

32. The method of any one of claims 28 to 31 wherein the breathing device includes one or more exit passageways that are one or more exit apertures allowing air to pass from the lung side of the mouth locator to the lip side of the mouth locator.

33. The method of any one of claims 28 to 32 wherein the airflow during exhalation is restricted by the size of one or more exit passageways.

34. The method of any one of claims 28 to 32 wherein the airflow during exhalation is restricted by one or more valves located within exit passageways.

35. The method of any one of claims 28 to 34 wherein the breathing assistance device is located within the mouth of a user using the teeth of a user.

36. The method of any one of claims 28 to 35 wherein the breathing assistance device is located within the mouth of a user between the teeth and the lips.

37. The method of any one of claims 28 to 36 wherein the front and / or tips of the teeth are used to position the breathing assistance device.

38. The method of claim 37 wherein at least the teeth between the incisors are used.

39. The method of any one of claims 28 to 38 wherein the breathing assistance apparatus is as claimed in any one of claims 1 to 27.

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