BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to patient interfaces particularly though not solely for use in delivering CP AP therapy to patients suffering from obstructive sleep apnoea (OSA). In particular, this invention relates to cushions used to support and seal the mask to a patient's face.

Description of the Related Art

In the art of respiration devices, there are well known variety of respiratory masks which cover the nose and/or mouth of a human patient in order to provide a continuous seal around the nasal and/or oral areas of the face such that gas may be provided at positive pressure within the mask for consumption by the patient. The uses for such masks range from high altitude breathing (i.e., aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications.

One requisite of such respiratory masks has been that they provide an effective seal against the patient's face to prevent leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for-the patient. This problem is most crucial in those applications, especially medical applications, which require the patient to wear such a mask continuously for hours or perhaps even days. In such situations, the patient will not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives thus will not be achieved, or will be achieved with great difficulty and considerable patient discomfort.

U.S. Pat. No. 5,243,971 and U.S. Pat. No. 6,112,746 are examples of prior art attempts to improve the mask system U.S. Pat. No. 5,570,689 and PCT publication No. WO 00/78384 are examples of attempts to improve the forehead rest.

U.S. Pat. No. 6,634,358 and U.S. Pat. No. 6,581,602 of ResMed Limited disclose a nasal mask cushion to sealingly connect a mask to a wearer's face. The cushion has a nose-receiving cavity bounded by a frame and membrane. The membrane is spaced away from the rim of the frame, and its outer surface is of substantially the same shape as the rim.

In the prior art mask cushions are provided that have a solid inner wall that provides support but doesn't allow much change in the shape of the cushion. Thus, such mask cushions can be uncomfortable for a user. Furthermore, often prior art mask cushions are made of foam which is neither waterproof nor durable.

SUMMARY OF THE INVENTION

It is an object of the present invention to attempt to provide a patient interface which gives some way to overcoming the abovementioned disadvantages in the prior art or which will at least provide the industry with a useful choice.

Accordingly in a first aspect the present invention consists in a cushion for a patient interface adapted to supply gas to a patient comprising:

a cushion body; and

an outer cover,

wherein said body and cover are substantially formed of the same elemental material.

Preferably said elemental material is polyurethane.

Preferably said cushion body is formed in polyurethane foam.

Preferably said outer cover is formed in polyurethane film.

Preferably said outer cover is adhered to said body.

Preferably said cushion body is assembled from more than one moulded component.

Preferably said cushion body includes an attachment adapted to engage a mask.

In a second aspect the present invention consists in a cushion for a patient interface adapted to supply gas to a patient comprising:

a cushion body having an outer cover, and

an outer sealing sheath,

wherein said cushion body is detachable from said outer sheath and said patient interface.

Preferably said cushion body and said outer sealing sheath are formed of the same elemental material.

Preferably said elemental material is silicone.

In a third aspect the present invention consists in a mask adapted to deliver gas to a patient comprising:

a cushion body wherein at least a portion thereof has a plurality of adjacent voids.

Preferably each of said voids has a hexagonal cross section.

Preferably each of said voids has an oval, square, rectangular, or other shaped cross section.

Preferably said cushion body has an outer cover and said mask further includes an outer sealing sheath.

