Patent ID: 8056561

Claim:
A mask assembly for delivery of a supply of gas to an entrance to the airways of a patient, said patient having a nasal bridge region, a cheek region and a lip region, said mask assembly comprising: a headstrap system to secure the mask assembly relative to the patient's head; a mask body defining a cavity to receive a nose of the patient; and a nasal cushion, said nasal cushion comprising: a first cushion portion secured to the mask body, a second cushion portion adapted to confront a face of a patient in use, and a wall-portion located between said first and second cushion portions, wherein: said second cushion portion comprises first and second membranes, each of said first and second membranes having respective first ends located adjacent said wall-portion, and each of said first and second membranes having respective second ends forming respective rims defining an aperture through which the patient's nose is received in use, said second membrane is more flexible and/or thinner than said first membrane, said second membrane is pre-formed with a shape adapted to be substantially complementary to a patient's facial contour, said second membrane defines a seal-forming portion on an outer surface thereof, said seal-forming portion having an inner periphery and an outer periphery, the inner periphery of said seal-forming portion is constructed and arranged to be positioned in use adjacent a nasal bridge region, along sides of the nose, and between a top lip and a base of a nose to effect a seal, the seal forming portion is structured such that it is not required to turn in on itself to conform with the patient's face, in use, said first membrane provides a supporting structure for the second membrane, and said second membrane covering said first membrane.