US Patent 8997742 Ergonomic and adjustable respiratory mask assembly with cushion

A respiratory mask assembly for delivering breathable gas to a patient includes a frame having a front surface and a rear surface adapted in use to face the patient. A cushion having a side wall is removably attachable to the frame. The cushion has a rim extending away from the side wall, and a membrane provided to substantially surround the rim. An inner edge of the membrane defines an aperture, the aperture having a generally trapezoidal shape.