US Patent 7597100 Ergonomic and adjustable respiratory mask assembly with vent cover

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. An elbow assembly is swivelably coupled to the front surface of the frame, the elbow assembly including one or more vent openings. A removable vent cover is detachably connected to the elbow assembly such that the vent cover is positioned in covering relation with respect to the one or more vent openings. The vent cover includes a main body and at least one vent aperture for gas washout. The vent cover includes a ring-shaped base defining an aperture into which a portion of the elbow assembly is inserted.