Patent ID: 8439039

Claim:
A respiratory mask, comprising: a mask shell defining an interior of the respiratory mask; the mask shell including a tubular mask inlet adapted to connect to a breathable gas supply conduit; and a gas washout vent passage having an inlet forming part of the mask shell and in fluid communication with the interior of the respiratory mask and an outlet in fluid communication with atmosphere, the outlet is adapted to direct washout gas in a direction substantially parallel to a longitudinal axis of the mask inlet and away from the mask inlet, wherein the mask shell includes a body portion and a cap portion, the body portion including an interior surface of the outlet, the interior surface of the outlet forming a smooth prolongation with an adjacent exterior surface of the mask shell, and the cap portion including an interior surface spaced apart from the interior surface of the body portion, the body portion interior surface and the cap portion interior surface including the gas washout vent passage therebetween.