Patent ID: 6923181

Claim:
A device for delivering a supply of gases to a user comprising a patient interface, in use in fluid communication with said supply of gases, engaging with said user and thereby supplying said gases to said user; and outlet means being integrated with or in fluid communication with said patient interface, said outlet means comprising: a valve body including an internal passage, in use at least a portion of said gases flowing through said internal passage, an external vent, and a flexible flap operatively connected to said valve body and having at least two configurations, a first configuration in use during inspiration of said patient substantially blocking said vent and a second configuration in use with said vent passing expired gases from said patient, said flexible flap externally connected to said valve body, a biasing means adapted to retain or actuate said flexible flap between said first configuration and said second configuration, wherein said biasing means is a venturi in said internal passage.