Patent ID: 7708016

Claim:
A medical gas conserving device for delivery a fixed volume of medical gas to a patient in response to an inhalation, comprising: a timing gas chamber for storing a user-adjustable volume of gas up to a first pressure; a vent to exhaust the gas stored in the timing gas chamber to atmosphere; a pilot valve disposed between the timing gas chamber and the vent, the pilot valve biased in a closed position to inhibit gas flow from the timing gas chamber to the vent, the pilot valve in gas communication with a patient via a passage such that a vacuum in the passage opens the pilot valve to allow gas flow from the timing gas chamber to the vent; and a slave valve disposed between a regulated supply of medical gas and a delivery passage to the patient, the slave valve in gas communication with the timing gas chamber such that when gas in the timing gas chamber is at the first pressure the slave valve is in a closed position to inhibit the flow of medical gas from the regulated supply to the delivery passage, and when gas in the timing gas chamber is below the first pressure the slave valve is in an opened position to allow medical gas to flow from the regulated supply to the delivery passage.