Methods for administering medical gases include providing the medical gas in compressed gas cartridges containing an amount of the medical gas preferably corresponding substantially to a unit dose of the medical gas and providing a patient with access to the medical gas from the gas cartridge upon need therefor. Apparatus for administering medical gases also includes a housing, a cassette associated with the housing containing at least one compressed gas cartridge preferably containing at least an amount of the medical gas substantially as required for a single dose and a patient supply interface to provide the medical gas to the patient.