Apparatus for wetting respiratory gas

An apparatus for wetting respiratory gas comprises a receiver having an interior wetting chamber and a cartridge receiving chamber which communicates at its lower end with the wetting chamber and which has an open end for receiving a heater cartridge. The heater cartridge is disposable in the cartridge receiving chamber and it includes an inner portion containing a heater element and an outer sleeve portion which has a lower end disposed in the wetting chamber and has side walls which are spaced from the wall of the inner portion of the cartridge containing the heater element. The receiver contains a duct for supplying water into the space between the sleeve and the inner portion of the cartridge containing the heater so that the water will be heated in its passage around the inner portion and may be discharged through openings at the lower end of the sleeve into the wetting chamber. The receiver also contains a duct for respiratory gas which is directed into an annular space between the sleeve and the walls bounding the cartridge receiving chamber for flow downwardly over the wetting chamber and out through a nozzle discharge after it has picked up a quantity of moisture. Air which is exhaled from a patient is directed through the receiver in a location adjacent the wetting chamber.