Abstract: Anesthesia or respirator apparatus is disclosed for supplying a gas stream to a patient, including a ventilator for delivering the gas stream, including an inhalation conduit and a compressible bag or bellows, with the gas stream being in contact with the inner surface of the compressible bag and with its outer surface being in contact with a propellant gas stream so that an increase in pressure in the gas stream within the compressible bag can be created by application of the propellant gas against the outer surface of the bag, and including a manual pump associated with the propellant gas stream so that increased pressure can be created in the propellant gas stream, thus resulting in application of the propellant gas stream against the outer surface of the bag, by actuation of the manual pump, and a resultant increase in the pressure in the gas stream within the bag, in turn resulting in an increased flow of the gas stream through the inhalation conduit to the patient.