Abstract: A method of ventilating a patient comprises initially determining the class of the lungs of a given patient, selecting a pressure or flowrate inspiratory waveform and other ventilatory parameters like inspiratory pause and inspiratory time, among others, appropriate for that lung class, and then ventilating the patient with the selected inspiratory waveform and other ventilatory parameters. New ventilation inspiratory waveforms are provided which have been found to be advantageous for certain lung classes.

Abstract: A combination ventilation apparatus and anesthesia delivery system comprises a circulation loop within which oxygen and air or other clinical gas, or a mixture of air, oxygen, nitrous oxide or other clinical gas and anesthetics, are circulated by a variable speed centrifugal blower to a Y-piece which connects the circulation loop to an endotracheal tube or other airway device communicating with a patient. A proportional flow control valve is operative to actively control the pressure or flow at the Y-piece in response to signals from pressure or flow sensors which are positioned to provide measurements representative of the actual pressure and flow conditions within the patient's lungs. Constant circuit volume is maintained by computer control of gas make-up valves in response to the movement of a weighted bellows located between the proportional flow control valve and centrifugal blower.