The method and system ventilates a patient's airway during the inspiratory phase and expiratory phase from a source of pressurized gas, typically from a compressor. The system and method supplies, to the patient airway during the inspiratory phase, a plurality of pulses of small volumes of gas from the gas source, and adds, in succession, pulses of small volumes of gas to provide successively greater volumes of gas successively increasing in pulsatile form the pressure of the gas in the patient's airway. This addition of successively greater volumes of gas serves to provide diffusive ventilation to the patient during the inspiratory phase, and, permits the patient to exhale during the expiratory phase.