Abstract: In various embodiments of a pulse dose and conservation oxygen delivery system, a control circuit, which is typically microprocessor based, monitors a differential pressure sensor coupled to a patient interface such as a cannula or a face mask. When a patient inhales, a negative pressure is detected at the patient interface point. This condition is sensed and an electrical signal corresponding to the condition is sent to the control circuit. The control circuit processes the signal and then energizes a valve, through driver circuitry, that connects the patient to the oxygen supply for a fixed period of time at a preselected amount. The control circuit continually monitors the pressure differentials at the patient interface and only delivers pulses of oxygen upon the inhalation of the patient. Oxygen delivery is based on a fixed volume of oxygen per breath which provides the advantage of a varying net volume being delivered to the patient per period of time depending on their respiratory rate.