A method of controlling bolus delivery in a pulse flow oxygen concentration system for a patient includes providing a pulse flow oxygen concentration system that delivers concentrated oxygen gas to the patient in boluses having a pulse bolus duration, the pulse flow oxygen concentration system including an open control for controlling the pulse bolus duration of the boluses determining one or more respiratory conditions of the patient and adjusting the open control to adjust the pulse bolus duration of the boluses in accordance with the determined one or more respiratory conditions of the patient.
