Abstract: A positive airway pressure support system (2, 7, 130) that includes a pressure generating device (4) structured to produce an intermittent or continuous flow of breathing gas at a selected positive pressure or pressures, and a patient interface device (2, 72, 132) operatively coupled to the pressure generating system and structured to deliver the flow of breathing gas to an airway of a patient. The patient interface device includes a helmet (30) structured to be worn on the head of the patient and a patient interface element (22) coupleable to the top portion (44), the left side portion (82) and/or the right side portion (84) of the helmet in manner which stabilizes the patient interface element relative to the helmet and resists forces applied to the patient interface element when the patient interface device is donned by the patient and the patient moves while in a supine position.