A patient interface (8) for use in delivering a flow of a breathing gas to an airway of a patient includes an inner mask (20) having an inner cushion (30) with an inward curving inner sealing portion (32) that is structured to sealingly engage the face of the patient, and an outer mask (22) coupled to the inner mask. The outer mask has an outer cushion (60) with an outward curving outer sealing portion (62) that is structured to sealingly engage the face of the patient completely around, and outward from, the inner sealing portion of the inner mask. The inner mask is sized and configured to define a positive pressure cavity (36) for receiving the flow of breathing gas and convey the flow to the airway of the patient. The outer mask is sized and configured to define a negative pressure cavity (66) that encompasses the inner mask and capture any gases escaping the inner mask.