Nasal cannula devices formed with through air-flow passages and circular membranes anchored centrally to retainers and operative upon inhaling by the patient to raise off the peripheral edges of respective seats for free flow of air into the nasal passages and, further, operative upon exhalation by the patient to seat on the seats.The invention further includes a method introducing the cannula devices with cushioning rings to cushion against the walls of the walls of the nasal passages.In another method the invention includes manufacturing a barrel with proximal and distal glands to friction fit on a shell formed in the body of the cannula and receiving an annular retainer friction fit in the distal cannula to mount a sealing membrane.
