A cannula configured to provide positive expiratory pressure (PEP) and oxygen to a patient, including: a base including an oxygen opening and an inhalation opening; a valve including an inhalation flap valve that closes the inhalation opening and a PEP flap valve; a valve retainer including a flow opening and an exhalation opening, wherein the PEP flap valve closes the exhalation opening; and a nasal pillow seated on the valve retainer.