A bi-level positive airway pressure device includes a housing that has a patient port for connecting to an airway of a patient. Within the housing is a device that generates a positive airway pressure directed towards to patient port. Also within the housing is a system that mechanically detects exhalation (by the patient that is connected to the patient port) that enters into the patient port. Responsive to detecting exhalation, a blocking device occludes the device that generating positive airway pressure, thereby reducing or stopping the positive airway pressure until the system that mechanically detects exhalation no longer detects exhalation, at which time the blocking device is operated to no longer occlude the device for generating positive airway pressure, thereby providing positive airway pressure to the patient port during, for example, inhalation.