An arrangement and method for detecting spontaneous respiratory effort of a patient receiving ventilatory support by a breathing circuit. The nasal cannula control system includes a nasal cannula assembly having two distinct lumens. A different pressure sensor is positioned to detect the pressure difference between each of the two lumens, thereby determining the differential pressure from within the patients nostrils and within a breathing mask. The nasal cannula control system includes a gas sampling system such that the amount of a monitored gas discharged or exhaled by the patient can be monitored using the same nasal cannula assembly used to generate the differential pressure signal.
