A nasal cannula which comprises a face piece comprising first and second nares which each communicate with a respective nostril of a patient. A septum divides the face piece into first and second flow paths such that the first flow path communicates with the first nare and the second flow path communicates with the second nare. A leading end of the first nare is configured to form a fluid barrier within a first nostril and facilitate only supplying an insufflation gas, via the first flow path, to the patient and prevent exhausting any of exhaust gas, of the patient, through the first nostril of the patient. A leading end of the second nare is configured to facilitate collecting some of the exhaust gas, from the patient, via the second flow path as well as exhausting a remainder of the exhaust gas out through a second nostril of the patient.
