A nasopharyngeal cannula comprising a body formed by a tubular portion that is curved so as to be inserted into a patient's nostril and a collar for resting on the base of the patient's nostril is described. The cannula also comprises a main channel forming a fluid passage between the collar and the tubular portion of the body and two auxiliary channels formed in the body and extending from the collar into the main channel. Each auxiliary channel opens into the collar at an inlet/outlet port oriented radially in relation to the axis of the main channel such as to be oriented laterally on each side of the patient's nostril when the cannula is in place on the patient.