Abstract: A nasal cannula interface is provided for supplying a gases flow to a patient comprising: a nasal cannula defining at least a portion of a gases flow path and comprising a body having a base portion and at least one prong extending from the base portion, the at least one prong being configured to direct the gases flow to an orifice of the patient, and one or more sensors configured to measure a parameter. The one or more sensors may comprise a pulse oximeter. The one or more sensors may be mounted on the nasal cannula body, or headgear to which the body is connector. The one or more sensors may be configured to be in contact with the face of the patient, and may be configured to be mounted in and/or substantially flush with, a cheek contacting portion of the interface.