A respiratory mask (10) for delivering inspiratory gas to a wearer, the mask comprising a mask body (12) shaped to define a cavity adapted to fit about the mouth and nose of the patient, wherein the mask body comprises a nose cavity portion (18) and a mouth cavity portion (16), the nose cavity portion comprising an inspiratory gas inlet port (26) and wherein the mouth portion comprises an expiratory gas monitoring port (34) at a location spaced from the inlet port. The gas monitoring port and may comprise an integral connector for a monitoring line and may be used to monitor carbon dioxide levels.