An HME has exchange elements ( 4 ) at opposite ends of a tubular housing ( 1, 101 ) and a central port ( 2 ) for connection to a tracheal tube ( 3 ). An oxygen port ( 5, 105, 105 ) is located centrally with the major part of it being contained within a recess ( 40, 140, 140 ) on the exterior of the housing and extending at right angles to the length of the housing. The oxygen port ( 5, 105, 105 ) opens into a wider passage ( 32, 32 ) extending within the housing, which opens on the external face ( 30 ) of the two exchange elements ( 4 ). A large suction aperture ( 60 ) aligns with the port ( 2 ) opening to the tracheal tube ( 3 ) and is covered by a hinged flap ( 61 ) when not in use.
