Single lever Humphrey A.D.E. lowflow universal anaesthetic breathing system. Part II: Comparison with Bain system in...

A clinical trial involving ten anaesthetized adult patients was conducted during controlled ventilation using the Humphrey A.D.E. system in the Mapleson "E" mode (lever down). With each patient acting as his or her own control, the parallel (non-coaxial) and coaxial versions of the single lever Humphrey A.D.E. system were compared, using capnography, to the Bain system (Mapleson D/E). All three systems behaved similarly with predictable patient normocarbia when a fresh gas flow of 70 ml X kg-1 X min-1 was used. The A.D.E. system has the added advantage that the switch from controlled to spontaneous ventilation (or vice versa) is achieved quickly and simply. Spontaneous, assisted or automatic controlled ventilation could be instituted at any time merely by the appropriate lever position.