A five-year survey of hypobaric chamber physiological incidents in the Canadian Forces.

Hypobaric chamber training forms an integral part of the Canadian Forces (CF) Aeromedical Training Programme (AMTP). There are four standard types of runs (Type I, II, III, IV) in which personnel are exposed to the reduced atmospheric pressures ranging from ground level (GL) to 43,000 ft (13,106 m) (0.16 ATA). Physiological incidents involving trapped gases in the hollow body organs resulting from exposure to these reduced atmospheric pressures are considered "normal" during chamber runs and are managed by well established procedures. Altitude decompression sickness (DCS) on the other hand is a potentially life-threatening disorder and must be managed accordingly. This report is a summary of all physiological incidents occurring in CF hypobaric chambers during the period 1 January, 1977-31 December, 1981, and emphasizes significant trends in the incidence of altitude DCS at these chambers.