Development of the DCIEM 1983 Decompression Model for Compressed Air Diving.

Abstract

The Kidd-Stubbs (KS) decompression computer model has been used at DCIEM for a considerable number of years to control experimental, operational, and training dives. Although the KS model has been successful with a low incidence of decompression sickness, several problems exist. These include overly conservative no-decompression limits and conservative decompression times for short exposures. As the bottom times increase, the decompression times become less conservative and the decompression stress increases. A critical study of the model, using the Doppler ultrasonic bubble detector, showed that there was a range of bottom times in which the decompression stress was severe with a high risk of decompression sickness. Beyond this range of bottom times, the KS model once again became excessively conservative. In order to improve the safety of the KS model and to satisfy Canadian Forces requirements for compressed air diving, the Kidd-Stubbs model was modified to increase the no-decompression limit, decrease the decompression requirements for moderate exposures, increase the decompression times for severe exposures and remove the anomaly of the excessively long and unnecessary decompression times caused by the third and fourth compartments of the model.