Calculation and verification of the simulated high altitude heliox conventional diving decompression schedule

Abstract

Objective To calculate the decompression schedule for the simulated high altitude heliox conventional dive,by using the ratio of high altitude air pressure and sea level air pressure to simulate heliox conventional dive at high altitude,and then to verify the safety of the decompression schedule.Methods Data at various depths in the heliox conventional diving schedule were revised by using the ratio of high altitude air pressure and sea level air pressure as an adjusting factor.Then,4 decompression schedules were developed for the high altitude heliox conventional diving.Four male healthy divers were exposed to 3000,4000 and 5200 m above sea level in the high-low pressure chamber and carried out simulated 30 m/60 min and 50m/60min heliox conventional dives.During the process of decompression,pre-cordial Doppler ultrasonic bubble detections and recordings inside the chamber were made every other decompression stage,and when the divers returned to ambient pressure at high altitudes.Results Static and dynamic Doppler bubble detection indicated that there were neither bubbles in the blood stream nor symptoms and signs of decompression sickness.Conclusions The diving decompression schedules developed through our research are safe and practically feasible. Key words: High altitude; Heliox conventional dive; Decompression schedule