[abstract] DIRECT (NO-STOP) DOCOMPRFSSION FROM AIR SATURATION.

Abstract

The depth limit for direct (no-stop) decompression from air saturation is important from both operational and theoretical standpoints, but remains vaguely defined. In a continuing study designed to provide this information, ten subjects have thus far been exposed to a pressure equivalent to 25.5 feet sea water gauge (fswg) in a dry chamber for 48 hours, and then decompressed directly to the surface in 1 minute. The subjects performed no exercise, ate a normal diet and took no medications during the exposure. Post-decompression symptoms, in order of decreasing incidence are: fatigue, pruritus, generalized aching and fitful sleep. Pruritus disappeared within 30 min. after decompression, and the other symptoms generally resolved in 24-48 hours, but in some cases persisted for 4 days. There are no diagnosed cases of decompression sickness. Precordial doppler monitoring show detectable venous gas emboli (VGE) in all subjects. The mean time of VGE appearance was about 2 hours after decompression, with peak scores between 5 and 6 hours. VGE generally persisted for more than 12 hours, but are undetectable 24 hrs post-surfacing. preliminary conclusions are that the depth limit for direct decompression from air saturation is close to, but greater than 25.5 fswg. More dives will be required to state this with statistical certainty. An additional ten subjects will have been tested at 29.5 fswg by the time of presentation.