Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level

摘要

Decompression procedures were developed for divers exposed to reduced atmospheric pressures shortly after diving. These procedures involved human subjects and multiple diving exposures in laboratory hyperbaric and altitude chambers. The studies were conducted in two phases. In Phase I, six exposure schedules were tested using 16 - 20 subjects per exposure. The six exposures tested--dive depth in feet sea water/no-decompression limit (minutes) for direct ascent to 10,000 ft--were: 130/7; 100/10; 80/14; 60/20; 40/34; and 10.75/1440. Exercise was performed at depth. Subjects remained at 10,000 ft for 4 hr, during which they exercised and breathed ambient chamber air. Then the subjects went to 16,000 ft for 1 hr, and used a diluter-demand oxygen system. Subjects were monitored for venous gas emboli (vge) by means of a precordial Doppler ultrasonic bubble detector. At 10,000 ft: 11.8% of the exposures produced vge, and 6.4% of exposures were terminated because of bends or high vge scores. At 16,000 ft: 4.9% of the 103 exposures ended with bends or vge. Phase II used three exposures--100/10, 80/14, and 60/20 schedules--and altitude exposures were changed from 10,000 to 8,500 ft, and from 16,000 to 14,250 ft. Of the 57 subject exposures in Phase II, none developed bends or high vge scores at 8,500 ft. At 14,250 ft, 5.3% developed bends or high vge scores.