[abstract] THE EFFECTS OF HYPERBARIC AND HYPEROXIC CONDITIONS ON PULMONARY FUNCTION DURING PROLONGED HYPERBARIC CHAMBER AIR SATURATION DIVES

Abstract

Three saturation dive profiles (10 dives) utilizing a total of 31 diver subjects have been completed. They were AIRSAT-I (60 fsw air saturation, 8-hour excursions to 100 fsw, 11 subjects), AIRSAT-II (60 fsw air saturation, six two-hour excursions to 150 fsw, 11 subjects), and AIRSAT-III (0.3 ATA O2 at 132 fsw saturation, three five-hour air excursions to 198 fsw, 9 subjects). In the latter, there was a shift to air at 132 fsw 24 hours before the decompression breathing air commenced. Forced vital capacity measurements for the majority (74 percent) of the 31 subjects showed no decrease, very minimal decrease, or only isolated measurements that decreased. Eight subjects (26 percent) had more persistent decrements of a physiologically significant magnitude. The individual lowest values for these eight subjects were 5, 7, 9, 9, 14, 17, 17, and 18 percent below mean control values for the individual subject. These 8 subjects all showed persistent decrements greater than 2 SD (5 percent confidence level) of their own control values for a period of from two days to two weeks. This decrement was generally much greater than 2 S.D.s; one extreme case was 57 times the S.D. of 0.018 1 (5.88 decreased to 4.86 liters). All subjects eventually recovered to their pre-dive control value. For some subjects this occurred during or immediately post-dive; others required several days after the dive for full recovery.