Role of oxygen in the production of human decompression sickness.
In the calculation of decompression schedules, it is commonly assumed that only the inert gas needs to be considered; all inspired O2 is ignored. Animal experiments have shown that high O2 can increase risk of serious decompression sickness (DCS). A trial was performed to assess the relative risks of O2 and N2 in human no-decompression dives. Controlled dives (477) of 30- to 240-min duration were performed with subjects breathing mixtures with low (0.21-0.38 ATA) or high (1.0-1.5 ATA) Po2. Depths were chosen by a sequential dose-response format. Only 11 cases of DCS and 18 cases of marginal symptoms were recorded despite exceeding the presently accepted no-decompression limits by greater than 20%. Analysis by maximum likelihood showed a shallow dose-response curve for increasing depth. O2 was estimated to have zero influence on DCS risk, although data variability still allows a slight chance that O2 could be 40% as effective as N2 in producing a risk of DCS. Consideration of only inert gases is thus justified in calculating human decompression tables.
Weathersby
P K
PK
Naval Medical Research Institute, Bethesda, Maryland 20814.
Hart
B L
BL
Flynn
E T
ET
Walker
W F
WF
D003665:Decompression Sickness / Q000209:etiology*; D004242:Diving; D005069:Evaluation Studies as Topic; D006801:Humans; D008297:Male; D008433:Mathematics; D010100:Oxygen / Q000009:adverse effects*; D011338:Probability Theory
D010100:Oxygen