Differences in spirometry and diffusing capacity after a 3-h wet or dry oxygen dive with a PO(2) of 150 kPa

Breathing oxygen with a partial pressure of >50 kPa causes pulmonary oxygen toxicity (POT), resulting in a decrease in vital capacity (VC) and in diffusing capacity for carbon monoxide (DLco). As submersion is thought to potentiate POT, we hypothesized that submerged oxygen divers are at increased risk for POT. To compare changes in lung function after submerged (wet) and non-submerged (dry) oxygen dives. Thirteen healthy male divers (mean ± SD: 25 ± 2 years, 184 ± 7 cm, 85 ± 10 kg) made a dry and a wet dive to 150 kPa for 3 h, during which they breathed 100% oxygen. At baseline, within 1 and 4 h after their dives, spirometry and diffusing capacity were measured. Data were analysed with ANOVA using Bonferroni correction and paired t-tests. Compared with baseline, there was a significant reduction in DLco (-1·6 mmol kPa(-1) min(-1)) after a wet oxygen dive but not after a dry dive. In addition, relative to baseline, there was a significant difference in ΔDLco and ΔVC when comparing wet and dry oxygen dives. Diffusing capacity is more impaired after a wet oxygen dive than after a dry one. This suggests that wet oxygen divers are at increased risk for POT. Monitoring studies during daily practice of professional divers are mandatory to determine the exact operational relevance of the present finding