Two Consecutive Five-Day Weeks of Daily Four-Hour Dives with Oxygen Partial Pressure 1.4 ATM

Abstract

Sixteen U.S. Navy divers began a series of 4-hour dives at a Po2 of 1.4 atm daily for two consecutive five-day weeks. Nine divers were able to finish; all withdrawals were for nonpulmonary reasons. Divers rested on the bottom of a 15-foot fresh water pool and breathed humidified 100percent oxygen open circuit from MK 20 full face masks. Flow-volume curves and diffusing capacity were measured at baseline, daily during diving, and after the series. Symptoms and changes in pulmonary function values were used to measure pulmonary oxygen toxicity, and the results were compared to earlier series of similar four-hour dives. During the two weeks of daily diving, one subject showed progressive pulmonary symptoms that increased from mild to moderate. All other symptoms and all pulmonary function changes were rated as mild. From these data and those gathered after other similar dives, we find no evidence of general accumulation of toxicity, though flow-volume changes are more common after two consecutive dives than after one. Diffusing capacity changes are sufficiently infrequent to be difficult to characterize. After any 4-hour, 1.4 atm Oxygen dive, 17percent of divers may report symptoms, and no more than 18percent are expected to show changes in flow-volume parameters.