Comparison of Lung Function Values of Trained Divers in 1.5 ATA Hyperbaric Chamber after Inhaling 100% Oxygen and Regular Air: A Crossover Study

Introduction: Diving is an activity performed in more than 1 atmosphere absolute pressure (ATA) either underwater or in a hyperbaric chamber. We aimed to compare lung function values of trained divers in 1.5 ATA hyperbaric chambers after inhaling 100% oxygen and regular air. Methods: This experimental study with crossover design involved 18 trained divers in 1.5 ATA hyperbaric room, which is equivalents to a 5-meter depth. The eighteen subjects as the supplementation group, using oro-nasal mask, inhaled 100% oxygen for 30 min followed by a one-day washout period. The subjects were then crossed-over into control group inhaling only regular air for 30 min. Lung function test was performed before and after supplementation. Results: In eighteen subjects inhaling regular air, there was a significant difference (p < 0.05) in FEV₁/FVC, PEF, FEF25, FEF50, and FEF75. Whereas in eighteen subjects inhaling 100% oxygen, significant difference (p < 0.05) was observed not only in FEV₁/FVC, PEF, FEF25, FEF50 and FEF75, but also in FEV₁. Conclusions: There were significant differences in lung function, especially in dynamic volume of trained divers in 1.5 ATA hyperbaric chamber after inhaling 100% oxygen and regular air for 30 min; while there were no significant differences in lung capacity (VC and FVC) in the both groups. Lung function returned to normal following supplementation with a 1-day washout period.