Lung function changes of divers after single deep heliox diving

Abstract

AbstractObjectivesThis study detects the changes in pulmonary function of divers after 80m, 100 m, and 120 m helium-oxygen (heliox) dive. Methods: A total of 26 divers participated in the experiment, of which 15 divers performed the 80m dive, 5 divers performed the 100m dive, and 6 divers performed the 120m dive. The exposure phases included breathing heliox or air in water and O2 in the hyperbaric chamber. Pulmonary function (forced flow-volume) was measured twice before diving, within 30 minutes after diving, and 24 hours after diving. The parameters examined were forced vital capacity (FVC), forced expired volume in 1 second (FEV1), forced expired flow from 25% to 75% volume expired (FEF25-75%), 25-75 percent maximum expiratory flow as compared with vital capacity (MEF 25-75%) and peak expiratory flow (PEF). Results: FEV1/FVC and MEF25% markedly decreased (p = 0.0395, p = 0.0496) within 30min after the 80m dive, but returned to base values at 24h after the dive. Other indicators showed a downward trend within 30min after 80m heliox diving (no statistical difference). Interestingly, FEV1, FEV1/FVC, PEF, MEF decreased after 100m heliox dives, but there was no statistical difference. However, in the 120m heliox dive, FEV1/FVC and MEF75% significantly decreased again after diving (p = 0.0098, p = 0.0073). The relatively small number and more proficient diving skills of divers in 100m and 120m diving may be responsible for the inconsistent results. But when the diving depth reached 120m, results again showed a significant statistical change. Conclusion: Single deep heliox diving can cause temporary expiratory and small airway dysfunction, which can be recovered at 24h after diving.