Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial

• Published in: PLOS ONE Vol. 11; no. 5; p. e0154761
• Main Authors: Souday, Vincent, Koning, Nick J., Perez, Bruno, Grelon, Fabien, Mercat, Alain, Boer, Christa, Seegers, Valérie, Radermacher, Peter, Asfar, Pierre
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science (PLoS) 10.05.2016; Public Library of Science
• Subjects: Adult; Anesthesiology; Biology and Life Sciences; Body fat; Body mass; Body mass index; Body size; Breathing; Bubble chambers; Bubbles; Bubbling; Compressed air; Cross-Over Studies; Decompression; Decompression - methods; Decompression Sickness; Decompression Sickness - etiology; Decompression Sickness - pathology; Decompression Sickness - prevention & control; Diving; Diving - adverse effects; Double-Blind Method; Double-blind studies; Experimental allergic neuritis; Female; Health aspects; Hospitals; Humans; Hyperoxia; Hyperoxia - etiology; Hyperoxia - pathology; Hyperoxia - prevention & control; Intensive care; Itching; Male; Medicine; Medicine and Health Sciences; Middle Aged; Nitrogen; Nitrogen - therapeutic use; Oxygen; Oxygen - therapeutic use; Oxygen Consumption; Oxygen Consumption - drug effects; Physical Sciences; Prospective Studies; Pulmonary Artery; Pulmonary Ventilation; Q; R; Randomization; Research and Analysis Methods; Research Article; Respiration; Respiration - drug effects; Science; Scuba diving; Simulation; Stress management; Toxicity; Ultrasonic imaging; Ultrasonography, Doppler, Pulsed; United States; France; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0154761

To test the hypothesis whether enriched air nitrox (EAN) breathing during simulated diving reduces decompression stress when compared to compressed air breathing as assessed by intravascular bubble formation after decompression. Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous gas bubbling. Twelve subjects prone to bubbling underwent a double-blind, randomized, cross-over trial including one simulated dive breathing compressed air, and one dive breathing EAN (36% O2) in a hyperbaric chamber, with identical diving profiles (28 msw for 55 minutes). Intravascular bubble formation was assessed after decompression using pulmonary artery pulsed Doppler. Twelve subjects showing high bubble production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the bubble score at all time points (cumulative bubble scores: 1 [0-3.5] vs. 8 [4.5-10]; P < 0.001). Three decompression incidents, all presenting as cutaneous itching, occurred in the air versus zero in the EAN group (P = 0.217). Weak correlations were observed between bubble scores and age or body mass index, respectively. EAN breathing markedly reduces venous gas bubble emboli after decompression in volunteers selected for susceptibility for intravascular bubble formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing. ISRCTN 31681480.