Introduction Massive bubble formation after diving can lead to decompression sickness (DCS) that can result in neurological disorders. In experimental dives using hydrogen as the diluent gas, decreasing the body's H2 burden by inoculating hydrogen-metabolizing microbes into the gut reduces the risk of DCS. In contrast, we have shown that gut bacterial fermentation in rats on a standard diet promotes DCS through endogenous hydrogen production. So we set out to test these experimental results in humans. Materials and methods 39 divers admitted into our hyperbaric center with neurological DCS (Affected Divers) were compared with 39 healthy divers (Unaffected Divers). Their last meal time and composition were recorded. Gut fermentation rate was estimated by measuring breath hydrogen 1-4 hours after the dive. Results Breath hydrogen concentrations were significantly higher in Affected Divers (15ppm [6-23] versus 7ppm [3-12]; p=0.0078). Using a threshold value of 16.5ppm, specificity was 87% (95%CI 73-95) for association with neurological DCS onset. We observed a strong association between hydrogen values above this threshold and an accident occurrence (OR=5.3, 95%CI 1.8-15.7, p=0.0025). However, high fermentation potential foodstuffs consumption was not different between between Affected and Unaffected Divers. Discussion and conclusion Gut fermentation rate at dive time seemed to be higher in Affected Divers. Hydrogen generated by fermentation diffuses throughout the body and could increase DCS risk. Prevention could be helped by excluding divers who are showing a high fermentation rate, by eliminating gas produced in gut or even by modifying intestinal microbiota to reduce fermentation rate during a dive.
- Decompression sickness
- Gut fermentation
- Copyright © 2016, Journal of Applied Physiology