title: Gut fermentation seems to promote decompression sickness in humans.
abstract: 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 H2burden 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. Therefore, we set out to test these experimental results in humans. Thirty-nine 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 h after the dive. Breath hydrogen concentrations were significantly higher in Affected Divers (15 ppm [6-23] vs. 7 ppm [3-12]; P = 0.0078). With the use of a threshold value of 16.5 ppm, specificity was 87% [95% confidence interval (CI) 73-95] for association with neurological DCS onset. We observed a strong association between hydrogen values above this threshold and an accident occurrence (odds ratio = 5.3, 95% CI 1.8-15.7, P = 0.0025). However, high fermentation potential foodstuffs consumption was not different between Affected and Unaffected Divers. 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.
authors.affiliation: Service de Médecine Hyperbare et Expertise Plongée, Hôpital d'Instruction des Armées Sainte-Anne, Toulon, France; sebastien.de-maistre@wanadoo.fr.
authors.forename: Sébastien
authors.identifier: 0000-0002-5165-5184
authors.initials: S
authors.lastname: de Maistre
authors.affiliation: Équipe Résidente de Recherche Subaquatique Opérationnelle, Institut de Recherche Biomédicale des Armées, Toulon, France; and.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vallee
authors.affiliation: Service de Médecine Hyperbare et Expertise Plongée, Hôpital d'Instruction des Armées Sainte-Anne, Toulon, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gempp
authors.affiliation: Service de Médecine Hyperbare et Expertise Plongée, Hôpital d'Instruction des Armées Sainte-Anne, Toulon, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Louge
authors.affiliation: Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023-CNRS/UCBL, Université Claude Bernard Lyon 1, Villeurbanne, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Duchamp
authors.affiliation: Équipe Résidente de Recherche Subaquatique Opérationnelle, Institut de Recherche Biomédicale des Armées, Toulon, France; and.
authors.forename: Jean-Eric
authors.initials: JE
authors.lastname: Blatteau
mesh_terms: D001944:Breath Tests; D003106:Colon / Q000382:microbiology* / Q000502:physiology*; D003665:Decompression Sickness / Q000382:microbiology* / Q000503:physiopathology*; D005260:Female; D005285:Fermentation / Q000502:physiology*; D000069196:Gastrointestinal Microbiome / Q000502:physiology*; D006801:Humans; D006859:Hydrogen / Q000032:analysis*; D008297:Male; D008875:Middle Aged
chemical_list: D006859:Hydrogen
keywords: decompression sickness; diving; gut fermentation; humans; hydrogen