AUTHOR=Balestra Costantino , Lévêque Clément , Mrakic-Sposta Simona , Vezzoli Alessandra , Wauthy Pierre , Germonpré Peter , Tillmans Frauke , Guerrero François , Lafère Pierre TITLE=Physiology of deep closed circuit rebreather mixed gas diving: vascular gas emboli and biological changes during a week-long liveaboard safari JOURNAL=Frontiers in Physiology VOLUME=15 YEAR=2024 URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1395846 DOI=10.3389/fphys.2024.1395846 ISSN=1664-042X ABSTRACT=

Introduction: Diving decompression theory hypothesizes inflammatory processes as a source of micronuclei which could increase related risks. Therefore, we tested 10 healthy, male divers. They performed 6–8 dives with a maximum of two dives per day at depths ranging from 21 to 122 msw with CCR mixed gas diving.

Methods: Post-dive VGE were counted by echocardiography. Saliva and urine samples were taken before and after each dive to evaluate inflammation: ROS production, lipid peroxidation (8-iso-PGF2), DNA damage (8-OH-dG), cytokines (TNF-α, IL-6, and neopterin).

Results: VGE exhibits a progressive reduction followed by an increase (p < 0.0001) which parallels inflammation responses. Indeed, ROS, 8-iso-PGF2, IL-6 and neopterin increases from 0.19 ± 0.02 to 1.13 ± 0.09 μmol.min⁻¹ (p < 0.001); 199.8 ± 55.9 to 632.7 ± 73.3 ng.mg⁻¹ creatinine (p < 0.0001); 2.35 ± 0.54 to 19.5 ± 2.96 pg.mL⁻¹ (p < 0.001); and 93.7 ± 11.2 to 299 ± 25.9 μmol·mol⁻¹ creatinine (p = 0.005), respectively. The variation after each dive was held constant around 158.3% ± 6.9% (p = 0.021); 151.4% ± 5.7% (p < 0.0001); 176.3% ± 11.9% (p < 0.0001); and 160.1% ± 5.6% (p < 0.001), respectively.

Discussion: When oxy-inflammation reaches a certain level, it exceeds hormetic coping mechanisms allowing second-generation micronuclei substantiated by an increase of VGE after an initial continuous decrease consistent with a depletion of “first generation” pre-existing micronuclei.