Scuba divers with patent foramen ovale (PFO) may be at risk for paradoxical nitrogen gas emboli when performing maneuvers that cause a rebound blood loading to the right atrium. We measured the rise and fall in intrathoracic pressure (ITP) during various maneuvers in 15 divers. The tests were standard isometric exercises (control), forceful coughing, knee bend (with and without respiration blocked), and Valsalva maneuver (maximal, gradually increased to reach control ITP, and as performed by divers to equalize middle ear pressure). All the maneuvers, as well as the downward slope of ITP at the release phase, were related to the control value.

Vascular gas emboli (VGE) start forming during the degassing of tissues in the decompression (ascent) phase of the dive when bubble precursors (micronuclei) are triggered to growth. The precise formation mechanism of micronuclei is still debated, with formation sites in facilitating regions with surfactants, hydrophobic surfaces or crevices. Ho wever, significant inter-subject variability to VGE exists for the same diving exposure and VGE may even be reduced with a single pre-dive intervention. The precise link between VGE and endothelial dysfunction observed post dive remains unclear and a nitric oxide (NO) mechanism has been hypothesized.

L'eau est une matière plurielle et ambivalente. Symboliquement associée à la purification, cause régulière de multiples ravages humains et écologiques, elle est aussi devenue un vaste terrain de jeu, d'expériences corporelles, d'immersions en tous genres. Retenir son souffle pour aller loin, profond, ou simplement rester longtemps immergé, passionne des pratiquants toujours plus nombreux. Il s'agit bien souvent de « se fondre » dans le milieu, repousser ses limites et surtout se reconnecter avec soi-même, explorer son propre corps et se sentir « bien ». L'apprentissage de l'apnée révèle les capacités d'adaptation du corps humain, actualisant des ressources inédites.

L'eau est une matière plurielle et ambivalente. Symboliquement associée à la purification, cause régulière de multiples ravages humains et écologiques, elle est aussi devenue un vaste terrain de jeu, d'expériences corporelles, d'immersions en tous genres. Retenir son souffle pour aller loin, profond, ou simplement rester longtemps immergé, passionne des pratiquants toujours plus nombreux. Il s'agit bien souvent de « se fondre » dans le milieu, repousser ses limites et surtout se reconnecter avec soi-même, explorer son propre corps et se sentir « bien ». L'apprentissage de l'apnée révèle les capacités d'adaptation du corps humain, actualisant des ressources inédites. Elle favorise l'émersion de sensations nouvelles du corps vivant.

Background: Several mechanisms allow humans to resist the extreme conditions encountered during breath-hold diving. Available nitric oxide (NO) is one of the major contributors to such complex adaptations at depth and oxidative stress is one of the major collateral effects of diving. Due to technical difficulties, these biomarkers have not so far been studied in vivo while at depth. The aim of this study is to investigate nitrate and nitrite (NOx) concentration, total antioxidant capacity (TAC) and lipid peroxidation (TBARS) before, during, and after repetitive breath-hold dives in healthy volunteers. Materials and Methods: Blood plasma, obtained from 14 expert breath-hold divers, was tested for differences in NOx, TAC, and TBARS between pre-dive, bottom, surface, 30 and 60 min post-dive samples.