Arterial Blood Gas Analysis in Breath-Hold Divers at Depth.


The present study aimed to evaluate the partial pressure of arterial blood gases in breath-hold divers performing a submersion at 40 m. Eight breath-hold divers were enrolled for the trials held at "Y-40 THE DEEP JOY" pool (Montegrotto Terme, Padova, Italy). Prior to submersion, an arterial cannula in the radial artery of the non-dominant limb was positioned. All divers performed a sled-assisted breath-hold dive to 40 m. Three blood samplings occurred: at 10 min prior to submersion, at 40 m depth, and within 2 min after diver's surfacing and after resuming normal ventilation. Blood samples were analyzed immediately on site. Six subjects completed the experiment, without diving-related problems. The theoretically predicted hyperoxia at the bottom was observed in 4 divers out of 6, while the other 2 experienced a reduction in the partial pressure of oxygen (paO2) at the bottom. There were no significant increases in arterial partial pressure of carbon dioxide (paCO2) at the end of descent in 4 of 6 divers, while in 2 divers paCO2 decreased. Arterial mean pH and mean bicarbonate ( HCO3- ) levels exhibited minor changes. There was a statistically significant increase in mean arterial lactate level after the exercise. Ours was the first attempt to verify real changes in blood gases at a depth of 40 m during a breath-hold descent in free-divers. We demonstrated that, at depth, relative hypoxemia can occur, presumably caused by lung compression. Also, hypercapnia exists at depth, to a lesser degree than would be expected from calculations, presumably because of pre-dive hyperventilation and carbon dioxide distribution in blood and tissues.





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Publication Info

Bosco, Gerardo, Alex Rizzato, Luca Martani, Simone Schiavo, Ennio Talamonti, Giacomo Garetto, Matteo Paganini, Enrico M Camporesi, et al. (2018). Arterial Blood Gas Analysis in Breath-Hold Divers at Depth. Frontiers in physiology, 9(NOV). p. 1558. 10.3389/fphys.2018.01558 Retrieved from

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Richard Edward Moon

Professor of Anesthesiology

Research interests include the study of cardiorespiratory function in humans during challenging clinical settings including the perioperative period, and exposure to environmental conditions such as diving and high altitude. Studies have included gas exchange during diving, the pathophysiology of high altitude and immersion pulmonary edema, the effect of anesthesia and postoperative analgesia on pulmonary function and monitoring of tissue oxygenation. Ongoing human studies include the effect of respiratory muscle training on chemosensitivity and blood gases during stressful breathing: underwater exercise.

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