Arterial blood gases in divers at surface after prolonged breath-hold.


PURPOSE:Adaptations during voluntary breath-hold diving have been increasingly investigated since these athletes are exposed to critical hypoxia during the ascent. However, only a limited amount of literature explored the pathophysiological mechanisms underlying this phenomenon. This is the first study to measure arterial blood gases immediately before the end of a breath-hold in real conditions. METHODS:Six well-trained breath-hold divers were enrolled for the experiment held at the "Y-40 THE DEEP JOY" pool (Montegrotto Terme, Padova, Italy). Before the experiment, an arterial cannula was inserted in the radial artery of the non-dominant limb. All divers performed: a breath-hold while moving at the surface using a sea-bob; a sled-assisted breath-hold dive to 42 m; and a breath-hold dive to 42 m with fins. Arterial blood samples were obtained in four conditions: one at rest before submersion and one at the end of each breath-hold. RESULTS:No diving-related complications were observed. The arterial partial pressure of oxygen (96.2 ± 7.0 mmHg at rest, mean ± SD) decreased, particularly after the sled-assisted dive (39.8 ± 8.7 mmHg), and especially after the dive with fins (31.6 ± 17.0 mmHg). The arterial partial pressure of CO2 varied somewhat but after each study was close to normal (38.2 ± 3.0 mmHg at rest; 31.4 ± 3.7 mmHg after the sled-assisted dive; 36.1 ± 5.3 after the dive with fins). CONCLUSION:We confirmed that the arterial partial pressure of oxygen reaches hazardously low values at the end of breath-hold, especially after the dive performed with voluntary effort. Critical hypoxia can occur in breath-hold divers even without symptoms.





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Publication Info

Bosco, Gerardo, Matteo Paganini, Alex Rizzato, Luca Martani, Giacomo Garetto, Jacopo Lion, Enrico M Camporesi, Richard E Moon, et al. (2020). Arterial blood gases in divers at surface after prolonged breath-hold. European journal of applied physiology, 120(2). pp. 505–512. 10.1007/s00421-019-04296-2 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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