Browsing by Author "Paganini, Matteo"

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    Arterial Blood Gas Analysis in Breath-Hold Divers at Depth.
    (Frontiers in physiology, 2018-01) Bosco, Gerardo; Rizzato, Alex; Martani, Luca; Schiavo, Simone; Talamonti, Ennio; Garetto, Giacomo; Paganini, Matteo; Camporesi, Enrico M; Moon, Richard E
    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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    Arterial blood gases in divers at surface after prolonged breath-hold.
    (European journal of applied physiology, 2020-02) Bosco, Gerardo; Paganini, Matteo; Rizzato, Alex; Martani, Luca; Garetto, Giacomo; Lion, Jacopo; Camporesi, Enrico M; Moon, Richard E
    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.