Effect of in-water recompression with oxygen to 6 msw versus normobaric oxygen breathing on bubble formation in divers

Ecole de Plongée Marine Nationale, 83800 Toulon Armées, France.
Arbeitsphysiologie (Impact Factor: 2.19). 06/2009; 106(5):691-5. DOI: 10.1007/s00421-009-1065-y
Source: PubMed


It is generally accepted that the incidence of decompression sickness (DCS) from hyperbaric exposures is low when few or no bubbles are present in the circulation. To date, no data are available on the influence of in-water oxygen breathing on bubble formation following a provocative dive in man. The purpose of this study was to compare the effect of post-dive hyperbaric versus normobaric oxygen breathing (NOB) on venous circulating bubbles. Nineteen divers carried out open-sea field air dives at 30 msw depth for 30 min followed by a 9 min stop at 3 msw. Each diver performed three dives: one control dive, and two dives followed by 30 min of hyperbaric oxygen breathing (HOB) or NOB; both HOB and NOB started 10 min after surfacing. For HOB, divers were recompressed in-water to 6 msw at rest, whereas NOB was performed in a dry room in supine position. Decompression bubbles were examined by a precordial pulsed Doppler. Bubble count was significantly lower for post-dive NOB than for control dives. HOB dramatically suppressed circulating bubble formation with a bubble count significantly lower than for NOB or controls. In-water recompression with oxygen to 6 msw is more effective in removing gas bubbles than NOB. This treatment could be used in situations of "interrupted" or "omitted" decompression, where a diver returns to the water in order to complete decompression prior to the onset of symptoms. Further investigations are needed before to recommend this protocol as an emergency treatment for DCS.

Download full-text


Available from: Jean-Eric Blatteau
  • Source
    • "the results from the present study confirm that oxygen breathing during decompression dramatically decreases the amount of bubbles after an air dive to 30 msw for 30 min breathing air. these results are in accordance with previous studies in an animal model of DcS (Mollerlokken et al. 2007) and in human divers (Blatteau and Pontier 2009). Several hypotheses can be considered to explain how the reduction of circulating bubbles may be attributable to oxygen breathing during decompression stop. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We highlighted a relationship between decompression-induced bubble formation and platelet micro-particle (PMP) release after a scuba air-dive. It is known that decompression protocol using oxygen-stop accelerates the washout of nitrogen loaded in tissues. The aim was to study the effect of oxygen deco-stop on bubble formation and cell-derived MP release. Healthy experienced divers performed two scuba-air dives to 30 msw for 30 min, one with an air deco-stop and a second with 100 % oxygen deco-stop at 3 msw for 9 min. Bubble grades were monitored with ultrasound and converted to the Kisman integrated severity score (KISS). Blood samples for cell-derived micro-particle analysis (AnnexinV for PMP and CD31 for endothelial MP) were taken 1 h before and after each dive. Mean KISS bubble score was significantly lower after the dive with oxygen-decompression stop, compared to the dive with air-decompression stop (4.3 ± 7.3 vs. 32.7 ± 19.9, p < 0.001). After the dive with an air-breathing decompression stop, we observed an increase of the post-dive mean values of PMP (753 ± 245 vs. 381 ± 191 ng/μl, p = 0.003) but no significant change in the oxygen-stop decompression dive (329 ± 215 vs. 381 +/191 ng/μl, p = 0.2). For the post-dive mean values of endothelial MP, there was no significant difference between both the dives. The Oxygen breathing during decompression has a beneficial effect on bubble formation accelerating the washout of nitrogen loaded in tissues. Secondary oxygen-decompression stop could reduce bubble-induced platelet activation and the pro-coagulant activity of PMP release preventing the thrombotic event in the pathogenesis of decompression sickness.
    Full-text · Article · Feb 2014 · Arbeitsphysiologie
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation in scuba divers was evaluated. Six volunteers participated in four diving protocols, with 2 wk of recovery between dives. On dive 1, before diving, all divers breathed normally for 20 min at the surface of the sea (Air). On dive 2, before diving, all divers breathed 100% oxygen for 20 min at the surface of the sea [normobaric oxygenation (NBO)]. On dive 3, before diving, all divers breathed 100% O2 for 20 min at 6 m of seawater [msw; hyperbaric oxygenation (HBO) 1.6 atmospheres absolute (ATA)]. On dive 4, before diving, all divers breathed 100% O2 for 20 min at 12 msw (HBO 2.2 ATA). Then they dove to 30 msw (4 ATA) for 20 min breathing air from scuba. After each dive, blood samples were collected as soon as the divers surfaced. Bubbles were measured at 20 and 50 min after decompression and converted to bubble count estimate (BCE) and numeric bubble grade (NBG). BCE and NBG were significantly lower in NBO than in Air [0.142+/-0.034 vs. 0.191+/-0.066 (P<0.05) and 1.61+/-0.25 vs. 1.89+/-0.31 (P<0.05), respectively] at 20 min, but not at 50 min. HBO at 1.6 ATA and 2.2 ATA has a similar significant effect of reducing BCE and NBG. BCE was 0.067+/-0.026 and 0.040+/-0.018 at 20 min and 0.030+/-0.022 and 0.020+/-0.020 at 50 min. NBG was 1.11+/-0.17 and 0.92+/-0.16 at 20 min and 0.83+/-0.18 and 0.75+/-0.16 at 50 min. Prebreathing NBO and HBO significantly alleviated decompression-induced platelet activation. Activation of CD62p was 3.0+/-0.4, 13.5+/-1.3, 10.7+/-0.9, 4.5+/-0.7, and 7.6+/-0.8% for baseline, Air, NBO, HBO at 1.6 ATA, and HBO at 2.2 ATA, respectively. The data show that prebreathing oxygen, more effective with HBO than NBO, decreases air bubbles and platelet activation and, therefore, may be beneficial in reducing the development of decompression sickness.
    Full-text · Article · Feb 2010 · Journal of Applied Physiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preventive measures to reduce the risk of decompression sickness can involve several procedures such as oxygen breathing during in-water decompression. Theoretical predictions also suggest that brief periods of recompression during the course of decompression could be a method for controlling bubble formation. The aim of this study was to get clearer information about the effects of different experimental ascent profiles (EAPs) on bubble reduction, using pure oxygen or recompression during decompression for nitrox diving. Four EAPs were evaluated using bubble monitoring in a group of six military divers using Nitrox 40% O(2) breathing with a rebreather. For EAP 1 and 2, 100% O(2) was used for the end stage of decompression, with a 30% reduction of decompression time in EAP 1 and 50% in EAP 2, compared to the French navy standard schedule. For EAP 3 and 4, nitrox 40% O(2) was maintained throughout the decompression stage. EAP 3 is based on an air standard decompression schedule, whereas EAP 4 involved a brief period of recompression at the end of the stop. We found that EAP 1 significantly reduced bubble formation, whereas high bubble grades occurred with other EAPs. No statistical differences were observed in bubbles scores between EAP 3 and 4. One diver developed mild neurological symptoms after EAP 3. These results tend to demonstrate that the "oxygen window" plays a key role in the reduction of bubble production and that breathing pure oxygen during decompression stops is an optimal strategy to prevent decompression sickness for nitrox diving.
    No preview · Article · Oct 2011 · Arbeitsphysiologie
Show more