Riera Florence, Horr Reed, Xu Xiaojiang, Melin Bruno, Regnard Jacques, Bourdon Lionel
Aviat Space Environ Med. 2014 May;85(5):509-17. doi: 10.3357/asem.3077.2014.
Human thermal responses during prolonged whole-body immersion in cold water are of interest for the military, especially French SEALS. This study aims at describing the thermo-physiological responses.
There were 10 male military divers who were randomly assigned to a full immersion in neutral (34 degrees C), moderately cold (18 degrees C), and cold (10 degrees C) water wearing their operational protective devices (5.5 mm wetsuit with 3.0 mm thick underwear) for 6 h in a static position. Rectal temperature (T(re)) and 14 skin temperatures (T(sk)), blood analysis (stress biomarkers, metabolic substrates), and oxygen consumption (Vo2) were collected.
At 34 degrees C, there were no significant modifications of the thermo-physiological responses over time. The most interesting result was that rates of rectal temperature decrease (0.15 +/- 0.02 degrees C x min(-1)) were the same between the two cold stress experimental conditions (at 18 degrees C and 10 degrees C). At the final experiment, rectal temperature was not significantly different between the two cold stress experimental conditions. Mean T(sk) decreased significantly during the first 3 h of immersion and then stabilized at a lower level at 10 degrees C (25.6 +/- 0.8 degrees C) than at 18 degrees C (29.3 +/- 0.9 degrees C). Other results demonstrate that the well-trained subjects developed effective physiological reactions. However, these reactions are consistently too low to counterbalance the heat losses induced by cold temperature conditions and long-duration immersion.
This study shows that providing divers with thermal protection is efficient for a long-duration immersion from a medical point of view, but not from an operational one when skin extremities were taken into account.
长时间全身浸入冷水中时人体的热反应对军方来说很重要，尤其是法国海军特种部队。本研究旨在描述热生理反应。
10名男性军事潜水员被随机分配，穿着其作战防护装备（5.5毫米厚潜水服加3.0毫米厚内衣），在静态下分别全身浸入中性（34摄氏度）、中度寒冷（18摄氏度）和寒冷（10摄氏度）的水中6小时。收集直肠温度（T(re)）、14个皮肤温度（T(sk)）、血液分析（应激生物标志物、代谢底物）和耗氧量（Vo2）。
在34摄氏度时，热生理反应随时间没有显著变化。最有趣的结果是，在两种冷应激实验条件下（18摄氏度和10摄氏度），直肠温度下降速率（0.15±0.02摄氏度×分钟(-1)）相同。在实验结束时，两种冷应激实验条件下的直肠温度没有显著差异。平均T(sk)在浸入的前3小时显著下降，然后在10摄氏度（25.6±0.8摄氏度）时稳定在比18摄氏度（29.3±0.9摄氏度）更低的水平。其他结果表明，训练有素的受试者产生了有效的生理反应。然而，这些反应始终过低，无法抵消低温条件和长时间浸入所导致的热量损失。
本研究表明，从医学角度来看，为潜水员提供热保护对于长时间浸入是有效的，但从操作角度考虑皮肤末梢时则不然。
