Faerevik Hilde, Reinertsen Randi Eidsmo
SINTEF Technology and Society, Department of Health Research, Trondheim, Norway.
Aviat Space Environ Med. 2012 Aug;83(8):746-50. doi: 10.3357/asem.2844.2012.
In cold water emergency situations, helicopter aircrew will enter the water with a raised body temperature due to wearing immersion suits. Prewarming has been demonstrated to accelerate core cooling during subsequent cold water immersion (CWI) when wearing swimsuits. For this study we hypothesized that wearing an immersion suit would slow the rate of cooling in subjects who were prewarmed compared to those kept in a normothermic state.
Two different groups of male subjects (age, 24.7 +/- 4.2 yr; height, 183.1 +/- 6.5 cm; weight, 86.7 +/- 15.0 kg; body fat, 16.8 +/- 3.3%) were used to gather data under two conditions: prewarming by exercise (Warm-CWI) and baseline (Base-CWI) when wearing a dry immersion suit (2.97 Clo). In Warm-CWI, seven subjects rested for 20 min and then cycled on an ergometer cycle for 20 min before immersion in water at 5 degrees C for 140 min. In Base-CWI, six subjects were directly immersed in 5 degrees C water after resting.
Tre and Tsk were significantly higher after Warm-CWI at start of CWI, resulting in faster core cooling rate, and a drop in Tre and Tsk during the first 10 min. In the long term, the overall core cooling did not differ between Warm-CWI (0.34 +/- 0.11 degrees C x h(-1)) and Base-CWI (0.31 +/- 0.05 degrees C x h(-1)).
Wearing a dry immersion suit eliminates long-term differences in core cooling between prewarmed subjects and those kept in a normothermic state. When entering cold water with a raised Tre and Tsk, different thermal responses during the first 10 min are expected, but this does not alter long-term core cooling.
在冷水紧急情况下，直升机机组人员由于穿着浸水服，入水时体温会升高。已有研究表明，穿着泳衣时，预热身会加速随后冷水浸泡（CWI）期间的核心体温下降。在本研究中，我们假设与处于正常体温状态的受试者相比，穿着浸水服会减缓预热身受试者的体温下降速度。
两组不同的男性受试者（年龄24.7±4.2岁；身高183.1±6.5厘米；体重86.7±15.0千克；体脂16.8±3.3%）在两种条件下收集数据：运动预热身（Warm-CWI）和穿着干式浸水服（2.97克罗）时的基线状态（Base-CWI）。在Warm-CWI组中，7名受试者休息20分钟，然后在测力计上骑行20分钟，之后浸入5摄氏度的水中140分钟。在Base-CWI组中，6名受试者休息后直接浸入5摄氏度的水中。
在CWI开始时，Warm-CWI组的直肠温度（Tre）和皮肤温度（Tsk）显著更高，导致核心体温下降速度更快，且在最初10分钟内Tre和Tsk下降。从长期来看，Warm-CWI组（0.34±0.11摄氏度×小时-1）和Base-CWI组（0.31±0.05摄氏度×小时-1）的总体核心体温下降没有差异。
穿着干式浸水服消除了预热身受试者和处于正常体温状态受试者之间核心体温下降的长期差异。当以升高的Tre和Tsk进入冷水时，预计在最初10分钟内会有不同的热反应，但这不会改变长期的核心体温下降。
