O'Brien Catherine, Castellani John W, Muza Stephen R
Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine , Natick, Massachusetts.
High Alt Med Biol. 2015 Sep;16(3):244-50. doi: 10.1089/ham.2015.0024. Epub 2015 Jun 4.
Mountain environments have combined stressors of lower ambient temperature and hypoxia. Cold alone can reduce finger temperature, resulting in discomfort, impaired dexterity, and increased risk of cold injury. Whether hypobaric hypoxia exacerbates these effects is unclear. To examine this, finger temperature responses to two cold water immersion tests were measured at sea level (SL, 99 kPa), 3000 m (70 kPa), and 4675 m (56 kPa) at the same air temperature (22°-23°C). Nine males sat quietly for 30 min, then completed the tests in balanced order. For the cold-induced vasodilation (CIVD) test, middle finger pad temperature was measured during immersion in 4°C water for 30 min. For the Rewarming test, finger temperature was measured for 30 min following a 5 min hand immersion in 16°C water. Average oxygen saturation was 98.6% during SL, 90.7% at 3000 m, and 75.8% at 4657 m. Mean finger temperature during the CIVD test (7.1°C) was similar among trials. There was no difference in CIVD parameters of nadir, apex, or mean finger temperatures; however both onset and apex times were earlier at 3000 m, compared to SL (0.6 min and 1.6 min, respectively). These differences did not persist at 4657 m. Rewarming after hand immersion was similar among trials, reaching 22.7°C after 30 min, compared to an initial finger temperature of 29.3°C. The results of this study provide no evidence that hypobaric hypoxia increases risk of cold injury. Previous findings of blunted finger temperatures at altitude are likely due to the lower ambient temperature that typically occurs at higher elevations.
山地环境存在环境温度较低和缺氧等综合应激源。仅寒冷就会降低手指温度，导致不适、灵活性受损以及冻伤风险增加。低压缺氧是否会加剧这些影响尚不清楚。为了对此进行研究，在相同气温（22°-23°C）下，于海平面（SL，99kPa）、3000米（70kPa）和4675米（56kPa）处测量了手指温度对两种冷水浸泡测试的反应。九名男性先安静地坐30分钟，然后按平衡顺序完成测试。在冷诱导血管舒张（CIVD）测试中，将中指垫浸于4°C水中30分钟期间测量温度。在复温测试中，手浸于16°C水中5分钟后测量手指温度30分钟。海平面测试期间平均血氧饱和度为98.6%，3000米处为90.7%，4657米处为75.8%。CIVD测试期间的平均手指温度（7.1°C）在各试验中相似。最低点、最高点或平均手指温度的CIVD参数没有差异；然而，与海平面相比，3000米处的起始时间和最高点时间更早（分别为0.6分钟和1.6分钟）。这些差异在4657米处没有持续存在。手浸后复温在各试验中相似，30分钟后达到22.7°C，初始手指温度为29.3°C。本研究结果没有提供证据表明低压缺氧会增加冻伤风险。先前关于高海拔处手指温度降低的研究结果可能是由于较高海拔通常出现的较低环境温度所致。
