Balldin Ulf I, O'Connor Robert R, Werchan Paul M, Isdahl Wayne M, Demitry Peter F, Stork Roger L, Morgan Thomas R
Air Force Research Laboratory, Biodynamics and Protection Division, Brooks Air Force Base, Texas 78235-5104, USA.
Aviat Space Environ Med. 2002 May;73(5):456-9.
Aircrew have reported increased heat stress when wearing the USAF Combined Advanced Technology Enhanced Design G-Ensemble or COMBAT EDGE (CE). The perceived thermal burden has been attributed to the fact that CE includes an inflatable counter-pressure vest to ease the work of positive pressure breathing during G (PBG). This study compared the heat load of CE with that of the standard USAF anti-G system (STD) without the vest, and measured heat stress effects on G-tolerance in both suits.
This study had 12 subjects (6 of them aircrew) who participated. Simulated preflight thermal stress (20 min walking at 35 degrees C with 85% relative humidity and radiant heat) was followed by return to a cooler environment (21 degrees C). G-tolerance and subjective stress levels were determined on the human centrifuge before and after the heat stress. Body weight, rectal and skin temperatures, and blood parameters were also assessed.
Baseline relaxed tolerance for +Gz gradual onset runs (GORs) were (mean +/- SD) 7.6 +/- 1.3 G for CE and 7.1 +/- 0.8 G for STD (p < 0.05). Maximal rectal temperature following heat stress peaked at 38.1 +/- 0.4 degrees C for both CE and STD, and mean nude weight loss was 1.10 +/- 0.24 kg for both. Relaxed GOR tolerances after heat stress were 7.1 +/- 1.3 for CE and 6.3 +/- 0.9 for STD (p < 0.01). The heat stress significantly reduced G tolerance for both CE and STD (p < 0.01).
Simulated preflight activity in hot conditions revealed no significant difference between CE and STD with regard to maximal core and skin temperature elevations or dehydration levels. CE supported a significantly higher baseline relaxed G-tolerance than STD, an advantage that persisted after heat stress and dehydration.
飞行员报告称，穿着美国空军联合先进技术增强设计G套装或“战斗边缘”（CE）套装时，热应激反应会增强。这种可感知的热负荷被认为是由于CE套装包含一个充气式反压背心，以便在承受正过载（PBG）时减轻正压呼吸的工作负担。本研究比较了CE套装与不含背心的标准美国空军抗荷系统（STD）的热负荷，并测量了两种套装中热应激对过载耐力的影响。
本研究有12名受试者（其中6名是飞行员）参与。先进行模拟飞行前热应激（在35摄氏度、相对湿度85%且有辐射热的环境下行走20分钟），然后回到较凉爽的环境（21摄氏度）。在热应激前后，在人体离心机上测定过载耐力和主观应激水平。还评估了体重、直肠温度、皮肤温度和血液参数。
对于+Gz逐渐增加的运行（GORs），CE套装的基线放松耐力（平均值±标准差）为7.6±.3G，STD套装为7.1±0.8G（p<0.05）。热应激后，CE套装和STD套装的最高直肠温度均在38.1±0.4摄氏度时达到峰值，平均裸体体重减轻均为1.10±0.24千克。热应激后，CE套装的放松GOR耐力为7.1±1.3，STD套装为6.3±0.9（p<0.01）。热应激显著降低了CE套装和STD套装的过载耐力（p<0.01）。
在炎热条件下进行模拟飞行前活动时，CE套装和STD套装在最高核心温度和皮肤温度升高或脱水水平方面没有显著差异。CE套装支持的基线放松过载耐力显著高于STD套装，这一优势在热应激和脱水后仍然存在。
