Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA.
The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Drive, Bethesda, MD, 20817, USA.
Eur J Appl Physiol. 2021 Sep;121(9):2543-2562. doi: 10.1007/s00421-021-04698-1. Epub 2021 Jun 5.
This study aimed at assessing the risks associated with human exposure to heat-stress conditions by predicting organ- and tissue-level heat-stress responses under different exertional activities, environmental conditions, and clothing.
In this study, we developed an anatomically detailed three-dimensional thermoregulatory finite element model of a 50th percentile U.S. male, to predict the spatiotemporal temperature distribution throughout the body. The model accounts for the major heat transfer and thermoregulatory mechanisms, and circadian-rhythm effects. We validated our model by comparing its temperature predictions of various organs (brain, liver, stomach, bladder, and esophagus), and muscles (vastus medialis and triceps brachii) under normal resting conditions (errors between 0.0 and 0.5 °C), and of rectum under different heat-stress conditions (errors between 0.1 and 0.3 °C), with experimental measurements from multiple studies.
Our simulations showed that the rise in the rectal temperature was primarily driven by the activity level (~ 94%) and, to a much lesser extent, environmental conditions or clothing considered in our study. The peak temperature in the heart, liver, and kidney were consistently higher than in the rectum (by ~ 0.6 °C), and the entire heart and liver recorded higher temperatures than in the rectum, indicating that these organs may be more susceptible to heat injury.
Our model can help assess the impact of exertional and environmental heat stressors at the organ level and, in the future, evaluate the efficacy of different whole-body or localized cooling strategies in preserving organ integrity.
本研究旨在评估人体暴露于热应激条件下的风险，通过预测不同体力活动、环境条件和着装下器官和组织水平的热应激反应来实现这一目标。
在这项研究中，我们开发了一个具有 50 百分位美国男性解剖细节的三维热调节有限元模型，以预测整个身体的时空温度分布。该模型考虑了主要的热传递和热调节机制以及昼夜节律效应。我们通过将模型对各种器官（大脑、肝脏、胃、膀胱和食管）和肌肉（股直肌和肱三头肌）在正常休息条件下（误差在 0.0 到 0.5°C 之间）以及在不同热应激条件下（误差在 0.1 到 0.3°C 之间）的温度预测与多项研究的实验测量进行比较，验证了我们的模型。
我们的模拟表明，直肠温度的升高主要是由活动水平（约 94%）驱动的，而环境条件或我们研究中考虑的着装的影响则要小得多。心脏、肝脏和肾脏的峰值温度始终高于直肠（约 0.6°C），整个心脏和肝脏的温度记录都高于直肠，这表明这些器官可能更容易受到热损伤。
我们的模型可以帮助评估器官水平的体力和环境热应激因素的影响，并在未来评估不同全身或局部冷却策略在保护器官完整性方面的效果。
