University of Colorado Center for Combat Medicine and Battlefield (COMBAT) Research, Aurora, CO 80045, USA.
Department of Emergency Medicine, University of Colorado School of Medicine, Aurora, CO 80045, USA.
Mil Med. 2024 Aug 30;189(9-10):2004-2008. doi: 10.1093/milmed/usad451.
Hypothermia increases mortality in trauma populations and frequently occurs in military casualties due to the nature of combat environments. The association between hypothermia and the time of year when injured remains unclear. We sought to determine the association between seasonal changes in temperature and hypothermia among combat casualties.
This observational study was a secondary analysis of a previously described Department of Defense Trauma Registry dataset which included U.S. military and Coalition casualties who received prehospital care from January 2007 to March 2020 in Afghanistan and Iraq. We tested for associations between hypothermia (<36.2°C) and seasonal ambient temperatures by constructing multivariable logistic regression models. Summer was defined as June through August and winter as December through February. We assumed that the combat operations occurred in the area near the point of first contact with the deployed military treatment facilities. This study was determined to be exempt from Institutional Review Board oversight.
There were 5,821 that met inclusion for this study. Within the multivariable logistic regression model, we adjusted for injury severity score, mechanism of injury, and imputed transport time, finding that combat casualties were 2.28 (odds ratio, 95% confidence interval 1.93-2.69) times more likely to develop hypothermia in the winter versus summer. When using temperature as a continuous outcome, casualties had a lower emergency department temperature during the winter (parameter estimate -0.133°C, P < 0.001) after adjusting for confounders. In casualties experiencing hypothermia, mortality was higher (4% versus 1%, P < 0.001), and composite median injury severity score values were higher (10 versus 5, P < 0.001). Among hypothermic casualties, serious injuries were significantly more common (all P < 0.001) to the head (15% versus 7%), thorax (15% versus 7%), abdomen (9% versus 6%), extremities (35% versus 22%), and skin (4% versus 2%).
We found a seasonal variation in the occurrence of hypothermia in a large cohort of trauma casualties. Despite adjustment for multiple known confounders, our findings substantiate probable ambient temperature variations to trauma-induced hypothermia. Furthermore, our findings, when taken in the context of other studies on the efficacy of current hypothermia prevention and treatment strategies, support the need for better methods to mitigate hypothermia in future cold-weather operations.
体温过低会增加创伤人群的死亡率，而且由于战斗环境的性质，在军事伤员中经常发生。体温过低与受伤时的季节之间的关系尚不清楚。我们试图确定季节性温度变化与战斗伤员体温过低之间的关系。
本观察性研究是对先前描述的国防部创伤登记数据集的二次分析，该数据集包括 2007 年 1 月至 2020 年 3 月在阿富汗和伊拉克接受院前护理的美国军事人员和联军伤员。我们通过构建多变量逻辑回归模型来测试体温过低（<36.2°C）与季节性环境温度之间的关系。夏季定义为 6 月至 8 月，冬季为 12 月至 2 月。我们假设战斗行动发生在与部署的军事治疗设施的第一个接触点附近的区域。这项研究被确定为免除机构审查委员会的监督。
共有 5821 人符合本研究的纳入标准。在多变量逻辑回归模型中，我们调整了损伤严重程度评分、损伤机制和推测的转运时间，发现与夏季相比，冬季战斗伤员发生体温过低的可能性高 2.28 倍（比值比，95%置信区间 1.93-2.69）。当使用温度作为连续结果时，在调整混杂因素后，冬季伤员在急诊室的温度较低（参数估计-0.133°C，P<0.001）。在发生体温过低的伤员中，死亡率更高（4%比 1%，P<0.001），综合损伤严重程度评分值更高（10 比 5，P<0.001）。在体温过低的伤员中，头部（15%比 7%）、胸部（15%比 7%）、腹部（9%比 6%）、四肢（35%比 22%）和皮肤（4%比 2%）严重损伤更为常见（所有 P<0.001）。
我们在大量创伤伤员队列中发现体温过低的发生存在季节性变化。尽管调整了多个已知混杂因素，但我们的研究结果证实了环境温度变化可能导致创伤性体温过低。此外，当将我们的发现与其他关于当前体温过低预防和治疗策略效果的研究结合起来时，我们的研究结果支持在未来寒冷天气行动中需要更好的方法来减轻体温过低。
