An analysis of the incidence of hypothermia in casualties presenting to emergency departments in Iraq and Afghanistan

Abstract

IntroductionHypothermia on the battlefield has been shown to be associated with severe injury and higher mortality. The incidence of battlefield casualties presenting with hypothermia are described. MethodsThe Department of Defense Trauma Registry (DoDTR) was queried from January 2007 to August 2016. We identified casualties with a documented temperature of <32°Celsius (C) (severe), 32–33.9 °C (moderate), 34–36 °C (mild). We defined serious injuries as those resulting in an AIS of ≥3 by body region. ResultsThere were 25,484 records with at least one documented temperature and 2501 (9.8%) casualties with hypothermia within our range. Nineteen (0.75%) casualties presented with severe hypothermia, 225 (9%) with moderate, and 2257 (90%) with mild. The mean injury severity score (ISS) for non-hypothermic, mild, moderate, and severe hypothermic casualties was 8 [4–14], 14 [6–24], 21 [13–29], and 21 [9–25], (p <0.001), respectively. Survival for casualties with severe hypothermia was 57.8%, moderate 80.9%, mild hypothermia 90.9%, and non-hypothermic group 97.6%, p<0.001. When adjusting for composite injury score, patient category, mechanism of injury, and location, this finding remained significant (OR 0.27, 0.21–0.34, p<0.001). Massive transfusion was more common in hypothermia casualties n = 566 (19%) versus non-hypothermic recipients n = 1734 (6.9%), p <0.001. ConclusionsThough the number of casualties that presented hypothermic was small, their injuries were more severe, and were more likely to receive massive blood transfusions. This cohort also had a higher mortality rate, a finding which held when adjusting for confounders. There appears to be an opportunity to improve hypothermia prevention for combat.