Hypothermia and the Global War on Terror: 18 Years of Minimal Progress

INTRODUCTION: The association between hypothermia, coagulopathy, and acidosis in trauma is well described. Hypothermia mitigation starts in the prehospital setting; however, it is often a secondary focus after other life-saving interventions. The deployed environment further compounds the problem due to prolonged evacuation times in rotary wing aircraft, resource limitations, and competing priorities. This analysis evaluates hypothermia in combat casualties and the relationship to resuscitation strategy with blood products. METHODS: Using the data from the Department of Defense Joint Trauma Registry from 2003 to 2021, a retrospective analysis was conducted on adult trauma patients. Inclusion criteria was arrival at the first military treatment facility (MTF) hypothermic (<95ºF). Study variables included: mortality, year, demographics, battle vs non-battle injury, mechanism, theater of operation, vitals, and labs. Subgroup analysis was performed on severely injured (15 < ISS < 75) hypothermic trauma patients resuscitated with whole blood (WB) vs only component therapy. RESULTS: Of the 69,364 patients included, 908 (1.3%) arrived hypothermic; the vast majority of whom (N = 847, 93.3%) arrived mildly hypothermic (90-94.9°F). Overall mortality rate was 14.8%. Rates of hypothermia varied by year from 0.7% in 2003 to 3.9% in 2014 (P <0.005). On subgroup analysis, mortality rates were similar between patients resuscitated with WB vs only component therapy; though base deficit values were higher in the WB cohort (-10 vs -6, P < 0.001). CONCLUSION: Despite nearly 20 years of combat operations, hypothermia continues to be a challenge in military trauma and is associated with a high mortality rate. Mortality was similar between hypothermic trauma patients resuscitated with WB vs component therapy, despite greater physiologic derangements on arrival in patients who received WB. As the military has the potential to conduct missions in environments where the risk of hypothermia is high, further research into hypothermia mitigation techniques and resuscitation strategies in the deployed setting is warranted.