As an outcome of combat injury and hemorrhagic shock, trauma-induced hypothermia (TIH) and the associated coagulopathy and acidosis result in significantly increased risk for death. In an effort to manage TIH, the Hypothermia Prevention and Management Kit™ (HPMK) was implemented in 2006 for battlefield casualties. Since no update has occurred in 14 years, the Committee on Tactical Combat Casualty Care (CoTCCC) decided to update the hypothermia prevention and management guidelines based on recent research findings, observations and lessons learned from the battlefield.

When combat casualties incur hemorrhage and shock, the effects of TIH result in significantly increased mortality while hypothermia prevention is the third most frequent life-saving intervention in battlefield casualties after vascular access and hemorrhage control. Therefore, the early recognition and prevention of hypothermia are essential during casualty assessment and care in battlefield trauma and hypothermia interventions should be implemented for every patient in shock or at risk of shock. Current CoTCCC hypothermia prevention guidelines do not mention the use of battery-powered intravenous (IV) blood/fluid warming devices with ideal output temperature and flow rates. However, it is suggested that one of essential hypothermia intervention is restoration of blood volume by infusing warm whole blood or blood components as one of active rewarming methods.

According to a prospective multicenter study of trauma patients who required massive transfusion, hypothermia on arrival was an independent predicator of mortality in that a lack of warm IV fluids is an iatrogenic contributor to the lethal triad. Resuscitation with blood products facilitates a return to baseline aerobic metabolism, increasing the body’s intrinsic ability to produce heat. However, infusion of blood at a storage temperature of 4°C–8°C (39°F–46°F) leads to a drop in core temperature. For example, with as little as 500mL of cold blood, a patient’s core temperature will drop by about 1°C and coagulation factor activity is reduced approximately 10%–15% for each 1°C drop in temperature. Furthermore, every decrease of 1.0°C (1.8°F) in core temperature below 36°C (96.8°F) results in a 10% increase in red blood cell (RBC) consumption in the first 24 hours of admission.

These associations between hypothermia and mortality as well as hypothermia and increase in blood-product consumption emphasize the need for effective hypothermia prevention at the point of injury (POI). In the proposed change to the guidelines, it is highlighted that the use of IV fluid/blood-warming devices is an essential component for managing hypothermia caused by either penetrating, blunt, or burn trauma. It is also specified that the devices should deliver consistent output temperatures at 38° (100°F) but no higher than 42°C (108°F) at a flow rate of up to 150mL/min and perform to standard within the extremes of military environments. Prehospital blood and IV fluid warming devices, therefore, must be fast, effective, and easy-to-use for rapid delivery of fluids or blood at the POI.

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