Expeditionary Immersion Circulating Heating Device: A Promising Technique for Treating Frostbite Injuries and Warming Intravenous Fluids in a Forward Deployed Cold Weather Environment

Introduction Cold weather injuries require prompt warm water immersion therapy, which proves to be a difficult task in the cold austere environment. Current guidelines recommend 104 °F water immersion, but producing and maintaining large volumes of warm water is challenging in sub-freezing temperatures. We describe a novel process of utilizing a sous vide immersion circulator to maintain warm fluids for immersion therapy and efficient fluid rewarming in a cold forward-deployed setting for the treatment of cold weather injuries in an effort to bridge the gap between current medical guidelines and practices. Materials and Methods Large water cans were warmed to 104 °F with the immersion circulator. A thermometer was inserted into a 1-inch steak, frozen to 30 °F, and placed in a basin with only the warmed water while the internal temperature was monitored until physiologic temperature was achieved. The time to this endpoint was recorded. A 1-L bag of normal saline and a 450-mL bag of whole blood were also separately warmed by the same technique. The temperature of the normal saline was monitored at 0-, 5-, 7-, 8-, 9-, and 10 -minute intervals. The process was similarly repeated, measuring the whole blood temperature at 0-, 5-, 7-, and 10-minute intervals. Results Ambient internal tent temperatures averaged 54 °F; outdoor temperatures were consistently sub-freezing. The 5-gallon cans of water at ambient temperature heated to 104 °F in 15 minutes. The water temperature remained constant for 3 weeks with the circulator running. The frozen steak started at 30 °F and reached 98 °F in 52 minutes and 45 seconds. The bag of normal saline and whole blood, refrigerated to 39 °F, achieved temperatures of 102 °F and 94 °F respectively after 10 minutes. Conclusion A heating immersion circulator device is a lightweight, flameless, and inexpensive way to consistently heat large volumes of water for treatment of cold weather injuries, hypothermia, and whole blood rewarming in a cold austere environment.