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.