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Emerg Med J. 2018 Sep;35(9):564-570. doi: 10.1136/emermed-2017-207112. Epub 2018 Jun 7.

Comparison of the performance of battery-operated fluid warmers.

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Department of Anesthesiology, Rambam healthcare campus, Haifa, Israel.
Ruth and Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel.
Surgeon General's Headquarters, Medical Corps, Israel Defense Forces, Tel Aviv, Israel.
Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin, USA.



Warming intravenous fluids is essential to prevent hypothermia in patients with trauma, especially when large volumes are administered. Prehospital and transport settings require fluid warmers to be small, energy efficient and independent of external power supply. We compared the warming properties and resistance to flow of currently available battery-operated fluid warmers.


Fluid warming was evaluated at 50, 100 and 200 mL/min at a constant input temperature of 20°C and 10°C using a cardiopulmonary bypass roller pump and cooler. Output temperature was continuously recorded.


Performance of fluid warmers varied with flows and input temperatures. At an input temperature of 20°C and flow of 50 mL/min, the Buddy Lite, enFlow, Thermal Angel and Warrior warmed 3.4, 2.4, 1 and 3.6 L to over 35°C, respectively. However, at an input temperature of 10°C and flow of 200 mL/min, the Buddy Lite failed to warm, the enFlow warmed 3.3 L to 25.7°C, the Thermal Angel warmed 1.5 L to 20.9°C and the Warrior warmed 3.4 L to 34.4°C (p<0.0001).


We found significant differences between the fluid warmers: the use of the Buddy Lite should be limited to moderate input temperature and low flow rates. The use of the Thermal Angel is limited to low volumes due to battery capacity and low output temperature at extreme conditions. The Warrior provides the best warming performance at high infusion rates, as well as low input temperatures, and was able to warm the largest volumes in these conditions.


critical care transport; environmental medicine, hypothermia; equipment evaluation; expedition medicine; hypothermia

[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Competing interests: AR reports receiving consultant fee from Medtronic outside the submitted work. This project received non-financial support from QinFlow Ltd, Tel-Aviv, Israel (providing a Belmont Buddy Lite, Estill Medical Technologies Thermal Angel and QinFlow Warrior units for testing) and from the Israel Defense Forces, Medical Corps (providing CareFusion enFlow unit for testing).

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