Pre-hospital rewarming methods for hypothermia casualties

Various methods exist for rewarming hypothermia casualties. Most of these methods necessitate sophisticated medical equipment or vigorous hemodynamic and electrolytic monitoring. Therefore, only a few methods remain suitable for pre-hospital scenarios. The current work reviews the literature regarding these pre-hospital rewarming methods, focusing on their efficacy and compatibility to the cold prehospital environment with its limited resources. By relying on endogenous heat producing mechanisms and by isolating the victim, one can achieve fairly efficient rewarming for mild hypothermia (rectal temperature of 32°C-35°C) casualties. Many consider this as an independent rewarming method (passive or endogeneous rewarming method), advisable for mild hypothermia cases. There are also many active rewarming methods, suitable for pre-hospital treatment. These methods, however, suppress the endogenous heat producing mechanisms, and therefore are not more efficient than passive rewarming for mild hypothermia cases. In moderate or severe hypothermia casualties, hypothermia (rectal temperature below 32°C) however, is characterized by suppressed or deficient endogenous heat producing mechanisms. Passive rewarming is not enough in these cases, necessitating the addition of active, central or peripheral rewarming methods. Studies regarding the use of various active rewarming methods in severe hypothermia casualties revealed low rewarming efficacy for the low heat capacity methods, such as warm air inhalation, and a high rewarming efficacy for the high heat capacity methods, such as forced air methods.