Pre-hospital torso-warming modalities for severe hypothermia: a comparative study using a human model.

Area of Science:

• Emergency Medicine
• Thermoregulation Research
• Hypothermia Management

Background:

• Severe hypothermia presents a significant medical challenge, particularly when shivering, the body's primary heat-generating mechanism, is suppressed.
• Effective rewarming strategies are crucial for improving outcomes in hypothermic patients.

Purpose of the Study:

• To compare the efficacy of five distinct active torso-warming modalities in a human model of severe hypothermia.
• To evaluate the impact of these modalities on core temperature afterdrop and rewarming rates when shivering is inhibited.

Main Methods:

• Six subjects were subjected to controlled hypothermia in 8°C water.
• Following cooling, subjects received one of five torso-warming interventions for 120 minutes, including forced-air warming (varying wattages and covers) and body-to-body contact.
• Intravenous meperidine was administered to inhibit shivering throughout the rewarming phase.

Main Results:

• All active warming modalities attenuated the core temperature afterdrop compared to spontaneous warming.
• The 850-W forced-air heater with a rigid cover demonstrated the lowest afterdrop (0.17°C) and the highest rewarming rate (1.45°C/hr).
• Forced-air warming with a rigid cover and charcoal heating were more effective than body-to-body contact or warming with a blanket.

Conclusions:

• Active torso-warming is effective in managing core temperature afterdrop and facilitating rewarming in non-shivering hypothermic individuals.
• Heat delivery focused on the chest and the amount of heat applied significantly influenced rewarming effectiveness.
• The studied modalities are practical and portable, making them suitable for pre-hospital hypothermia management, especially when transport times are extended.