Hypothermia Prevention, Recognition and Treatment.
Articles, Protocols and Research on Life-saving skills.

The recommended treatment of hypothermia in the field is core rewarming to prevent post-rescue collapse.

Treating Hypothermia: A life-saving skill

The growing popularity of outdoor recreation has resulted in greater demand for an effective on-site method for treating hypothermia. Other than for mild cases, the most effective and safest treatment for all levels of hypothermia is the addition of heat to the body core, rather than via the periphery.

The most important phase of treatment is the prevention of post-rescue collapse during the first 30 minutes following rescue, and during transportation to a medical facility.

Phases and treatment of hypothermia.

After-drop

A further cooling of core temperature occurs after the victim is removed from the cold environment. This after-drop is often responsible for post-rescue collapse.

Pre-hospital stabilization

Preventing respiratory heat loss and progressive cooling, of the heart through the tissues is essential. This cooling if not arrested, can lead to ventricular fibrillation of the heart. Patients who are unconscious, with a temperature below 30°C or 80°F, may not respond to defibrillation. Thermally stabilizing a patient with suitable equipment is necessary, both before transportation and enroute to the hospital to prevent additional cardiac complications.

Core rewarming

This is the most effective treatment for all cases of moderate to severe hypothermia, whether treatment occurs in the hospital or in the field.

Inhalation rewarming

As the only non-invasive hospital treatment suitable for active core rewarming in the field, inhalation rewarming donates heat directly to the head, neck, and thoracic core (the critical core) through inhalation of warm, water-saturated air at 43 - 45°C (107 - 122°F). This method also warms the hypothalemus, the temperature regulation center, the respiratory center, and the cardiac center at the base of the brainstem. In many cases, this rewarming of the central nervous system at the brainstem reverses the cold-induced depression of the respiratory centers and improves the level of consciousness.

Beside this strategic donation of heat, inhalation rewarming also eliminates . .
Respiratory heat loss
This accounts for 10% to 30% of the body's heat loss. This is particularly important in rescue situations where the ambient air is cold (cooling of the core through respiration).

In summary, inhalation rewarming is highly effective in providing "basic life support" through thermally stabilizing the core and brainstem temperatures. It is safe for treatment for all levels of hypothermia, but is particularly important for severe cases, because insulating alone (blankets), does not prevent further cooling of the core.

The first half hour during rescue is the most critical phase of hypothermia management!

Avoid having the victim assist with their own rescue!

Muscular activity by the hypothermic victim pumps cold peripheral blood from the arms and legs into the central circulation causing the core temperature to drop even further. Gentle handling is critical! A cold heart is particular susceptible to ventricular fibrillation, and some victims may suffer fatal ventriculation when jolted about during initial handling or transportation.

" The inhalation rewarming method is now our first choice in the re-warming treatment of all stages of hypothermia in the wilderness environment. " ( Dr. Ian Taylor, Medical Adviser to the North Shore Rescue Team, Vancouver B.C.).

Sources:
¹ Danzl, D. Accidental hypothermia. Emergency Medicine: Concepts in Clinical Practice. Rosen et al. Mosby Publishers.
² Hayward, J.S. et al. Thermal and cardiovascular changes during three methods of resuscitation from mild hypothermia. Resuscitation 11:21-33.
³ Harnett, R.M. et al. A review of the literature concerning resuscitation from hypothermia, Aviation Space Environmental Medicine. Part I 54(5):425-434. Part II 54(6):487-495.
⁴ Danzl, D. et al Accidental hypothermia: Always a Danger. Patient Care 17 (19):116-151, and personal communication.
⁵ Morrison, J.B. et al. Influence of respiratory heat transfer on thermogenesis and heat storage after cold immersion. Clinical science 63:127-135.
⁶ Collis, M.L. et al. Accidental Hypothermia: A Study of Practical Rewarming Methods.  Aviation Space Environmental Medicine. 48 (7) 625-632.
⁷ Hayward, J.S. et al. Accidental Hypothermia: An Experimental Study of Inhalation Rewarming. Aviation Space Environmental Medicine.  46(10):1236-1240, and personal communication.

Published by Robert Douwens.

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