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As core temperature decreases below 82°F (28°C) (severe hypothermia), the heart
is at risk of ventricular fibrillation either spontaneously due to low heart temperature, or
as a reflex response to mechanical stimulation. The patient loses consciousness and
pupils may be dilated and fixed. The torso will be cold to touch. The patient may be rigid
and unresponsive, with non-palpable pulse and respirations, but not dead (the patient
cannot be presumed dead unless these conditions persist after warming, or if obvious
signs of fatal trauma are present).
II. GUIDELINES FOR FIELD TREATMENT
A) General Principles: The general principles of treatment apply for all cases of
hypothermia. The patient must be gently removed from the cold exposure and remain in
a horizontal position. REMOVE WET CLOTHING CAREFULLY AND INSULATE
THE PATIENT COMPLETELY (i.e., with one or even two sleeping bags), while
maintaining an adequate exposure of the airways. This will minimize convective and
conductive heat loss. A vapor barrier (i.e., plastic sheet, space blanket etc.) can be added
to eliminate evaporative heat loss and PROTECT THE INSULATION FROM
BECOMING WET. If wet clothing cannot be removed safely, place the vapor barrier
between the clothing and insulation. If the patient is dry, the barrier could be placed
outside the insulation.
B) Mild Hypothermia: A mildly hypothermic patient will normally be shivering
vigorously and may be dehydrated. Administer fuel for shivering with warm high-energy
drinks (non-alcohol) and foods, providing the patient is alert and can swallow without
choking.
External heat sources, such as chemical or charcoal heat packs and hot water
bottles can be used. For rewarming purposes, the heat should be applied preferentially to
the chest and armpits. During winter transport heat should be applied to the soles of the
feet to prevent frostbite (PROVIDED FROSTBITE IS NOT ALREADY PRESENT).
Place the palms of the hands on the chest. Do not apply these heat sources directly to the
patient's skin, but over a thin layer of clothing.
Exercise will generate heat but may also precipitate a significant drop in core
temperature (afterdrop). If the patient is otherwise healthy and vigorously shivering, mild
exercise may be initiated only after 45 to 60 minutes of shivering in an insulated
environment. At this point the afterdrop should be reversed. However, if any
deterioration in physical or mental condition occurs during exercise, it should stop
immediately.
C) Moderate-to-Severe Hypothermia: Whether a patient is moderately or severely
hypothermic, the clinical condition is serious: treatment is the same UNDER ALL
CIRCUMSTANCES. The patient must be handled very gently and kept in the horizontal
position. Because of the risk of inducing ventricular fibrillation, remove wet clothing and
take care to minimize patient movement while performing other life-sustaining measures.
Make arrangements to transfer the patient to medical facilities as soon as possible.
Shivering will be weak, intermittent or nonexistent and the patient will not
rewarm spontaneously. The condition may degenerate progressively. Application of
