Management of hypothermia
Hypothermia is a life-threatening condition. Mild hypothermia alone should not result in death when treated appropriately, but the mortality rate from severe hypothermia is very high. The prime aim in the management of hypothermia in the field is the prevention of further heat loss. Patients with mild hypothermia can usually rewarm themselves if further heat loss is prevented. Even with special equipment it is virtually impossible to rewarm the profoundly hypothermic patient in the field, and prevention of further heat loss is the prime treatment, while awaiting urgent evacuation.
If hypothermia is suspected, commence treatment immediately. Do not continue to shelter. Shelter from cold, wind, rain, and snow should be provided by whatever means possible (e.g. tent, snow wall, bivvy bag). The patient must be kept as dry as possible. Attempt to provide a warm environment. Placing several rescuers inside the tent with the patient may help raise the air temperature.
If the patient is sufficiently alert to assist in the process, wet clothing can quickly be removed and replaced with dry, provided that this does not expose the patient to further heat loss. Cutting off clothing may speed this process. This may only be achievable in an environment of warm, still air. Gentle handling of the patient at all times is extremely important. With more severe hypothermia, or in adverse conditions, removal of wet clothing is usually too risky, in which case the use of a vapour barrier is recommended.
The vapour barrier principle
This is the accepted treatment for severe hypothermia in the field, and involves enclosing the patient, complete with all clothing, in waterproof material (e.g. Gore-Tex, plastic garbage bags), and then in a sleeping bag. Remember to cover the head and neck (keeping the face clear), as these are sites of high heat loss; up to 80% of total body heat loss may occur from the head and neck regions.
Ground insulation is essential, and improvisation to increase insulation with clothing or newspapers may be possible. The patient should be placed in a single prewarmed sleeping bag, or two bags zippered together, with one or two other rescuers dressed lightly in thermal underwear. The awake patient may be rehydrated with warm sweet drinks and high energy foods if they are able to swallow.
Heat sources such as chemical heat packs or hot water bottles may be applied to the patient's neck, armpits and groin. These are sites where large blood vessels lie close to the surface of the body, the aim being to provide heat to the body's core, rather than the surface. The heat source must be adequately wrapped in clothing or padding so as not to be too hot and not in direct contact with the skin, which risks burning the patient. Particular care must be taken in the semi-conscious or unconscious patient. The patient should be kept horizontal, as the hypothermic patient is prone to a fall in blood pressure (leading to fainting) if they are placed in an upright position. Exertion or massage of the extremities must not be allowed, as these increase heat loss.
The patient's condition may deteriorate in the first few hours following commencement of treatment due to shock or a further fall in body temperature. Excessively rough handling in treating hypothermic patients is a suspected cause of death. The comatose hypothermic patient must be handled extremely carefully because the heart is very sensitive; rough handling may precipitate cardiac arrest and death. The gentle, vigilant care of the semi-conscious or comatosed patient is a very taxing task, requiring the assistance of several rescuers.
Once a mildly hypothermic patient is rewarmed, well hydrated and has returned to normal function, then there is no need for evacuation, although care must be taken to prevent recurrence. If circumstances are such that adequate first aid measures cannot be delivered to the patient with mild hypothermia, then great care must be taken to monitor the patient for further deterioration while walking out.
Any patient who does not respond to the rewarming measures, who deteriorates or who has profound hypothermia must be treated with maximum first aid measures and evacuation arranged urgently.
Resuscitation of hypothermic patients
If breathing is absent, initiate mouth-to-mouth resuscitation immediately. For hypothermic patients it is wise to feel for a pulse at the carotid pulse for at least one minute, before declaring the patient pulseless. This is because in severe hypothermia the pulse may be slow, faint and very difficult to feel. CPR should not be undertaken in hypothermia if:
- there are obvious lethal injuries present
- chest wall depression is not possible (due to a rigid, frozen chest)
- any signs of life are present (e.g. pulse, breathing, movement)
- if there is danger to rescuers.
Management of the hypothermic patient
- Observe all party members.
- Treat as an emergency.
- Stop at the suspicion of hypothermia in any party member.
- Reassure victim and check whole party.
- Shelter from cold, wet, wind.
- Handle extremely gently at all times.
- Insulate from the cold, including the ground.
- Remember head insulation.
- Replace wet clothing with warm and dry clothing, but only if patient's state of consciousness and risk of further heat loss is minimal.
- Apply vapour barrier principle to retain warmth.
- Use prewarmed sleeping bags, with warmth from other bodies.
- Warming devices (e.g. hot water bottles) should be carefully applied to neck, armpits and groin.
- Wrap the patient in layers (e.g. clothing, vapour barrier, sleeping bag, insulation, tent or other shelter).
- Warm the air around the patient if possible (e.g. inside the tent).
- No alcohol.
- No activity.
- No rubbing or massaging.
- Monitor and record your management and the victim's condition.
- Seek urgent rescue and evacuation if severe hypothermia is suspected.
Ensure that other party members are not placed at risk of hypothermia during care of the first patient. Maintain the morale of the patient and other party members (including self!). It may be useful to delegate providing reassurance, explanation and comfort to a specific team member not involved in other aspects of patient care.
Summary of management of the hypothermic patient
In the hypothermic patient always consider that there may be other injuries present, particularly if the circumstances are not clear (e.g. finding an unconscious skier). Care of the unconscious patient should follow standard practice.