This report is aimed at those doctors, nurses, paramedics and first aiders who may be involved with the immediate out of hospital management of casualties suffering the effects of cold.

The Royal College of Physicians of London has defined Accidental Hypothermia as a state which exists when the body core temperature falls below 35^oC. To avoid confusion with the medical definition of hypothermia, the term "cold casualty" will be used in this report.

During exposure to a cold environment, a cold casualty results if the rate of heat being lost from the body exceeds that being produced by metabolism. This can occur as a result of heat production being overwhelmed by the cold stress of the environment, for example during immersion. A cold casualty can also occur in an environment that is only moderately cold if heat production is impaired due to exhaustion or intoxication from drugs or alcohol, or when injury or some accident causes immobilisation. The combination of exhaustion and exposure can be very threatening; this is classically encountered on the hills. Deterioration can be rapid. Those with early chilling are at considerable risk particularly if their clothing is wet or flimsy, and the wind speed is significant.

The very old and very young are particularly vulnerable to the cold.

Recognition

As the onset of body cooling may be insidious, an awareness of this potential risk is essential for its prevention, early recognition and treatment. Early signs may include: shivering; behavioural or personality changes; slurring of speech; inco-ordination; stumbling and slowing of physical and mental activity.

In the situations in which casualties are likely to be suffering the effects of cold (exposure and immersion), it would be unusual for a thermometer, particularly a low reading rectal thermometer, to be available. For practical purposes, therefore, a casualty may be considered to be suffering the effects of cold if his body feels "as cold as marble" and in particular, if the armpit is profoundly cold.

Rescue

At all times it is important to ensure the safety of the rescuer as well as the casualty. This becomes particularly important when the casualty is in a hostile environment, such as in the water or on a hillside. The rescuer must ensure that he does not also become a casualty from the cold, either through exhaustion or due to loss of insulation as a result of donating his own clothing to the casualty.

Management

General guidelines on management are given for three broad categories of casualty:

A. all cold casualties;

B. cold, conscious or confused casualty;

C. unconscious or semi-conscious casualty

Additional guidance is given for two specific situations: immersion and those at home or "sleeping rough".

(A) All Cold Casualties

1. Lay the casualty flat, give essential first aid for any injury, and undertake resuscitation if indicated. (see below)

2. Prevent further heat loss by enclosing the casualty in a casualty bag or sleeping bag, or cover with any available material such as a blanket or spare clothing, and include cover for the head. Insulate from the ground and provide overall waterproof and windproof protection if required, for example by using a polythene cover. Once this protective cocoon has been established any disturbance risks further heat loss.

The "space blanket" is expensive and largely ineffective in hostile outdoor environmentswhere radiation is relatively insignificant compared with other routes of heat loss.

3. Provide further protection from the wind and elements by finding or creating shelter if possible. As a temporary measure two rescuers lying alongside a cold casualty and "hugging" him can be surprisingly effective. If the environment remains cold and hostile, do not attempt to undress the casualty. Instead insulate and enclose him in an impermeable covering. (see paragraph 2 above)

4. If possible the casualty should be carefully moved, lying flat, to a warmer environment, for example a shelter or house, to reduce further heat loss.

5. Ideally, rewarming should be passive with the heat coming from the core of the body rather than the surface. Even in a warm environment, the casualty should be wrapped in blankets or a sleeping bag to insulate from external heat; there is otherwise a danger that rewarming may occur too quickly from the surface, resulting in a potentially catastrophic fall in blood pressure.

6. Consider "airway insulation" (commonly but incorrectly referred to as "airway warming") if a suitable device is available, provided that its use does not result in any delay in rescue. The simplest device is a heat and moisture exchanger - even a loose scarf over the nose and mouth can help, provided the airway is not compromised. Oxygen can be valuable but should not be given if the cylinder is very cold.

7. Maintain close observation of the casualty’s pulse and respiration.

8. Obtain help as soon as possible and transport the casualty to hospital.

ADDITIONAL MANAGEMENT

(B). Cold, Conscious or Confused Casualty

1. Once under shelter, if the casualty’s clothing is dry he should be kept in blankets or a sleeping bag with cover over his head and allowed to rewarm slowly. If his clothing is wet he should be given assistance to replace his wet clothing with dry.

2. Offer a warm sweet drink if available but only if the casualty is able to swallow easily. This will have little effect on raising body temperature but may be comforting. Do no give any alcohol. Enquire about coexisting illness such as diabetes, epilepsy etc., as this information may be valuable to subsequent medical attendants.

3. If evacuation to hospital is not immediately possible and facilities are available, a casualty who is conscious, shivering and uninjured, may be immersed to the neck in a hot bath, provided he can get into it with minimal assistance. The temperature of the bath should approximate but not exceed 40^oC (which feels comfortable to your own elbow and to the casualty), and should be maintained at this temperature by constantly stirring and adding hot water as necessary. This treatment will require a large supply of hot water. Heavy outer clothing should be gently removed before the casualty is immersed. Assistance should be given to remove the remaining clothing when the casualty is comfortably settled in the bath. Cessation of shivering will occur almost immediately on immersion in the hot water butthis should not be interpreted as an indication for removing the casualty. When the casualty becomes comfortably warm help him out of the bath, encourage him tolie flat, dry and cover him with blankets. Do not allow him to remain in the bath if he complains of feeling hot or starts sweating.

4. Keep the casualty lying flat until he is warm both subjectively and to the touch.

(C). Unconscious or Semi-conscious Casualty: (unable to help himself without assistance)

The profoundly cold casualty should be regarded as being in a critical condition. The major objective of management is the prevention of further heat loss to enable passive rewarming to occur. Any unnecessary movement of the casualty should be avoided as it may precipitate cardiac arrest.

1. Once under shelter the casualty should be carefully wrapped in blankets or a sleeping bag. Wet clothing should only be removed if sufficient rescuers are available to dothis with minimum movement of the casualty. This will almost inevitably necessitate cutting some of the clothing.

2. Carefully place the casualty in the recovery position until he regains consciousness, and then maintain him lying flat until he is warm both subjectively and to the touch.

CARDIOPULMONARY RESUSCITATION IN COLD CASUALTIES

1. If breathing is absent, becomes obstructed or stops, standard expired air ventilation (mouth-to-mouth with or without aduncts such as airways and masks) should be instituted.

2. Chest compression should be started only if:

a. there is no carotid pulse detectable after feeling in the correct place for at least one minute. this length of time is needed because if the pulse is frequently slow and weak in profound hypothermia

and

b. cardiac arrest is observed (i.e. pulse was present when rescued or found but subsequently disappears) or there is a reasonable possibility that a cardiac arrest occurred with the previous 2 hours

and

c. there is a reasonable expectation that effective CPR can be provided continuously (or with only brief periods of interruption for movement of the casualty) until the casualty can be transported to a hospital or site where full advanced life support can be provided. In practice, this is likely to mean being within 2 hours travelling time of a suitable hospital.

Cardiopulmonary resuscitation that cannot be maintained effectively will only serve to exhaust the rescuers and lead in turn to them becoming casualties.

3. The rates for both expired air ventilation and chest compression should be the same as for normothermic casualties. It must be recognised, however, thar hypothermia may cause stiffness of the chest wall so that more resistance is met. The aims should be inflate with a volume of air sufficient to cause the chest to rise visibly, and to compress the chest (sternum) to a depth of 4-5 cms in an adult (2.3 cms in a child; 1-1.5 cms in an infant).

4. If at any time a pulse is detected there should be no further attempt at cardiopulmonary resuscitation whilst it is still present.

Immersion

Drowning remains the most commonly encountered problem associated with immersion casualties. However, the casualty who has visibly maintained his face clear of the water is more likely to be suffering from the effects of cold. This may cause loss of the normal blood pressure regulatory reflexes which, together with the sudden loss of supportive hydrostatic squeeze from the water, may lead to severe hypotension on removal from the water. If possible the casualty should be rescued horizontally. It is, however, often more important to get the casualty out of the water quickly than to delay to enable horizontal rescue.

No attempt should be made to empty water out of the lungs since the little free fluid that is likely to be there is difficult or impossible to get out; there is the added danger that any water expelled will be from the stomach and may then be aspirated into the lungs.

If a casualty is rescued from ice cold water, attempts at resuscitation should be made even if the casualty has been totally submerged for up to one hour. Particularly in children, death should not be assumed. The diagnosis of death should only be made in hospital.

At home or "sleeping rough"

A cold casualty found collapsed at home or outdoors "sleeping rough", should be wrapped in blankets and transported to a hospital, observing normal first aid principles and safeguarding the airway.

If signs of life are present when the casualty is found, but subsequently respiration or pulse disappears, standard cardiopulmonary resuscitation should be instituted.

 30/12/01