Hypothermia reduces the energy production and oxygen consumption in the body. When the core temperature is reduced by 10 degrees C, the oxygen consumption is halved. To counteract a further fall in temperature, the body will try to increase the heat production by means of muscular activity – shivering. This activity drains the easily convertible energy sources (carbohydrates) present in the liver and muscles. When the temperature has fallen below 33 degrees C, the shivering seizes. From this point, the temperature will sink even quicker. Confusion and disorientation will increase with a further fall in temperature, and the body movements will become uncoordinated. The consciousness is increasingly slurred, and below 30 degrees C most victims are unconscious. At temperatures between 30 and 26 degrees C, disturbances of the heart rhythm are likely to occur e.g. heart fibrillation with circulation failure. Manhandling the victim may trigger this condition. Therefore, moving of the victim must be performed with great care
- fall into cold water
- lasting state of unconsciousness caused by injuries, drugs or medicaments
Stages of hypothermia
Mild hypothermia (34-35 degrees C)
Moderate hypothermia (30-34 degrees C)
Each of these conditions is characterized by:
- reduced consciousness
- low pulse rate
- low respiration rate,
- low blood pressure
Deep hypothermia ( below 30 degrees C)
- loss of consciousness
- difficult to monitor pulse and respiration
- rigid muscles
- dilated pupils
- great danger of heart fibrillation
- circulation failure
- body temperature (use an electronic thermometer in the rectum)
- pupil reaction to light
- respiration rate
- pulse rate
First aid. Unconscious patient
- if no respiration: perform mouth to mouth inflation , or preferably use a ventilation bag
with oxygen. Handle the victim with great care
- if no pulse: start heart compression
- stop further heat loss
- start re-warming if evacuation to hospital is not possible
Because the pump function of the heart is strongly reduced in hypothermia, re-warming should ideally start with the heart. This is not possible, but there are methods to re-warm the inner organs without having to re-warm the large skin areas on the extremities first.
Victim unconscious (Temperature below 30 degrees C)
The best method of re-warming is either to warm the chest and abdomen with hot water (42 degrees C), or to place the arms of and legs of the victim in containers with water that is gradually heated to 42 degrees C. Each of these methods provides an efficacious re-warming of central organs without the unwanted re-warming of the muscle mass. With the latter method the arms and legs act as radiators and warm blood is transported to the heart. In addition, it is recommended to administer intravenous infusion of heated (42 degrees C) 5 per cent glucose solution, 0.9 NaCl solution or Ringer acetate solution.
Victim awake (Temperature above 30 degrees C)
Because the blood glucose will be low, the patient should receive sweetened beverages. He should rest and not be left alone.
One fourth of deaths in hypothermia occurs during treatment
The reason for this is that the pump function of the heart is impaired and the ability to keep a sufficient blood pressure is reduced. The patient should remain in the supine position. Physical activity and standing up will make the blood pressure to drop Warm showers in the standing position are not recommended.
If the patient has been in the water for a long time, the blood volume will be reduced due to increased urine production. The victim should therefore increase his intake of fluid, preferably in the form of sweet beverages.
During re-warming the core temperature may drop another few degrees before starting to increase. During these period disturbances of the heart rhythm may occur
Frostbites occur in low temperatures combined with wind, humidity and physical passivity.
A damage will result when the temperature in the tissue has reached the freezing point and the local circulation comes to a halt. A part of the tissue may die and leave a wound.
Fig. 2 Stages of frost bite
In superficial frostbites the damage is limited to the superficial layer of the skin. The affected area is white like wax and painful. The sensitivity to needle prick and touching may be reduced or lost
Fig. 3 Superficial frost bite
In deep frostbites there is injury to all layers of the skin. The symptoms are the same as for superficial frostbites, but the affected area feels hard to touch. Wounds and blisters may develop
Fig 3 Deep frost bite
The most efficacious treatment is rapid re-warming of the affected area. Use water that is heated to 42 degrees C in the course of 10 minutes. The treatment will induce pain and swelling. Wounds and blisters should be treated in the same way as in burns.