Risk factors
Particularly at risk of suffering hypothermia are
- Old and sick people (especially dementia patients)
- Miners and divers
- Homeless
- Under- or malnourished persons
- Alcoholized persons
- People with thermoregulation disorders
- Diabetics and thyroid gland patients, because their temperature sensation is disturbed
- Newborn babies
Symptoms and stages
The symptoms of hypothermia depend on the extent of the hypothermia; the further the body core temperature drops, the more life-threatening the condition becomes for the body. Hypothermia is divided into four phases, which are composed of the degree of hypothermia and the physical reactions of the hypothermic person.
- Phase 1 = Defense stage: In this stage, the body temperature is between 34.0 and 36.0°C.
The body tries to produce heat by shivering and to maintain the lowered temperature. The blood vessels contract (constriction) so that the extremities in particular are supplied with less blood. This creates a centralized blood circulation and the narrowed vessels lead to an increase in blood pressure.
In addition, the heartbeat is increased and breathing is accelerated. Unconsciousness does not yet occur at this stage.
- Phase 2 = Exhaustion stage: The body temperature is between 30.0 -34.0°C.At this stage, the body already gives up the attempt to maintain body temperature by counterregulation. There is no more shivering and the hypothermic patient becomes increasingly apathetic and disoriented.
The heart no longer tries to keep the body core warm by increasing its beat rate and the blood pressure drops. The pupils are dilated and the reflexes are reduced, noticeably especially the gag reflex. The body begins to become stiff overall, making it difficult to move the joints.
Therefore, when finding a hypothermic person, as few movements as possible should be made in order not to cause injury.
- Phase 3 = Paralysis stage: The body temperature has dropped to 27.0 to 30.0°C The patient becomes unconscious and physical reactions in the form of a defence mechanism occur only in response to a pain stimulus. There is the possibility of falling into a coma. Blood pressure and heart rate continue to drop and cardiac arrhythmias occur, which can go as far as fatal ventricular fibrillation.
- Phase 4 = suspended animation stage: The body temperature in this stage is only 24.0 to 27.0°C.
The unconscious person no longer reacts even to pain stimuli and is in a coma. The pupils are dilated and no longer react to light stimuli. The brain activity is measurably reduced. Both pulse and respiration can no longer be determined with certainty, so that a clear decision as to whether death has already occurred is hardly possible. In this state, a respiratory or circulatory arrest is possible at any time.
