The human body can endure low temperature of environment a long time. Under the influence of cold skin blood vessels become narrower, limiting heat loss through the skin, muscle tone increases, there is a fever that increases metabolism and heat generation. These compensatory mechanisms act as long as the muscles are able to operate and produce heat, but an organism has an adequate supply of carbohydrates and fats for energy.
After the exhaustion of compensatory mechanisms (while continuing exposure to cold) there is a weakness, drowsiness, numb limbs, pulse and breathing become rare. In the final, arise brain ischemia, cardiac and respiratory arrest. Lethal cooling develops at a temperature of 0 ° C for 10-12 hours, while staying in the icy water - 30 minutes.
Deep hypothermia decreases the intensity of metabolic processes, reduces the oxygen demand even of cells of the cerebral cortex. At the deep hypothermia an organism can outlive 20-minute circulatory arrest. Therefore, distinguish the deep freezing from death presents certain difficulties. Even a straight line on the ECG and dilation of the pupils in cooled patient are not a reliable sign of death and did not rules out the possibility of recovery. To solve the problem of the reversibility state of the victim possible only after attempts to warm him.
Do not try for the victim with hypothermia to carry out resuscitation measures associated with changes in body position (external cardiac massage, tilting the head). Attempt defibrillation also wll not successful until the body temperature below +28 ° C. Such patients should be as fast as possible to send to prolonged artificial lung ventilation in an intensive care unit. At the same should continue external rewarming of the victim under anesthesia.
When fading from hypothermia should remember that when the body temperature drop below +30 ° C, change occurs the body's reaction to the introduction of medicinal substances. Therefore, the introduction of drugs until enhancing the body temperature should be carried out with great care.