Hypothermia

Hypothermia occurs when the body temperature drops below 35°C due to excessive heat loss.

Causes of hypothermia

 * Environmental influence - 'hypothermia (+ high humidity, wind, physical exhaustion, drunkenness, injuries, ...)
 * Reduced metabolism - severe hypothyroidism, hypoglycemia, hypopituitarism, ketoacidosis, malnutrition
 * Intoxication (alcohol, barbiturates, sedatives)
 * Brain damage, trauma, sepsis
 * Increased heat loss through the skin - burns

Consequences of hypothermia

 * The first signs arise from the effect of abnormal temperature on the CNS - ataxia, amnesia, speech disorders, behavior (paradoxical undressing), hallucinations, ...
 * Below 33 °C, muscle tremors stop, metabolism decreases (at 28°C by 50%)
 * Hematocrit and viscosity of the blood increase
 * Impaired renal function - cold diuresis followed by oliguria


 * Rise in pH (spontaneous return when the temperature rises)
 * Impaired detoxification and conjugation function of the liver, hyperglycemia
 * Often pancreatitis and gastric bleeding

Effect on the heart
 * Progressive decline of heart rate and MSV!
 * Blood pressure first rises, then falls - poorly palpable pulse
 * Despite hyperkalemia, myocardial excitability increases - frequent atrial fibrillation
 * When the temperature drops below 28 - 30 °C risk of ventricular fibrillation! (terminal stage!)
 * Changes on ECG (Osborn wave)

The body can cope with hypothermia (up to 20 °C) surprisingly well. This is because there is a reduction in metabolism and requirements for O2. Therefore, prolonged resuscitation is recommended and justified in critical hypothermic states. In case of death due to hypothermia, the postmortem signs are - purple skin, swelling in the face, gastric erosion, multi-organ infarctions as a result of hypothermic shock.

Use of hypothermia in medicine

 * Controlled surgical hypothermia (heart, brain surgery), local anesthesia
 * Cold treatment (hypoxic conditions, physiotherapy, sports, swelling, inflammation, hardening, cryotherapy, cryosauna, ...)

Related Articles

 * Hyperthermia
 * Cryosurgery
 * Cryotherapy
 * Thermoregulation
 * Effects of extreme temperatures on living organisms