Environmental exposure (hypothermia cold)

Head | General Practice | Environmental exposure (hypothermia cold) (Disease)


Exposure to cold can cause a dangerously low body temperature (hypothermia). The very old, very young, those with chronic illnesses, and the intoxicated are most susceptible. Becoming wet during the process increases the rate of body temperature drop. Death can result from cardiovascular collapse.

Symptoms of a cold injury depend on the underlying injury. Symptoms range from symptoms of frostnip and frostbite to symptoms of hypothermia. Symptoms of frostnip include pale skin, skin numbness, burning skin pain, and cool skin surface. Symptoms of frostbite include worsening skin pain and numbness, skin redness, and clear blisters. Early symptoms of hypothermia may include fatigue, irritability, poor judgment, dizziness, numbness, pale skin, and shivering.

Causes and Risk factors

A person with a cold injury has an abnormally low temperature or damage to the body, caused by exposure to a cold environment. Cold injuries include frostbite, frostnip, and hypothermia.

As the temperature falls, the body shunts blood away from the skin and exposure to the elements. Blood flow is increased to the vital organs of the body including the heart, lungs, kidney, and brain. The heart and brain are most sensitive to cold, and the electrical activity in these organs slows in response to cold. If the body temperature continues to decrease, organs begin to fail, and eventually death will occur.

The decrease in brain function occurs in direct relationship to the decrease in body temperature (the colder the body, the less the brain function). Brain function stops at a core temperature of 68 F (20 C).

The heart is subject to abnormal electrical rhythms as hypothermia progresses. Ventricular fibrillation, a disorganized rhythm in which the heart is unable to pump, may occur at core temperatures below 82. 4 F (28 C). This is one type of cardiac arrest.

Diagnosis and Treatment

The patient should be removed from the cold environment and placed in a warm shelter away from the wind. Wet clothing should be removed and replaced with a warm, dry covering including head covering. Emergency medical services should be called.

Passive rewarming with warm clothing in a warm environment may be all that is required for a conscious person who is shivering. Active rewarming may be considered for those who are colder, showing signs of confusion, or have other medical conditions that need attention. Warmed intravenous fluids, warming blankets, and warmed humidified air may be provided in the hospital. More aggressive core rewarming may include infusing warm fluids into the stomach or bladder, irrigating warm solutions into the chest or abdominal cavity, and in some situations, placing the patient on dialysis or heart bypass to rewarm the body. ...