Hypothermia is caused by prolonged exposures to very cold temperatures. When exposed to cold temperatures, your body begins to lose heat faster than it’s produced. Lengthy exposures will eventually use up your body’s stored energy, which leads to lower body temperature.
Body temperature that is too low affects the brain, making the victim unable to think clearly or move well. This makes hypothermia especially dangerous, because a person may not know that it’s happening and won’t be able to do anything about it.
While hypothermia is most likely at very cold temperatures, it can occur even at cool temperatures (above 40°F) if a person becomes chilled from rain, sweat, or submersion in cold water.
What Are the Risk Factors for Hypothermia?
People at increased risk for hypothermia include:
- The elderly, infants, and children without adequate heating, clothing, or food
- People with mental illness
- People who are outdoors for extended periods
- People in cold weather whose judgement is impaired by alcohol or drugs
What Are the Symptoms of Hypothermia?
Hypothermia symptoms for adults include:
- Shivering, which may stop as hypothermia progresses (shivering is actually a good sign that a person's heat regulation systems are still active. )
- Slow, shallow breathing
- Confusion and memory loss
- Drowsiness or exhaustion
- Slurred or mumbled speech
- Loss of coordination, fumbling hands, stumbling steps
- A slow, weak pulse
In severe hypothermia, a person may be unconscious without obvious signs of breathing or a pulse
Hypothermia symptoms for infants include:
- Cold-to-touch, bright red skin
- Unusually low energy
How Is Hypothermia Diagnosed?
Recognizing the symptoms is the first step in diagnosing hypothermia. A specialized thermometer, available in most hospital emergency rooms, can detect very low core body temperatures and confirm a diagnosis.
Temperatures for mild, moderate, and severe hypothermia generally range from:
Mild hypothermia: 89-95 degrees Farenheit
Moderate hypothermia: 82-89 degrees Farenheit
Severe hypothermia: Lower than 82 degrees Farenheit
Because response to hypothermia varies among individuals, temperatures may differ.
What Is the Treatment for Hypothermia?
Hypothermia is a potentially life-threatening condition that needs emergency medical attention.
If medical care isn't immediately available:
Remove any wet clothes, hats, gloves, shoes, and socks.
Protect the person against wind, drafts, and further heat loss with warm, dry clothes and blankets.
Move gently to a warm, dry shelter as soon as possible.
Begin rewarming the person with extra clothing. Use warm blankets. Other helpful items for warming are: an electric blanket to the torso area and hot packs and heating pad on the torso, armpits, neck, and groin; however, these can cause burns to the skin. Use your own body heat if nothing else is available.
Take the person's temperature if a thermometer is available.
Offer warm liquids, but avoid alcohol and caffeine, which speed up heat loss. Don't try to give fluids to an unconscious person.
If the hypothermic person is unconscious, or has no pulse or signs of breathing, call for emergency help right away. CPR (cardiopulmonary resuscitation) should be given immediately if a pulse can’t be felt and there is no sign of breathing. Feel for the pulse for up to a whole minute before starting CPR, because the heart rate may be extremely slow and you should not start CPR if there is any heart beat present.
CPR should be continued, in the absence of signs of breathing or a pulse, until paramedics arrive or the person is taken to a hospital.
In cases of advanced hypothermia, hospital treatment is required to rewarm the core temperature. Hypothermia treatment may include warmed IV fluids, heated and humidified oxygen, peritoneal lavage (internal "washing" of the abdominal cavity), and other measures. Complications during recovery can include pneumonia, heart arrhythmias, ventricular fibrillation (a dangerous "fluttering" rhythm of the heart), cardiac arrest (a sudden stopping of the heartbeat), and death.
Seek immediate medical help for anyone with hypothermia. Call 911 if you suspect severe hypothermia.
Hypothermia is reduced body temperature that happens when a body dissipates more heat than it absorbs. In humans, it is defined as a body core temperature below 35.0 °C (95.0 °F). Symptoms depend on the temperature. In mild hypothermia there is shivering and mental confusion. In moderate hypothermia shivering stops and confusion increases. In severe hypothermia, there may be paradoxical undressing, in which a person removes his or her clothing, as well as an increased risk of the heart stopping.
Hypothermia has two main types of causes. It classically occurs from exposure to extreme cold. It may also occur from any condition that decreases heat production or increases heat loss. Commonly this includes alcohol intoxication but may also include low blood sugar, anorexia, and advanced age. Body temperature is usually maintained near a constant level of 36.5–37.5 °C (97.7–99.5 °F) through thermoregulation. Efforts to increase body temperature involve shivering, increased voluntary activity, and putting on warmer clothing. Hypothermia may be diagnosed based on either a person's symptoms in the presence of risk factors or by measuring a person's core temperature.
The treatment of mild hypothermia involves warm drinks, warm clothing, and physical activity. In those with moderate hypothermia, heating blankets and warmed intravenous fluids are recommended. People with moderate or severe hypothermia should be moved gently. In severe hypothermia, extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass may be useful. In those without a pulse, cardiopulmonary resuscitation (CPR) is indicated along with the above measures. Rewarming is typically continued until a person's temperature is greater than 32 °C (90 °F). If there is no improvement at this point or the blood potassium level is greater than 12 mmol/liter at any time, resuscitation may be discontinued.
Hypothermia is the cause of at least 1,500 deaths a year in the United States. It is more common in older people and males. One of the lowest documented body temperatures from which someone with accidental hypothermia has survived is 13.0 °C (55.4 °F) in a near-drowning of a 7-year-old girl in Sweden. Survival after more than six hours of CPR has been described. For those for whom ECMO or bypass is used, survival is around 50%. Deaths due to hypothermia have played an important role in many wars. The term is from Greek ὑπο, ypo, meaning "under", and θερμία, thermía, meaning "heat". The opposite of hypothermia is hyperthermia, an increased body temperature due to failed thermoregulation.