HYPOTHERMIA: CAUSES, SIGNS, HOW TO STAY PROTECTED

Medically Reviewed by Dr. Rosmy Barrios

Hypothermia, or extreme cold exposure, is a potentially life-threatening condition. It is defined as a core body temperature below 95°F (35°C). It occurs due to an imbalance between heat loss and production. The body relinquishes heat faster than it can produce, causing its core temperature to drop. Severe heat loss is a medical emergency that can lead to morbid complications or even death if not treated promptly.

It is most commonly associated with exposure to extreme cold yet can also occur in milder temperatures if the body is wet or exposed to wind.

Symptoms and Hypothermia Stages

Hypothermia is classified according to three stages based on the severity of symptoms and body temperature^[1]:

1. Mild hypothermia: body temperature between 90-95°F (32-35°C); normal or nearly normal conscious state with shivering, cold, pale skin, slow movements, and numbness in the extremities.
2. Moderate hypothermia: body temperature between 82-90°F (28-32°C); shivering stops and is accompanied by confusion, slurred speech, loss of coordination, and difficulty breathing.
3. Severe hypothermia: body temperature below 82.4°F (28°C); loss of consciousness and difficulty detecting vital signs.

In severe cases, hypothermia can lead to organ failure and even death.

Complications of Hypothermia

If left untreated, hypothermia can lead to severe complications, including

• Frostbite: Frostbite occurs when the body's tissues freeze due to exposure to extreme cold temperatures. Low temperatures cause vasoconstriction in tissues (reducing blood flow); if this phenomenon persists for a significantly long time, the tissue dies (gangrene).
• Cardiac arrest: In severe cases of hypothermia, the heart may stop beating, leading to cardiac arrest. Organ failure can also occur due to slower metabolism.
• Death: If not treated promptly, hypothermia can be fatal.

Hypothermia Warning Signs

According to the CDC, warning signs in adults include^[2]:

• Shivering
• Exhaustion or feeling very tired
• Confusion
• Fumbling hands
• Memory loss
• Slurred speech
• Drowsiness
• Trying to undress despite being ice-cold

Signs of hypothermia in infants:

• Chilled skin that is bright red
• Minimal energy

What Causes Hypothermia?

There are many causes of rapid heat loss. Being in contact with something colder than body temperature or insufficient energy to sustain heat production can lead to hypothermia.

In cold temperatures, heat loss (up to 90%) mostly occurs through the skin, with the remainder exhaled from the lungs. Wind, moisture, and cold water accelerate heat loss significantly. The hypothalamus controls body temperature through processes like shivering and vasoconstriction, which generate heat and narrow blood vessels to conserve heat when cold.

Metabolism decreases as body temperature drops, which causes the heart and the liver to slow down. This can result in slowed brain activity, breathing, and heart rate, leading to confusion and eventual loss of consciousness.

There are three main types of hypothermia, each with unique causes.

Primary or Accidental Hypothermia

Results from prolonged unintentional exposure to cold temperatures in the environment.

Causes of accidental hypothermia include:

• Exposure to cold weather: Exposure to extreme frigid temperatures causes rapid heat loss, leading to hypothermia.
• Wet clothing: Wet clothing can decrease the body's ability to retain heat, making individuals more susceptible to hypothermia.
• Wind: Wind can increase the rate of heat loss from the body, making individuals more susceptible to hypothermia.
• Inadequate clothing: Not wearing enough warm clothing increases the risk of hypothermia.
• Immersion hypothermia: Occurs when the body loses heat rapidly due to immersion in cold water. Cold water can increase heat loss as much as 25 times.

Secondary Hypothermia

Secondary hypothermia is caused by underlying medical conditions or illnesses that affect the body's ability to regulate temperature. These include Parkinson's disease, brain tumors, multiple sclerosis and other neurological disorders, diabetes, hypothyroidism, and cardiovascular disease.

Medications, such as certain anesthetics, can lower core body temperature and the body's ability to regulate temperature by suppressing brain function. Other medicines that can interfere with temperature control include Clonidine and beta blockers.^{[3] [4]}

Risk Factors

Anyone can develop hypothermia, but certain factors can increase the risk, including:

• Age: Infants and older adults are more vulnerable to acquiring a dangerously low body temperature due to their bodies' decreased ability to regulate temperature.
• Medical conditions: Certain medical conditions, such as diabetes, hypothyroidism, and cardiovascular disease, can increase the risk of hypothermia.
• Alcohol: Alcohol can impair judgment and lower the ability to regulate core temperature, making individuals susceptible to hypothermia.
• Outdoor activities: People participating in outdoor activities such as skiing, hiking, and camping are at a higher risk of developing hypothermia.
• Inadequate shelter: People who are homeless or do not have access to proper shelter are at a higher risk of developing hypothermia.

Paradoxical Undressing: What is it and Why Does it Happen?

Paradoxical undressing is a phenomenon that occurs in some cases of hypothermia, where the individual begins to remove their clothing despite being in a state of extreme cold. This behavior is counterintuitive and can be dangerous as it can lead to further heat loss and worsen the condition.

The exact mechanism behind paradoxical undressing has yet to be fully understood. Researchers think it happens as a result of vasoconstriction and disorientation.^[5]

In severe hypothermia, the blood vessels dilate, leading to a feeling of warmth that confuses the victim and causes them to undress to "cool down". Extreme low core temperature also affects the brain, leading to confusion, hallucinations, and disorientation, which might be contributing factors.

Paradoxical undressing happens just before terminal burrowing, an even more bizarre behavior in which a person tries to dig or bury themselves. Hypothermia victims have been found in unexpected places, such as under beds, in closets, or behind bookshelves due to terminal burrowing. Researchers believe this is the same as a hibernation instinct displayed by other mammals.^[6]

Hypothermia Myths

The myths covered below about hypothermia can be dangerous as they may lead to a failure to seek timely medical attention.

Myth: We lose more heat through the head and should cover it to get warm.

Fact: Heat loss happens through any exposed skin area. The head is only about 10% of the body's surface area. Other body parts (e.g., hands, abdomen) would lose the same heat if exposed.

Parents should cover children's heads to prevent heat loss, as a baby's head accounts for over 20% of their body surface area at birth. The higher level of heat loss and inability to regulate temperature elevates their risk of hypothermia compared to adults with uncovered heads.^[7]

Myth: Get warm inside after being in the cold for too long.

Fact: Rapid rewarming can be harmful, mainly in severe hypothermia. For mild to moderate cases, gradual rewarming (indoors) is recommended. The body changes in extreme cold to adapt, like narrowing blood vessels and redirecting blood flow to vital organs. Suddenly exposing the body to warmth can cause a drop in blood pressure, dizziness, or cardiovascular issues. It can also lead to underestimating the severity of hypothermia.

Instead, monitor your temperature, remove wet clothing, wrap in blankets, and drink warm fluids to warm up gradually. Seek medical attention immediately if hypothermia is moderate to severe.

Diagnosis and Treatment of Hypothermia

If you suspect a person in your vicinity has hypothermia, urgently seek medical help. A doctor will perform a physical exam and may request blood tests to confirm the cause.

First Aid for Hypothermia

If you or someone you know is showing signs of hypothermia, call for medical help immediately.^[8]

Acting quickly to prevent complications is critical. While waiting for emergency services, you need to remove any causes of hypothermia. Here are some steps to take:

• Move the person slowly and gently to a sheltered area. Do not move them directly into a warm room, which may shock their system.
• Replace wet clothing with dry clothing.
• Passive Rewarming - Use careful methods to warm the body, such as extra clothing or blankets. Monitor their temperature for improvements. Do not administer direct heat, such as a heating pad, hot water, or a heat lamp, to warm up the individual since these methods can shock their system and exacerbate complications.
• If their temperature rises, start using warming devices near their core temperature. Offer warm drinks that are not too hot. Avoid caffeine or alcohol, as these can promote heat loss.

For an unconscious person, check their airways and pulse to see if they are breathing. If breathing is less than six breaths per minute, begin rescue breathing or CPR until an ambulance arrives.

Medical Treatment for Hypothermia

At a hospital, healthcare professionals will attempt to revive the patient. They will monitor their vitals, and if external rewarming methods fail to work, they will resort to internal methods, such as^[9]:

• Active internal rewarming: In severe cases of hypothermia, active internal rewarming may be necessary. This involves administering humidified air or warm intravenous fluids to raise the body's core temperature.
• Extracorporeal rewarming can help in cases of severe hypothermia, where other methods have failed. It involves using a machine to circulate warm blood through the body.

Prevention of Hypothermia

Avoiding exposure to extreme cold temperatures is one of the best prevention measures to take. Here are some tips to help you stay safe in cold weather:

• Wear warm, layered clothing that is resistant to the elements, and cover exposed skin to prevent heat loss.
• Avoid getting wet in cold weather, and change into dry clothing if you do get wet.
• Stay out of strong winds in frigid weather.
• Limit factors that can lower blood circulation, such as smoking, clothes or shoes that are too tight, awkward postures (such as squatting or crouching for long periods), and fatigue.
• If stranded in a very cold environment, do not move around too much and huddle with others if possible to conserve energy.
• If moving between warmer environments, movement can help maintain a stable temperature.
• Heat the home above 68 F (20 C) in icy weather.
• Drink plenty of fluids to stifle dehydration, which can increase the risk of hypothermia.
• If you are outdoors, seek shelter in a warm, dry place. Remember to allow your body to gradually adjust to a warmer temperature to avoid shocking your system.
• Avoid excessive alcohol consumption in freezing weather, as it can impair judgment and decrease the body's ability to regulate temperature, making individuals more susceptible to hypothermia.

Cold Water Safety

If you plan to travel across or near water in icy weather, you need to prepare. Dress appropriately to keep warm, and ensure you have a life jacket.

If you fall into cold water, use the life jacket to remain afloat, and do not swim unless you have a quick escape route. Get out of the water as soon as possible. If you cannot, fold your knees into your body to minimize heat loss.This position is also known as the heat escape lessening posture (HELP). Else, if you are with others, huddle for warmth. Do not remove clothing, and make sure your clothing is fastened until you can change into warm spares on dry land.

Snow Travel Preparation

To avoid the risks of hypothermia, it is vital to prepare for unexpected situations, such as your vehicle breaking down or getting stuck in the snow.

For those living in snowy areas, keeping an anti-hypothermia kit in the car is a good idea. Include warm blankets, extra clothing, hand warmers, non-perishable food, water, a flashlight, and a fully charged mobile phone.

Before leaving, tell someone your destination route and when you will arrive or return home.

Being prepared can help you stay warm and comfortable should a scenario arise where you are awaiting assistance.

Conclusion

Hypothermia is an acute condition that can occur in freezing or milder temperatures if the body is wet or exposed to wind. It is vital to seek emergent medical assistance if you suspect someone is experiencing hypothermia. By understanding the stages, symptoms, causes, and treatment of hypothermia, as well as the phenomenon of paradoxical undressing, you can take steps to prevent and treat this potentially life-threatening condition. Stay safe and warm this winter season.

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