Hypothermia is caused by exposure to cold water or air that lowers body temperature. The body loses heat, particularly to its vital organs, at a rate faster than it can warm up. This cooling off of the body’s core can be fatal if it is not addressed in its early stages. Normal body temperature is 98.6 degrees Fahrenheit (37 degrees Celsius). Hypothermia will occur when the body’s temperature falls below 96 degrees Fahrenheit (or 35.5 degrees Celsius). This is a gradual process, and the initial symptoms of hypothermia may not be noticed. However, they often begin with confusion and difficulty thinking. The effects of hypothermia will last from three to 12 hours with treatment.
Older adults, infants, younger children and individuals who have low body fat may be at greater risk for hypothermia in cold temperatures. This is especially true if they have other illnesses or are on medications that may affect the body’s ability to regulate its core temperature.
There are several stages of hypothermia:
- Mild hypothermia: The individual may be shivering but is alert and coherent.
- Moderate hypothermia: The individual will probably be shivering but may abruptly stop; they may become irrational and experience a lack of coordination.
- Severe hypothermia: Shivering may or may not be present. Some victims may act combative, experience a sense of warmth, and attempt to remove clothing. Hiding from the rescue party has been observed with severe hypothermia, followed by unconsciousness. Extremities (arms and legs) must be moved very slowly to prevent blood that has cooled in the extremities from moving to the body’s core, which may result in cardiac arrest.
What to Look For
Call 911 immediately if you observe someone experiencing any of these symptoms:
- Difficulty speaking
- Slow, shallow breathing
- Shivering (older adults may not have this symptom)
- Exhaustion
- Irrational behavior
- Hallucinations
- Forgetfulness
- Dilated pupils
- Blue skin
- Confusion
- Rigid muscles
- Dizziness
- Nausea
If emergency services are not available, proceed as follows:
- If the person is not breathing, start CPR immediately.
- Keep the victim away from direct contact with the ground.
- Wet clothing (especially cotton) should be removed and replaced with dry clothing and/or blankets.
- Do not confine the person by wrapping a blanket around them; cover the person's head, but not their face.
- You may hold or lie next to the victim to transfer body heat.
- If possible, move the victim to a warmer location; this must be done very slow and gently.
- Don't apply direct heat or use hot water, heating pads or a heating lamp to warm the victim. Apply warm towels to the neck, chest wall and groin. Do not attempt to warm the arms and legs. Heat applied to the arms and legs forces cold blood back toward the heart, lungs and brain, causing the core body temperature to drop. This can be fatal.
- If the person is alert, give warm, not hot, liquids. If the person is vomiting, do not give food or liquids. Do not give the individual alcohol or try to force them to eat or drink. If the person is able to eat, they should have carbohydrate‐rich foods.
- Give the person a warm (not hot) bath if possible.
- Individuals with severe hypothermia should not walk and need to be treated at a hospital as soon as possible.
Preventing Hypothermia
With adequate preparation and packing, you can help to prevent hypothermia. Here are some guidelines:
- Carry a backpack equipped with a rain fly, or have a heavy-duty plastic bag to act as a waterproof cover.
- Bring a knife or small hatchet, a space blanket or a piece of plastic to use as a temporary shelter, a raincoat, hat or hooded sweatshirt and gloves, waterproof boots, and two pairs of wool or fleece socks.
- Keep hydrated. Drink plenty of nonalcoholic liquids. If the weather is cold, drink warm liquids.
- Pack a tin cup for heating water or melting snow.
- Have high‐energy food along for emergencies.
- Carry matches, a butane lighter or a magnesium fire starter.
- Dress in layers. Use an inner layer to wick moisture away from your skin; polypropylene or polyester is a good choice. Wool or fleece is good as a middle layer for insulation. The outer layer must be both waterproof and breathable so that it does not trap moisture or humidity inside the garment. Remember, you can always remove clothing if you get hot, but you can’t put on what you don’t have.
- If the outside temperature rises or if you are exerting a lot of energy, remove a layer or layers of clothing. Sweating increases the chances of hypothermia. Be sure your clothing is dry before putting it back on.
- Clothing and footgear should not be tight fitting as this will cut off circulation.