What Is Hypothermia? - Definition, Causes, Symptoms & Treatment

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

You're probably familiar with the term hypothermia, but do you know the specifics? Read this lesson to learn what causes it, what the real symptoms are, and how hypothermia is treated if caught in time.

What is Hypothermia?

Have you ever been so cold your body starts convulsing? Like shivering but much worse? You may have had early stages of hypothermia. Hypothermia is a drop in body temperature to dangerously low levels, usually as a result of prolonged exposure to the cold. In contrast, hyperthermia is when the body temperature raises to dangerously high levels. The normal body temperature is 98.6 degrees Fahrenheit. Hypothermia is classified as body temperatures that drop below 95 degrees. Hypothermia is problematic because the body stops functioning normally when its temperature is too high or too low.

Causes of Hypothermia

The most common cause of hypothermia is exposure to cold weather for extended periods of time. This exposure causes the body to lose heat faster than it can be replaced, producing a net loss in body heat. Cold, winter air and cold water can both stimulate hypothermia. We usually think of winter weather when we hear about hypothermic cases, but it's also possible to experience hypothermia during the summer months! A common scenario is hikers setting out for a day trip, getting lost or facing unexpected inclement weather, and having to spend the night outside, ill equipped for wind or dropping night temperatures. Hypothermia can happen even when it's nice outside, not just when the weather is snowy and below-freezing.

Hypothermia can be triggered by prolonged exposure to cold weather, especially if clothing is inadequate.

Symptoms of Hypothermia

Initial signs of hypothermia include those commonly experienced when you're cold. These include shaking, shivering, nausea, increased heart rate or breathing, fatigue, lack of coordination, and difficulty thinking or speaking. Your body is trying to figure out ways to warm itself up and it will try to keep as much blood in the core as possible.

Hypothermia can progress, and symptoms will also intensify. Shivering may increase in intensity; confusion or drowsiness may get more pronounced; the heart rate and breathing rate will slow down; and speech will slow or stop. At this stage, the body may take on a slight blue appearance. Once hypothermia has reached its most intense stages, the person may lose consciousness, lose all sense of reality, and even believe they are too warm, causing them to strip off their clothing in a misguided attempt at helping themselves. They are also at the risk of experiencing frost bite or gangrene if the blood flow stops. Eventually, if not treated, hypothermia will cause the heart to fail, and the person will die.

Treatment Options

How is hypothermia treated? If the person is wet, removing the wet clothes is critical because more body heat is lost in water than in air. Obviously, the goal is to warm them up through the use of blankets, warm compresses, or other body heat. If compresses are used, they should only be used around the core of the body rather than the limbs. Applying direct heat is never advised.

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