What is hypothermia?
Hypothermia is any time your body’s temperature drops below 95 degrees. The commonly accepted normal temperature is 98.6, with some slight variations for individuals, but anything below 95 is considered hypothermia regardless of your base temperature. Hypothermia can occur at environmental temperatures higher than you might suspect. Contrary to popular belief, hypothermia does not require outdoor temperatures at freezing (32 degrees) or less. It can occur at 50 degrees and sometimes even higher.
Individuals may also have different sensitivities to the cold. I, for example, am someone who gets cold very quickly. If it’s below 68 degrees outside, you can believe that I wear a jacket to keep myself nice and warm. Other environmental factors can increase the risk of hypothermia. Rainy or windy weather can lead to hypothermia, even in temperatures higher than 50 degrees. Let me discuss the types of heat loss that will explain this phenomenon.
There are four types of heat loss, three of which we will examine in this blog:
1. Conductive
2. Evaporative
3. Convection
4. Radiation
Conductive heat loss can contribute to hypothermia in the following manner. If a person sits on a cold metal bench or ground, a heat-cold exchange occurs in which the heat is dispersed to that surface as the cold is also dispersed to the individual. The body typically loses 2 percent of its heat through conduction.
The second type of heat loss is evaporative and occurs directly from the body to the environment. An example is heat loss if you don’t have a hat on your head in the cold. Any exposed areas will lose heat relatively quickly.
Convection is the third type of heat loss. This involves the transfer of heat from a body to moving molecules such as air or liquid. An extreme example of this cold water emersion. An individual can become hypothermic in water up to 70 degrees. Cold water carries heat away from the body 25 times faster than air which is the same temperature. Cold water shocks the body and leads to abnormal heart rhythms, which may be deadly. Wind hitting any part of your body also leads to heat loss but at a slower rate than the water of the same temperature.
What are the signs of hypothermia?
The first stage is shivering. Shivering is your body’s mechanism of generating heat in an effort to keep you warm. As the body temperature continues to decline, shivering may stop, and a decreased level of consciousness may occur. People tend to become drowsy, have slurred speech, and may develop some coordination loss. At this point, confusion may set in. Next, if an individual loses consciousness, they have lost their final bit of protection, and unless found quickly, they will succumb to the cold.
What can you do to prevent this outcome?
You want to be prepared when you must go out into the elements.
- Staying covered is a crucial component. Wear loose-fitting clothes and multiple layers. These layers should ideally be made of wool, silk, or some synthetic fabrics capable of retaining heat better. If you start to get cold, if possible, go inside and try to get warm.
- If you must stay outside, keep as much of your body as possible off any cold surfaces. For example, sitting on a cold metal bench through conductive heat loss will worsen the situation.
- Avoid becoming overexerted. If you recall what I stated earlier, you’re going to lose heat faster with increased moisture, and if you start to sweat and your clothes become damp, you will dissipate heat more quickly. This is a situation where caution is advised. If you exert yourself with shoveling or other strenuous activity, take frequent breaks to go inside and re-acclimate.
What is the treatment for hypothermia?
If you are cold, do not use hot water to warm yourself. This practice can cause more harm than good. Instead, use lukewarm or room-temperature water to allow for slow reheating. Similarly, do not get too close to a heater. Rapid rewarming will cause capillaries and the blood vessels in the body to expand and potentially rupture, causing increased damage. Rapid warming of extremities can cause the shunting of cold blood back to your heart because it wants to go to your body’s core first. This shunting can cause irregular heart rhythms called arrhythmias and even lead to cardiac arrest. Gradual rewarming with warm blankets is preferred.
In severe cases, it is necessary to go to the emergency department for more aggressive treatment. In the ED, the body can be rewarmed using IV fluids. And in some cases, a machine is connected to the body and cycles the blood for direct rewarming.
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