The Dangers of Heat and Cold: Heat Stroke

A person collapsed in a sandy washAs soon as the ambient temperature rises above that of your body, it can no longer lose heat through radiation. Instead your body begins to gain heat from the surrounding environment, and must therefore find some way to dissipate that heat. Evaporation of sweat works well in dry weather, but in high humidity it’s a bit less effective.

Heat exhaustion is the most common form of heat-related illness. It results when the body generates or absorbs more heat than it is able to dissipate. If heat exhaustion isn’t controlled, it can eventually result in a more serious situation called heat stroke. Risk factors for heat exhaustion and heat stroke include hot or humid days, heavy physical activity, dehydration, and hyponatremia (low salt-concentration in body fluids). Mix a few of these variables together and you have a great recipe for heat injury.

Fortunately the human body is a remarkable machine which has the ability to adapt to its surroundings. People who live and work in hot climates can adapt to a small degree. Their bodies tend to retain more water. They sweat more profusely and earlier than others who are not acclimatized to heat. Of course, this doesn’t mean that someone who lives in Phoenix is immune to heat stroke—it just means that you should be extra careful if you or someone in your group isn’t used to hot weather.

The signs and symptoms of heat exhaustion can be difficult to pin down. While short, bulleted lists are easy to remember, they can be misleading by oversimplifying a complex issue. Symptoms of heat exhaustion may include nausea and vomiting, headache, muscle pain, irritability, dizziness, weakness, or loss of conciousness.

An individual suffering from heat exhaustion will usually have a body temperature less than 106 degrees Fahrenheit; it may even be normal. If the situation worsens, the body’s heat regulation systems begin to break down. This can result in an uncontrolled spiral of rising temperature.

If heat stroke is suspected, immediately begin evacuation for hospitalized care. The longer a case of heat stroke remains untreated or unmanaged, the worse the long-term prognosis becomes for the victim. Heat stroke can easily result in debilitating organ dysfunction or death.

Once core temperature rises past 106 degrees Fahrenheit, cells within the body only last a short period of time before sustaining damage (sometimes it’s as short as 45 minutes). If body temperature rises high enough, or the condition lasts long enough, cells begin to die and organs will shut down. This condition is referred to as heat stroke.

Signs and symptoms of heat stroke include all the symptoms of heat exhaustion plus a few more. Victims may also experience confusion, altered mental status, hallucinations, or coma. Furthermore, heat stroke victims may exhibit shock-like symptoms including rapid heart rate and rapid breathing. The victim may or may not be sweating. Perspiration, or lack thereof, is no indication of whether or not heat stroke is occurring. The victim’s skin may feel warm and dry, wet, or cold and moist. None of these is a conclusive indicator.

If you even suspect heat exhaustion or heat stroke, move the victim out of the heat as quickly as possible. If an air-conditioned vehicle or building is not available, move the victim to a shaded area and remove excess clothing. If ice is available, gently apply ice packs to the neck, armpits, and groin. This facilitates rapid cooling since the carotid, brachial, and femoral arteries approach the surface of the body in these areas. If ice is not available, apply small amounts of water and fan the body in order to speed up evaporative cooling. Alternatively, you may lay a wet sheet or towel loosely across the victim’s body.

With agressive management such as the methods described above, heat exhaustion should resolve within two or three hours. If the victim’s condition does not seem to be quickly improving, evacuate and seek professional medical attention.

If heat stroke is suspected, immediately begin evacuation for hospitalized care. Be sure to facilitate cooling during transportation. Use an air-conditioned vehicle if possible, or roll down the windows and apply water to the victim. The longer a case of heat stroke remains untreated or unmanaged, the worse the long-term prognosis becomes for the victim. Heat stroke can rapidly result in debilitating organ dysfunctions or death.

Fortunately, heat-related illness is often one of the more preventable types of injury experienced in the backcountry. First and foremost, avoid heavy activity in hot environments. For example, if you’re backpacking in the desert in the middle of July, it’s best to avoid hiking during the hottest hours of the day. Dress appropriately. Wear light, loose clothing, and remember that dark colors absorb more heat from the sun than light colors. Perhaps most importantly, stay well-hydrated at all times. A person engaging in physical activity in hot weather can require up to a liter of water per hour in order to remain well hydrated. If you will be hiking or backpacking in terrain devoid of water sources, a common recommendation is to bring at least one gallon of water per person, per day.

Surviving in the wilderness is mostly a matter of being observant and using your head. Take responsibility for your own safety, and those in your group as well. It’s true that injury and death in the backcountry are sometimes the result of unfortunate, unpredictable accidents. Far more often, however, a bit of forethought and preparatory knowledge are all you need to remain alive and unhurt.

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