What is a heat injury?
Heat Cramps – These are the mildest form of heat injury, but in a crisis situation, could be debilitating. Your body sweats to lose heat buildup. The hotter your body becomes, the heavier you sweat. The heavy sweating causes your body to lose salt and water. That can cause heat cramps, usually as intermittent muscle cramps in the calves and thighs.
Heat Exhaustion/Heat Prostration – This is more severe. It indicates that your body has lost a significant amount of water. Symptoms include weakness, headaches, dizziness, profuse sweating, clammy skin, and elevated body temperature.
Heat Stroke – This when your body’s core temperature exceeds 105.8°F (41°C). Symptoms include confusion, aggressive behavior, red, dry skin, and may quickly lead to unconsciousness and death.
All of these result from the body failing to regulate its heat. Factors in that failure may be internal (not acclimatized, health and fitness issues, recent alcohol intake, not rehydrating, and prior heat injury) or external (direct sunlight/lack of shade, constricting or heavy clothing, extremely high temperature, high humidity, and high levels of activity).
There are five basic factors associated with preventing heat injuries.
Acclimatization – As we live much of our lives in air-conditioned splendor, our bodies have gotten use to it. The office worker who goes out on a 90° Saturday to do yard work is going to be much more susceptible to a heat injury than the person laying hot asphalt all summer in 95°. The office worker is not acclimatized, the asphalt layer is. That doesn’t give you the excuse to stay on the couch all weekend! If you are not acclimatized, you simply need to take more prevention measures and pay closer attention to symptoms. If you anticipate long term exposure to hot environments (new job, summer camping trip, etc…) start gradually building your activities and heat exposure for a week or two prior to the new activity.
Hydration – most people are dehydrated on a regular basis. If you are thirsty, it’s too late. A cold beer or an iced tea, while they might make your feel good as you drink them, are bad in a heat environment. The alcohol and caffeine are diuretics and contribute to dehydration. You need to maintain hydration by drinking water or diluted sports drinks on a regular basis, no matter your feelings of thirst or not. Drink a half quart to a quart and a half every hour, depending on how much you are exerting. Keep an eye on your urine output. It should be as close to clear as possible. Dark yellow urine indicates dehydration. Stop your activity and rehydrate before resuming.
Don’t ration water. Drink up to maintain hydration. There are countless stories of people dying in the desert with water still in their canteens. A sip here and a sip later will dehydrate you. Drinking your fill when you have the chance may keep you hydrated until you find relief or rescue.
Do what you can to have water available. We always carry a couple of gallons in our vehicles. I carry a bottle of water to work and refill it throughout the day. We store several cases of bottled water in the house. I have a Katydin Combi-Filter that will make even the nastiest of water safe to drink. I have several water tasks on the to-do list. I need to get several bottles of purification tablets, build a bucket system to use our well if the pump or power fails, and get a Big Berkey filter system to sit on the kitchen counter.
Work/Rest Cycle – The hotter it is and the harder the work, the shorter the work rotation and shorter the rest rotation. For “hard work” in a Heat Category 1 (78° - 81.9°F), the Army indicates 40 minutes of work to 20 minutes of rest. In a Heat Category 5 (>90°), they indicate only 10 minutes of work to 50 minutes of rest. Now, I’m not sure it’s realistic to work 10 - rest 50 when it’s 91°, but be sure you are resting sufficiently to cool your body down.
Shade – In a hot environment, shade is your friend. Old time desert travelers would hunker down and rest under a rock outcropping or build a lean-to for shade during the heat of the day and travel early in the morning or late in the afternoon, maybe even at night if the moon light was bright enough. Even if you have to work in direct sunlight, try to find or make shade for your rest breaks.
Clothing – We’ve all seen the old Western movies where the Mexican towns’ people wear the loose, cotton, long-sleeved shirts, large, straw sombreros, and woven ponchos. That wasn’t just for Hollywood, that was for real. They lived, worked, and yes, took afternoon siestas, in the hot Southwest sun. The Bedouin tribesmen of the Arabian peninsula dress in layers of loose, natural fibers and wear keffiyeh that keep their heads shaded and double as protection from sandstorms.
Take clues from the people who have lived and thrived in hot environments for generations. Wear loose, natural fibers. Keep exposed skin covered. A hat with a large brim made of breathable materials will do wonders for keeping you cooler. Some people rave about Under Armor and similar new wicking fabrics for keeping cool. I don’t have any experience with them. Please leave comments about them if you do.
For most heat casualties, first aid needs to happen rapidly to ensure it does not get worse and lead to death. I’m going to reference the Army’s “7 R Management Model” for responding to heat injuries.
- Recognize the symptoms as a heat injury
- Rest in the shade or in air conditioned location
- Remove clothing – maybe just loosen it if the casualty is not severe
- Resuscitate – a person with heat stroke may lose consciousness and stop breathing – apply CPR as indicated, or monitor if CPR is not needed
- Reduce temperature as fast as possible with wet towels, fanning, ice water, etc…
- In the Mojave Desert, several of our Marines suffered heat stroke. Submerging them to the neck in ice water tubs helped prevent permanent damage or death.
- Rehydrate with cool water if the person is conscious
- Rush to medical treatment if circumstance dictate
Prevention is far better than treatment. Heat can kill or put out of commission the strongest and fittest of us under the wrong circumstances. Hydrate, rest, dress right, and seek out shade if you in a hot environment. Be alert for the symptoms of heat injury, both for yourself, and for others around you. Start treatment at the first sign of heat injury, and don’t delay seeking professional medical treatment if needed.
Resource: USMC Heat Injury Prevention