Tuesday, July 19, 2011

Apple #537: Heat Exhaustion vs. Heat Stroke

I have a weather band radio in my car, and because of the high temperatures the past few days, it's been warning me about heat exhaustion and heat stroke. The way the automated voice says it, it's more like "heet stROKe and heet egsAUSStion."

Temperature and humidity can work together to make conditions more likely for heat-related illnesses. This chart shows the likelihood of developing heat exhaustion, heat cramps, and heat stroke (a.k.a. sun stroke) as the temperature and humidity levels rise.
(Chart from NOAA's National Weather Service)

The weather warnings have been telling me I should know the warning signs of heat exhaustion and heat stroke, but they don't say what those warning signs are. So I thought I'd find out. And what's the difference between the two, anyway?

  • Heat stroke is much more severe than heat exhaustion.
  • On the less severe end of the spectrum, judging by the description of heat exhaustion, it's pretty easy to get yourself there.
  • I'm pretty sure I've had heat exhaustion several times. Though it's happened to me quite a few times, I remember each one of those episodes. They weren't exactly big fun.
  • I'll start with the least severe of the heat illnesses and work my way up to most severe.

This is a very basic diagram of how sweating works. Your body heats up, either through exercise or through ambient temperature, your hypothalamus tells the sweat glands to start making sweat, and the evaporation of the sweat cools the body. Heat exhaustion and all the heat-related illnesses that follow it are what happens when this process doesn't work right.
(Diagram from by Ka Botzis at picture book)

  • Heat exhaustion -- or any heat-related illness -- happens when your body heats up faster than sweating can cool it down.
  • If you're exercising or working in the hot sun, or even if you're in a very hot environment like a hot car or a stuffy, closed-in apartment, your body temperature might rise faster than it can cool itself off.
  • Your body also attempts to cool itself by sending more blood toward the skin, where it's more likely to lose heat. This means less blood is going to your muscles and to your brain, which is why you'll feel weak and dizzy or disoriented if you get too hot.
  • The whole thing gets worse if you don't drink enough water. Your body loses a lot of moisture through sweating, and if you don't have enough water coming in to replace that lost water, you'll get dehydrated. Once dehydrated, your body has less fluid available to produce more sweat, your body will get hotter still, and the whole thing escalates.

These guys are a little bit of a special case, but they're still good examples of heat exhaustion. They're all wet because they're cosmonauts whose spacecraft landed in the Black Sea, where they bobbed around for a couple of hours before getting picked up. They've now got heat exhaustion, as evidenced by their red faces, their inability to hold up their heads, their tendency to keep their eyes closed.
(Photo from First African in Space)

  • The CDC says that heat exhaustion can develop over several days, but other sites suggest that the time-period in which you can get heat exhaustion may be much shorter.
  • Heat exhaustion is the first heat-related illness that you'll encounter.
  • You might experience:
      • dizziness or lightheadedness
      • weakness
      • headache
      • nausea
  • Your skin may feel cool and moist to the touch, but your pulse will be fast and shallow, and your breathing will be shallow too.
    • If this is happening, the best thing to do is
        • Get out of the hot sun
        • Get into a shady or better yet, cool environment
        • Drink cool water or a sports drink like Gatorade
        • Do NOT drink alcohol or caffeine
        • Rest

    On hot, humid days like the ones we've been having lately, a glass of cool water may be your best friend.
    (Photo from Teplok)

    • If you don't take a break when you hit heat exhaustion, your body will continue to heat up and dehydrate, and it will progress to the next stage of heat-related illnesses.

    • Some people classify heat cramps as a symptom of heat exhaustion. Some people say it's its own category.
    • Heat cramps are pretty intense or painful muscle spasms.
    • They happen when muscles are overexerted and depleted of water and essential nutrients.
    • They can occur anywhere on the body, but most commonly they happen in the abdomen, legs, or arms.

    Athletes are susceptible to heat cramps. Andre Agassi, in his autobiography Open, said he'd rather deal with his spondylolisthesis, a degenerative disc disorder in his back which caused shooting pains up and down his spine, than get heat cramps.
    (Photo from National First Aid Training Institute)

    • If you start cramping, stop what you're doing and rest.
    • Drink a cool beverage that has more nutrients than plain water. Light fruit juices or sports drinks are best.
    • Gently stretch or massage the cramping areas, but do so slowly and carefully.

    Shade and rest are your friends, too, when you've got heat exhaustion and heat cramps.
    (Photo from Fooyoh)

    • If the cramps don't subside after an hour, go to the doctor.
    • Even after the cramps have subsided, don't do anything strenuous for the next several hours. Your muscles will need time to rejuvenate, and if you pressure them too soon, they'll go back to cramping again, or you could progress to the next level of heat illness.


    • This one is bad news, sister. You do not want heat stroke.

    Quick & dirty pictogram of heat stroke. The super-red danger-red may be the best indicator of what heat stroke is.
    (Image from wellness of health)

    • At this point, your body is completely unable to regulate its own temperature. All the body's cooling mechanisms have failed, and the heat simply takes over.
    • Once this happens, your body temperature can rise to danger level extremely fast, within about 10 or 15 minutes.
    • Danger level -- and the main sign of heat stroke -- is a body temperature above 103°F.
    • Some sites say that the danger line is a core/rectal temperature of 105°F. But if I'm feeling this lousy, no way am I putting a thermometer in my rectum to find out just how bad it is.
    • Here's what else may be happening, in addition to the high temperature:
        • Throbbing headache
        • Skin is hot and dry, no perspiration
        • Skin rash (possibly)
        • Rapid, strong pulse
    • From here, if the heat stroke continues, your body may progress along the badness that is heat stroke through the following:
        • Dizziness
        • Nausea
        • Difficulty breathing
        • Confusion or disorientation
        • Hallucinations
        • Seizure
        • Fainting / Unconsciousness
        • Coma
    • If heat stroke isn't treated immediately and as an emergency, it is often fatal.
    • If someone is experiencing heat stroke, call 911.
    • Until the ambulance gets there, do the following:
        • Move the person to a cool, shady area
        • Put them in front of a fan or fan them yourself
        • Loosen or remove clothing
        • Apply cool water to the skin, either with damp sheets or a wet sponge or a spray
        • If they're conscious and can drink liquids, give them cool water
        • Place ice packs under the armpits or at the groin

    This looks like a silly cartoon at first, but it's really the best depiction of how to treat a heat stroke victim. She's put him in the shade, taken off his shirt, she's dousing him with water, and she's fanning him with a little hand-held fan. The only thing that's missing is giving him water to drink. Presumably, she's already called 911.
    (Drawing by Kathryn Born, from the American Academy of Family Physicians)

    • Even when heat stroke is treated successfully, people can still suffer damaging effects from it for several months afterward.
    • Most people who have had heat stroke later experience some form of neurological or mental impairment. Some people experience problems with their kidneys or blood clots. Some experience lung malfunctioning.
    • About 25% of the people who survived heat stroke died within the year.
    • Again, you do not want to get heat stroke.
    • Those who are most at risk for heat stroke are
        • infants
        • elderly
        • obese
        • alcoholics
        • people who abuse prescription drugs
        • people with cardiovascular disease
        • people who have difficulty sweating under normal conditions
    • But anyone can get heat stroke if they don't take care of themselves when the first warning signs of heat illness appear.
    • So the moral is, when it's hot, drink lots of water, don't push yourself too hard, give your body chances to rest and cool off.
    • If you feel that tight hot throbbing in your face, stop what you're doing and help your body cool off.
    • You're not a wimp for resting. You're taking care of your body so it can continue to function at its best.

    See? This is a tough guy. But he's taking a break to stay hydrated. He's also wearing a loose-fitting white cotton shirt, a hat, and sunglasses, all of which will help him stay cool and protected from the heat. Tough guys take care of themselves!
    (Photo from Safety Rocks)

    Related entry: It's the Humidity

    CDC, Frequently Asked Questions About Extreme Heat
    MedicineNet.com, Heat Exhaustion, Heat Stroke Treatment
    WebMD, Understanding Heat-Related Illnesses -- the Basics, Heat Exhaustion and Heat Stroke Treatment
    Mayo Clinic, Heat Cramps: First Aid, Heatstroke: First Aid
    infohealthz.org, Heat Stroke Long Term Effects, July 7, 2011

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