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Dr. Karen DeSalvo, an associate professor of medicine and chief of the Section of General Internal Medicine and Geriatrics at Tulane Health Sciences Center, discusses how heat can affect the body and what to do when it does.

Q: How big a health problem is heat and is it worse here than in other places?

A: There are certain parts of the country that are more susceptible to heat-related problems, where individuals are less likely to have air conditioning, or in rural areas where older people are less likely to be checked on regularly. In a medium-sized emergency room, [health workers] might see three people a week (with heat-related problems) during certain times of the year.

Q: What are the biggest problems that stem from heat exposure during a normal summer?

A: The big problem would be people who become first dehydrated and go on to develop possible heat stroke. Dehydration happens more commonly in children and people over 60; in older folks, it's more commonly because they're on medications that act like diuretics. With dehydration, the effects can be simple things like fatigue and loss of productivity or more serious things like confusion, and you start moving into heat stroke. One of the reasons we have such a problem in Louisiana is that it is so humid. One of the ways we control body heat is through evaporation -- we sweat. The sweating reaction becomes ineffective at about 75 percent humidity.

Q: What groups are most at risk?

A: Children and people over age 60. Others at high risk are anybody on certain medications: diuretics, some anti-depressants, things like Benedryl; people with psychiatric diseases, because of some of the medications they happen to be on; people with a history of stroke, because your body temperature is regulated in your brain and some kinds of strokes [throw that process off]; and anyone who is physically impaired and can't get to water.

Q: What are the signs of heat stroke and what should a person do about it?

A: The most common symptoms are people would start with dry mouth and thirst, dizziness, headache and become very, very fatigued somewhat suddenly. They could become very disoriented and confused. ... Then it gets more serious: loss of consciousness, seizure. When you check on them, you will notice they feel hot to the touch -- 105-degree body heat is the definition of heat stroke -- they may have a very fast heart beat, and if you try to arouse them, they won't wake up easily. As a caveat to that, there are two kinds of heat stroke. The classic, which high-risk people get, children, the elderly and people on the drugs we've mentioned and people who are obese. The other broad class is exertional: people without the risks who develop heat stroke from, say playing tennis in the heat and they just drop. Most people don't have any long-term effects from heat stroke; generally, people recover with appropriate medical treatment. The summer, though, is a high-risk time for the elderly and for pets, too. The elderly, especially, sometimes have lost the ability to regulate their body temperature for several reasons ... and they lose the perception that they're hot. It's really an important time to check on them regularly just to make sure they're not getting in trouble.

Q: How do you prevent heat exhaustion and dehydration?

A: Keep well hydrated. I usually tell people that they should gauge [how much liquid they need to drink] by the color of their urine. It should be light colored, no darker than the color of a manilla folder. If you are thirsty, drink water. Stay away from caffeinated beverages, they dehydrate you. If you find you are needing to drink a lot of water and you're going to be outside for awhile, you should drink the sports beverages; they have electrolytes in them. The other thing is to wear cool clothing that is light colored. Wear protective things like hats and sunglasses, and use an umbrella.

Q: How should you cool down someone who is very overheated?

A: The first thing to do ... is to move the person to a cool place, get them out of the sun, and get some breeze on them, whether it is to sit them under a fan or physically fan them. If you wet them totally with some regular water (or spray them) then blow the fan on them it will help cool them down tremendously. If they're awake, have them drink some water. They used to recommend ice packs in the armpits and groin area, but that sometimes can cause their blood vessels to constrict, and you need those open so they can radiate the heat and do the cool-down process. Then get them to the emergency room.

Q: How do you know if they need to go to the emergency room?

A: Clearly anybody who is very confused or has lost consciousness should go. The elderly or very young or people on certain medications or with underlying diseases should be taken to the emergency room.

Q: Tell us how to deal with heat cramps and heat rash.

A: For heat rash, they're typically wet rashes -- it's usually in a sweaty area. You can either develop a simple dermatitis ... and so you usually want to try to dry the area (with powder or something) and it will heal on its own. Heat cramps are just kind of a version of dehydration. You have a problem where you have loss of water, salt, potassium. When you have lost some of those important electrolytes, you develop cramps in your muscles and they can't function normally because they need electrolytes to expand and contract. That's when the sports drinks are good. There are some other causes like bad circulation leg cramps. If you get those at other times, like when it's cool, you need to talk to your doctor about it.

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