Keeping your cool

As the mercury rises this summer, so does your risk of developing a serious heat-related illness. The key to beating the heat is making sure you drink plenty of fluids and seeking out an air-conditioned sanctuary if your home is not adequately equipped.

What Is Heat Illness?

Everyone’s body has a thermostat. When you get hot, you sweat, cooling off the skin and maintaining your normal 37°C body temperature. "At very high temperatures, however, your body sometimes can’t keep up, especially if there’s also a high humidity – over 80 or 90 percent – which makes the controlling mechanism ineffective," says Audrey Chun, MD, assistant professor of Geriatrics at the Mount Sinai School of Medicine in New York.

There are several types of heat-related illness – heat exhaustion and heat stroke are the most serious. Other forms include heat cramps (painful muscle knots usually occurring during exercise and strenuous activity), heat edema (swelling of the feet and ankles), and heat syncope (a sudden loss of consciousness).

The signs of heat exhaustion are cool, clammy skin, headaches, dizziness, fatigue, nausea, dry mouth, weak or rapid pulse, and profuse sweating. Your body temperature will elevate only slightly, if at all. Symptoms can occur slowly over time. If this should happen to you, move to a cool environment to rest as soon as you notice something is wrong. The best place is somewhere air-conditioned. You should also drink plenty of non-alcoholic fluids. If you ignore the warning signs, heat exhaustion can lead to heat stroke, which can be fatal.

Heat stroke is, by far, the most serious type of heat illness and requires immediate medical attention. It occurs swiftly, often within 10-15 minutes of the onset of symptoms, and can cause death or permanent damage to organs. Symptoms might include a dangerously high body temperature, fainting, hot, dry skin (i.e., no sweating), convulsions, bizarre behavior, unusually strong or weak breathing and pulse, and disorientation.

Greater Risk For Older Adults

>Certain body mechanisms change as you get older. For one, your ability to feel thirsty diminishes with age. "The thirst mechanism is controlled by your brain," says Dr. Chun. "As people get older, that safety mechanism becomes less sensitive, so they can’t depend on feeling thirsty."

So by the time you feel thirsty, you may already be quite dehydrated and, therefore, very susceptible to heat illness.

Kidney function also changes with age. The kidneys maintain normal fluid balance. When you drink too much, you urinate more. When you’re dehydrated, the body’s safety mechanism keeps you from excreting too much urine. But as you age, you may lose this ability.

Older adults are also more likely to have chronic health conditions that require special medications. High blood pressure, for instance, requires diuretic medications, which increase urination, causing the body to lose the important nutrients and fluids necessary for keeping cool. This can trigger quicker dehydration in hot weather when the body is already working overtime to keep perspiration flowing.

Several other factors can make you vulnerable to heat illness. Some older adults may live alone – and may not have air-conditioning – and have no one checking on them, a dangerous combination in the summer. People living by themselves who experience symptoms might lack the cognitive ability to realize they’re in trouble and by the time somebody discovers them, it might already be too late. In the summer of 2003, an unusually brutal heat wave killed an estimated 15,000 people in France. In July 1995, 700 people died in Chicago during a week of sizzling temperatures. In both cases, most were seniors who lived alone without proper ventilation.

Cool It

To reduce your risk, you should stay well-hydrated during the summer months. Since you can’t rely on your body to tell you when you’re thirsty, you should feed it water throughout the day. How much is open to debate.

Many medical experts recommend that the average healthy, sedentary adult, regardless of age or weight, drink eight eight-ounce glasses of water a day. While some doctors advise avoiding caffeinated beverages and alcohol due to their diuretic properties, others insist that such drinks count toward your intake of fluids.

Dr. Chun recommends that anyone who drinks a caffeinated or alcoholic beverage follow it with at least the same amount of water or juice or sports drink to counteract the dehydrating effects.

But others aren’t convinced that eight glasses of water a day are necessary. An article in the August 2002 issue of the American Journal of Physiology by Heinz Valtin, MD, a kidney specialist at Darthmouth Medical School, reported no scientific evidence supports the recommendations. He traced the guidelines back to a memorandum posted by the Food and Nutrition Board of the US National Research Council in 1945, which stated that the average person needs approximately eight cups of water per day. But Dr. Valtin believes the sentence that followed, "Most of this quantity is contained in prepared food," was lost in translation.

Many foods do contain large amounts of water. Fruits and vegetables can be 80 to 90 percent water; bread, about 35 percent; and meat, fish, and poultry, 50 to 60 percent. Today, however, food is rarely, if ever, mentioned as a possible source for the eight-glasses-of-water rule.

However, Katherine Beals, PhD, associate professor of nutrition at Ball State University in Muncie, Indiana, says, "Eight glasses a day can be a good start. However, you probably need more than 64 ounces to replace fluid loss if you live and work in a warm place, or lead an active lifestyle. The average sedentary person loses about 2 to 2.5 liters a day; athletes and active people can lose much more," says Beals, herself a triathlete.

What’s the bottom line? With wide-ranging opinions on how much water you need, your best bet may be the safe middle ground. Get your five daily fruit-and- vegetable servings, and aim for 6-8 daily glasses of healthy liquids.

What You Can Do

Here are some ways you can do to lower your risk of heat illness:

• Drink plenty of fluids, preferably caffeine-free and non-alcoholic.

• Take a cool shower or bath.

• Ask someone to check on you at least once or twice a day.

• Eat salty snacks, which help you perspire, but check with your doctor first.

• Avoid crowded places.

• Avoid strenuous activity or exercise.

• Wear light-colored, loose-fitting clothing.

• If symptoms occur, seek shelter in a cool place immediately and drink water.

Keeping your cool when the heat is on is crucial in avoiding dangerous heat illness.