Chronic illnesses, anti-depressants add to risk in heat

Diabetes, other conditions make cooling off difficult

August 01, 1999|By Diana K. Sugg | Diana K. Sugg,SUN STAFF

In this summer's searing heat, Americans know they should protect their most vulnerable, the babies and the old. But there are millions of others also at risk: people who have chronic illnesses or use some popular prescription drugs.

Conditions such as diabetes, kidney disease, asthma and cardiac problems interfere with the body's ability to stay cool. And certain medicines -- including some anti-depressants and heart drugs -- often make it more difficult to handle the heat.

Many people leading active lives have been surprised to find they can't cope with the high temperatures. Anastasia Scherr, 31, a diabetic who has carefully controlled her disease for years, was hospitalized twice in July.

"I was outside. It was brutal," the Pikesville woman said, remembering when she noticed something was wrong. "It wasn't until I actually got in the hospital that I realized how serious it was."

People with chronic health problems often don't recognize they're getting into trouble until it's too late, experts say. A healthy person playing tennis who gets dehydrated shows symptoms rather quickly. But in someone with diabetes or asthma, the trouble develops over a few days. By that time, cognitive skills might be impaired, and the person might not seek help.

`Perfectly preventable'

"It's so important because people are dying of this, and it's a perfectly preventable thing," said Terrie T. Wetle, deputy director of the National Institute on Aging.

So far this summer, Maryland has had 18 confirmed heat-related deaths, mostly among the elderly; more than 140 have died across the nation since July 19. Several Baltimore-area hospitals reported a higher volume of patients with chronic illnesses last month, including several diabetic patients who had to be admitted to Greater Baltimore Medical Center's critical care unit.

On Monday, Dr. John Wogan, GBMC's chairman of emergency medicine, handled three cases in one shift of diabetic patients in danger of death because of their illnesses' interaction with the heat. Wogan typically sees one such case a month.

All three patients were admitted to critical care, where nurses scrambled to stabilize them, pumping liters of fluids and closely monitoring blood sugars spiraling out of control.

The body has a few simple systems to cool itself. When a person sweats, moisture evaporates off the skin, slightly chilling it. And when the heart, acting like a radiator, pumps warm blood to the body's periphery, heat dissipates as the blood circulates near the skin's surface. This means that any condition -- or medicine -- that interferes with circulation, or perspiring, hampers the body's cooling mechanisms.

Tricylic anti-depressants -- including amitriptyline and nortriptyline, but not the widely prescribed Prozac and Zoloft -- increase the body's heat production at the same time they impair the ability to sweat.

"It's a double whammy," said Dr. Gary Green, an attending physician at Johns Hopkins Hospital's emergency department. "This means people are more prone to heat stroke, heat exhaustion, the full range of heat-related diseases."

Sedatives, including Valium and Ambien, and anti-psychotic drugs also can interfere with the body's ability to perspire, said Wetle, of the National Institute on Aging. That increases a person's body temperature and the chance of a heat stroke.

Green added that these drugs, as well as pain medications such as Demerol, will alter a person's perception.

"A person who is completely healthy, you just start to feel the heat, and you know when it's time to get out," Green said. "But people who are on sedatives and tranquilizers some of the earlier warning signs that somebody else might feel, they may ignore or never feel."

Beta blockers and calcium channel blockers, two classes of common heart drugs, also make it harder for the body to release heat. Rather than allowing the heart to pump more when needed to circulate the blood and reduce warmth, these drugs keep the heart rate stable, unable to make the necessary adjustment.

GBMC sees a high volume of diabetic patients because of its Geckle Diabetes and Nutrition Center. What alarmed GBMC's physicians recently is that even the most careful of diabetic patients were showing up at the emergency department, shivering and sweating, with headaches and uncontrollable vomiting. The condition, ketoacidosis, can lead to coma and death.

Most of the eight patients admitted at GBMC over the past two weeks, including one Friday, were under 50, active and knowledgeable about their disease.

Time in the sun

Scherr's most recent health crisis started last weekend, when she was relishing the summer: a big walk on Friday, cheering for the Orioles on Saturday, a crab feast on Sunday, all in the heat and humidity. She noticed her blood sugars running high and gave herself more insulin to compensate.

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