When the weather gets sizzling hot
April 18, 2006 | 12:00am
In the summer of 2003, a nine-day heat wave hit France, causing 14,800 deaths. The Chicago heat wave of 1995 was blamed for nearly 500 deaths. And nearer home, many countries, such as India and Pakistan, have had killer heat waves in the past few years.
Such terrible heat waves may become more common. Global warming not only raises average temperatures but causes more extreme weather. The population worldwide is also getting older and heavier and therefore more vulnerable to the effects of heat. In the United States, for example, more Americans died of heat in the 1990s than from hurricanes, tornadoes, floods, and lightning combined.
Heat is a by-product of all metabolic processes. Muscles when they move also generate it. Normally, our bodies do a fine job of shedding the excess. About two-thirds just radiates from the skin into the cooler air outside our bodies. Most of the rest leaves in sweat evaporating from the skin or in moisture in air exhaled from the lungs.
As the air temperature climbs, the amount of heat radiated from the skin falls, and we have to depend more on the evaporation of sweat. But when it’s humid, sweat doesn’t evaporate as easily because the air is already full of moisture.
Advancing years may make things worse. The older sweat gland becomes fibrotic, so it doesn’t produce as much sweat as it used to. Thirst declines with age, so people get dehydrated, further reducing the amount of sweat. The sweat that is produced tends to contain more salt, so electrolyte imbalance can be a problem. Lack of salt in the body can be just as serious as lack of water because it can lead to sudden drops in blood pressure.
Older people are also more likely than younger folks to be taking medications that cause fluid loss (and therefore dehydration), including some laxatives, furosemide (Lasix) for water retention, and other diuretics for blood pressure control. The vulnerability of older people to heat is reflected in the mortality statistics from the French heat wave. Slightly more than two-thirds of those who died were age 75 or over.
Here are the heat-related illnesses, discussed from bad to worse:
• Heat cramps. Heat cramps are muscle cramps caused by profuse sweating, usually during exercise, and the consequent loss of electrolytes (salts). You have to be careful in high-heat, low-humidity areas where you may not notice how much you’re sweating because the moisture evaporates so fast. You can deal with a mild case of heat cramps by eating salty foods and drinking sports beverages like Gatorade.
• Heat exhaustion. Typical symptoms include weakness, lethargy, wooziness, headache, and nausea. Muscle cramps may also occur. Because heat exhaustion clouds thinking, people often don’t recognize the problem as it develops. Serious cases require intravenous fluids and electrolytes. For a mild case, get the person to a cool place and see to it that he/she has fluids to drink, preferably with some salt.
• Heat stroke. Heat stroke is a medical emergency – the killer in the killer heat wave. It may start out feeling like heat exhaustion, but the symptoms progress and are more severe: Lethargy, weakness, and confusion develop into delirium, stupor, seizures, and even coma. Body temperature rises drastically, often exceeding 106°F. In younger people, the pulse tends to race. In older people, it’s usually slow and weak, and blood pressure may drop. Despite the excess heat, the victim’s skin looks pale and feels dry because normal sweating has stopped.
People suffering from heat stroke need to have their body temperatures brought down quickly to prevent permanent cardiovascular, neurological, and other types of damage. Often, a cool bath is the best way to do that. Cool compresses on the neck, in the armpits, or in the groin area also quickly lower body temperature.
To reduce your risk, you should stay well-hydrated during the summer months. Since you can’t always rely on your body to tell you when you’re thirsty, you should feed it with 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 8-ounce glasses of water a day. Note also that 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.
Here are some suggestions to avoid heat-related illness:
• Listen to your body. Muscle cramps, fatigue, weakness, impaired concentration, confusion, light-headedness, nausea, labored breathing, chest discomfort, and a rapid or erratic pulse can all be signs of trouble. Heed your body’s warning signals. If you feel ill – even just a little – go to a cool place, drink plenty of cool water, and be sure that help is available if you don’t improve promptly.
• Head for the AC. Air-conditioning is a true life-saver in a heat wave. Even spending just a few hours in an air-conditioned room helps.
• Dress appropriately. Loose, light-colored garments reflect sunlight, making it easier for the skin to cool off and sweat to evaporate.
• Stay out of the sun. You’d be surprised at how many people each summer end up getting sick because they didn’t follow this advice. If you’re at the beach, gardening, or watching a sports event in an open field, it is easy to forget how much sun you are getting.
• Review your medications. Some medications have a dulling effect on the hypothalamus, the part of the brain that serves as the body’s thermostat. As a result, people taking those drugs don’t sweat as much as they should. Pain-killers may be a hazard because they can reduce awareness of the heat. The fluid loss from diuretics or blood pressure medications normally isn’t a problem, but it can be in hot weather because of the risk of dehydration. Some experts say beta blockers may increase the risk of a heat stroke by slowing down the heart. You shouldn’t quit taking a drug just because it’s hot outside, but you might talk with your doctor about your medications if temperatures are climbing, especially if you’re not protected by air-conditioning.
You can get yourself or a companion through an episode of heat exhaustion or heat stroke by recognizing the signs and responding appropriately.
Know the danger signs. Symptoms of dehydration and overheating include the following: Severe thirst and dry tongue; feeling of impatience or irritability; lightheadedness; heavy sweating; pale, cold, clammy skin; cramps in stomach, legs, or arms; headache; rapid weak pulse; nausea and vomiting; diarrhea; dizziness; fainting.
If you begin to feel the signs of overheating, get out of the sun, drink cool fluids, spray or splash yourself with water if you can, and rest until you feel better. Don’t tough it out.
If you are attending to a companion who has become ill, lay the victim down, loosen any tight clothing, and elevate the legs.
If the symptoms worsen, especially toward loss of consciousness, get to an emergency room. Heat stroke is life-threatening.
Lower the patient’s body temperature as quickly as possible. One way is to wet the victim’s exposed skin and fan vigorously. If possible, immerse the person in cool water – such as a bath tub.
Above all, don’t panic. Stay cool!
Such terrible heat waves may become more common. Global warming not only raises average temperatures but causes more extreme weather. The population worldwide is also getting older and heavier and therefore more vulnerable to the effects of heat. In the United States, for example, more Americans died of heat in the 1990s than from hurricanes, tornadoes, floods, and lightning combined.
As the air temperature climbs, the amount of heat radiated from the skin falls, and we have to depend more on the evaporation of sweat. But when it’s humid, sweat doesn’t evaporate as easily because the air is already full of moisture.
Advancing years may make things worse. The older sweat gland becomes fibrotic, so it doesn’t produce as much sweat as it used to. Thirst declines with age, so people get dehydrated, further reducing the amount of sweat. The sweat that is produced tends to contain more salt, so electrolyte imbalance can be a problem. Lack of salt in the body can be just as serious as lack of water because it can lead to sudden drops in blood pressure.
Older people are also more likely than younger folks to be taking medications that cause fluid loss (and therefore dehydration), including some laxatives, furosemide (Lasix) for water retention, and other diuretics for blood pressure control. The vulnerability of older people to heat is reflected in the mortality statistics from the French heat wave. Slightly more than two-thirds of those who died were age 75 or over.
• Heat cramps. Heat cramps are muscle cramps caused by profuse sweating, usually during exercise, and the consequent loss of electrolytes (salts). You have to be careful in high-heat, low-humidity areas where you may not notice how much you’re sweating because the moisture evaporates so fast. You can deal with a mild case of heat cramps by eating salty foods and drinking sports beverages like Gatorade.
• Heat exhaustion. Typical symptoms include weakness, lethargy, wooziness, headache, and nausea. Muscle cramps may also occur. Because heat exhaustion clouds thinking, people often don’t recognize the problem as it develops. Serious cases require intravenous fluids and electrolytes. For a mild case, get the person to a cool place and see to it that he/she has fluids to drink, preferably with some salt.
• Heat stroke. Heat stroke is a medical emergency – the killer in the killer heat wave. It may start out feeling like heat exhaustion, but the symptoms progress and are more severe: Lethargy, weakness, and confusion develop into delirium, stupor, seizures, and even coma. Body temperature rises drastically, often exceeding 106°F. In younger people, the pulse tends to race. In older people, it’s usually slow and weak, and blood pressure may drop. Despite the excess heat, the victim’s skin looks pale and feels dry because normal sweating has stopped.
People suffering from heat stroke need to have their body temperatures brought down quickly to prevent permanent cardiovascular, neurological, and other types of damage. Often, a cool bath is the best way to do that. Cool compresses on the neck, in the armpits, or in the groin area also quickly lower body temperature.
Many medical experts recommend that the average healthy, sedentary adult, regardless of age or weight, drink eight 8-ounce glasses of water a day. Note also that 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.
Here are some suggestions to avoid heat-related illness:
• Listen to your body. Muscle cramps, fatigue, weakness, impaired concentration, confusion, light-headedness, nausea, labored breathing, chest discomfort, and a rapid or erratic pulse can all be signs of trouble. Heed your body’s warning signals. If you feel ill – even just a little – go to a cool place, drink plenty of cool water, and be sure that help is available if you don’t improve promptly.
• Head for the AC. Air-conditioning is a true life-saver in a heat wave. Even spending just a few hours in an air-conditioned room helps.
• Dress appropriately. Loose, light-colored garments reflect sunlight, making it easier for the skin to cool off and sweat to evaporate.
• Stay out of the sun. You’d be surprised at how many people each summer end up getting sick because they didn’t follow this advice. If you’re at the beach, gardening, or watching a sports event in an open field, it is easy to forget how much sun you are getting.
• Review your medications. Some medications have a dulling effect on the hypothalamus, the part of the brain that serves as the body’s thermostat. As a result, people taking those drugs don’t sweat as much as they should. Pain-killers may be a hazard because they can reduce awareness of the heat. The fluid loss from diuretics or blood pressure medications normally isn’t a problem, but it can be in hot weather because of the risk of dehydration. Some experts say beta blockers may increase the risk of a heat stroke by slowing down the heart. You shouldn’t quit taking a drug just because it’s hot outside, but you might talk with your doctor about your medications if temperatures are climbing, especially if you’re not protected by air-conditioning.
Know the danger signs. Symptoms of dehydration and overheating include the following: Severe thirst and dry tongue; feeling of impatience or irritability; lightheadedness; heavy sweating; pale, cold, clammy skin; cramps in stomach, legs, or arms; headache; rapid weak pulse; nausea and vomiting; diarrhea; dizziness; fainting.
If you are attending to a companion who has become ill, lay the victim down, loosen any tight clothing, and elevate the legs.
If the symptoms worsen, especially toward loss of consciousness, get to an emergency room. Heat stroke is life-threatening.
Lower the patient’s body temperature as quickly as possible. One way is to wet the victim’s exposed skin and fan vigorously. If possible, immerse the person in cool water – such as a bath tub.
Above all, don’t panic. Stay cool!
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