Heat-related Illness

What happens to the body as a result of exposure to extreme heat? 

People suffer heat-related illness when the body’s temperature control system is overloaded. The  body normally cools itself by sweating. But under some conditions,  sweating just isn’t enough. In such cases, a person’s  body temperature rises rapidly. Very high body temperatures may damage the brain or other vital organs. Several factors affect the body’s ability  to cool itself during extremely hot weather. When  the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing  heat quickly. Other conditions that can limit the ability to regulate temperature include old age, youth (age 0-4), obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, and prescription drug use and alcohol use.
  
Who is at greatest risk for heat-related illness? 

Those at greatest risk for heat-related illness include infants and children up to four years of age, people 65 years of  age and older, people who  are overweight,  and people who are ill or on certain medications. 

What is heat stroke? 

Heat stroke is the  most serious heat-related illness. It occurs when the body becomes unable to control its temperature: the body’s temperature rises rapidly, the sweating mechanism fails,  and the body is unable to cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes. Heat stroke  can cause death or permanent disability if emergency treatment is not provided. 

What are the warning signs of  a heat stroke? 

Warning signs of heat stroke vary but  may include the following: 

• An extremely high body temperature (above 103°F) 
• Red, hot, and  dry skin (no sweating) 
• Rapid,  strong pulse
• Throbbing headache 
• Dizziness  
• Nausea  
• Confusion  
• Unconsciousness  

What should I do if I see someone with any of the warning signs of heat stroke? 

If you see any of these signs, you may be dealing with a life-threatening emergency. Have someone call for immediate medical assistance while you begin cooling the victim. Do the following: 

• Get the victim to a shady area. 
• Cool the victim rapidly, using whatever methods you can. For example, immerse the victim in a tub of cool water; place the person in a cool shower; spray the victim with cool water from a garden hose; sponge the person with cool water; or if the humidity is low, wrap the victim in a cool, wet sheet  and fan him or her vigorously.   
• Monitor body temperature and continue cooling efforts until the body temperature drops to 101-102°F. 
• If emergency medical personnel are delayed, call the hospital emergency room for further instructions. 
• Do not give the victim alcohol to drink. 
• Get medical assistance as soon as possible. 

What is heat exhaustion? 
  
Heat exhaustion is a milder form of heat-related  illness that can develop after several days of exposure to high temperatures  and inadequate or unbalanced replacement of fluids. Those most prone to heat exhaustion are elderly people, those with high blood pressure, and those working or exercising in  a hot environment. 

What are the warning signs of heat exhaustion? 
 
The warning signs of heat exhaustion include the following: 

• Heavy  sweating
• Paleness
• Muscle cramps 
• Tiredness  
• Weakness  
• Dizziness  
• Headache   
• Nausea or vomiting 
• Fainting  

The skin may be cool and moist. The pulse rate will be fast and weak, and breathing will be fast and shallow. If  heat exhaustion is untreated, it may progress  to heat stroke. See medical attention if symptoms worsen or last longer than one hour. 

What steps can be taken to cool the body during heat exhaustion?   

• Drink cool, nonalcoholic beverages. 
• Rest.  
• Take  a cool shower, bath, or sponge bath. 
• Seek an air-conditioned environment. 
• Wear lightweight clothing. 

What are heat cramps and who is affected? 
 
Heat cramps are muscle pains  or spasms – usually in  the abdomen, arms, or legs – that may occur in association with strenuous activity. People who  sweat a lot during strenuous activity are prone  to heat cramps. This sweating depletes the body’s salt  and moisture. The low salt level in the muscles causes painful cramps.  Heat cramps may also be a symptom of heat exhaustion. If you have heart problems or are on a low-sodium diet, seek medical attention for heat cramps. 
  
What should I do if I have heat cramps? 
 
If medical attention  is not necessary, take the following steps: 

• Stop all activity and sit quietly  in a cool place. 
• Drink clear juice or a sports beverage. 
• Do not return to strenuous activity for a few hours after the cramps subside because further exertion  may lead to heat exhaustion or heat stroke. 
• Seek medical attention for heat cramps if they do not subside  in 1 hour. 

What is heat rash? 
  
Heat rash is a skin irritation caused by excessive sweating during hot, humid weather. It  can occur at any age but is most common in young children. Heat rash looks like a red cluster of pimples or small blisters.  It is more likely to occur on  the neck and upper chest, in the groin, under  the breasts,  and in elbow creases. 
 
What is the best treatment for heat rash? 
 
The best treatment for heat rash is to provide  a cooler, less humid environment. Keep the affected area dry. Dusting powder may be used to increase comfort. 

Can medications increase the risk of heat-related illness? 
  
The risk for heat-related illness and death may increase among people using  the following drugs: (1) psychotropics,  which affect psychic function, behavior, or experience (e.g. haloperidol or chlorpromazine); (2) medications for Parkinson’s disease, because they can inhibit perspiration; (3) tranquilizers such as phenothiazines, butyrophenones,  and thiozanthenes; and (4) diuretic medications or "water pills" that affect fluid balance in  the body. 

How effective are electric fans  in preventing heat-related illness? 

Electric fans may provide comfort, but when  the temperature is in  the high 90s, fans will not prevent heat-related illness. Taking  a cool shower or bath or moving to an air-conditioned place is a much better way to cool off. Air conditioning is  the strongest protective factor against heat-related illness. Exposure  to air conditioning for even a few hours a day will reduce the risk for heat-related illness. Consider visiting a shopping mall or public library for a few hours. 

How can people protect their health when temperatures are extremely high? 

Remember to keep cool and use common sense. Drink plenty  of fluid, replace salts and minerals, wear appropriate clothing and sunscreen, pace yourself, stay cool indoors, schedule outdoor activities carefully, use a buddy system, monitor those at risk, and adjust  to the environment. 

How much should I drink during hot weather? 

During hot weather you will need to drink more liquid than your thirst indicates. Increase your fluid intake, regardless  of your activity level. During heavy exercise in a hot environment, drink two to four glasses (16-32 ounces) of cool fluids each hour. Avoid drinks containing alcohol because they will actually cause you to lose more fluid. 

Should I take salt tablets during hot weather? 

Do not take salt tablets unless directed by your doctor. Heavy sweating removes salt and minerals from  the body. These are necessary for your body  and must be replaced. The easiest and safest way to do this is through your diet. Drink fruit juice or a sports beverage when you exercise or work in  the heat. 

What  is the best clothing for hot weather or a heat wave? 

Wear as little  clothing as possible when you are at home. Choose lightweight, light-colored, loose-fitting clothing. In  the hot sun, a wide-brimmed hat will provide shade and keep the head cool. If you must go outdoors, be sure to apply sunscreen 30 minutes prior to going out and continue to reapply according  to the package directions. Sunburn affects your body’s ability to cool itself and causes a loss  of body fluids. It also causes pain and damages  the skin.

What should I do if I work in a hot environment? 

Pace yourself. If you are not accustomed to working or exercising in a hot environment, start slowly and pick up  the pace gradually. If exertion in  the heat makes your heart pound  and leaves you gasping for breath, STOP all activity. Get into a cool area or at least in the shade, and rest, especially if you become lightheaded, confused, weak, or faint. 

Notes: Dr. Nelson Crumfield

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EditText of this page (last edited July 12, 2010)