Some Like It Hot – Summer Heat and Stress
Healthy aging requires us to take a few preventative measures when the weather heats up. With summer approaching, it’s time to prepare for the annual onslaught of heat, humidity and penetrating sun by remaining aware of two important things. First, as we age, we are less able to deal with heat. The second thing to remember is the importance of drinking water.
We all know that the body has a wonderful way of regulating body temperature. In fact, if our thermometer varies much from 98.6 degrees Fahrenheit, we know something is wrong.
The cardiovascular system and sweat glands regulate the body remarkably well even when it is hot and humid. One of the main ways the body cools itself is by vasodilatation; veins in the skin dilate to help dissipate heat.
The second way we cool ourselves is through perspiration. In fact, hot and humid days are the kind of Low Country days my father called “three shirt days.” A three shirt day meant that you needed a dry shirt in the morning, another in the afternoon, then a third one in the evening.
Water is important on hot days for three reasons. First, we must stay hydrated so that the circulatory system can continue to pump warm blood to cooler skin. Second, staying hydrated helps us to perspire effectively, which helps cools the body. Finally, staying hydrated is important because humidity in the air makes it more difficult for the perspiration to evaporate from our skin.
Another important fact to remember is that heat illnesses can result when heat from the environment and heat generated by physical activity exceed our capacity to eliminate it through vasodilatation, increased cardiac output and sweating. These illnesses range from simple heat fatigue that is benign if treated to heatstroke, which can a mortality as high as 15 percent.
Susceptibility to Heat Stress
Who is susceptible to heat illness? Anyone who is exposed to humidity and heat greater than 85 degrees Fahrenheit is susceptible, as well as people performing vigorous exercise, especially while in the sun. The risk of heat illness goes up exponentially as the humidity increases because perspiration does not evaporate. Other risk factors include advanced age, heart disease and other chronic diseases, extreme exercise, sunburn, obesity, sleep deprivation, alcoholism and certain drugs. Patients taking beta-blockers, tricyclic antidepressants, aspirin and diuretics are predisposed to heat disorders.
During heat illnesses, the cardiovascular system cannot maintain the elevated cardiac output because body fluids are lost to sweating and internal swelling, then the blood vessels in the skin collapse. Finally, the body is unable to sweat. As a result, heat cannot be dissipated and will build up within the body, ultimately causing a variety of symptoms that can lead to serious medical consequences if left untreated.
Symptoms are a weak but rapid pulse, rapid breathing, no sweating, headache, confusion, clumsiness, disturbed gait, dizziness and unconsciousness in severe cases. A rectal temperature will be elevated. A temperature greater than 105 degrees meets the criteria for heatstroke. Lesser temperature elevations and symptoms are categorized as heat exhaustion or heat illness.
Several precautions can help us avoid heat stress. (See Table.) Most precautions are well known. The most important preventative measure is to stay hydrated with fluids that contain some carbohydrates and salt, such as. Regular Gatorade should be diluted with water to about 50 percent to avoid too much salt intake. Alcohol should not be used for hydration because it is a vasodilator and diuretic, which could deplete blood volume. Coffee and tea are also diuretics.
To treat heat stress, rest in an air conditioned room, if possible. If air conditioning is not available, remove most clothing and spray the body with a mist of tepid water while fanning. If possible, immerse in cool water if the person is conscious. If the person is alert enough, fluids should be taken by mouth and the legs should be elevated at approximately 15 degrees. Medical attention should be obtained by transport to a doctor or hospital. If the subject is unconscious, dial 911 immediately.
When the temperature outside is high, the humidity even higher, and the sun out, plan vigorous activity for cooler parts of the day. And, always take preventative measures. Enjoy the summer!
1. Drink plenty of fluids with carbohydrates-electrolytes (Gatorade or other sports drink)
2. Wear light colored clothing that wicks perspiration (cotton)
3. Avoid strenuous exercise during the hottest part of the day in full sun
4. Get acclimated – increase exercise gradually each day in the heat
5. Avoid sunburn
6. Enjoy air conditioning – that’s why it was invented
MUSCHealth.com Online Library Links:
Preventing Unintentional Injuries
Dehydration and Heat Stroke
The danger of dehydration and heat stroke:
Dehydration and heat stroke are two very common heat-related diseases that can be life threatening if left untreated.
What is dehydration?
Dehydration can be a serious heat-related disease, as well as being a dangerous side effect of diarrhea, vomiting, and fever. Children and persons over the age of 60 are particularly susceptible to dehydration.
What is heat stroke?
Heat stroke is the most severe form of heat illness and is a life-threatening emergency. It is the result of long, extreme exposure to the sun, in which a person does not sweat enough to lower body temperature. The elderly, infants, persons who work outdoors, and those on certain types of medications are most susceptible to heat stroke. It is a condition that develops rapidly and requires immediate medical treatment.