June 29, 2007

Doctor’s Corner

Beat the Heat, drink plenty of water

By Dr. Eduardo Grunvald

During the winter, my waiting room is full of patients coughing, congested, hoping I somehow have discovered a magic pill to cure the common cold or the flu. But during the summer months, people would be surprised to know that I also see an increase in seasonal related problems.

I have a large number of geriatric patients in my practice, and older people don’t always like the heat. As the mercury in thermometers steadily rises over the next several weeks, this would be an appropriate time to review some interesting facts about why seniors need to be particularly careful in hot weather and those around them to be aware of their well being.

Understanding heat related illness is crucial, and so is taking preventive measures against problems like dehydration, heat exhaustion, fainting, and heat stroke. This is not a trivial problem. It is estimated that 4,000 people die every year in the United States from heat stroke.

Heat related illness is a spectrum of mild discomfort from dehydration, to a more serious condition called heat exhaustion, causing symptoms of headache, nausea, vomiting, dizziness, and cramps. Heat stroke, the most severe form of heat related sickness, is life threatening and causes confusion and disorientation. It can lead to kidney failure, liver damage, muscle breakdown, and death.

If you are not yet of the age that gets you senior discounts at the movies, excessive exposure to heat may deprive you of your usual pep, but at least your body has ways of compensating against any serious imbalance.

The longer you are exposed to heat, the faster you lose fluid through sweating, thereby causing dehydration, a process whereby the amount of volume flowing through your arteries and veins decreases, much like a stream slowly dries out during a drought.

Unlike younger folk, older people lose the ability to compensate by tightening the tone of these blood vessels. In addition, the heart has to speed up to help prevent the blood pressure from dropping too low. People of advanced age can lose this ability, either because of sick nerves that control this process, medications, chronic disease, or a combination of these factors.

Sweating is actually a remarkable trait built in to our bodies to prevent overheating. The act of evaporation on the skin cools the surface, which in turn cools the blood running in the tiny vessels underneath. Older people have weaker hearts and may not be able to keep up with increased blood flow necessary to carry cooler blood from the skin to the center of the body.

By the way, babies, at the other end of the life cycle, are also prone to heat related problems, and should never be left in very hot environments for a prolonged period of time.

I would guess that the stock of companies with fancy names that put water from exotic places into cheap plastic bottles goes up quite a bit around this time of year. They are banking on a primitive urge we share with almost all other creatures called thirst. We all take it for granted. It is actually controlled in a part of our brains called the hypothalamus, as it is in monkeys, dogs, rabbits and other animals. I don’t know about our four legged friends, but in us humans, as we get older this “sensor” loses its ability to respond to changes in the amount of body fluid or the concentration of sodium in our blood. In other words, we won’t feel thirsty when we should. This is the reason why you must coax the elderly people in your life to drink more water, especially during the hot summer months.

Even if thirst kicks in, many older people may not be able to get to water if unassisted because of weakness, arthritis, or imbalance problems, especially if they live alone or reside in nursing homes.

Of course, there are additional important factors that can worsen a person’s sensitivity to the heat, like diabetes, chronic medical conditions – such as liver, kidney or heart disease - and certain medications, especially water pills, blood pressure medications, and other drugs that can affect one’s blood pressure. Always consult your doctor before considerably adjusting the amount of water you drink, especially if you have chronic conditions that require medical treatment.

Help your older loved ones stay well hydrated. It will make for a cooler and healthier summer!

Dr. Grunvald is Associate Clinical Professor, Department of Medicine at the Perlman Internal Medicine Group, UCSD Medical Center.

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