FAMILY MEDICINE® COLUMN

By John C. Wolf, D.O.
Associate Professor of Family Medicine
Ohio University College of Osteopathic Medicine

HEAT -- HEAT -- WHAT SHOULD I DO IN ALL THIS HEAT?

Question: My work keeps me outdoors on many of these summer days. Because of the heat, I drink plenty of water. Despite this, I got quite hot two days ago. I drank some sports drink and soaked in a cool bathtub when I got home. Later that evening, and still today, I had some nausea and feel generally weak. Did I catch some type of flu or is this a mild form of heat stroke?

Answer: Infectious illnesses like influenza do occur in the summer, although they are more prevalent in the winter months. Food poisoning and other conditions can cause symptoms like nausea and feeling weak. With your description of the circumstances, however, I’d assume that you had a mild form of heat-related illness.

Our organs operate efficiently in a very narrow range of temperatures, about 98 to 100 degrees Fahrenheit. The reason we can function well in a wide variety of environments -- from cold winter weather to the heat of summer -- is that the human body has effective methods for controlling the temperature of the organs in the head, chest and abdomen.

In a warm environment, the body generates more heat than it needs to keep the organs at their optimal working temperature. The body deals with this situation by pumping the warmed blood to areas where its heat can be released to the environment. This is why on a hot day you become "flushed" as the circulation in the blood vessels close to the surface of the skin is increased. In addition, the temperature exchange is augmented by the cooling effect of evaporation of sweat from the skin.

Normally these and other temperature-control mechanisms, including air exchange in the lungs, do a satisfactory job. In some situations, however, these methods may not be sufficient to keep the body temperature down where it belongs. Prolonged exercise while in bright sunlight on a hot summer day -- such as you experienced -- is one of these situations.

If the internal temperature of the body increases above the optimal level, the body's organs start to work less efficiently. A mild elevation, say to a temperature of 101 or 102, causes some general muscle weakness, nausea, headaches, dizziness, muscle cramps and clammy skin. This milder form of heat-related illness is called heat exhaustion. This is probably what you had, and the treatment you took -- consuming liquids and cooling off in the tub, is appropriate. Despite the prompt return of your body temperature to normal, the nausea, muscle aching and general “not feeling your best” sensations often take a day or two more to resolve.

In the most extreme cases of heat-related illness, the internal temperature may reach 105 to 107 degrees and cause serious damage to the liver, kidneys, brain and heart. This is called heat stroke, and it’s a much more serious condition than the heat exhaustion you had. Heat stroke can be fatal without immediate medical intervention. This is an important point to understand.

The best thing to do when you think someone has heat stroke is to call emergency medical services immediately. While waiting for the ambulance to arrive, move the victim into the shade. It will help lower the body temperature if you spray his or her bare head, chest and abdomen with cool but not cold water. Offer liquids to drink if the person is able, but above all else, get emergency help as quickly as possible!

As in most situations, prevention of a heat-related illness is the best approach. To avoid getting into trouble again this summer, I’d suggest that you take frequent breaks to get out of direct sunlight. Wear lightweight, light-colored clothing, put on a sunscreen with an SPF of 15 or higher, and drink large quantities of liquids. Water is fine, and sports drinks are OK, too. The easiest way to tell if you have been drinking enough liquid is by your frequency of urination. If it’s been over four hours -- then it’s time for a water break.

"Family Medicine" is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, P.O. Box 110, Athens, Ohio 45701. Past columns are available online at http://www.FamilyMedicineNews.org.