Heat Exhaustion
The recent heat wave along the eastern US has brought up this topic once again. There have been many fatalities, especially among the elderly, chronically ill, and the extremely young population. The most important thing is to get into cooler surroundings, even if it means leaving ones home. Air conditioning is available in shopping malls, theaters, and public buildings, even unlikely places such as libraries, museums, and restaurants. Dressing coolly is also important. Unless one plans to spend a lot of time in direct sunlight, it is always wise to dress lightly.
The body's cooling mechanism is perspiration. When the surrounding environment is hotter than the body temperature, human beings are capable of producing water on the skin by means of sweat glands located all over the body. When the rate of perspiration is low, the concentration of sodium and chloride is higher; as the rate accelerates, the concentration of both elements approach that of serum. This means that, for every 1000 cc's of water, the human body loses about 5 grams of salt. Therefore it is important that one replenishes salt in the same ratio.
The human body also loses an obligatory amount of water and sodium chloride in the urine. In the normal person, it is necessary to use about 750cc of saline to rid the body of waste products. In addition about 500 to 1000 ccs of water are lost during normal breathing. Using this calculation, it is important to ingest about 1250 to 1750 ccs of water and four grams of salt.
When the body is unable to produce enough perspiration to cool itself, it can get overheated. The enzyme systems of the human body can not operate above 40 degrees Celsius (or about 103.4 Fahrenheit). Continued hyperthermia above this level, even for a few hours, is rapidly fatal.
Things to avoid in hot weather are diuretic agents, the most common abused diuretics being alcohol and caffeine. Caffeine containing colas, many of which contain phosphates in addition, can be dangerous both in its diuretic effects and as a causative factor in formation of calcium phosphate renal stones.
Therefore, the most important things to do: (1) Stay out of the heat, (2) Drink plenty (2000ccs plus per day) of water (not alcohol or soft drinks), (3) Ingest about 4 grams of salt, (4) Get plenty of rest, avoid strenuous exercise.