The body responds to heat by dilating the blood vessels in the skin and increasing the heartbeat. The body loses heat by conduction and convection which is caused by the cooling effect of air flowing next to the skin, radiation of heat to surrounding objects which come in contact with the skin, and evaporation of sweat. Excess sweating, however, causes loss of salt and water from the body fluids, which creates an increased workload on the circulatory system.
Physical work increases the effects of high temperature on the body. Other conditions make people more vulnerable to heat injury; at high risk are persons with:
There are three types of heat injuries – heat cramps, heat exhaustion, and heat stroke:
Heat Cramps – Caused by excessive loss of salt from the body
Symptoms: Painful cramps in muscles of the extremities and abdominal wall. Body temperature is normal.
Treatment: Have the person drink a 0.1 % salt solution (mix 2 ten grain salt tablets or 1 tsp. salt in 1 quart of water).
Heat Exhaustion – Caused by excessive loss of water and salt
Symptoms: Profuse perspiration, skin is cool and pale, rapid pulse (140-200 beats per minute), low blood pressure, headache, mental confusion, dizziness, drowsiness, weakness, loss of appetite, vomiting, visual disturbance, occasional cramps of extremities or abdominal muscles.
Treatment: Put in a cool place, encourage the individual to rest, elevate the feet, massage the extremities. Give a 0.1% saline solution by mouth as freely as the patient will take it. DO NOT ADMINISTER SALT TABLETS WITHOUT WATER
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Heat Stroke – Caused by a breakdown of the body’s heat regulating mechanism. A very serious condition in which there is extremely high body temperature – can lead to coma or death.
Risk: Persons not acclimatized to heat; physical exertion; alcoholism; diarrhea.
Symptoms: Absence of sweating, cool skin surface, headache, dizziness, mental confusion, weakness, nausea, urination. Early stages are characterized by hot, red, dry skin; full and rapid pulse; normal or elevated blood pressure; rapid and deep respiration; body temperature 106-110F. The onset is usually dramatic with collapse and loss of consciousness. Convulsions may occur.
Treatment: Lower the body temperature by removing clothes, immersing the patient in water (or in a tub of water and ice), give a sponge bath, or cover with a blanket soaked in cold water. Fan the patient to increase air flow. Rub the extremities and trunk briskly to increase skin circulation. Check temperature every 10 minutes – be careful not to lower temperature. Constant supervision and transport to a medical facility IMMEDIATELY.