Hyperthermia is an elevated body temperature due to failed thermoregulation. It occurs when the body produces or absorbs more heat than it can dissipate. When the elevated body temperatures are sufficiently high, hyperthermia is a medical emergency and requires immediate treatment to prevent disability and death. The most common causes are heat stroke and adverse reactions to drugs. Heat stroke is an acute condition of hyperthermia that is caused by prolonged exposure to excessive heat and/or humidity. The heat-regulating mechanisms of the body eventually become overwhelmed and are unable to effectively deal with the heat, causing the body temperature to climb uncontrollably – sometimes to 106 degrees F or higher. Heat stroke is also caused by dehydration; a person may not be able to sweat fast enough to dissipate heat, which causes the body temperature to rise.
Exposure to high temperatures can also lead to heat cramps or heat exhaustion. Heat cramps are muscle contractions, usually in the hamstring muscles (the muscles at the back of the calves). These contractions are forceful and painful. The cramps seem to be connected to heat, dehydration and poor conditioning, rather than to lack of salt or other mineral imbalances. They usually improve with rest, drinking water and a cool environment. Although partly due to exhaustion and feeling like exhaustion, as the name implies heat exhaustion is also a result of excessive heat and dehydration. The signs of heat exhaustion include paleness, dizziness, nausea, vomiting, fainting, and a moderately increased temperature (101-102 degrees F) which is not truly a fever, but caused by the heat. Rest and water may help in mild heat exhaustion, and ice packs and a cool environment (with a fan blowing) may also help. More severely exhausted patients may need IV fluids, especially if vomiting keeps them from drinking enough. It’s also important to measure temperature properly. In particular, if you suspect problems with heat cramps or heat exhaustion you should measure temperature using an oral or rectal thermometer, not an ear or forehead thermometer (which may give a falsely low temperature, especially with forehead thermometers and lots of sweat).
The symptoms of heat exhaustion (mentioned above) vary somewhat from heat stroke. Heat stroke symptoms develop rapidly and suddenly without warning. Different people may have different symptoms, but common signs of heat stroke include extremely high body temperature (106 degrees F or higher), the absence of sweating, hot and red, dry skin, a rapid pulse, difficulty breathing, hallucinations or strange behavior, disorientation, agitation, seizure or even coma. Those most susceptible to heat stroke include infants, the elderly, outdoor workers and athletes.
The most common measures to prevent heat stroke are taking frequent breaks to hydrate yourself, drinking plenty of fluids, avoiding vigorous physical activities in hot and humid weather, wearing hats and light-colored, loose and lightweight clothing, replenishing electrolytes, i.e. sodium with plenty of water or sports drinks, and avoiding drinks that have alcohol or caffeine.
If you find any kind of altered mental status, the victim probably is having a heat stroke. First and foremost, cool the individual. Get the person to a shady area, remove clothing and apply cool or tepid water to the skin, fan the victim to promote sweating and place icepacks under the armpits and groins. If the victim starts to shiver, the cooling process should be slowed, as shivering will increase the core temperature of the body. If possible, the temperature should be taken every ten minutes to avoid a continued temperature drop, which could result in hypothermia. The individual should be transported immediately to a hospital setting, as again, this is a medical emergency and the mortality rate ranges anywhere from 40-80%.