Evaluation and treatment of heat-related illnesses.

The body's ability to regulate core temperature depends on both host (internal) and environmental (external) factors. Although athletes are commonly thought to be most at risk for heat illnesses, children and the elderly are particularly vulnerable. Heat cramps, which are caused by fluid and electrolyte imbalances, are treated with massage, and fluid and electrolyte replacement. Heat exhaustion occurs both as water- and sodium-depleted types, with associated symptoms such as malaise, vomiting, and confusion. Treatment involves taking the affected person to a cool environment and replacing fluids and electrolytes if needed. In more serious cases, intravenous hydration may be necessary, although monitoring of serum sodium levels is important to prevent cerebral edema. If not treated promptly, heat exhaustion may evolve into heatstroke, a deadly form of heat illness. Heatstroke occurs in classic and exertional forms and is present when the core body temperature exceeds 40 degrees C (104 degrees F). The patient may experience cardiac arrhythmias, rhabdomyolysis, serum chemistry abnormalities, disseminated intravascular coagulation, and death. Heatstroke is a medical emergency that should be treated immediately with temperature-lowering techniques such as immersion in an ice bath or evaporative cooling. Fluid resuscitation is important but should be closely monitored, and renal function may need to be protected with mannitol and diuretics. It is important to be vigilant for heat illnesses because they occur insidiously but progress rapidly.