Emergency medical services
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When a disease process becomes life-threatening, it is termed to be malignant. Hyperthermia is a heat illness that arises from one of two basic causes: 1) the body's normal thermoregulatory mechanisms are overwhelmed by the environment (an exogenous heat load) or, more commonly, by excessive exercise in a moderate-to-extreme environment (an endogenous heat load); or 2) failure of the thermoregulatory mechanisms, such as those encountered in the elderly or debilitated patient. Either cause can lead to heat illnesses such as heat cramps, heat exhaustion or heatstroke. ⋯ As the illness progresses, peripheral vasodilation occurs, resulting in hypotension and shunting. As internal temperatures rise, myocardial contractility begins to decrease, manifested by bradycardia and irritability of the myocardium. No matter the age group, the presence of hypotension and decreased cardiac output indicates a poor prognosis for the patient.