Wednesday 25 March 2009
Heat stroke is associated with high ambient temperatures and high humidity. Thermoregulatory mechanisms fail, sweating ceases, and core body temperature rises. Body temperatures of 112° to 113°F have been recorded in some terminal cases. Clinically, a rectal temperature of 106°F or higher is considered a grave prognostic sign, and the mortality rate for such patients exceeds 50%.
The underlying mechanism is marked generalized peripheral vasodilation with peripheral pooling of blood and a decreased effective circulating blood volume.
Necrosis of the muscles (rhabdomyolysis) and myocardium (myocardial necrosis) may occur. Cardiac arrhythmias, disseminated intravascular coagulation (DIVC), and other systemic effects are common.
Elderly persons, individuals undergoing intense physical stress (including young athletes and military recruits), and persons with cardiovascular disease are prime candidates for heat stroke.