injuries poisoning
Overview of Heat Illness
Etiology of Heat Illness
Heat disorders are caused by some combination of increased heat input and decreased output (see table). Excess heat input typically results from strenuous exertion, high environmental temperatures, or both. Medical disorders and use of stimulant drugs can increase heat production. Impaired cooling can result from obesity, high humidity, high environmental temperatures, wearing heavy clothing, and anything that impairs sweating or evaporation of sweat. Clinical effects of heat illnesses are exacerbated by the following: Inability to tolerate increased cardiovascular demands (eg, due to aging, heart failure, chronic kidney disease, respiratory disorders, liver failure) Dehydration Electrolyte disturbance Use of certain drugs (see table) Older people and the very young are at increased risk. Older adults are at high risk because they more often take medications that can increase risk, have higher rates of dehydration and heart failure, and have age-related loss of heat-shock proteins. Children are at high risk due to their greater surface-area-to-body-mass ratio (resulting in greater heat gain from the environment on a hot day), and slower rates of sweat production. Children are slower to acclimatize and have less of a thirst response. Both older adults and young children may be relatively immobile and thus have difficulty leaving a hot environment. 