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the accumulation of excess heat in the body of humans or animals, with an elevation of body temperature, caused by external factors that hinder the transfer of heat to the external environment or increase heat intake from outside the body. Hyperthermia arises when there is maximum strain on the physiological mechanisms of thermoregulation (perspiration, dilation of cutaneous blood vessels, and so forth); if the causes are not removed, it progresses, ending with heat stroke at a body temperature of approximately 41°-42° C.
Hyperthermia is accompanied by an increase of metabolism and qualitative disturbances of it, loss of water and salts, and disruption of blood circulation and the delivery of oxygen to the brain, causing agitation and sometimes convulsions and fainting. High temperature during hyperthermia is tolerated less readily than it is in other feverish diseases. The development of hyperthermia is promoted by an increase in heat production (for example, during muscular work), disruption of thermoregulation mechanisms (with narcosis, drunkenness, and certain diseases), or age-related failure of these mechanisms (in very young children). Artificial hyperthermia is used in treating certain nervous and slowly progressing chronic diseases.
P. N. VESELKIN