Acta anaesthesiologica Scandinavica. Supplementum
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Despite minor daily and monthly cyclical variations, body temperature remains relatively constant. Core temperature is maintained by thermoregulatory responses such as sweating, vasoconstriction and shivering, which are largely controlled by the hypothalamus. Within the hierarchy of neural structures regulating autonomic thermoregulatory responses, the preoptic area of the anterior hypothalamus plays a dominant role. ⋯ The increasing phase of fever is often associated with shivering, which can markedly increase heart rate and cardiac output. Defervescence (and passive hyperthermia) is also often accompanied by tachycardia resulting from active precapillary vasodilation. Thus, cardiovascular complications are common throughout the febrile course and constitute the major clinical consequence of fever.
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The new nondepolarizing muscle relaxant rocuronium belongs to the chemical group of aminosteroidal muscle relaxants and is similar to vecuronium in its chemical structure and pharmacologic action. The principal clinical advantage of rocuronium over vecuronium is the short time to onset of the neuromuscular block. The two other new muscle relaxants, mivacurium and cis-atracurium, belong to the group of benzylisoquinoline muscle relaxants. ⋯ While its action is similar to that of atracurium, it does not release histamine and its administration is not accompanied by marked changes in blood pressure or heart rate. Even the simple tactile monitoring of the neuromuscular transmission enables the clinician to adjust the doses of these and other muscle relaxants to the needs of individual patients. Precise adjustment of the doses of muscle relaxants contributes to their safer clinical use by avoiding an excessively deep and unnecessarily prolonged neuromuscular block.