[Sevoflurane]

Abstract

Sevoflurane, a methylethylether halogenated solely with fluorine, is characterized by a low blood/gas solubility (blood/gas partition coefficient = 0.65). This feature allows in a more rapid uptake and elimination than with more soluble agents. MAC is about 2 vol% in young adults and 2.5 vol% in children of more than 6 months of age. It undergoes degradation by soda lime in various components. Among them, compound A (an olefin) produces renal toxicity in rats. Total sevoflurane metabolism represents about 5% of inhaled dose and produces inorganic fluorides. However no renal toxic effects has been reported up to now in animals and in patients. The effects on central nervous and cardiovascular systems are close to those of isoflurane. It decreases cerebral vascular resistances and cerebral oxygen consumption, but does not cause convulsive activity. It decreases myocardial contractility, systolic arterial pressure and systemic vascular resistances, but heart rate remains basically unchanged up to 1 MAC. It does not sensitize the myocardium to catecholamines. It depresses ventilation in a dose-dependent fashion, this effect being more pronounced than that of halothane but less than that of both isoflurane and enflurane. It is not irritant for the airways and has some bronchodilatory effect. In adults, recovery is more rapid than with isoflurane. In children, sevoflurane seems a promising agent owing to its good acceptance for mask induction, as well as its favourable haemodynamic profile. However due to its rapid elimination, analgesic drugs should be administered early enough to decrease the incidence of postoperative pain.