NEW INHALATIONAL ANESTHETICS

Recently, two new halogenated volatile anaesthetics, sevoflurane and d esflurane, have been approved for clinical use in Germany. Their low s olubility in blood is the most important common property, and this rep resents the most obvious difference from the inhalational anaesthetics currently used. Extensive clinical and experimental evaluations have confirmed the superior pharmacokinetic properties predicted. Both sevo flurane and desflurane provide more rapid emergence from anaesthesia, permit easier titration of the anaesthetic dose during maintenance and offer more rapid recovery from anaesthesia. For sevoflurane, there ar e additional advantages: a pleasant odor, negligible airway irritation , and excellent pharmacodynamic characteristics that even provide card iovascular stability comparable to isoflurane. A certain disadvantage and source of potential nephrotoxicity result from the metabolism of s evoflurane (2-5%) to anorganic fluoride and degradation to compound A in carbon dioxide absorbents. The extensive clinical data reported to date have revealed no evidence that sevoflurane has adverse renal effe cts. New insight into the pathomechanism of nephrotoxicity associated with either production of fluoride or compound A may well support clin ical experience. Desflurane strongly resists in vivo metabolism and be cause of this it appears to be devoid of toxicity. Nevertheless, poten tial side-effects may result from degradation in dry absorbents and su bsequent release of CO, from its extreme pungency and irritating airwa y effects. Thus, desflurane is not recommended for induction of anaest hesia, especially in children. The tendency for desflurane transiently to stimulate sympathetic activity, especially at concentrations above 1.0 MAC, limits its application in patients with cardiac disease.