[Uptaken distribution and metabolism of sevoflurane]

The inhalational anaesthetic fluor-methyl-trifluor-1-(trifluoromethyl)-ethylether sevoflurane has been known for more than 20 years and is structurally related to the currently available volatile anaesthetics. This anaesthetic is characterized by a low blood/gas partition coefficient of 0.69 and high fat solubility, leading to a sharp rise in alveolar concentration and quick anaesthesia induction. As opposed to desflurane, sevoflurane does not boil at ambient temperature, thus making a special vaporizer unnecessary. The alveolar uptake of sevoflurane is 20% and 66% faster than that of isoflurane and halothane respectively. Elimination of sevoflurane from the blood is twice as quick as that of halothane; the younger the patient, the earlier awakening from anaesthesia occurs. When administered in oxygen the minimal anaesthetic concentration (MAC) of sevoflurane in adults is 1.71 vol%; when administered in 60% nitric oxide, the MAC decreases to 0.66 vol%. The variations of published MAC determinations seem to results from geographical or population-specific potency differences of sevoflurane. In children MAC varies between 2.03 and 2.49 vol%. Biodegredation of sevoflurane occurs immediately following inhalation, leading to separation of ionized and of organically bound fluoride. As opposed to methoxyflurane, which may be nephrotoxic due to its microsomal metabolism in kidney tissue, sevoflurane does not seem to cause clinical inhibition of renal function even at plasma fluoride levels above 50 mumol/l, a concentration thought to be associated with renal tubular impairment. A possible reason for this observation is lower metabolism of sevoflurane within renal tissues. Due to its quick onset and fast elimination, sevoflurane is an interesting new volatile anaesthetic offering various clinical advantages.