Toxicity of sevoflurane in rats

Sevoflurane, an experimental potent volatile anesthetic with a low blood/gas partition coefficient, degrades in the presence of soda lime to products the toxicity of which is unknown. We tested whether toxic products were produced by the passage of sevoflurane through soda lime, and a comparison was made of the toxicity of sevoflurane passed through soda lime with the toxicity of other potent volatile anesthetics in current clinical use. Halothane, isoflurane, sevoflurane (all in 1-MAC concentrations), or no anesthetic (control) were passed through soda lime for 4 hr with 12, 14, or 100% oxygen to groups of rats with hepatic microsomal enzyme induction. Separate groups of 12-13 rats were given 1 MAC of sevoflurane that had not passed through soda lime and either 14 or 100% oxygen. Sevoflurane was no more toxic than isoflurane and both of these anesthetics were less toxic than halothane. Soda lime was not a factor in any toxicity produced. Hepatic injury with all agents varied inversely with the oxygen concentration administered during anesthesia.