Stability of sevoflurane in soda lime

Stability of halogenated volatile anesthetic is important because of the potential toxicity associated with the breakdown products. The authors enclosed 100 ml of gas containing sevoflurane with 100 g of soda lime in a 581-ml flask for periods up to 24 h. The rate of degradation of sevoflurane by soda lime was several-fold greater than previously reported, and the degradation was temperature-dependent. At 22 degrees C, soda lime degraded 6.5% of the sevoflurane per hour. The rate increased by 1.6% per hour per degree rise in temperature, reaching 57.4% degradation per hour at 54 degrees C. In contrast, isoflurane was not degraded by soda lime. Halothane did not degrade at 22 degrees C or 37 degrees C, but did degrade (2.2% per hour) at 54 degrees C.