SEVOFLURANE DEGRADATION PRODUCT CONCENTRATIONS WITH SODA LIME DURING PROLONGED ANESTHESIA

Study Objectives: To evaluate the decomposition of sevoflurane in soda lime during prolonged sevoflurane anesthesia in humans. To evaluate f or evidence of renal or hepatotoxicity as a result of exposure to thes e sevoflurane degradation compounds. Design: Prospective evaluation in healthy volunteers. Setting: Clinical research unit and postanesthesi a care unit of a university hospital. Patients: Six healthy male volun teers. Interventions: Subjects were anesthetized with sevoflurane 1 to 1.2 minimum alveolar concentration for greater than 9 hours with a se miclosed circuit anesthetic technique (5-liter total flow) with fresh soda lime as the absorbent. Measurements and Main Results: Laboratory tests of renal and hepatic function were performed before anesthesia a nd 1 and 5 days after anesthesia. During sevoflurane anesthesia, inhal ation and exhalation circuit limb gas samples were obtained for degrad ation compound analysis. Only one degradation product, fluoromethyl-2, 2-difluoro-1-(trifluoromethyl) vinyl ether (compound A), was detected. Inhalation concentration was maximal (7.6 +/- 1.0 ppm) at 2 hours and did not increase further after this time point. There were no differe nces in preanesthesia and postanesthesia tests of hepatic and renal. f unction. Conclusions: Levels of the degradation compound (compound A) produced in semiclosed circuit sevoflurane anesthesia with soda lime a re well below potential toxic levels and thus appear safe. When sevofl urane is administered under these conditions for prolonged anesthesia, concentrations of compound. A do not continue to increase throughout anesthesia.