Serum Fluoride Concentration and Urine Osmolality After Enflurane and Sevoflurane Anesthesia in Male Volunteers

The purpose of this study was to measure the serum fluoride concentration after enflurane or sevoflurane anesthesia and to compare the effects of prolonged anesthesia with these drugs on renal concentrating function in male volunteers. The study was subdivided into three stages; an ascending dose study of 3.0 and 6.0 minimum alveolar anesthetic concentration (MAC) hours of sevoflurane alone, a 6.0-MAC-hour comparison of enflurane and sevoflurane, and a 9.0-MAC-hour comparison of enflurane and sevoflurane. Renal concentrating function was assessed by an 18-h period of fluid deprivation and the serum fluoride concentration was measured at intervals until 60 h postanesthesia. The maximum serum fluoride concentration was greater in the volunteers exposed to sevoflurane and reached a peak in the 9-MAC-hour sevoflurane group of 36.6 microM (SD 4.3) compared with 27.5 microM (SD 2.6) in the 9-MAC-hour enflurane group. However, the rapid decrease in the serum fluoride concentration after sevoflurane was such that there was no difference between the areas under the fluoride concentration-time curves. There were no significant differences between the median maximum urine osmolalities after enflurane or sevoflurane anesthesia. Prolonged anesthesia with enflurane or sevoflurane is not associated with impaired renal concentrating function despite an increase in the serum fluoride concentration.