SERUM FLUORIDE CONCENTRATION AND URINE OSMOLALITY AFTER ENFLURANE ANDSEVOFLURANE ANESTHESIA IN MALE-VOLUNTEERS

The purpose of this study was to measure the serum fluoride concentrat ion after enflurane or sevoflurane anesthesia and to compare the effec ts of prolonged anesthesia with these drugs on renal concentrating fun ction in male volunteers. The study was subdivided into three stages; an ascending dose study of 3.0 and 6.0 minimum alveolar anesthetic con centration (MAC) hours of sevoflurane alone, a 9.0-MAC-hour comparison of enflurane and sevoflurane, and a 9.0-MAC-hour comparison of enflur ane and sevoflurane. Renal concentrating function was assessed by an 1 8-h period of fluid deprivation and the serum fluoride concentration w as measured at intervals until 60 h postanesthesia. The maximum serum fluoride concentration was greater in the volunteers exposed to sevofl urane and reached a peak in the 9-MAC-hour sevoflurane group of 36.6 m u M (sD 4.3) compared with 27.5 mu M (so 2.6) in the 9-MAC-hour enflur ane group. However, the rapid decrease in the serum fluoride concentra tion after sevoflurane was such that there was no difference between t he areas under the fluoride concentration-time curves. There were no s ignificant differences between the median maximum urine osmolalities a fter enflurane or sevoflurane anesthesia. Prolonged anesthesia with en flurane or sevoflurane is not associated with impaired renal concentra ting function despite an increase in the serum fluoride concentration.