Effects of renal function on serum fluoride level in dogs during and after enflurane anesthesia

To study the effect of renal function on the increased serum inorganic fluoride level produced by the metabolism of enflurane, three groups of beagle dogs were exposed to prolonged enflurane anesthesia, 1.25 MAC for 8 h. One group was studied both with and without renal function, one group only without renal function, and one group on two different occasions with renal function intact. Serum inorganic fluoride levels were determined every hour during the enflurane anesthesia and on termination for a further 4 h. In dogs with no renal function, the increase rate and the peak of serum inorganic fluoride level were significantly higher than in dogs with renal function. The average peak level in dogs with renal function was 21.4 mumol/l and in dogs with no renal function 38.4 mumol/l. Renal function was found to have the same capacity to increase the inorganic fluoride elimination from serum as other routes of elimination. At corresponding serum levels, the rate of decrease after terminating enflurane anesthesia was 3.5-4.0 mumol/l/h lower without renal function. Reanesthesia after 3 weeks did not significantly change the serum inorganic fluoride levels compared to the first anesthesia.