RENAL-FUNCTION AND SERUM FLUORIDE CONCENTRATIONS IN PATIENTS WITH STABLE RENAL-INSUFFICIENCY AFTER ANESTHESIA WITH SEVOFLURANE OR ENFLURANE

Sevoflurane is metabolized to hexa-fluoro-isopropanol and inorganic fl uoride by the human liver. Its use as an anesthetic may lead to peak p lasma fluoride concentrations exceeding those seen after enflurane. Al though there is no nephrotoxicity after sevoflurane anesthesia in huma ns with normal kidneys, those with chronically impaired renal function might be at increased risk because of increased fluoride load due to prolonged elimination half-life. In this study, measures of renal func tion after sevoflurane anesthesia were compared to those after enflura ne in patients with chronically impaired renal function. Forty-one ele ctive surgical patients with a stable preoperative serum creatinine co ncentration greater than or equal to 1.5 mg/dL were randomly allocated to receive sevoflurane (n = 21) or enflurane (n = 20) at a fresh gas inflow rate of 4 L/min for maintenance of anesthesia. Serum fluoride c oncentrations were measured by ion-selective electrode. Renal function (creatinine, urea, sodium, osmolality) was assessed in serum and urin e preoperatively and for up to 7 days postoperatively. Peak serum inor ganic fluoride concentrations were significantly higher after sevoflur ane than after enflurane anesthesia (25.0 +/- 2.2 vs 13.3 +/- 1.1 mu M ; mean +/- SEM). Laboratory measures of renal function remained stable throughout the postoperative period in both groups. No patient suffer ed a permanent deterioration of preexisting renal insufficiency and no ne required dialysis. Thus, neither sevoflurane nor enflurane deterior ated postoperative renal function in these patients with preexisting r enal insufficiency. There is no evidence that fluoride released by met abolism of sevoflurane metabolism worsened renal function in these pat ients with stable, permanent serum creatinine concentrations more than 1.5 mg/dL. Ow data also suggest that the peak fluoride concentrations measured in peripheral blood may not be a good predictor of nephrotox ic potential after sevoflurane anesthesia in these patients.