Methoxyflurane anesthesia in pediatric patients: evaluation of anesthetic metabolism and renal function.

Serum ionic fluoride concentrations during and following low-dose (6.0 mg/100 ml, 3 hours) methoxyflurane anesthesia and elective operation were measured in 13 pediatric patients (mean age 10.2 years; mean weight 34.5 kg). Peak measured serum ionic fluoride concentration was 21.6 plus or minus 3.3 mumol/1 24 hours after anesthesia. In a previously reported study of adult patients (47.5 years; 71.9 kg), the peak measured serum ionic fluoride concentration was 43.9 plus or minus 5.7 mumol/1 24 hours after low-does (6.8 mg/100 ml,3 hours) methoxyflurane anesthesia. Possible explanations for lower serum ionic fluoride concentrations in pediatric patients comared with adults include 1) slower metabolism of nethoxyflurand; 2) increased renal clearance of ionic fluoride from the blood; 3) greater sorage of ionic fluride in bone; 4) more rapid methoxyflurane elimiantion in the postoperative period. Serum uric acid increased (4.4 to 6.4 mg/100 ml, not significant) 24 hours after anesthesia and operation, while blood urea nitrogen and serum creatinine and osmolality were unchanged postoperatively.