Renal fluoride excretion during and after enflurane anaesthesia: dependency on spontaneous urinary pH-variations.

Renal function, fluoride formation and excretion were studied in seven patients during and after enflurane anaesthesia and surgery. The mean maximal plasma level of fluoride was 17.4 microM. It was reached 2 h after termination of anaesthesia. Pre-operatively, fraction fluoride clearance (CF/CIn) was 0.31. During anaesthesia and surgery it decreased to 0.10 and postoperatively rose to 0.55 and 0.77 during two consecutive measurement periods. There was a highly significant correlation (P less than 0.001) between this increase in CF/CIn and the simultaneous rise in urinary pH between the two periods (r = 0.91).