Serum and urine inorganic fluoride levels following prolonged low-dose sevoflurane anesthesia combined with epidural block.

STUDY OBJECTIVES

To determine whether serum and urine inorganic fluoride levels with prolonged (more than 7 hours) low-dose (0.8 to 2.0 vol %) sevoflurane anesthesia plus epidural anesthesia were increased as compared with isoflurane anesthesia plus epidural anesthesia. To measure the urine tubular enzymes N-acetyl-beta-glucosaminidase (NAG), alpha 1-microglobulin (alpha 1-M), and beta 2-microglobulin (beta 2-M) for renal tubular injury in both groups.

DESIGN

Randomized, prospective study.

SETTING

University hospital.

PATIENTS

15 ASA physical status I and II adults (7 males, 8 females) who were scheduled for prolonged laparotomy (lasting 9.5 to 10.2 hours) with general anesthesia.

MEASUREMENTS AND MAIN RESULTS

Epidural anesthesia was administered before induction of general anesthesia. General anesthesia was induced with thiamylal administered intravenously (IV), and the trachea was intubated following administration of vecuronium IV. It was maintained with either sevoflurane or isoflurane in nitrous oxide and oxygen. Standard monitoring was used in all patients. Serum and urine inorganic fluoride and urine tubular enzymes were measured periodically. Serum inorganic fluoride was 54 mumol/L at 4.3 minimum alveolar concentration (MAC) hours of sevoflurane; the peak level for isoflurane was 8 mumol/L at the same MAC hours. Sevoflurane also increased urine inorganic fluoride excretion to 96 mumol/hr 8 hours. NAG excretion started to increase after inhalation of either sevoflurane or isoflurane. alpha 1-M and beta 2-M excretion increased markedly postoperatively. Even though fluoride levels and tubular enzymes were high, there was no evidence of postoperative renal dysfunction.

CONCLUSIONS

There was no increase in urinary enzymes, which are indicators of tubular injury, specific to sevoflurane. There was no postoperative renal dysfunction, as indicated by unchanged serum creatinine and blood urea nitrogen levels.