Minimal-flow and low-flow anesthesia provide many advantages, including reduced costs and pollution, and conservation of body heat and airway humidity. However, low-flow sevoflurane anesthesia is associated with an increase in the circuit concentration of compound A, which causes nephrotoxicity in rats. Therefore, this study was conducted to assess the effects of prolonged minimal-flow sevoflurane anesthesia on hepatic and renal function.

Forty female patients who underwent free flap surgery lasting more than 8 hours randomly received either high-flow (5 L/min) or minimal-flow (0.5 L/min) sevoflurane anesthesia. Hepatic functions were then assessed by measuring the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total bilirubin levels. In addition, renal functions were assessed by measuring the blood urea nitrogen (BUN) and serum creatinine levels and by spot urinalysis. Venous blood and spot urine samples were obtained prior to administration of the anesthesia, and then on the first, third and fifth days following administration of the anesthesia.

The anesthetic time (9.9 ± 1.7 vs. 9.6 ± 2.0 h) and sevoflurane exposure (8.2 ± 1.7 vs. 7.4 ± 1.9 MAC-h) were not different between the high-flow and minimal-flow anesthesia group. The serum AST, ALT, ALP and total bilirubin levels were within the normal range throughout the study period in both groups. Additionally, the BUN and serum creatinine levels were within the normal range throughout the study period in both groups. Furthermore, there were no significant differences in any hepatic or renal biomarkers between the two groups.

No significant differences in postoperative hepatic and renal function were observed between the minimal-flow and high-flow sevoflurane anesthesia groups.