Purpose: In liver transplantation patients under intravenous anesthesia, the vecuronium dose is known to be reduced, especially during the anhepatic phase. Volatile anesthetics potentiate a muscle relaxation effect of neuromuscular blocking agents, so the vecuronium dose is supposed to further decrease if sevoflurane is used during liver transplantation. The purpose of this study was to determine the appropriate dose of vecuronium at each phase of liver transplantation under sevoflurane anesthesia.
Methods: Thirty-five patients scheduled for living donor liver transplantation because of liver cirrhosis were enrolled in this study. They were anesthetized with 1 MAC of sevoflurane and intermittent administration of fentanyl. Continuous infusion of vecuronium (0.5 mg/ml) was used for muscle relaxation, which was adjusted every 15 min for consistent muscle relaxation aimed at T1/Tc of 0.1 monitored by ulnar nerve stimulation. Vecuronium infusion was stopped after hepatic artery anastomosis was finished. The infusion rate of each operative phase-dissection, anhepatic, and neohepatic-was calculated and analyzed by one-way analysis of variance. The recovery time from train-of-four (TOF) count 1 to TOF ratio 25% was also measured.
Results: The vecuronium infusion rate of each operation phase for adequate muscle relaxation was as follows: 0.033 ± 0.009 mg/kg/h during dissection phase, 0.031 ± 0.009 mg/kg/h during anhepatic phase, and 0.026 ± 0.006 mg/kg/h during early neohepatic phase. There was a statistically significant difference between doses at each phase (P = 0.033). The recovery time from TOF count 1 to TOF ratio 25% was 103 ± 29 min.
Conclusions: The required vecuronium dose in all phases was less than the known dose in the anhepatic phase (0.036 mg/kg/h) under midazolam-fentanyl anesthesia. In addition, the vecuronium infusion dose was not reduced in the anhepatic phase compared to the dissection phases.