Background
The minimum alveolar concentration (MAC) is the measure of the potency of volatile anesthetics. The MAC is defined as the alveolar concentration of a volatile anesthetic at which 50% of individuals do not move after a single painful stimulus. Evidence suggests that patients with end-stage liver disease (ESLD) have decreased anesthetic requirements. However, the MAC of sevoflurane has never been assessed in patients with ESLD. 
Objective
The aim of this prospective, blinded study was to determine whether the MAC of sevoflurane is lower in patients with ESLD than patients with normal liver function.
Methods
The MAC of sevoflurane was assessed in patients with ESLD, who underwent orthotopic liver transplantation. Patients with no history of liver disease undergoing major abdominal surgery served as control. The MAC was calculated by applying Dixon’s “up-and-down” method. The primary endpoint was the patient’s motor response within one minute after initial skin incision. Differences in MAC values between groups were analyzed by unpaired t-test. This study was approved by the ethics committee of the Medical University of Vienna.The MAC of sevoflurane was assessed in patients with ESLD, who underwent orthotopic liver transplantation. Patients with no history of liver disease undergoing major abdominal surgery served as control. The MAC was calculated by applying Dixon’s “up-and-down” method. The primary endpoint was the patient’s motor response within one minute after initial skin incision. Differences in MAC values between groups were analyzed by unpaired t-test. This study was approved by the ethics committee of the Medical University of Vienna.
Results
20 patients with ESLD and 20 control patients were included in this study. The mean age of patients did not differ between groups (x vs x, P=X). The MAC of sevoflurane was 1.3 % in patients with ESLD compared to 1.7 % in patients with no history of liver disease (P<0.001). 
Conclusion
The MAC of sevoflurane is lower in ESLD patients than in patients with normal liver function. 
Our results suggest that patients with ESDL require approximately 30% less of the volatile anesthetic sevoflurane than patients with preserved liver function for anesthesia.

Minimum alveolar concentrations of sevoflurane in patients with end-stage liver disease