Effect of the severity of liver dysfunction on the minimum alveolar concentration of sevoflurane responding to an electronic stimulation in cirrhotic patients

BACKGROUND: It has been observed that patients with liver dysfunction need lower dose anesthetic compared patients with normal liver function. The minimum amount of volatile anesthetic to achieve an optimal depth of anesthesia for these patients is still unclear. In this study, Minimum alveolar concentration (MAC) of the sevoflurane was determined using an electric stimulation and the effect of severity of liver dysfunction on the MAC was observed in cirrhotic patients. METHODS: Thirty patients undergoing upper abdominal surgery were divided into the following groups: group N (normal liver function), group A (Child-Pugh grade A) and group B (Child-Pugh grade B-C). Neuropsychological tests were performed before surgery. We measured MAC(electric) (minimum alveolar concentration that prevents movement in response to an electric stimulation in 50 % of patients) of sevoflurane in cirrhotic patients with liver dysfunction using an electrical stimulation of 80 mA at 50 Hz, and analyzed factors that associated change of MAC. RESULTS: According to the neuropsychological tests, there were 7 and 4 patients with minimal hepatic encephalopathy in Groups B and A, respectively. MAC(electric) in cirrhotic patients with liver dysfunction decreased significantly compared to that in healthy liver patients (1.51 ± 0.16 vol. %, 1.33 ± 0.14 vol. % and 1.17 ± 0.13 vol. % in Group N, A and B, respectively), while MAC(electric) was comparable between the cirrhotic patients with different Child-Pugh grade. The Alanine Aminotransferase (ALT) and baseline values of bispectral index (BIS) were risk factors associated with the lowering of MAC(electric) (p < 0.05). CONCLUSION: MAC(electric) of sevoflurane in cirrhotic patients was significantly lower than that of patients with a healthy liver. The severity of liver dysfunction had no effect on the MAC(electric) of sevoflurane in cirrhotic patients. TRIAL REGISTRATION: This study has been registered in the Chinese Clinical Trial Register in August 3, 2011 (No. ChiCTR-TRC-11001507).