Effect of remifentanil on MACBAR of sevoflurane in patients with hepatic dysfunction undergoing laparoscopic surgery

Objective To evaluate the effect of remifentanil on the minimum alveolar concentration of sevoflurane required to blunt the adrenergic response (MACBAR) in the patients with hepatic dysfunction undergoing laparoscopic surgery. Methods The patients, aged 18-64 yr, with body mass index < 30 kg/m2, undergoing elective laparoscopic hepatobiliary surgery, were selected.Patients with normal liver function were selected as control group (C group), and patients with liver dysfunction (Child-Pugh grade B) were selected as test group and divided into 3 subgroups by a random number table method: no remifentanil group (R0 group) and different target plasma concentrations of remifentanil groups (R1 group and R2 group). Anesthesia was induced by intravenously injecting propofol 2-3 mg/kg, remifentanil 2 μg/kg and cisatracurium 0.15 mg/kg.After endotracheal intubation, mechanical ventilation was performed.The end-tidal sevoflurane concentration was adjusted to the preset concentration in each group and maintained at the level for 20 min before the pneumoperitoneum was established.Anesthesia was maintained as follows: remifentanil was not used in C group and R0 group, and the target plasma concentration of remifentanil was 1 and 2 ng/ml in group R1 and group R2, respectively, and sevoflurane was inhaled.The MACBAR of sevoflurane was determined using the sequential method.The initial end-tidal sevoflurane concentrations were 5.0%, 4.6%, 2.6% and 2.4% in group C, group R0, group R1 and group R2, respectively.MAP and HR were recorded and blood samples were collected before and after pneumoperitoneum, and the plasma epinephrine and norepinephrine concentrations were measured by enzyme-linked immunosorbent assay, and the difference in MAP and HR before and after pneumoperitoneum was calculated. Results A total of 14 cases in group C, 19 cases in group R0, 19 cases in group R1 and 15 cases in group R2 completed the study.Compared with group C, the MACBAR of sevoflurane and plasma adrenergic concentration before and after pneumoperitoneum were significantly decreased (P 0.05). Compared with group R0, the MACBAR of sevoflurane was significantly decreased in group R1 and group R2, and HR before and after pneumoperitoneum and the difference were significantly decreased in group R2(P<0.05). The MACBAR of sevoflurane was significantly lower in group R2 than in group R1 (P<0.05). Conclusion Remifentanil can decrease the MACBAR of sevoflurane and enhance the efficacy in inhibiting the stress responses in the patients with hepatic dysfunction undergoing laparoscopic surgery. Key words: Anesthetics, inhalation; Piperidines; Hepatic insufficiency; Dose-response relationship, drug