Effects of different remifentanil target concentrations on MAC_BAR of sevoflurane in patients with liver dysfunction...

Remifentanil can effectively decrease the sevoflurane concentration to block sympathetic adrenergic response to CO₂ pneumoperitoneum stimulus,and liver dysfunction will significantly reduce the MAC_BAR (minimum alveolar concentration for blocking adrenergic response) of sevoflurane. However, the effects of different remifentanil concentrations on the MAC_BAR of sevoflurane in patients with liver dysfunction are unclear. The aim of this study was to observe the effects of different remifentanil concentrations by intravenous target-controlled infusion on the MAC_BAR of sevoflurane in patients with grade B liver dysfunction under carbon dioxide pneumoperitoneum stimulus.

Seventy-five patients with grade B liver dysfunction undergoing elective laparoscopic surgery were selected, and randomly divided into three groups with remifentanil plasma target concentrations of 0 (group R₀ ), 1 (group R₁ ) and 2 (group R₂ ) ng/ml. Anaesthesia was induced by intravenous injection of propofol 2-3 mg/kg, remifentanil 2 μg/kg and cisatracurium 0.15 mg/kg. All groups were inhaled different concentrations of sevoflurane. The determination of sevoflurane MAC_BAR in each group was used a method of sequential-allocation technique, and venous blood samples were taken before and after the creation of carbon dioxide pneumoperitoneum to determine plasma adrenaline and noradrenaline concentrations.

The MAC_BAR of sevoflurane in groups R₀ , R₁ and R₂ was 4.83%, 3.00% and 2.10%, respectively. The MAC_BAR of sevoflurane was significantly difference among the three groups. When a similar effect of MAC_BAR had achieved in each group, no significant differences were found in the changes of plasma adrenaline and noradrenaline concentrations before and after the creation of pneumoperitoneum. What is new and conclusion Target-controlled infusion of different concentrations of remifentanil can reduce sevoflurane MAC_BAR during pneumoperitoneum stimulation in patients with liver dysfunction in some degree. However, the changes of plasma adrenaline and noradrenaline concentrations are consistent in the three groups when patient's stress response was inhibited at the same degree.