不同浓度瑞芬太尼对地氟醚最低肺泡有效浓度的影响

目的:观察不同浓度瑞芬太尼对地氟醚最低肺泡有效浓度(MAC)的影响。方法:以脑电双频谱指数(BIS)=50作为指标来确定地氟醚的ED50值(MACBIS50),将80例患者鼓室成形术随机分为A、B、C、D、E5组(每组16例),接受瑞芬太尼静脉输注靶控血浆浓度分别为0,2,4,6,8ng/ml。患者术前用阿托品0.01mg/kg肌肉注射,全麻诱导采用咪达唑仑0.02mg/kg,异丙酚2mg/kg,维库溴铵0.1～0.2mg/kg。诱导插管后按靶控血浆浓度泵控输注瑞芬太尼并吸入地氟醚,待地氟醚呼气末浓度(ET%)达到预定值并稳定10min后,手术切皮并记录相应的BIS值。采用上下波动法分别计算各组的地氟醚MACBIS50,BIS值和ET%进行直线回归分析。结果:5组患者地氟醚MACBIS50值分别为7.18%,6.31%,4.18%,2.86%和2.19%。与A组比较,其余4组的MACBIS50显著降低(P<0.05)。各组BIS和ET%直线相关。结论:瑞芬太尼复合地氟醚麻醉可显著降低地氟醚MAC,并呈剂量依赖性降低,瑞芬太尼超过8ng/ml时,下降速度趋缓,逐渐出现封顶效应。并保持BIS值和呼气末浓度的直线相关性。

Effect of remifentanil on minimum alveolar concentration of desflurane

Objective:To determine the minimum alveolar concentration(MAC)of desflurane in the presence of different concentrations of remifentanil by using bispectral index of the electroencephalogram(BIS)value of 50 as the criterion(MACBIS50).Methods:Eighty patients were randomly assigned to receive different target plasma concentrations of remifentanil(0,2,4,6,and 8 ng/ml).The patients were pretreated by intramuscular injection of 0.01 mg/kg of atropine.General anesthesia was induced with 2 mg/kg of propofol,0.1 to 0.2 mg/kg of vecuronium,and 0.02 mg/kg of Midazolam.Anesthesia was maintained with desflurane.The end-tidal concentration(ET%)of desflurane and BIS were continuously monitored.When the steady state end-tidal concentratin of desflurane was maintained for 10 minutes,the BIS value was recorded while incising.MACBIS50 was measured by using up-and-down method.Results:MACBIS50 in patients receiving 0,2,4,6,and 8 ng/ml of remifentanil was 7.18%,6.13%,4.18%,2.86%,and 2.19%,respectively.Compare with patients receiving 0 ng/ml of remifentanil,MACBIS50 in other patients significantly decreased(P<0.05).There was linear correlation between BIS value and ET% in each group.Conclusion:Remifentanil plus desflurane could significantly decrease the MAC of desflurane in a dose-dependent manner.A ceiling effect is found when the concentration of remifentanil is greater than 8 ng/ml.