Department of Anaesthesiology and Critical Care, Hospital Xeral-Cíes, Vigo, Spain.
Br J Anaesth. 2010 Jun;104(6):733-9. doi: 10.1093/bja/aeq081. Epub 2010 Apr 12.
Propofol and sevoflurane act on the GABA(A) receptor, modulating the function of this receptor in an additive manner. The pharmacodynamic interaction of both drugs considering their effect on EEG activity analysed by the bispectral index (BIS) was identified as additive, but this has not been studied in a clinical setting. The objective of this study was to analyse the pharmacodynamic interaction of propofol and sevoflurane on BIS using a surface response model in patients undergoing general anaesthesia with i.v. induction and inhalation maintenance.
We performed a prospective study in 24 patients undergoing general anaesthesia with propofol induction and sevoflurane maintenance. Anaesthetic depth was measured with a BIS VISTA Bilateral monitor. Propofol biophase concentration was determined using a three-compartment pharmacokinetic model, and sevoflurane end-tidal concentration was measured continuously. The response surface model described by Minto and colleagues was used to analyse the interaction. Statistical analysis was performed with Excel 2002 and SPSS v11.0.
The mean value of U(50)(theta) was 0.956 (sd 0.029) in the overall estimated data, and remained within the predefined range for all ratios of the drugs, fulfilling the criterion of additivity. The median of the weighted residuals between the actual BIS value and the BIS value predicted by the model was -5.926%.
Under the study conditions, it was confirmed that sevoflurane and propofol have an additive effect on BIS, with no evidence suggesting the existence of a synergistic effect for the concentrations of both drugs typically used in clinical practice.
丙泊酚和七氟醚作用于 GABA(A)受体，以相加的方式调节该受体的功能。这两种药物对脑电图活动的影响通过双频谱指数（BIS）进行分析，其药效学相互作用被确定为相加，但尚未在临床环境中进行研究。本研究的目的是分析静脉诱导和吸入维持全身麻醉患者中丙泊酚和七氟醚对 BIS 的药效学相互作用，使用表面响应模型。
我们对 24 例接受丙泊酚诱导和七氟醚维持全身麻醉的患者进行了前瞻性研究。麻醉深度使用 BIS VISTA 双侧监测仪进行测量。使用三房室药代动力学模型确定丙泊酚生物相浓度，连续测量七氟醚呼气末浓度。使用 Minto 同事描述的响应面模型分析相互作用。使用 Excel 2002 和 SPSS v11.0 进行统计分析。
总体估计数据中 U(50)(theta)的平均值为 0.956（sd 0.029），所有药物比值均在预定范围内，满足相加性标准。实际 BIS 值与模型预测的 BIS 值之间加权残差的中位数为-5.926%。
在研究条件下，证实七氟醚和丙泊酚对 BIS 具有相加作用，没有证据表明两种药物的浓度存在协同作用，这与临床实践中常用的浓度一致。
