Rehberg B, Bouillon T, Zinserling J, Hoeft A
Klinik und Poliklinik für Anaesthesiologie und spezielle Intensivmedizin, University of Bonn, Germany.
Anesthesiology. 1999 Aug;91(2):397-405. doi: 10.1097/00000542-199908000-00013.
The most common measure to compare potencies of volatile anesthetics is minimum alveolar concentration (MAC), although this value describes only a single point on a quantal concentration-response curve and most likely reflects more the effects on the spinal cord rather than on the brain. To obtain more complete concentration-response curves for the cerebral effects of isoflurane, sevoflurane, and desflurane, the authors used the spectral edge frequency at the 95th percentile of the power spectrum (SEF95) as a measure of cerebral effect.
Thirty-nine patients were randomized to isoflurane, sevoflurane, or desflurane groups. After induction with propofol, intubation, and a waiting period, end-tidal anesthetic concentrations were randomly varied between 0.6 and 1.3 MAC, and the EEG was recorded continuously. Population pharmacodynamic modeling was performed using the software package NONMEM.
The population mean EC50 values of the final model for SEF95 suppression were 0.66+/-0.08 (+/- SE of estimate) vol% for isoflurane, 1.18+/-0.10 vol% for sevoflurane, and 3.48+/-0.66 vol% for desflurane. The slopes of the concentration-response curves were not significantly different; the common value was lambda = 0.86+/-0.06. The Ke0 value was significantly higher for desflurane (0.61+/-0.11 min(-1)), whereas separate values for isoflurane and sevoflurane yielded no better fit than the common value of 0.29+/-0.04 min(-1). When concentration data were converted into fractions of the respective MAC values, no significant difference of the C50 values for the three anesthetic agents was found.
This study demonstrated that (1) the concentration-response curves for spectral edge frequency slowing have the same slope, and (2) the ratio C50(SEF95)/MAC is the same for all three anesthetic agents. The authors conclude that MAC and MAC multiples, for the three volatile anesthetics studied, are valid representations of the concentration-response curve for anesthetic suppression of SEF95.
比较挥发性麻醉剂效能最常用的指标是最低肺泡有效浓度（MAC），尽管该值仅描述了量反应浓度 - 效应曲线上的一个点，且很可能更多反映的是对脊髓而非大脑的作用。为获取异氟烷、七氟烷和地氟烷对大脑作用更完整的浓度 - 效应曲线，作者使用功率谱第95百分位数处的频谱边缘频率（SEF95）作为大脑效应的指标。
39例患者被随机分为异氟烷、七氟烷或地氟烷组。用丙泊酚诱导、插管并经过等待期后，呼气末麻醉药浓度在0.6至1.3 MAC之间随机变化，同时持续记录脑电图。使用NONMEM软件包进行群体药效学建模。
最终模型中SEF95抑制的群体平均EC50值，异氟烷为0.66±0.08（±估计标准误）vol%，七氟烷为1.18±0.10 vol%，地氟烷为3.48±0.66 vol%。浓度 - 效应曲线的斜率无显著差异；共同值为λ = 0.86±0.06。地氟烷的Ke0值显著更高（0.61±0.11 min⁻¹），而异氟烷和七氟烷的单独值与共同值0.29±0.04 min⁻¹相比，拟合效果并无更好。当将浓度数据转换为各自MAC值的分数时，未发现三种麻醉药的C50值有显著差异。
本研究表明：（1）频谱边缘频率减慢的浓度 - 效应曲线具有相同斜率；（2）三种麻醉药的C50（SEF95）/MAC比值相同。作者得出结论，对于所研究的三种挥发性麻醉药，MAC及MAC倍数是麻醉抑制SEF95的浓度 - 效应曲线的有效表示。
Zotero 插件