Bischoff P, Drögemeier K, Scholz J, Nahm W, von Knobelsdorff G, Schulte am Esch J
Abteilung für Anästhesiologie, Universitäts-Krankenhaus Eppendorf, Hamburg.
Anasthesiol Intensivmed Notfallmed Schmerzther. 1998 Feb;33(2):88-95. doi: 10.1055/s-2007-994217.
There is controversy about relevant EEG signal changes indicating adequate or inadequate anaesthesia. Differences of drug-induced and nociceptive mediated signal changes have not been studied in detail. The present study investigates whether signal changes during decreases of depth of anaesthesia due to surgical stimulation depend on different isoflurane concentrations during sufentanil anaesthesia.
Following IRB approval and written informed consent 28 patients (ASA: I; age 43 +/- 11 y) scheduled for elective abdominal surgery were included in the study. Anaesthesia: propofol (2.0 mg/kg) and sufentanil (1.0 micrograms/kg). Following endotracheal intubation (vecuronium 0.1 mg/kg) patients were normoventilated (P(ET)CO2: 36-38 mmHg). Randomly assigned to steady-state anaesthesia (group 1: P(ET)Isoflurane 0.2%, (14n); group 2: P(ET)Isoflurane 0.6%, (14n) during the start of surgery. Monitoring: heart rate (HF), mean arterial blood pressure (MAP), P(ET)CO2, arterial oxygen saturation and rectal temperature. EEG (16 channels referenced to Cz; CATEEM, Medisyst, Linden) recorded 5 min before until 10 min after the start of surgery. EEG-analysis (FFT: 4s, 256/s, 0.45-35.0 Hz): topographical distribution of power spectral densities (delta, theta, alpha 1, and alpha 2). Artifact control: ECG and EOG.
Surgical stimulation resulted in increases of MAP in both groups (p < 0.05 vs BL), whereas HR was only slightly affected in group 2 when compared with BL. Other variables except of EEG data did not change over time. In group 1 (0.2% isoflurane) surgical stimulation resulted in decreases of delta over the whole cortex (F2, C3, P3, O1) and in marked increases of alpha predominantly at central leads (C3)(p < 0.05 vs BL). In group 2 (0.6% isoflurane) nociceptive stimulation was associated with decreases of faster waves (alpha: F3)(p < 0.05 vs BL) and increases in delta at fronto-central areas (F3, C3)(p < 0.05 vs BL).
EEG recordings are useful in assessing pharmacodynamic drug effects. In contrast, intraoperative EEG recordings have a low correlation to clinical signs of changes in the anaesthetic state. Previous studies demonstrate paradoxical EEG-arousal reactions during isoflurane anaesthesia. The present data suggest that classical or even paradoxical EEG arousal due to nociceptive stimulation may depend on the isoflurane concentration. It seems reasonable that the ascending reticular formation is functionally blocked by isoflurane in a dose-dependent manner.
关于表明麻醉充分或不充分的相关脑电图（EEG）信号变化存在争议。药物诱导和伤害性刺激介导的信号变化差异尚未得到详细研究。本研究调查在舒芬太尼麻醉期间，由于手术刺激导致麻醉深度降低时的信号变化是否取决于不同的异氟烷浓度。
经机构审查委员会（IRB）批准并获得书面知情同意后，28例计划进行择期腹部手术的患者（美国麻醉医师协会分级：I级；年龄43±11岁）纳入本研究。麻醉方式：丙泊酚（2.0mg/kg）和舒芬太尼（1.0μg/kg）。气管插管（维库溴铵0.1mg/kg）后，患者进行正常通气（呼气末二氧化碳分压[P(ET)CO2]：36 - 38mmHg）。在手术开始时随机分配至稳态麻醉（第1组：呼气末异氟烷浓度0.2%，n = 14；第2组：呼气末异氟烷浓度0.6%，n = 14）。监测指标：心率（HF）、平均动脉血压（MAP）、P(ET)CO2、动脉血氧饱和度和直肠温度。EEG（16通道，参考电极置于 Cz；CATEEM，Medisyst，林登）在手术开始前5分钟记录至开始后10分钟。EEG分析（快速傅里叶变换：4秒，256采样/秒，0.45 - 35.0Hz）：功率谱密度（δ、θ、α1和α2）的地形图分布。伪迹控制：心电图（ECG）和眼电图（EOG）。
手术刺激导致两组患者的MAP均升高（与基础值相比，p < 0.05），而与基础值相比，第2组患者的HR仅受到轻微影响。除EEG数据外，其他变量随时间未发生变化。在第1组（0.2%异氟烷）中，手术刺激导致整个皮层（F2、C3、P3、O1）的δ波减少，且主要在中央导联（C3）的α波显著增加（与基础值相比，p < 0.05）。在第2组（0.6%异氟烷）中，伤害性刺激与较快波（α波：F3）减少（与基础值相比，p < 0.05）以及额中央区域（F3、C3）的δ波增加（与基础值相比，p < 0.05）相关。
EEG记录有助于评估药物的药效学作用。相比之下，术中EEG记录与麻醉状态变化的临床体征相关性较低。先前的研究表明异氟烷麻醉期间存在矛盾的EEG觉醒反应。目前的数据表明，伤害性刺激引起的经典或甚至矛盾的EEG觉醒可能取决于异氟烷浓度。异氟烷以剂量依赖的方式功能性阻断上行网状结构似乎是合理的。
