联合脑电图和听觉诱发电位用于区别志愿者不同的麻醉深度

背景有证据显示，脑电图（EEG）和听觉诱发电位（AEP）联合应用能很好地区分意识清醒与意识消失。最近的研究中，我们寻找一种EEG／AEP联合的监测标准，除了能区别清醒与意识消失外，且能辨别不同水平的镇静与催眠状态下的各种麻醉深度。方法15例未使用手术前用药的志愿者参与了这项随机交叉试验。试验由2个连续部分组成，志愿者需接受七氟烷或丙泊酚诱导的单药麻醉。通过意识消失（LOC）和脑电暴发抑制（BSP）来定义全麻程度。此外，根据BSP和LOC，将麻醉药浓度划分成三等分，从而形成两个浓度点，LOC（最小浓度）和BSP（最大浓度）。采集的数据用来测试之前所提到的EEG／AEP联合监测仪（即意识监测仪）能否同时将从LOC到BSP之间的麻醉效果区分开来。结果以往的镇静监测仪在本研究中区分不同麻醉水平的预测概率（Pk）为0．77。新的EEG／AEP监测仪为0．94，用于之前的研究中可达到R为0．89。结论结果显示联合EEG／AEP的新的监测仪参数能辨别较广范围下不同程度的麻醉效应，即从意识清醒到深麻醉。

BACKGROUND： It has been shown that the combination of electroencephalogram （EEG） and auditory evoked potentials （AEP） allows a good separation of consciousness from unconsdousness. In the present study, we sought a combined EEG/AEP indicator that allows both separation of consciousness from unconsciousness and discrimination among different levels of sedation and hypnosis over a wider range of anesthesia. METHODS： Fifteen unpremedicated volunteers received mono-anesthesia with sevoflurane or propofol in a randomized crossover design in two consecutive sessions. Loss of consciousness （LOC） and EEG burst suppression （BSP） defined end-points from the upper and lower range of general anes- thesia. In addition to those two extremes, the difference between anesthetic concentration at BSP and LOC was divided into three equal intervals, resulting in two intermediate levels which divided the concentration from LOC （minimum） to BSP （max- imum） into three equal steps. This data set was used to test whether a previously described combined EEG/AEP indicator ＂detector of consciousness＂ can also discriminate among degrees of anesthetic effects from the awake state to BSP. Further- more, a new improved combined EEG/AEP indicator was developed on the basis of the data from the current study, and sub- sequently this new indicator was tested for its ability to separate consciousness from unconsciousness with the patient data set. RESULTS： The former ＂detector of consciousness＂ showed a prediction probability （PK） of 0. 77 to separate different levels of anesthesia from the current study, whereas for the new combined EEG/AEP indicator, PK was 0.94. The new indicator was further applied to the previous study and achieved a PK of 0. 89. CONCLUSIONS： These results show that with the new indicator presented here, a combination of EEG and AEP parameters can be used to differentiate degrees of anesthetic effects over a wide range of hypnosis, from the conscious state to deep anesthesia （i. e., BSP）.