Intraoperative monitoring of depth of anesthesia by automated EMG-analysis

脑电活动与麻醉剂和止痛剂浓度之间的相关性的观察导致了经过处理的脑电单参数的发展。在这些数字中，BIS(双谱指数)得到了广泛的使用。然而，关于这种方法的争议仍在继续。虽然在B-Aware试验中显示出术中意识的显著降低，但这些结果在B-Aware试验中不能重现。10多年来，我们团队一直致力于术中脑神经肌电数据的自动分析。在开发和测试这些技术的外科手术过程中，观察到大量EMG活动的自发发作，主要是在喉部、舌部和咽部的肌肉。在这些发作开始后的几分钟内，在几个情况下会出现相当大的病人移动。因此，假设这些肌肉的激活表明保护性反射的启动，由此产生的肌电活动可能作为一个警告参数。进行了一项初步研究，并对喉部、舌部和咽部肌肉的肌电进行了量化。同时，对国际清算银行进行了评估。用这些数据比较拔管和监测参数(BIS和EMG)明显上升的时间间隔。BIS的中位时间间隔为5.9min，而Medium的肌电参数在拔管前12.3min升高。结果，使用曼恩-惠特尼检验计算了肌电参数的显著更长的警告间隔(p=0.026)。在这项研究和当代文献中所做的观察表明，这些发现原则上应该可以转移到面神经肌电图上，而面神经肌电图在日常实践中可能会以一种更简单的方式进行评估。计划中的项目的目标是开发和评估一种全自动量化系统，该系统依赖于面神经肌电作为指示唤醒反应和待定患者行动的警告参数。为了评估该系统，生成的警告参数应与BIS和以下附加参数相关：a.)PRST-得分b。)止痛深度(ANI-监护仪)c.)镇痛药理深度：计算所用阿片类药物的效应室浓度。)催眠的药理深度：计算异丙酚的效应室浓度。在本项目的后续工作中，这些结果可以用于在不同的阿片类药物效应室浓度下，随着手术刺激的不同，肌电参数的变化的前瞻性评估。

The observation of a correlation between EEG-activity and concentrations of anaesthetic and analgetic agents led to the development of processed EEG-monoparameters. Amount these, the BIS (bispectral index) has come to widespread use. However, there is ongoing controversy regarding this method. While a significant reduction of intraoperative awareness has been demonstrated in the B-aware-trial, these results were not reproducible in the B-unaware-trial. Our group has investigated automated analysis of processed intraoperative cranial nerve EMG data for more than 10 years. During surgical procedures in which these techniques were developed and tested, spontaneous episodes of massive EMG-activity, mainly in the muscles of throat, tongue and pharynx, have been observed. Minutes after the beginning of these episodes, considerable patient movement would occur on several occasions. Thus, it was hypothesized that the activation of these muscles indicates the initiation of protective reflexes, and that the resulting EMG-activity might serve as a warning parameter. A pilot study was conducted, and EMG from the muscles of throat, tongue and pharynx was quantified. In a parallel fashion, the BIS was assessed. With these data, the time interval between extubation and clear rise of the monitoring parameters (BIS and EMG) was compared. A median time interval of 5.9min was found for the BIS, while the EMG-parameter would rise 12.3min before extubation in median. As a result, a significantly longer warning-intervall was calculated for the EMG-parameter with the Mann-Whitney-test (p = 0.026). Observations made during this study and contemporary literature suggest that these findings should in principle be transferable to facial nerve EMG, which may be assessed in a much more simple way in routine practice. The goal of the planned project is the development and evaluation of a fully automated quantitative system, which relies on facial nerve EMG as a warning parameter indicating arousal reactions and pending patient movement. In order to evaluate this system, the resulting warning parameter is to be correlated with the BIS and the following additional parameters: a.) PRST-score b.) Depth of analgesia (ANI-monitor) c.) Pharmacological depth of analgesia: Calculated effect compartment concentration for utilized opiate d.) Pharmacological depth of hypnosis: Calculated effect compartment concentration for Propofol. In succession of this project, these results may be used for a prospective evaluation of variations in the EMG-parameter with constant surgical stimulus under varying effect compartment concentrations of opiates.