Scheller Bertram, Schneider Gerhard, Daunderer Michael, Kochs Eberhard F, Zwissler Bernhard
Department of Anesthesiology, Johann-Wolfgang-Goethe Universität Frankfurt, Frankfurt, Germany.
Anesthesiology. 2005 Nov;103(5):944-50. doi: 10.1097/00000542-200511000-00007.
The dose-dependent suppression of midlatency auditory evoked potentials by general anesthetics has been proposed to measure depth of anesthesia. In this study, perioperatively recorded midlatency auditory evoked potentials were analyzed in a time-frequency space to identify significant changes induced by general anesthesia.
Perioperatively recorded auditory evoked potentials of 19 patients, recorded at varying levels of anesthesia, were submitted to a multiscale analysis using the wavelet analysis. Energy contents of the signal were calculated in frequency bands 0-57.1 Hz, 57.1-114.3 Hz, 114.3-228.6 Hz, and 228.6-457.1 Hz. A Friedman test and a Dunn multiple comparisons test were performed to identify significant differences.
Statistical evaluation showed a highly significant decrease of the wavelet energies for the frequency bands 57.1-114.3 Hz (P < 0.0001), 114.3-228.6 Hz (P < 0.0001), and 228.6-457.1 Hz (P < 0.0001) for the measuring points representing deep general anesthesia. This decrease is accompanied by a decrease in the wavelet energy of the frequency band 0-57.1 Hz of no statistical significance (P = 0.021) (level of significance set to P = 0.01). The changes are most prominent in the poststimulus interval between 10 and 30 ms.
This study describes the presence of high-frequency components of the auditory evoked potential. The amount of these components is higher during responsiveness when compared to unconsciousness. Temporal localization of the high-frequency components within the auditory evoked potential shows that they represent a response to the auditory stimulus. Further studies are required to identify the source of these high-frequency components.
全身麻醉药对中潜伏期听觉诱发电位的剂量依赖性抑制作用已被用于测量麻醉深度。在本研究中，对围手术期记录的中潜伏期听觉诱发电位在时频空间进行分析，以确定全身麻醉引起的显著变化。
对19例患者在不同麻醉水平下围手术期记录的听觉诱发电位进行小波分析的多尺度分析。计算信号在0 - 57.1Hz、57.1 - 114.3Hz、114.3 - 228.6Hz和228.6 - 457.1Hz频段的能量含量。进行Friedman检验和Dunn多重比较检验以确定显著差异。
统计评估显示，代表深度全身麻醉的测量点在57.1 - 114.3Hz频段（P < 0.0001）、114.3 - 228.6Hz频段（P < 0.0001）和228.6 - 457.1Hz频段（P < 0.0001）的小波能量显著降低。这种降低伴随着0 - 57.1Hz频段小波能量的降低，但无统计学意义（P = 0.021）（显著性水平设定为P = 0.01）。这些变化在刺激后10至30毫秒的时间间隔内最为明显。
本研究描述了听觉诱发电位高频成分的存在。与无意识状态相比，这些成分在反应性期间的含量更高。听觉诱发电位中高频成分的时间定位表明它们代表了对听觉刺激的反应。需要进一步研究以确定这些高频成分的来源。
