Visser G H, Wieneke G H, Van Huffelen A C, De Vries J W, Bakker P F
Department of Clinical Neurophysiology, University Hospital Utrecht and Rudolf Magnus Institute for Neurosciences, Utrecht, The Netherlands.
J Clin Neurophysiol. 2001 Mar;18(2):169-77. doi: 10.1097/00004691-200103000-00009.
The EEG was monitored in 56 patients during implantation of an internal cardioverter defibrillator. The purpose of this study was to determine the main EEG frequency ranges that represent ischemic changes during short periods of circulatory arrest. The EEG was recorded with a 16-channel common reference montage (Cz). After onset of circulatory arrest, the log spectral changes of three-epoch moving averages were calculated relative to the baseline spectrum. For factor analysis, 17 EEG periods were selected that showed changes progressing to an isoelectrical period. Topographic differences and the time course of quantitative EEG (qEEG) changes were studied in all 56 patients. For each patient the EEG period with the longest duration of circulatory arrest was chosen. Factor analysis revealed four factors that represented the spectral EEG changes occurring during circulatory arrest and recovery. The frequency intervals of these factors were 0 to 0.5 Hz, 1.5 to 3 Hz, 7.5 to 9.5 Hz, and 15 to 20 Hz for all channels. Only minor topographic differences were found in the power of the spectral changes; the sequence of events was similar for all electrode positions. The first EEG change after circulatory arrest was an initial increase in alpha power and a decrease in beta power. On average, after approximately 15 seconds alpha power started to decrease, beta power decreased further, delta-1 power started to increase, and delta-2 power started to decrease. After approximately 25 seconds, the delta-1 power increase appeared to plateau or to decrease. A circulatory arrest longer than approximately 30 seconds resulted in an isoelectrical EEG. After restoration of the circulation, there was a fast transient increase in delta-1 and delta-2 power, followed by a decrease to baseline. alpha and beta power showed a more gradual increase in power toward baseline and were the last to restore after 60 to 90 seconds. In general, the spectral changes in the alpha and beta frequency ranges were most pronounced and consistent. In conclusion, to detect intraoperative cerebral ischemia, monitoring of changes in the four frequency ranges found is preferable to monitoring changes in the classically defined frequency bands. Furthermore, these results stress the importance of the alpha and beta ranges in detecting cerebral ischemia.
在56例植入体内心脏复律除颤器的患者中监测了脑电图。本研究的目的是确定在短时间循环骤停期间代表缺血变化的主要脑电图频率范围。脑电图采用16通道公共参考导联（Cz）记录。循环骤停开始后，计算相对于基线频谱的三个时段移动平均值的对数频谱变化。为了进行因子分析，选择了17个脑电图时段，这些时段显示变化进展至等电位期。对所有56例患者研究了地形差异和定量脑电图（qEEG）变化的时间进程。为每位患者选择循环骤停持续时间最长的脑电图时段。因子分析揭示了四个因子，它们代表了循环骤停和恢复期间发生的脑电图频谱变化。所有通道这些因子的频率区间为0至0.5Hz、1.5至3Hz、7.5至9.5Hz和15至20Hz。在频谱变化的功率方面仅发现微小的地形差异；所有电极位置的事件顺序相似。循环骤停后的首次脑电图变化是α波功率最初增加和β波功率降低。平均而言，大约15秒后α波功率开始降低，β波功率进一步降低，δ-1波功率开始增加，δ-2波功率开始降低。大约25秒后，δ-1波功率增加似乎达到平台期或降低。循环骤停超过大约30秒会导致脑电图呈等电位。循环恢复后，δ-1波和δ-2波功率迅速短暂增加，随后降至基线。α波和β波功率向基线逐渐增加，并且在60至90秒后最后恢复。一般来说，α波和β波频率范围内的频谱变化最为明显和一致。总之，为了检测术中脑缺血，监测所发现的四个频率范围内的变化比监测经典定义的频段变化更可取。此外，这些结果强调了α波和β波范围在检测脑缺血中的重要性。
