BACKGROUND Although electroencephalography (EEG)-based indices may show artifactual values, raw EEG signal is seldom used to monitor the depth of volatile induction of general anesthesia (VIGA). The current analysis aimed to identify whether bispectral index (BIS) variations reliably reflect the actual depth of general anesthesia during presence of different types of epileptiform patterns (EPs) in EEGs during induction of general anesthesia. METHODS Sixty patients receiving either VIGA with sevoflurane using increasing concentrations (group VIMA) or vital capacity (group VCRII) technique or intravenous single dose of propofol (group PROP) were included. Monitoring included facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), minimal alveolar concentration (MAC) of sevoflurane, BIS, standard EEG, and hemodynamic parameters. RESULTS In the PROP group no EPs were observed. During different stages of VIGA with sevoflurane in the VIMA and VCRII groups, presence of polyspikes and rhythmic polyspikes in patients' EEGs resulted in artifactual BIS values indicating a false awareness/wakefulness from anesthesia, despite no concomitant change of FiAA, FeAA, and MAC of sevoflurane. Periodic epileptiform discharges did not result in aberrant BIS values. CONCLUSION Our results suggest that raw EEG correlate it with values of BIS, FiAA, FeAA, and MAC of sevoflurane during VIGA. It seems that because artifactual BIS values indicating false awareness/wakefulness as a result of presence of polyspikes and rhythmic polyspikes in patients' EEGs may be misleading to an anesthesiologist, leading to unintentional administration of toxic concentration of sevoflurane in ventilation gas.

中文翻译：

---

七氟烷全身麻醉挥发性诱导过程中的多峰和节律性多峰导致脑电双频指数变化

背景虽然基于脑电图 (EEG) 的指标可能会显示伪值，但原始 EEG 信号很少用于监测全身麻醉 (VIGA) 挥发性诱导的深度。当前的分析旨在确定在全麻诱导期间脑电图中存在不同类型的癫痫样模式 (EP) 期间双频指数 (BIS) 变化是否可靠地反映全麻的实际深度。方法 包括 60 名接受 VIGA 和七氟烷使用增加浓度（VIMA 组）或肺活量（VCRII 组）技术或静脉单剂量异丙酚（PROP 组）的患者。监测包括面部肌电图 (fEMG)、吸入七氟醚分数 (FiAA)、过期七氟醚分数 (FeAA)、七氟醚最低肺泡浓度 (MAC)、BIS、标准脑电图和血流动力学参数。结果 在 PROP 组中未观察到 EP。在 VIMA 和 VCRII 组七氟醚 VIGA 的不同阶段，尽管 FiAA、FeAA 和 MAC 没有伴随变化，但患者脑电图中多峰和节律性多峰的存在导致人为的 BIS 值，表明麻醉后的错误意识/觉醒七氟烷。周期性癫痫样放电不会导致 BIS 值异常。结论 我们的结果表明，原始脑电图与 VIGA 期间七氟醚的 BIS、FiAA、FeAA 和 MAC 值相关。由于患者脑电图中存在多峰和节律性多峰导致虚假的 BIS 值表明错误的意识/觉醒，这似乎会误导麻醉师，