EEG ANALYSIS AS A MEANS OF MONITORING DEPTH OF PSYCHOSEDATION

我们根据一氧化二氮浓度或客观确定的镇静状态检查每项指标的变化，并在静脉注射安定或咪达唑仑后，证实根据脑电功率谱计算的频段中值脑电频率和成分比率的波动反映了镇静的深度。在研究的临床部分，我们评估了在精神状态和患者客观发现的情况下进行牙科治疗期间上述指标的变化。结果显示，吸入20%-30%一氧化二氮通常提供最佳镇静效果的脑电频率中值为5-6赫兹，而吸入40%一氧化二氮导致睡眠状态的脑电频率中值低于5赫兹。另一方面，静脉注射安定或咪达唑仑后，中位数脑电频率在最初增加后逐渐下降，在开始镇静后趋于稳定。频带成分比率显示，吸入亚氮后，a波和慢波成分增加，快波成分减少：相反，在苯二氮卓类衍生物中，观察到快速成分最初上升，随后在整个镇静状态持续时间内a成分增加。这表明，服用苯二氮卓类衍生物后，脑电频率的中位数最初上升是由于苯二氮卓类药物特有的快波。在研究的临床部分，服用苯二氮卓类衍生物后，脑电频率的中位数也有所上升：然而，在镇静状态下的频率是稳定的，每当患者感到疼痛或镇静作用减弱时，频率就达到峰值。上述结果提示，脑电中位数频率的变化反映了精神镇静深度和疼痛等应激状态。因此，脑电中位数频率可作为反映精神镇静深度的有用指标。

We examined changes in each of the indices according to nitrous oxide concentration or objectively determined sedation state, and after intravenous infusion of diazepam or midazolam, confirmed that the fluctuation of median EEG frequency and component ratios according to a frequency band computed from the EEG power spectrum reflected the depth of sedation. In the clinical component of the study, we assessed such changes in the above indices during dental treatment performed under the psychosedation and the patient's objective findings.The results showed a median EEG frequency of 5-6Hz for inhalation of 20%-30% nitrous oxide, which generally provides optimum sedation, versus one of less than 5 Hz for inhalation of 40% nitrous oxide, which induces a sleep state. With intraveno us diazepam or midazolam, on the other hand, median EEG frequency gradually declined after an initial increase, becoming stable after the onset of sedation. The frequency band component ratios showed an increase in the a-and slow-wave components and a decrease in the fast-wave component in response to nitrous inhalation : in contrast, with the benzodiazepine derivatives an initial rise in the fast component was observed, followed by an increase in the a-component throughout the duration of the sedated state. This suggests that the initial rise in median EEG frequency with benzodiazepine derivatives is due to a fast-ware unique to benzodiazepines.In the clinical component of the study, median EEG frequency also rose after administration of the benzodiazepine derivatives : however, frequency in the sedated state was stable, peaking whenever the patients experienced pain or the sedative effect weakened. The above findings imply that changes in median EEG frequency reflect depth of mental sedation and stress states due to pain, et c. It is concluded that median EEG frequency appears to be a useful index of the depth of psychsedation.