Lorsomradee Suraphong, Punjasawadwong Yodying
Department of Anesthesiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
J Med Assoc Thai. 2005 Nov;88(11):1574-81.
The present study was undertaken to provide basic information about bilateral frontal cerebral electrical activity after induction, before and after skin incision, and at a steady state during sevoflurane anesthesia at the end tidal concentration 1, 1.2, 1.4 and 1.6 MAC and determine the association between the electrical cerebral activity with other clinical end points, i.e. motor responses and post-operative recall.
the Dual Channel Brain Activity, ABM2 (DATEX) was used to continuously monitor frontal EMG and electrical cerebral activities (i.e. frequency and amplitude) of both hemispheres in 20 adult female patients undergoing balanced anesthesia in Maharaj Chiang Mai Hospital. The eligible patients were randomly assigned to receive 1.0 MAC, 1.2MAC, 1.4MAC or 1.6MAC of a mixture of sevoflurane and 66.67% nitrous oxide in oxygen during anesthesia. The anesthesia was induced with 5 mg/kg thiopental and supplemented with 1-1.5 microgram per kilogram of fentanyl. The standard dose of pancuronium or atracurium was given during maintenance.
After induction with 5 mg/kg thiopental, the mean (95% confidence interval) of frontal EMG significantly decreased from 2.66 (1.63,4.29) to 1.41 (0.2,1.61). When eyelash reflex was absent, the mean (95%CI) frequency and amplitude of the right frontal EEG was 3.89 (3.29, 4.497) Hz, 39.58 (32.11, 47.05) microvolt and left frontal EEG was 3.84 (3.43, 4.25) Hz, 33.55 (28.59, 38.61) microvolt. The findings were consistent with the raw EEG shown on the monitor, i.e. a progressive decrease in the frequency and an increase in the amplitude. During maintenance with the inhaled anesthetics, there was a statistically significant decrease in frequency of right frontal in those who had received the inhaled anesthetic concentration to reach 1.4 and 1.65 MAC (p < 0.05) (repeated measure ANOVA). At the steady state of end tidal concentration of the sevoflurane there was consistency in decreasing frequencies and increasing amplitudes of both hemispheres of the groups with higher MAC values (p < 0.05) (Table 3). However, the authors failed to demonstrate the relationships between EEG changes and other clinical responses.
The present study has provided basic information about cerebral electrical activity during the balanced anesthesia with sevoflurane. As anesthesia deepened by increased MAC, the frequency decreased and the amplitude increased.
本研究旨在提供有关七氟醚麻醉诱导期、皮肤切开前后以及呼气末浓度为1、1.2、1.4和1.6MAC稳态时双侧额叶脑电活动的基础信息，并确定脑电活动与其他临床终点（即运动反应和术后回忆）之间的关联。
采用双通道脑电活动监测仪ABM2（Datex），对清迈玛哈拉吉医院20例接受平衡麻醉的成年女性患者的双侧额叶肌电图和脑电活动（即频率和振幅）进行连续监测。符合条件的患者在麻醉期间随机接受七氟醚与66.67%氧化亚氮在氧气中的混合气体，浓度分别为1.0MAC、1.2MAC、1.4MAC或1.6MAC。麻醉诱导采用5mg/kg硫喷妥钠，并补充1-1.5μg/kg芬太尼。维持期间给予标准剂量的潘库溴铵或阿曲库铵。
静脉注射5mg/kg硫喷妥钠诱导后，额叶肌电图的平均值（95%置信区间）从2.66（1.63，4.29）显著降至1.41（0.2，1.61）。睫毛反射消失时，右侧额叶脑电图的平均（95%CI）频率和振幅分别为3.89（3.29，4.497）Hz、39.58（32.11，47.05）μV，左侧额叶脑电图为3.84（3.43，4.25）Hz、33.55（28.59，38.61）μV。这些结果与监测仪上显示的原始脑电图一致，即频率逐渐降低，振幅增加。在吸入麻醉维持期间，吸入麻醉浓度达到1.4和1.65MAC的患者右侧额叶频率有统计学显著下降（p<0.05）（重复测量方差分析）。在七氟醚呼气末浓度稳态时，MAC值较高组的双侧半球频率降低和振幅增加具有一致性（p<0.05）（表3）。然而，作者未能证明脑电图变化与其他临床反应之间的关系。
本研究提供了七氟醚平衡麻醉期间脑电活动的基础信息。随着MAC增加麻醉加深，频率降低，振幅增加。
