Abstract: Methods This study was performed by two kinds of classification methods. Firstly, 60 patients were assigned to dexmedetomidine group （group D, n=30） and contral group （group C, n=30）. The patients in the group D received dex with a dose of 0.5 μ g/kg after the regular introduction of general anesthesia, while those in group C were treated with equal amount of 0.9% NaCl. EEG spectrum was collected by the Narcotrend monitor during the period before patients receiving general anesthesia till 30 minutes after removal of the endotracheal tube（including the EEG of preoperative waking state ：T Base and the period from washing out to extubation：T0）. The outcomes of RASS at the moment of T1（the right time when patients were removed of the endtracheal tube），T2（10 min after T1），T3（20 min after T1），T4 （30 min after T1）. Sedation score and the EEG spectrum were compared between two groups. Secondly，according to the RASS sedation score of awakening period, all patients were grouped into two groups： Awakening period calm state group（AC；in T1，T1，T3，T4 moment RASS score all negative）and Emergence Agitation group （EA；in T1，T1，T3，T4 moment at least one RASS score positive）. By comparing the EEG in T0 moment between group AC and group EA，observe whether the change of EEG before extubation can predict emergence agitation. Results 1）The comparation of the Intraoperative vital signs of group D and group C ：Comparison of the the mean arterial pressure MAP （mmHg）；Heart rate HR （times/min）；end?tidal CO2 tension EtCO2 ；Pulse oxygen saturation SpO2 （% ）between two groups is not statistically significant difference （P>0.05）. 2） The comparation of the status of the RASS results during awakening period of group D and group C ：there was significant difference of two groups .The negative value of RASS of group D is bigger than group C at the four moment which contains T1（the moment that patients removed of the endotracheal tube），T2（10 minutes after T1），T3（20 minutes after T1），T4（30 minutes after T1）respectivily（P<0.05）. The incidence of postoperative agitation of group C is higher than group D （P>0.05）. 3） The comparation of the EEG spectrum collected by Narcotrend monitor of group D and group C ：The total Power value of EEG in patients of group D collected by Narcotrend monitor is less than that in group C at the moment of T0 and T1 ；the percentence of Delta wave in group D is larger（P<0.05）at the moment of T1；while the other EEG data have no significance difference （P>0.05）. 4） The power and the percent of β wave in the EEG during the T0 period of EA group is bigger than that of AC group, the percent of δ wave is less than that of AC group， which can be used to predict the occurrence of emergence agitation. Conclusion DEX can provide a better postoperative sedation in patients suffering LC surgery with general anesthesia. DEX can decrease the power value of EEG spectrum and increase the percent of δ wave，which maybe the electrophysiological mechanism of the inhibitory effect on emergence agitation of DEX. The EEG changes including increasing the percent of β wave and decreasing the percent of δ wave before extubation can predict the occurrence of emergence agitation.

Key words: dexmedetomidine , frequency pectrum, narcotrend , LC , emergence agitation , power spectrum, EEG

摘要： 【摘要】目的 通过对患者脑电分段频谱的分析，研究术中短时间内输注右旋美托咪定对行腹腔镜胆囊切除术（LC）的全身麻醉患者苏醒期躁动抑制作用的电生理因素，并确认拔出气管导管前的脑电变化能否预测术后躁动的发生。方法 选取2014年12月到2016年3月期间择期LC的全麻患者60例。采用两种分类方法进行数据统计：（1）将患者分为研究组（右旋美托咪定组，D组）和对照组（空白组，C组），每组各30例。D组于常规剂量静吸复合麻醉药物诱导插管后的10 min内给予0.5 μg/kg的右旋美托咪定稀释液；C组则相应给与相同体积的生理盐水注射液。收集患者从麻醉前清醒状态到清醒拔管后30 min内经Narcotrend脑电监测仪器记录的脑电图数据（包括术前清醒时刻Base的脑电图和停止吸入麻药并washout时刻T0的脑电图），记录拔管后即时（T1），拔管后10 min时（T2），拔管后20 min时（T3），拔管后30 min时（T4）的苏醒期RASS镇静评分以及患者术中的生命体征数据，比较D组与C组的苏醒期RASS镇静评分差异、脑电分段频谱差异。（2）根据苏醒期RASS镇静评分将所有患者重新分组为镇静组（AC组，T1、T2、T3、T4时刻的RASS评分均≤-1）和躁动组（EA组，T1、T2、T3、T4时刻至少有一个RASS评分≥1），通过比较AC组与EA组患者对应的T0时刻的脑电分段频谱，探讨拔管前脑电改变对术后躁动是否有预测作用。结果 （1）D组与C组在术中的平均动脉压（MAP）；心率（HR）；呼气末二氧化碳浓度（EtCO2）；脉搏血氧饱和度（SpO2）方面的比较没有统计学差异（P>0.05）。（2）D组与C组苏醒期RASS镇静评分的比较，T1时刻，D组发生躁动（RASS评分≥1）的概率小于C组发生躁动（RASS评分≥1）的概率（P=0.022）；T3时刻,D组发生躁动的概率小于C组发生躁动的概率（P=0.026）；T2时刻，T4时刻D组与C组发生躁动的差异没有统计学意义；D组与C组中苏醒期躁动（RASS评分≥1）绝大部分发生在T1时刻（66.7%），少部分发生在T2时刻（33.3%）。（3）D组与C组各时间段脑电图分段频谱的比较中，D组与C组在Base、T0、T1、T2、T3、T4时刻的脑电NTI、α波β波θ波功率百分比比较,差异均无统计学意义；但D组在T0、T1时刻的脑电总功率power较C组降低,且T1时刻δ波的百分比增加（P<0.05）。（4）EA组与AC组的T0时刻脑电图分段频谱的比较中，EA组较AC组T0时刻脑电总功率Power、β波百分比增加，δ波百分比降低（P<0.05）。结论 （1）右旋美托咪定能够抑制LC患者全麻苏醒期躁动,使术后镇静情况更好；能够引起脑电信号总功率Power值降低，δ波的比例增加，这种脑电改变可能是抑制苏醒期躁动的电生理因素。（2）患者拔管前的脑电β波百分比增加、δ波的百分比下降，对术后躁动的发生可能有预测作用。

关键词: Narcotrend, LC, 脑电功率, 术后躁动, 脑电图, 脑电频率, 右旋美托咪定