摘要目的 探讨硬膜外阻滞期间,肌电活动(electromyographic avtivity,EMG)的变化对Narcotrend和脑电双频指数(bispectral index,BIS)监测右美托咪啶(dexmedetomidine,Dex)镇静深度准确性的影响. 方法 择期拟行硬膜外阻滞的患者16例,男9例、女7例,美国麻醉医师协会(ASA)分级Ⅰ～Ⅱ级,年龄18岁～60岁,体重51 kg～93 kg,体重指数19.2 kg/m2～27.8kg/m2.硬膜外阻滞效果确切后,经静脉持续输注浓度4 mg/L Dex负荷量0.5 μg/kg(输注15 min),继以0.4 μg·kg-1·h-1恒速泵入维持至术毕.每隔1 min记录Narcotrend指数(Narcotrend index,NTI)、BIS及EMG(信号及数据采集来自BIS监护仪),并采用警觉/镇静评分(the Observer's Assessment of Alterness/Sedation Scale,OAA/S)评估镇静深度. 结果 高EMG活动(EMG＞50dB)时,BIS、NTI未随EMG增高而升高(r=-0.113,P=0.249；r=0.160,P=0.249).BIS及NTI值“虚高”,即BIS、NTI ≥85而OAA/S≤3分,分别发生在50％(8/16)和56 ％(9/16)的患者中,此时BIS中位数(四分位数间距)87(86～91)与EMG 34(32～36)；NTI 90(87～94)与EMG 41(37～48)均不存在相关关系(r=-0.046,P=0.855；r=0.090,P=0.732). 结论 硬膜外阻滞下Dex镇静期间,高EMG活动不引起BIS及NTI升高；BIS、NTI“虚高”与EMG活动增加无关,即Narcotrend及BIS对Dex镇静深度判断的准确性未受EMG增加的明显干扰.

abstractsObjective To investigate the effects of electromyographic activity on the accuracy of Narcotrend and bispectral index (BIS) during sedation with dexmedetomidine (Dex) under epidural anesthesia.Methods Sixteen patients scheduled for epidural anesthesia,9 males and 7 females,ASA Ⅰ or Ⅱ,aged 18 y-60 y,weighing 51 kg-93 kg,BMI 19.2 kg/m2-27.8 kg/m2 were prospectively studied.After the induction of epidural anesthesia,a loading dose of Dex was administered at 0.5 μg/kg per 15 min,followed by a continuous infusion at 0.4 μg ·kg-1 ·h-1,BIS and Narcotrend were monitored simultaneously,both values and EMG which was indicated on the BIS platform were recorded every minute.Sedation was assessed using the Observer's Assessment of Alterness/Sedation Scale (OAA/S) as well.The correlation between Narcotrend index (NTI)/BIS and EMG was analyzed.Results As the EMG activities above 50 dB elevated,BIS and NTI values were not increased (r=0.113,P=0.249;r=0.160,P=0.249).The misleading high BIS/NTI ≥85 occurred among 8 (50％ of all cases) and 9 (56％ of all cases) patients,respectively,at OAA/S ≤3.While there was no correlation (r=-0.046,P=-0.855) between BIS M (QR)87 (86-91) and EMG 34 (32-36),and there was no correlation (r=0.090,P=0.732) between NTI 90 (87-94) and EMG 41 (37-48),either.Conclusions During sedation with Dex under epidural anesthesia,high EMG activities do not result in BIS/NTI value increases.Impractical high BIS/NTI values are not caused by EMG elevation.Under sedation with Dex,the Narcotrend and BIS monitor are comparatively reliable with regard to their insusceptibility to increased EMG activity.