Using EEG-BIS and HRV to Evaluate the Effects of Patient-Controlled Sedation During Thyroidectomy Under Regional Anesthesia<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

王　晖Wang Hui, 温　洪Wen Hong, 岳　云Yue Yun. 
Department of Anesthesia, Beijing Red Cross Chaoyang Hospital, Affiliated Capital University of Medical Sciences, Beijing 100020, China.

ABSTRACT

Objective：To evaluate the effect of patient-controlled sedation(PCS) and doctor-controlled sedation(DCS) during thyroidectomy under regional anesthesia using bispectral index (BIS) and heart rate variability (HRV).
　Methods：Forty patients of ASAⅠ～Ⅱ undergoing thyroidectomy with regional anesthesia were randomly divided into PCS group (n=20) and DCS group (n=20). Loading dose of 0.75μg/kg fentanyl and 40μg/kg droperidol was administrated before operation for both groups. Then PCS was performed in PCS group and a half dose of Innovar (0.1mg fentanyl and 5mg droperidol)  was given at a interval of 30min in DCS group.BP,HR,ECG, RR and BIS,HRV were continuously monitored.
　Results：There were no significant differences in BIS,HRV and HR between PCS group and DCS group. However, a significant decreasing of BIS occured 10 min earlier in PCS group than in DCS group. HRV decreased markedly 30 min after administration of drugs for both groups. No severe sedation and respiratory depression were found, and the quality of sedation was the same in both groups.
　Conclusion：Evaluated with BIS and HRV, there was little difference between PCS and DCS groups during thryoidectomy with regional anesthesia.
　Key words：Patient-controlled sedation; Doctor-controlled sedation; Bispectral index; Heart rate variability; Fentanyl; Droperidol

病人自控镇静(PCS)是指局麻手术中，病人按照自己的需求控制微电脑泵给药,以求得最适宜的镇静、松弛状态。本研究利用脑电双频谱指数(BIS)和心率变异性(HRV)作为客观参数，从镇静程度和对伤害性刺激的自主反应程度两个方面来评价PCS的临床效果，同时与医生控制镇静(DCS)法进行比较，报道如下。

资料和方法<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

一、一般资料　
　　选择40例拟在局麻下行甲状腺手术病人，ASAⅠ～Ⅱ级，男21例，女19例，年龄25～56岁，体重52～74kg。随机将病人均分为两组，其中PCS组男11例、女9例；DCS组男10例、女10例。手术前向病人介绍PCA泵的使用方法。
二、麻醉及监测　
　　术前均不给镇静药。均在1%普鲁卡因或1%利多卡因局部浸润麻醉下施行甲状腺手术。用HP监护仪监测BP、HR、ECG、RR；用HXD-1型脑电图仪（黑龙江华翔公司产品）连续监测BIS和HRV。所有病人均常规面罩吸氧，氧流量3L/min。在手术前5min两组均给氟芬合剂（芬太尼 0.75μg/kg和氟哌啶40μg/kg）静脉慢注。PCS组用芬太尼2mg+氟哌啶10mg+生理盐水至100ml装入PCA泵，每次自控注药量0.5ml，间隔时间3min，持续背景流量0.2ml/h，病人按需求自控用药。DCS组则由医生每隔30min给半量氟芬合剂。
三、数据采集　
　　两组病人均每间隔10 min记录相应的BP、HR、SpO₂、RR、BIS和HRV。SpO₂＜90%为低氧血症，RR＜8bpm为呼吸抑制。术后即予询问病人的满意程度：1分(不舒适)；2分(较舒适)；3分(舒适)。所得数据采用Microsoft Excel 97进行统计学处理。组间和组内比较均采用t检验，P＜0.05〖KG×2〗认为有显著性差异。

结　果

两组间年龄、体重无显著性差异。两组间满意程度评分无显著性差异。两组BIS、HRV和HR在各时点组间比较均无统计学差异。但组内比较，PCS组给药后20 min BIS较基础值开始出现显著性降低P＜0.05；而DCS组在给药后30 min才开始出现明显降低。两组HRV均在给药后30 min明显下降P＜0.05。HR两组间均无统计学改变。见附表。

讨　论

BIS能反映病人的镇静程度或麻醉深度，两者有非常好的相关性；HRV通过心交感活性的变化能及时反映病人对术中各种刺激的应激反应程度，从而可间接反映麻醉镇痛的效果。因此，动态观察BIS（镇静）与HRV（镇痛）的变化，通过数据统计处理，可以反映PCS与DCS的实际效果，使评估镇静与镇痛两方面的结果具有较高的临床实用价值。
　　BIS和HRV数据结果显示，PCS似乎并不比DCS有更多的优势。分析可能有如下两方面原因：首先，笔者选用小剂量氟芬合剂作为镇静用药，其镇静、镇痛程度可能有所不足；其次，病人在较长时间局麻下手术，由于病情个体差异(如甲状腺肿物大小、部位、有无气管压迫症等)以及对手术牵拉刺激的耐受程度等因素各不相同，其镇静、镇痛的最终效果也会受到明显影响。氟芬合剂用于PCS技术是适宜的，对病人要求术中保持清醒者尤其适用，但用法用量尚需要进一步研究探讨。
　　本文观察到BIS值在PCS组较DCS组提前10min出现统计学意义，但尚不能据此肯定PCS比DCS更好，还需要更多的样本作进一步研究后判定。HRV值在PCS或DCS组，均于病人或医师给药后出现波动，但PCS组的HRV显然比DCS组者更快地趋于平稳，且手术时间越长，这种平稳趋势表现越明显。这可能与PCS组的血药浓度比DCS组能更快达到稳态有关。同样PCS在快速达到镇静状态方面略优于DCS组，而在镇痛方面两者的效果类似。显然，BIS与HRV只是从下个角度来评估PCS与DCS的效果，尚不能对二者的优点与不足作出全面的比较，即在实用性方面尚存在一定的局限性。