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Effect of plasma level of fen tanyl on recovery from propofol anesthes ia：mon itor ing with EEG－BIS

米卫东  张宏

北京市，解放军总医院麻醉科  100853

MIWei dong，ZHANG Hong. Department of Anesthesiology，Chinese PLA General Hospital，Beijing   100853

Abstract

　　Objective：To investigate the effect of different plasma levels of fentanyl on the concentration of propofol required for patients to regain consciousness and the changes of EEG bis－pectral index（BIS）.

　　Methods：Twenty－eight patients，aging 20－50years，scheduled for elective surgery were included in the study. Anesthesia was induced and maintained by interm ittent injection of fentanyl and constant infusion of propofol. Propofol infusion was stopped at the end of surgery，and then consciousness and orientation were assessed once per 22minute. Blood samples for plasma propo－foland fentanyl concent rations（PCp and FCp）were taken immediately，and BIS was recorded when patients regained consciousness and orientation. BIS was also recorded. Patients were divided into three groups depending on FCp at awaking：groupⅠwith FCp>1ug/L（n＝8）；groupⅡ with FCp<1ug/L and>0.45ug/L（n＝9）；and groupⅢ with FCp<0.45ug/L（n＝11）；PCp，BIS，recovery time and other data were compared between three groups.

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　　Results：Demographic values，the duration of surgery，and consumption of propofol and fentanyl were not different between three groups. The patients in groupⅢ regained consciousness at significantly higher PCp of 3.2mg/L compared with those in groups Ⅰ and Ⅱ（P<0.05）. However，the BIS values at awaking were no difference between three groups.

　　Conclusion：The plasma levels of fentanyl affect the concent rations of propofol required for patients to regain consciousness. The BIS values for wakefulness are unaltered at the different concent rations of combinations of propofol and fentanyl. Thus the BIS appears a useful indicator for level of consciousness during emergence from propofol/fentanyl intravenous anesthesia.

　　Key words：Fentanyl   Propofol   Bispectral index

　　本试验旨在研究异丙酚和芬太尼全静脉麻醉恢复期，不同芬太尼血浆浓度对麻醉苏醒时异丙酚血浆浓度及脑电双频指数（BIS）的影响。

资料与方法

　　选ASAⅠ～Ⅱ级病人28例，年龄20～50岁，拟在全身麻醉下行五官、肢体和腹部的择期手术，手术时间1～4小时。有精神、神经疾患史或服用精神、神经系药物的病人被排除在外，严重嗜酒、嗜烟病人也不在选择范围内。

　　病人入室后，连接试验及手术所需各项监测，包括心电图、脉搏氧饱和度。局麻下桡动脉穿刺、置管，用于动脉测压、抽取血标本。脑电BIS用美国A－1050型微机化双频道EEG监测仪（A－1050，Aspect Medical System，Natick，MA，USA）测定。电极放置：四枚单次使用银2氯化银电极（Zipprep，Aspect M edical System，MA，USA），分别贴于标准脑电检测电极区的At1、At2、Fpz和Fp2区位，其中At1和At2作为测量电极，Fpz为参考电极，Fp2处为零位电极。各电极的电阻保证在2000Ω以下。BIS由A－1050EEG监测仪取5秒的脑电波形直接计算、显示、记录，每15秒自动计算显示1次。

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　　麻醉诱导以芬太尼2ug/kg、异丙酚2mg/kg静脉注射，维库溴铵静注后气管插管。麻醉维持采用异丙酚加芬太尼的全静脉麻醉方法。异丙酚以输液泵持续推注，调节速率维持BIS值在45±5范围内，一般为7～12mg/kg/h，至手术结束。芬太尼根据手术要求间断静注，用量1～4ug/kg/h，最后1次静注距手术结束的时间，各病人并不相同。手术结束后，每2分观察1次病人意识恢复情况，以病人对语言命令有正确反应为意识恢复时点。意识恢复后，询问病人其姓名、生年月日、居住地址及现地点，以4项均回答正确为定向力恢复时点。记录两时点的动脉压、心率、脉搏氧饱和度与BIS值，并抽取动脉血标本各4ml，离心后取上清血浆，－20℃保存至药物浓度测定。异丙酚采用高压液相色谱分析，芬太尼用气相色谱2质谱分析方法。根据意识恢复时血浆芬太尼浓度，将28例病人分为3组。组Ⅰ（n＝8），芬太尼浓度高于1100ug/L；组Ⅱ（n＝9），芬太尼浓度低于1100ug/L、高于0.45ug/L；组Ⅲ（n＝11），芬太尼浓度低于0.45ug/L。各指标用平均数±标准差（x±s）表示。组间比较用完全随机分组F检验，P<0.05为差异有统计学意义。

结　果

　　3组病人的平均年龄、体重、单位时间芬太尼和异丙酚用量、以及手术时间等见表1，组间比较未见显著性差异。

　　各组病人的基础BIS值平均约为95％，组间无差异。意识和定向力恢复时血压、心率、脉搏氧饱和度3组间比较未见显著性差异。BIS值、芬太尼和异丙酚的血药浓度及恢复时间等见表2和表3。在两个时点，组间芬太尼浓度比较均有显著性差异（P<0.01）。意识恢复时，平均异丙酚浓度组Ⅰ和组Ⅱ比较无明显差异，组Ⅲ明显高于前两组（P<0.05）。定向力恢复时组Ⅲ的异丙酚浓度较另两组无明显差异。两个时点的BIS值各组间比较也无明显不同。意识及定向力恢复时间，3组间比较未见差异。

讨　论

　　麻醉诱导期，麻醉性镇痛药增强异丙酚对意识的抑制作用，有许多报道，其结果相似^[1－4]。而麻醉恢复期，芬太尼血浆浓度是否对麻醉清醒所需异丙酚浓度产生影响，未见文献报道。本研究可见，芬太尼浓度低于0.45ug/L的病人，清醒时异丙酚浓度明显高于另两组芬太尼浓度在0.45ug/L以上的病人。说明芬太尼在0.45ug/L以上时，能协助异丙酚产生意识的抑制，而低于此浓度，影响明显减弱。关于麻醉后意识恢复所需异丙酚浓度，早期的研究结果多在2mg/L左右或以下^[5，6]，这与本研究结果有差异。本试验中，芬太尼浓度在0.45ug/L以下时，病人清醒的异丙酚浓度为312mg/L，此结果与Smith^[4]、Vuyk^[7]和Howell^[8]的报道相近。这些结果提示，单用异丙酚或仅辅用极少量麻醉镇痛药时，如要维持充分的意识消失状态，需使异丙酚浓度高于有文献建议的310mg/L^[9]。

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