脑电双频谱指数和脑电熵指数监测全麻患者镇痛水平的评价

Can bispectral index and entropy be used as measures of level of analgesia during general anesthesia？

目的 评价脑电双频谱指数（BIS）和脑电熵指数监测全麻患者镇痛水平的可行性。方法择期全麻腹部手术患者26例，随机分为2组（n=13）：试验组和对照组。常规监测行硬膜外置管后，试验组硬膜外注入1％利多卡因5ml，对照组注入等量生理盐水，8min后测定阻滞平面，根据结果试验组硬膜外追加1％利多卡因和0．5％罗哌卡因的混合制剂5～10ml，对照组硬膜外追加生理盐水8ml。麻醉诱导前确保试验组的感觉阻滞节段超过手术切口范围。连接BIS监测仪和脑电熵指数监测仪监测BIS、状态熵（SE）和反应熵（RE）。靶控输注异丙酚（初始血浆靶浓度4μg／ml）和瑞芬太尼（效应室靶浓度2ng／ml）进行全麻诱导，调整异丙酚靶浓度，维持BIS 40—50。静脉注射罗库溴铵0．9mg／kg，气管插管，机械通气，试验组停止输注瑞芬太尼，对照组继续输注瑞芬太尼，效应室靶浓度为2ng／ml。切皮前3min每分钟记录BIS、RE、SE、HR、SP、DP、MAP，取其平均值作为基础值，切皮后2min内要求外科医师停止包括使用电刀在内的手术操作，每分钟记录上述指标。2min后开始使用电刀，进行正常手术操作，并继续每分钟记录上述指标直到切皮后6min，取其平均值。结果与基础值比较，切皮后1min时对照组BIS、RE—SE、SP、DP和MAP均升高（P〈0．05），试验组各指标差异无统计学意义（P〉0．05），切皮后3～6min内2组BIS、RE和RE—SE均升高，对照组BP升高（P〈0．05）。切皮后1min，对于判断镇痛是否足够的准确性，△SP〉△RE—SE〉△MAP〉△BIS，判断准确性均中等。而在电刀干扰时，只有BP的变化可以作为判断指标区分不同的分组，△〉△MAP。结论 BIS、熵指数和BP并不能反映镇痛水平，但BIS、RE．SE和BP都能够在镇痛不足的情况下对伤害性刺激表现出明显升高。对于镇痛不足的判断准确性，△SP〉△RE—SE〉△BIS，准确性均中等。

Objective To investigate the feasibility of using bispectral index （BIS） and entropy as measures of level of analgesia during general anesthesia. Methods After hospital ethics committee approval and written informed consent, 26 ASAⅠ or Ⅲ patients aged 18-64 yr weighing 50-90 kg undergoing elective abdominal operation under general anesthesia were randomly allocated to one of 2 groups （ n = 13 each） ： experiment group （L） and control group （S）. Epidural catheter was placed into epidural space at T9.10 interspace in both groups. Epidural placement was confirmed by a test dose of 1% lidocaine 5 ml and then a mixture of 1% lidocaine ＋ 0.5 % ropivacaine 5-10 ml was given epidurally in experiment group. The incision was within the sensory block area. While in control group equal volume of normal saline （NS） was given instead of lidocaine and ropivacaine. ECG, BP, HR, SpOt, BIS （Aspect, USA） and entropy [response entropy （RE）, state entropy （SE）] （Datex- Ohmeda, Finland） were continuously monitored. General anesthesia was induced with TCI of propofol （initial target plasma concentration 4 μg/ml） and TCI of remifentanil （target effect-site concentration 2 ng/ml ）. The target concentration of propofol was progressively increased until BIS value reached 40-50. Tracheal intubation was facilitated with rocuronium 0.9 mg/kg. After intubation remifentanil infusion was discontinued in experiment group but was continued （target effect site concentration 2 ng/ml ） in control group. Skin incision was made about 20 min after tracheal intubation. BIS, RE, SE, BP （SP, DP, MAP） and HR were recorded every minute for 3 min before （baseline） until 6 min after skin incision. The surgeons were asked to wait for 2 min after skin incision without doing anything including electrocantery. Results At 1 min after skin incision, BIS, the difference between RE and SE （RE-SE） and BP were significantly increased as compared with the baseline in control group; while in experiment group there was no significant change in BIS, RE-SE and BP. When electrocantery was employed BIS, RE and RE-SE were significantly increased as compared with the baseline in both groups but BP was significantly increased only in control group. The area under the receiver operator characteristic curve （AUCROC） of the changes in all monitoring variables was calculated to evaluate their diagnostic accuracy for inadequate analgesia. At 1 min after skin incision, △SP 〉 △-SE 〉 △MAP 〉 △BIS（moderate diagnostic accuracy）. When electrocautery was employed, only the changes in BP had moderate diagnostic accuracy, △SP 〉 △MAP. Conclusion BIS, entropy and conventional hemodynamic parameters can not predict the level of analgesia, but BIS, RE-SE and BP can respond to nociceptive stimulus during skin incision under inadequate analgesia. As the predictors of inadequate analgesia △SP 〉 △RE-SE 〉 △BIS, all have moderate diagnostic accuracy.