Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China.
Chin Med J (Engl). 2012 Apr;125(8):1389-92.
As a new electroencephalogram (EEG) signal processing technique for monitoring the depth of anesthesia, entropy consists of two indices: reaction entropy (RE) and state entropy (SE). Our study compared entropy with classical bispectral index (BIS) in reduction of myoelectrical interference and noxious stimuli with EEG signals.
Two hundred and eighty patients (ASA I-II, 18-60 years old) undergoing scheduled surgeries from seven medical centers were enrolled. Anesthesia induction was managed with propofol via the target-controlled infusion (TCI) system. The results of BIS, RE, SE, mean arterial pressure (MAP) and heart rate (HR) were recorded before anesthesia induction, at the moment of unconsciousness, before and 2 minutes after administration of muscle relaxant, and before and one and three minutes after the tracheal intubation.
The values of half maximum effective concentrations (EC50), 5% effective concentrations (EC05) and 95% effective concentrations (EC95) of propofol effect-site concentration at the onset of unconsciousness were 1.2 (1.1-1.3 µg/ml), 2.5 (2.4-2.5 µg/ml) and 3.7 (3.7-3.8 µg/ml), while those of the predicted plasma propofol concentration were 2.8 (2.7-2.9 µg/ml), 3.9 (3.8-3.9 µg/ml) and 4.9 (4.8-5.0 µg/ml), respectively. The values of BIS, SE and RE were 62, 59 and 63 when 50% of patients lost consciousness, and 79, 80, 85 and 42, 37, 44, respectively, when 5% and 95% of patients were unconscious. The values of BIS, RE and SE dropped two minutes after the injection of muscle relaxant, but there were no significant differences between RE and SE. MAP and HR increased visibly, which indicated a reaction to tracheal intubation; the values of BIS, RE and SE, however, did not display any significant changes.
This large-sample multicentric study confirmed the values of RE and SE as approximating BIS value, at the onset of unconsciousness during propofol TCI anesthesia. After elimination of myoelectrical activation, all values of RE, SE and BIS decreased significantly and the three indices were less sensitive to noxious stimuli than cardiovascular responses.
作为一种新的用于监测麻醉深度的脑电图（EEG）信号处理技术，熵由两个指标组成：反应熵（RE）和状态熵（SE）。我们的研究比较了熵与经典的双频谱指数（BIS）在减少脑电图信号中的肌电干扰和有害刺激方面的效果。
本研究纳入了来自七个医学中心的 280 名接受择期手术的患者（ASA I-II 级，18-60 岁）。采用丙泊酚靶控输注（TCI）系统诱导麻醉。在麻醉诱导前、意识丧失时、肌松药给药前和给药后 2 分钟、气管插管前和插管后 1 分钟和 3 分钟记录 BIS、RE、SE、平均动脉压（MAP）和心率（HR）的结果。
丙泊酚效应部位浓度起始无意识的半最大有效浓度（EC50）、5%有效浓度（EC05）和 95%有效浓度（EC95）分别为 1.2（1.1-1.3μg/ml）、2.5（2.4-2.5μg/ml）和 3.7（3.7-3.8μg/ml），而预测的血浆丙泊酚浓度分别为 2.8（2.7-2.9μg/ml）、3.9（3.8-3.9μg/ml）和 4.9（4.8-5.0μg/ml）。当 50%的患者失去意识时，BIS、SE 和 RE 的值分别为 62、59 和 63，当 5%和 95%的患者失去意识时，BIS、RE 和 SE 的值分别为 79、80、85 和 42、37、44。肌松药注射后两分钟，BIS、RE 和 SE 值下降，但 RE 和 SE 之间没有显著差异。MAP 和 HR 明显升高，提示气管插管反应；然而，BIS、RE 和 SE 值没有显示出任何显著变化。
这项大样本多中心研究证实，在丙泊酚 TCI 麻醉诱导期间，RE 和 SE 值接近 BIS 值，可用于意识丧失的起始。消除肌电激活后，RE、SE 和 BIS 的所有值均显著下降，并且这三个指标对有害刺激的敏感性均低于心血管反应。
