维库溴铵对全麻患者脑电熵指数和脑电双频谱指数监测镇静深度的影响

目的观察全身麻醉过程中,维库溴铵对脑电熵指数——状态熵（AE）和反应熵（RE）以及脑电双频谱指数（BIS）的影响。方法ASAⅠ级或Ⅱ级择期手术患者60例,随机分为4组（n=15）：Ⅰ组为对照组,静脉注射生理盐水;Ⅱ组、Ⅲ组、Ⅳ组为试验组,分别静脉注射维库溴铵0．03、0．06、0．12 mg/kg。麻醉诱导采用异丙酚靶控输注（TCI）,当效应室浓度（CE）达到3．5μg/ml时,按组别静脉注射维库溴铵或等容积生理盐水,5 min后静脉注射芬太尼3μg/kg,行气管插管,观察5 min后将Ⅰ组、Ⅱ组、Ⅲ组维库溴铵剂量补足到0．12 mg/kg。记录诱导前即刻、CE达到3．5μg/ml、注射维库溴铵或生理盐水后1、2、3、4、5 min、气管插管前即刻、插管后即刻及插管后1、3、5 min的RE、AE、BIS、HR和MAP。结果与维库溴铵静脉注射前即刻比较,4组静脉注射后各时点RE、SE、BIS、HR、MAP差异无统计学意义（P＞0．05）;4组间静脉注射前后RE、SE、BIS、HR、MAP比较差异无统计学意义（P＞0．05）。与插管前即刻比较,4组插管后即刻及插管后1min时RE、SE、BIS、HR和MAP均升高（P＜0．05或0．01）;与Ⅰ组比较,Ⅱ组、Ⅲ组、Ⅳ组插管后即刻和插管后1 min RE、SE和BIS降低（P＜0．05）,但3组间比较差异无统计学意义（P＞0．05）。结论在深度镇静且无伤害性刺激时,维库溴铵对脑电熵指数和BIS无影响;存在伤害性刺激时（如气管插管）,即使小剂量（0．03 mg/kg）的维库溴铵也可降低脑电熵指数和BIS的升高幅度。     

状态熵指数监测患者靶控输注异丙酚全麻诱导时镇静深度的准确性

目的评价状态熵指数(SE)监测患者靶控输注异丙酚全麻诱导时镇静深度的准确性。方法择期全麻手术患者17例,年龄21～64岁,ASAⅠ级或Ⅱ级,靶控输注异丙酚行全麻诱导,初始效应室靶浓度设定为1.5μg/ml,效应室靶浓度达到设定浓度后1 min以0.5μg/ml的浓度梯度递增,靶控输注开始后每30秒进行1次警觉,镇静评分(OAA/S评分),直至患者意识消失(OAA/S评分≤1分),记录每次OAA/S评分即刻的SE及BIS。分析SE和BIS与OAA/S评分的相关性,计算SE和BIS的镇静深度预测概率(P_K)、患者意识消失时SE_(50)、SK_(90)、BIS_(50)、BIS_(90)及其95%可信区间。结果BIS、SE与OAA/S评分的相关系数分别为0.726(P<0.05)和0.824(P<0.05);BIS与SE的相关系数为0.855 (P<0.05);SE的镇静深度P_K(0.874±0.021)高于BIS(0.820±0.028)(P<0.05)。SE_(50)和BIS_(50)分别为59(48～65)、62(53～67),SE_(90)和BIS_(90)分别为39(16～49)、44(23～53)。结论SE监测患者靶控输注异丙酚全麻诱导时镇静深度的准确性高于BIS。     

数量化脑电图监测异丙酚麻醉时意识状态

目的：比较异丙酚镇静、意识消失和意识恢复时的脑电图变谱指数和边缘频率变化。方法：26例ASA Ⅰ～Ⅱ级全麻病人,微量泵静注异丙酚(40～50mg／min),观察者不断给病人言语指令,待失去语言指令反应和睫毛反射消失时,定为意识消失;停止静注异丙酚,恢复言语指令和睫毛反射时,定为意识恢复。分别监测清醒、意识消失及意识恢复时的数量化脑电图变化。术后第1天随访,了解病人在异丙酚全麻恢复即刻时的回忆。结果：26例病人中,有3例术后存在模糊记忆,意识恢复即刻原始脑电图呈“高频高振幅”特异波,意识消失期间的变谱指数(BIS)和边缘频率(SEF)明显低于意识恢复期。BIS 63、SEF 11时判断意识消失特异性为100％,敏感性分别为14％和21％;BIS96和SEF27时判断意识恢复特异性为100％,敏感性分别为19％和12％。结论：脑电图数量化参数BIS和SEF能用于判断意识消失和意识恢复两种状态;异丙酚麻醉恢复即刻,虽已发生全麻知晓,但只有少数病人对术后存在模糊记忆。     

小剂量氯胺酮对脑电熵指数和脑电双频指数的影响

目的比较小剂量氯胺酮对脑电熵指数(RE、SE)和脑电双频指数(BIS)的影响。方法22例ASAⅠ或Ⅱ级择期行腹腔镜子宫切除术及卵巢囊肿切除术患者,随机均分为氯胺酮组(K组)和生理盐水组(S组)。麻醉诱导:丙泊酚1～2mg/kg、雷米芬太尼1～1.5μg/kg和维库溴铵0.1～0.15mg/kg,气管插管。麻醉维持:丙泊酚6～8mg.kg-1.h-1、维库溴铵0.1mg.kg-1.h-1和雷米芬太尼7～10μg.kg-1.h-1。在稳定的麻醉和手术状况下,分别单次给予患者氯胺酮0.5mg/kg(K组)或等量的生理盐水(S组),记录给药前(基础值)、给药后5、10、15、20、25和30min七个时点MAP、HR、RE、SE和BIS的数值。结果K组和S组MAP、HR、RE、SE和BIS的基础值差异均无统计学意义。K组RE、SE和BIS在给药后迅速升高,然后逐渐下降,在给药后10min达到峰值,分别比基础值升高了43.8%(P<0.01)、43.2%(P<0.01)和28.8%(P<0.01)。RE和SE增加的幅度显著高于BIS,熵指数和BIS增加持续的时间分别为25min和20min。S组在给药后RE、SE和BIS值与基础值相比差异均无统计学意义。K组和S组在给药前后MAP和HR变化差异无统计学意义。结论在丙泊酚-雷米芬太尼麻醉期间,单次加入小剂量的氯胺酮,熵指数和BIS均不能准确反映其真正的麻醉深度。     

熵指数麻醉深度监测仪在全麻苏醒期患者意识监测的应用

目的评价熵指数在全麻苏醒期监测患者意识状态的效能。方法选择25例ASAⅠ或Ⅱ级在全麻下择期行胆囊切除术的患者,手术期间通过丙泊酚、雷米芬太尼和阿曲库铵维持麻醉,术毕采用熵指数监测麻醉深度,采用镇静/警觉(OAA/S)评分评估患者全麻后意识恢复程度,并记录不同OAA/S评分时所对应熵指数(RE和SE)的值。计算这些参数对应意识状态的相关系数(r)。结果rSE、rRE与患者全麻苏醒期意识状态变化显著相关(P<0.01)。结论熵指数在全麻苏醒期能够及时有效地反映患者意识状态的变化。     

舒芬太尼复合异丙酚麻醉下体外循环冠脉搭桥术患者双频谱指数与熵指数的关系

目的评价非肌松、深麻醉状态下,双频谱指数(BIS)反映麻醉深度的准确性。方法选择ASAⅢ级的冠脉搭桥术患者59例,麻醉诱导:静脉注射异丙酚2 mg／kg、舒芬太尼1μg／kg、罗库溴铵0．6 mg／kg,术中麻醉维持采用静脉持续输注异丙酚3-4 mg·kg-1·h-1、舒芬太尼1μg·kg-1·h-1。于麻醉诱导前、麻醉诱导开始后1、2、3、4 min、气管插管后即刻、气管插管后1 min、切皮后即刻和劈胸骨后即刻记录BIS、状态熵(SE)和反映熵(RE)。结果与麻醉诱导前相比,麻醉诱导开始后1、2、3、4 min和气管插管后即刻、气管插管后1 min、切皮后即刻及劈胸骨后即刻BIS、SE和RE均下降(P<0．05)。与SE相比,RE在各观察点均升高(P<0．01)。麻醉诱导期间BIS与SE和RE各时间点观察值之间呈明显正相关,r分别为0．898、0．908(P<0．01)。结论在非肌松、深麻醉状态下,BIS对舒芬太尼复合异丙酚静脉麻醉深度的监测不受肌电活动的影响。     

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

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5 ml,对照组注入等量生理盐水,8 min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5～10 ml,对照组硬膜外追加生理盐水8 ml.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4 μg/ml)和瑞芬太尼(效应室靶浓度2 ng/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0.9 mg/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2 ng/ml.切皮前3 min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2 min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.2 min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6 min,取其平均值.结果 与基础值比较,切皮后1 min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3～6 min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,△SP＞△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.     

脑电熵指数和双频指数与丙泊酚镇静深度的相关性观察

脑电双频指数（BIS）能较好地监测大脑皮层的功能状态及其变化,已成为麻醉镇静深度监测的重要指标。熵指数是近年来Datex-Ohmeda公司研究开发的监测麻醉镇静深度的新产品,包括反应熵（responseentropy,RE）和状态熵（stateentropy,SE）两个参数。本观察旨在比较RE、SE和BIS与丙泊酚镇静深度的相关性。     

罗库溴铵对维族患者全麻诱导时熵指数的影响

目的 探讨罗库溴铵对维族患者全麻诱导时熵指数的影响.方法 择期行全麻手术的维族患者40例,性别不限,年龄20～50岁,体重45～70kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为2组(n=20):生理盐水对照组(NS组)和罗库溴铵组(R组).靶控输注异丙酚,初始血浆靶浓度为2μg/ml,每隔4 min递增0.5μg/ml,直至反应熵(RE)降至45并维持4 min,血浆浓度和效应室浓度平衡时,R组静脉注射罗库溴铵0.6 mg/kg,NS组给予等容量生理盐水,3 min后静脉注射芬太尼3μg/kg诱导气管插管后行机械通气.于麻醉诱导前即刻(T0)、注射罗库溴铵前(T1)、注射后2 min(T2)、气管插管后即刻、1、2和3 min时(T3-6)记录状态熵(SE)和RE,并计算RE-SE差值.结果 与NS组相比,R组T3,4时RE值降低,T2-5时RE-SE差值降低(P＜0.05).结论 罗库溴铵可降低维族患者全麻诱导时RE值和RE-SE差值的增高幅度,可能影响熵指数监测麻醉深度的准确性.

Abstract：

Objective To investigate the effect of rocuronium on spectral entropy during induction of general anesthesia in patients of Uygur nstionality. Methods Forty ASA Ⅰ or Ⅱ patients (Uygur nationality) of both sexes, aged 20-50 yr, weighing 45-70 kg, undergoing elective surgery under general anesthesia, were divided into 2 groups ( n = 20 each): normal saline (NS) group and rocuronium group (group R). Anesthesia was induced with target-controlled infusion of propofol. The initial target plasma concentration wan net at 2 μg/ml. The concentration wan then increased by 0.5 μg/ml every 4 min until response entropy (RE) was decreased to 45 and maintained for 4 min. When the plasma concentration was equal to the effect-site concentration, iv rocuronium 0.6 mg/kg was injected in group R, while group NS received the equal volume of NS instead. Fentanyl 3 μg/kg was injected intravenously at 3 min after recuronium administration. The patients were tracheal intubated and mechanically ventilated. State entropy (SE) and RE were recorded immediately before induction (baseline, To), before rocuronium administration (T1), 2 main after rocuronium administration (T2) and at 0, 1, 2 and 3 min after intubation (T3-6). The difference between RE and SE wan calculated. Results The RE value at T3 and T4 and the difference between RE and SE at T2.5 were significantly lower in group R than in group NS ( P ＜ 0.05). Conclusion Rocuronium can decrease the RE value and degree of increase in the difference between RE and SE during induction of general anesthesia in patients of Uygur nationality, which may affect the accuracy of spectral entropy in monitoring the depth of anesthesia.     

七氟醚、异氟醚不同呼气末浓度对熵和脑电双频指数的影响

目的 观察不同呼气末浓度的七氟醚和异氟醚对熵、脑电双频指数(BIS)及血流动力学的影响.方法 40例ASA Ⅰ或Ⅱ级全麻手术患者随机均分为七氟醚组(Ⅰ组)和异氟醚组(Ⅱ组).麻醉诱导用丙泊酚1 mg/kg,1 min后吸入七氟醚或异氟醚;维持反应熵(RE)、状态熵(SE)、BIS45～55,6 min后置入喉罩.调节吸入浓度使两组患者呼气末浓度分别为0.4、0.6、0.8、1.0和1.3MAC时各维持10 min,记录RE、SE、BIS、HR和MAP.结果 两组患者不同呼气末浓度七氟醚和异氟醚RE、SE、BIS随浓度增加而逐渐下降(P<0.05),HR逐渐减慢、MAP逐渐降低(P<0.05).两组间各指标差异均无统计学意义.RE、SE、BIS间直线相关性随呼气末浓度增大相关系数有增加趋势.结论 熵和BIS均能有效监测七氟醚、异氟醚麻醉深度.     

Time-frequency balanced spectral entropy as a measure of anesthetic drug effect in central nervous system during sevoflurane, propofol, and thiopental anesthesia

BACKGROUND: Time-frequency balanced spectral entropy of electroencephalogram (EEG) and frontal electromyogram (FEMG) is a novel measure of hypnosis during anesthesia. Two Entropy parameters are described: Response entropy (RE) is calculated from EEG and FEMG; and State Entropy (SE) is calculated mainly from EEG. This study was performed to validate their performance during transition from consciousness to unconsciousness under different anesthetic agents. METHODS: Response entropy, SE [S/5 Entropy Module, M-ENTROPY (later in text: Entropy), Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland] and BIS (BIS XP, A-2000, Aspect Medical Systems, Newton, MA) data were collected from 70 patients; 30 anesthetized with propofol 2 mg kg-1, 20 with sevoflurane inhalation, and 20 with thiopental 5 mg kg-1. Loss and regaining of consciousness (LOC, ROC) was tested every 10 s, and sensitivity, specificity, and prediction probability (Pk) were calculated. Behavior of the indices was studied. RESULTS: Sensitivity, specificity, and Pk values for consciousness were high and similar for all indices. During regaining of consciousness after propofol bolus, RE, SE, and BIS values recovered by 81 +/- 22%, 75 +/- 26%, and 59 +/- 18% (mean +/- SD), respectively, from the minimum relative to their baseline. After thiopental bolus, RE, SE, and BIS values recovered by 86+/-21%, 88 +/- 13%, and 63 +/- 14%, respectively. The relative rise was higher in RE and SE compared with BIS (P < 0.01). During deep levels of hypnosis, RE and SE decreased monotonously as a function of burst suppression ratio, while BIS showed biphasic behavior. On average, RE indicated emergence from anesthesia 11 s earlier than SE, and 12.4 s earlier than BIS. CONCLUSIONS: All indices, RE, SE, and BIS, distinguished excellently between conscious and unconscious states during propofol, sevoflurane, and thiopental anesthesia. During burst suppression, Entropy parameters RE and SE, but not BIS, behave monotonously. During regaining of consciousness after a thiopental or propofol bolus, RE and SE values recovered significantly closer to their baseline values than did BIS. Response entropy indicates emergence from anesthesia earlier than SE or BIS.     

Comparative evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index monitor during propofol-remifentanil anesthesia

BACKGROUND: Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index(R) monitor (BIS(R); Aspect Medical Systems, Newton, MA) during propofol-remifentanil anesthesia. METHODS: The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 microg/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 microg . kg(-1) . min(-1)) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability. RESULTS: SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate. CONCLUSION: SE, RE, and BIS revealed similar information about the level of sedation and allowed the authors to distinguish between different steps of anesthesia. Both monitors provided useful additional information for the anesthesiologist.     

Comparative Evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index® Monitor during Propofol-Remifentanil Anesthesia

Background: Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index(R) monitor (BIS(R); Aspect Medical Systems, Newton, MA) during propofol-remifentanil anesthesia.

Methods: The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 [mu]g/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 [mu]g [middle dot] kg-1 [middle dot] min-1) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability.

Results: SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate.     

听觉诱发相关电位，脑电双频指数和熵用于判断重症监护病房患者的不同镇静状态

背景包括镇静评分和常规镇静暂停在内的镇静方案,有助干减少机械通气时间和重症监护病房（ICU）入住时间。因临床上对于镇静深度的评估工作量大、仅能间断进行且干扰镇静和睡眠,所以通过脑电生理信号评估镇静深度的替代方法已经开始倍受青睐：我们想明确听觉诱发相关电位（ERPs）、脑电双频指数（BIS）和墒（Entropy）是否也能够评估临床镇静深度。方法选择10例择期全麻下行胸部或腹部手术的患者。手术后进入ICU,逐渐减少丙泊酚和瑞芬太尼靶控镇静程度[采用Rickmond Agitation镇静评分（RASS）,-5分极深镇静,-4分深度镇静,-3～-1分中度镇静,0分清醒]期间,记录脑电图、BIS、状态熵（SE）、反应墒（RE）和ERPs。手术前或手术后数天测量指标的相关基础水平。结果基线、PASS-5分、RASS-4分、RASS-3至-1分和PASS-0分,对应的BIS值分别是94[4]（中位数,四分位数间距）、47[15]、68[9]、75[10]和88[6];对应的SE值分别是87[3]、46[10]、60[22]、74[21]和87[5];对应的RE值分别是97[4]、48[9]、71[25]、81[8]和96[3]（P〈0．05,Friedman检验）。BIS和墒都有高变异度。当单独考虑ERP振幅100时,各个镇静水平的ERPs值差异无显著性：但是、复括双参数主要变量分析的ERP辨别分析显示区别深度镇静、中度镇静和清醒状态的推算概率PK大约是0．89。与PK对应的RE,SE和BIS值分别是0．88、0．89和0．85。结论ERPs、BIS和熵均不能替代基于标准评分系统的临床镇静评估。全麻后对于极深镇静、深度到中度镇静和清醒的辨别,ERPs和脑电图仅能提供相似的PK值。BIS和熵存在较高的个体间和个体自身变异度,使其难以确定预测镇静水平的目标值范围,因而在危重患者中的使用受到限制。ERPs的变异度还不清楚。     

Evaluation of the sedation level with propofol with electroencephalographic Entropy in comparison with bispectral index monitor

BACKGROUND: Entropy, a newly available electroencephalographic monitor, demonstrates two parameters, response entropy (RE) and state entropy (SE). The aim of this study is to compare RE and SE with bispectral index (BIS) during anesthetic induction with propofol. METHODS: Fifteen patients received target controlled infusion of propofol starting at 3 microg x ml(-1). We measured RE, SE and BIS and recorded effect-site concentrations of propofol at three sedation levels: VR1; conscious state before infusion of propofol, VR2; no response to verbal command, and VR3; no response to verbal command and shaking. Spearman rank correlations and prediction probability for sedation level were analyzed. RESULTS: Effect-site concentrations of propofol at VR1, VR2, and VR3 were 0, 1.8 +/- 0.7, and 2.4 +/- 0.7, respectively. All three parameters showed significant correlations with sedation levels. Prediction probability values of SE, RE, and BIS were 0.905, 0.894, and 0.890, respectively. CONCLUSIONS: Response entropy and SE can provide similar information as BIS about the sedation level with propofol.     

Electromyographic activity increases the bispectral index up to 98 during anesthesia

We report the patients who developed sudden unpredicted increases of bispectral index (BIS) value during sevoflurane and fentanyl anesthesia. After the epidural catheter placement, anesthesia was induced with propofol and fentanyl, and muscular relaxation was obtained by vecuronium for tracheal intubation. Anesthesia was maintained with 1-1.5% sevoflurane, intermittent administration of fentanyl and epidural infusion of ropivacaine. The nociceptive stimuli might be unchanged during the surgical procedure of reconstruction, but sudden increases of BIS value were found. At first, the BIS was decreased with small dose of supplemental anesthetics, but finally, it was up to 98 and the depth of anesthesia could not be assessed by BIS value. Because slight shivering was found in the patient immediately after emergence, electromyographic activity might have falsely elevated the BIS excessively. No clear recall or explicit memory during operation was observed after anesthesia, but anesthesiologists might better pay much more attentions to unpredictable changes of anesthetic depth during anesthesia.     

Spectral entropy and bispectral index as measures of the electroencephalographic effects of propofol

Recently, Datex-Ohmeda introduced the Entropy Moduletrade mark for measuring depth of anesthesia. Based on the Shannon entropy of the electroencephalogram, state entropy (SE) and response entropy (RE) are computed. We investigated the dose-response relationship of SE and RE during propofol anesthesia in comparison with the Bispectral Indextrade mark (BIS). Twenty patients were studied without surgical stimulus. Anesthesia was induced by a constant propofol infusion of 2000 mg/h (451 +/- 77 microg x min(-1) x kg(-1)) via a large forearm vein. Propofol was infused until substantial burst suppression occurred (more than 50%) or mean arterial blood pressure decreased to <60 mm Hg. Hereafter, infusions were stopped until recovery of BIS values up to 60 was reached. Subsequently, the constant propofol infusion of 2000 mg/h was restarted to increase depth of anesthesia and again decreased (infusion was stopped) within the BIS value range of 40-60. The coefficient of determination (R2) and the prediction probability (P(K)) were calculated to evaluate the performance of SE, RE, and BIS to predict changing propofol effect-site concentrations. R2 values for SE, RE, and BIS of 0.88 +/- 0.08, 0.89 +/- 0.07, and 0.92 +/- 0.06, respectively, were similar. The calculated P(K) values, however, revealed a significant difference between SE and RE compared with BIS, with P(K) = 0.77 +/- 0.09, 0.76 +/- 0.10, and 0.84 +/- 0.06, respectively. BIS seems to show slight advantages in predicting propofol effect-site concentrations compared with SE and RE, as measured by P(K) but not as measured by R2.     

异丙酚复合芬太尼妇科门诊手术麻醉中熵指数的应用

目的：观察妇科门诊异丙酚复合芬太尼麻醉中熵指数-反应熵和状态熵的变化。方法：ASAⅠ-Ⅱ级妇科门诊无痛刮宫或人流患者30例．入室后常规监测,然后静脉给予芬太尼（1μg·kg）和异丙酚（2-2．5mg·kg）。记录麻醉前和麻醉后直至苏醒期间RE、SE、MAP、HR、SP02,OAA／S。结果：与麻醉前相比,麻醉后1、2,3．4、5,6、7min各观察点MAP、RE．SE、OAA／S均下降（p〈0．05或0．01）;HR的变化幅度正常;与SE相比RE在各观察点均升高（p〈0．01）。结论：熵指数能较好地反映异丙酚复合芬太尼麻醉的深度。     

A comparison of state and response entropy versus bispectral index values during the perioperative period

Cerebral monitoring indices are associated with a large degree of inter-patient variability and electrical signal interference during surgery. We designed this clinical study to test the hypothesis that use of the spectral entropy (Entropy) module is associated with less frequent intraoperative interference with the displayed indices than the bispectral index (BIS) monitor when used during general anesthesia with propofol and desflurane. Thirty consenting patients scheduled for major laparoscopic surgery procedures were enrolled in this prospective study. The elapsed time to obtain a baseline index value was recorded, as well as the simultaneous state entropy (SE), response entropy (RE), and BIS values at specific time intervals during the induction, maintenance, and emergence periods in patients administered a standardized general anesthetic technique. During the maintenance period, the changes in these indices were evaluated after a bolus dose of propofol (20 mg IV) and a 2% increase or decrease in the inspired concentration of desflurane. As expected, the baseline SE values were less than the RE and BIS values (88 +/- 2 versus 96 +/- 3 and 96 +/- 4, respectively). However, the SE and RE values correlated with the BIS value during the induction (r = 0.77 and 0.78, respectively) and emergence (r = 0.86 and 0.91, respectively) periods. The area under the receiver operating characteristic curve for detection of consciousness also indicated a similar performance of the SE (0.93 +/- 0.04) relative to the RE (0.98 +/- 0.04) and BIS (0.97 +/- 0.04). During the maintenance period, the responses to changes in propofol and desflurane concentrations were consistent with all three indices. Finally, the entropy indices were less interfered with by the electrocautery unit during the operation (12% versus 62% for the BIS monitor). Because the average selling prices of the Entropy and BIS disposable electrode strips (14.25 dollars versus 14.95 dollars USD, respectively) are comparable, we conclude that the Entropy module is a cost-equivalent alternative to the BIS monitor.