七氟醚和依托咪酯镇静催眠效应的相互作用

目的 评价七氟醚和依托咪酯镇静催眠效应的相互作用.方法 择期全麻手术患者24例,ASA Ⅰ或Ⅱ级,年龄18～59岁,体重指数17～27 kg/m2.试验Ⅰ 12例患者靶控输注依托咪酯,效应室靶浓度依次为0.05、0.1、0.2、0.3、0.4、0.5 μg/ml.效应室浓度依次达到预设浓度2 min时,记录反应熵(RE)、状态熵(SE)和警觉/镇静(OAA/S)评分,然后停止输注依托咪酯.随机分为3组(n=4),A1组、B1组、C1组吸入七氟醚,呼气末浓度分别为0.5%、1%、2%.七氟醚呼气末浓度达预定浓度的95%或以上时,靶控输注依托咪酯,效应室靶浓度依次为0.2、0.3、0.4、0.5 μg/ml.效应室浓度依次达到预设浓度2 min时,记录RE、SE和OAA/S评分.试验Ⅱ 12例患者吸入七氟醚,呼气末浓度依次为0.5%、1%、2%、3%、4%、5%.依次达到预定呼气末浓度时,记录RE、SE和OAA/S评分,然后停止吸人七氟醚,吸氧洗脱七氟醚.随机分为3组(n=4),A2组、B2组、C2组靶控输注依托咪酯,效应室靶浓度分别为0.05、0.1、0.2 μg/ml.效应室浓度达到预设浓度2 min时,吸入七氟醚,呼气末浓度依次为0.5%、1%、2%、3%、4%、5%.依次达到预定呼气末浓度时,记录RE、SE和OAA/S评分.采用反应曲面法评价RE、SE和OAA/S评分,判断七氟醚和依托咪酯镇静催眠效应的相互作用.结果 RE和SE的相互作用指数的拟合值及其95%可信区间分别为0.32(-0.07～0.71)、0.25(-0.12～0.63)(P>0.05).OAA/S评分的相互作用指数的拟合值及其95%可信区间为2.25(0.58～3.93)(P<0.05).结论 以脑电熵指数反映镇静催眠效应时七氟醚和依托咪酯为相加作用;以OAA/S评分反映镇静催眠效应时七氟醚和依托咪酯为协同作用.     

依托咪酯ke0用于靶控输注系统的性能

目的 验证由峰效应时间法(TFEAK)计算的依托咪酯血浆-效应室平衡速率常数(ke0)值在效应室浓度(Ce)靶控时的准确性.方法 69例患者随机均分为三组,靶控输注依托咪酯400ng/ml持续15 min,计算血浆浓度.Ⅰ组靶控血浆浓度,Ⅱ组、Ⅲ组分别以ke0为0.48/min和1.02/min的Ce.记录依托咪酯浓度、BIS的经时变化过程,同时监测BP、HR和意识消失(LOC)时间;用两种ke0值分别模拟Ⅰ组患者LOC时的Ce.结果 与Ⅱ组比较,Ⅲ组能更好地预测依托咪酯药物效应的时间过程.Ⅰ组患者LOC中位数(75 s)显著大于Ⅱ组和Ⅲ组(40 s,P＜0.05).ke0为1.02/min时,Ⅰ组患者LOC时模拟的Ce(336 ng/ml)与Ⅲ组患者靶控效应室输注LOC时的浓度387ng/ml差异无统计学意义.各组间SBP的最低值和DBP的最大降幅的平均值差异无统计学意义.结论 源自BIS监测所得的峰值时间及其计算所得的ke0值1.02/min能更准确地预测依托咪酯效应位靶控输注时药物效应的时间过程.     

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。     

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。     

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.     

艾司洛尔、拉贝洛尔和尼卡地平对气管插管期间心血管反应、脑电双频指数和熵指数的影响

目的探讨艾司洛尔、拉贝洛尔和尼卡地平对气管插管期间心血管反应、腑电双频指数(BIS)和熵指数的影响。方法 60例择期腹部手术的患者,随机均分为四组:艾司洛尔组、拉贝洛尔组和尼卡地平组、生理盐水组。四组均采用丙泊酚分步靶控输注诱导,BIS≤80时各组分别静注艾司洛尔0.3 mg/kg、拉贝洛尔0.04 mg/kg、尼卡地平0.03 mg/kg 和生理盐水。当 BIS≤50后1 min行气管插管。观察反应熵(RE)、状态熵(SE)、BIS、HR 和 MAP 的变化。结果艾司洛尔组、拉贝洛尔组和尼卡地平组 MAP、HR 在插管后1 min 显著高于插管前1 min(P<0.05或 P<0.01)。各组RE、SE、BIS 插管前后差异无统计学意义。结论艾司洛尔、拉贝洛尔或尼卡地平均可减轻患者气管插管时的心血管反应,但对 BIS、RE、SE 无显著影响。     

熵指数监测全麻患者镇静水平的准确性

目的 评价反应熵和状态熵监测全麻患者镇静水平的准确性.方法 择期行腹部手术患者20例,ASAⅠ或Ⅱ级,入室后监测反应熵(RE)、状态熵(SE)及脑电双频谱指数(BIS),静脉注射异丙酚、维库溴铵和芬太尼麻醉诱导,气管插管后机械通气,吸入七氟烷、间断静脉注射维库溴铵和芬太尼维持麻醉.分别于入室时、意识消失前10min、意识消失即刻、气管插管时、手术1 h、意识恢复前10 min、意识恢复即刻、拔管后10 min时记录RE、SE和BIS.结果 RE、SE和BIS在意识改变前后差异均有统计学意义(P＜0.05),RE、SE和BIS判断意识消失的临界值分别为76、73和68,灵敏度分别为94%、95%和92%,特异度分别为92%、94%和9l%,临界值判断意识消失的准确度分别为93%、95%、94%;判断意识恢复的临界值分别为82、75和70,灵敏度分别为95%、95%和91%,特异度分别为93%、96%和93%,临界值判断意识恢复的准确度分别为98%、96%和97%.结论 熵指数能够准确地监测全麻患者镇静水平.     

近日节律对靶控输注依托咪酯镇静效应的影响

目的通过上午、下午靶控输注(TCI)依托咪酯麻醉诱导时依托咪酯血浆靶浓度测定,探讨近日节律对TCI依托咪酯镇静效应的影响。方法选择术前未用药患者60例,ASAⅠ或Ⅱ级,随机分为上午组(8:00~10:00,A组,30例)和下午组(14:00~16:00,P组,30例)TCI依托咪酯进行全麻诱导。以血浆靶浓度150 ng/ml为起点,达到预期的血浆靶浓度5 min后,每次增加50 ng/ml,直到患者意识消失(睫毛反射消失及OAA/S评分≤3分,且BIS≤50)。记录BIS为50和意识消失时的依托咪酯血浆靶浓度。结果 BIS达50和意识消失时,两组患者HR、MAP、SpO2、BIS差异均无统计学意义。与P组比较,BIS达50和意识消失时,A组依托咪酯血浆靶浓度明显升高(P0.05)。结论近日节律对依托咪酯的镇静作用有影响,下午组TCI依托咪酯患者BIS达50和意识消失时所需血浆靶控浓度较低。     

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.     

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.     

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

BACKGROUND: Recently, entropy algorithms have been proposed as electroencephalographic measures of anesthetic drug effects. Datex-Ohmeda (Helsinki, Finland) introduced the Entropy Module, a new electroencephalographic monitor designed for measuring depth of anesthesia. The monitor calculates a state entropy (SE) computed over the frequency range of 0.8-32 Hz and a response entropy (RE) computed over the frequency range of 0.8-47 Hz. The authors investigated the dose-response relation of SE and RE during sevoflurane anesthesia in comparison with the Bispectral Index (BIS). METHODS: Sixteen patients were studied without surgical stimulus. Anesthesia was induced by sevoflurane inhalation with a tight-fitting facemask. Sevoflurane concentrations were increased and subsequently decreased and increased two to four times until the measurement was stopped and patients were intubated for surgery. The performances of SE, RE, and BIS to predict the estimated sevoflurane effect site concentration, obtained by simultaneous pharmacokinetic and pharmacodynamic modeling, were compared by calculating the correlation coefficients and the prediction probability. RESULTS: State entropy, RE, and BIS values decreased continuously over the observed concentration range of sevoflurane. Correlation coefficients were slightly but not significantly better for entropy parameters (0.87 +/- 0.09 and 0.86 +/- 0.10 for SE and RE, respectively) than for BIS (0.85 +/- 0.12). Calculating the prediction probability confirmed these results with a prediction probability of 0.84 +/- 0.05 and 0.82 +/- 0.06 for SE and RE, respectively, and 0.80 +/- 0.06 for BIS. CONCLUSION: State entropy and RE seem to be useful electroencephalographic measures of sevoflurane drug effect.     

Spectral Entropy and Bispectral Index as Measures of the Electroencephalographic Effects of Sevoflurane

Background: Recently, entropy algorithms have been proposed as electroencephalographic measures of anesthetic drug effects. Datex-Ohmeda (Helsinki, Finland) introduced the Entropy Module, a new electroencephalographic monitor designed for measuring depth of anesthesia. The monitor calculates a state entropy (SE) computed over the frequency range of 0.8-32 Hz and a response entropy (RE) computed over the frequency range of 0.8-47 Hz. The authors investigated the dose-response relation of SE and RE during sevoflurane anesthesia in comparison with the Bispectral Index (BIS).

Methods: Sixteen patients were studied without surgical stimulus. Anesthesia was induced by sevoflurane inhalation with a tight-fitting facemask. Sevoflurane concentrations were increased and subsequently decreased and increased two to four times until the measurement was stopped and patients were intubated for surgery. The performances of SE, RE, and BIS to predict the estimated sevoflurane effect site concentration, obtained by simultaneous pharmacokinetic and pharmacodynamic modeling, were compared by calculating the correlation coefficients and the prediction probability.

Results: State entropy, RE, and BIS values decreased continuously over the observed concentration range of sevoflurane. Correlation coefficients were slightly but not significantly better for entropy parameters (0.87 +/- 0.09 and 0.86 +/- 0.10 for SE and RE, respectively) than for BIS (0.85 +/- 0.12). Calculating the prediction probability confirmed these results with a prediction probability of 0.84 +/- 0.05 and 0.82 +/- 0.06 for SE and RE, respectively, and 0.80 +/- 0.06 for BIS.     

Spectral entropy as a measure of hypnosis in children

BACKGROUND: The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland), using time-frequency balanced Spectral Entropy, is a novel tool for monitoring the hypnotic state during anesthesia. The Entropy Module produces two values, State Entropy (SE) and Response Entropy (RE), and in adults, it has been shown to measure reliably the hypnotic effects of various drugs. In children, Spectral Entropy has been only preliminary studied. The authors' aim was to study Spectral Entropy as a marker of hypnotic state during general anesthesia in infants and children. METHODS: Twenty infants (aged 1 month-1 yr) and 40 children (aged 1-15 yr) were anesthetized for surgery using standardized sevoflurane-nitrous oxide-based anesthesia. The relationships between SE, RE, or Bispectral Index (BIS) and (1) a modified Observer's Assessment of Alertness/Sedation Scale, (2) non-steady state end-tidal concentration of sevoflurane, (3) steady state end-tidal concentration of sevoflurane, and (4) hemodynamic values were calculated using prediction probability, nonlinear regression, and correlation coefficients, as appropriate. The performances of SE, RE, and BIS were compared. RESULTS: The prediction probability values (+/- SEM) of SE, RE, and BIS versus the modified Observer's Assessment of Alertness/Sedation Scale in the induction phase were 0.83 +/- 0.06, 0.88 +/- 0.06, and 0.87 +/- 0.08 for children and 0.76 +/- 0.08,0.79 +/- 0.08, and 0.73 +/- 0.10 for infants; values in the emergence phase were 0.68 +/- 0.05, 0.74 +/- 0.04, and 0.64 +/- 0.05 for children and 0.64 +/- 0.07, 0.69 +/- 0.06, and 0.72 +/- 0.06 for infants, respectively. SE, RE, and BIS values were inversely proportionally related to the end-tidal concentration of sevoflurane for children, but for infants, the correlation was much less clear. No significant correlations were found between SE, RE, or BIS values and the hemodynamic values. CONCLUSIONS: Spectral Entropy may be a useful tool for measuring the level of hypnosis in anesthetized children and seems to perform as well as BIS. In infants, the clinical usefulness of both these electroencephalogram-derived methods must be evaluated in further controlled studies.     

Spectral Entropy as a Measure of Hypnosis in Children

Background: The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland), using time-frequency balanced Spectral Entropy, is a novel tool for monitoring the hypnotic state during anesthesia. The Entropy Module produces two values, State Entropy (SE) and Response Entropy (RE), and in adults, it has been shown to measure reliably the hypnotic effects of various drugs. In children, Spectral Entropy has been only preliminary studied. The authors' aim was to study Spectral Entropy as a marker of hypnotic state during general anesthesia in infants and children.

Methods: Twenty infants (aged 1 month-1 yr) and 40 children (aged 1-15 yr) were anesthetized for surgery using standardized sevoflurane-nitrous oxide-based anesthesia. The relationships between SE, RE, or Bispectral Index (BIS) and (1) a modified Observer's Assessment of Alertness/Sedation Scale, (2) non-steady state end-tidal concentration of sevoflurane, (3) steady state end-tidal concentration of sevoflurane, and (4) hemodynamic values were calculated using prediction probability, nonlinear regression, and correlation coefficients, as appropriate. The performances of SE, RE, and BIS were compared.

Results: The prediction probability values (+/- SEM) of SE, RE, and BIS versus the modified Observer's Assessment of Alertness/Sedation Scale in the induction phase were 0.83 +/- 0.06, 0.88 +/- 0.06, and 0.87 +/- 0.08 for children and 0.76 +/- 0.08,0.79 +/- 0.08, and 0.73 +/- 0.10 for infants; values in the emergence phase were 0.68 +/- 0.05, 0.74 +/- 0.04, and 0.64 +/- 0.05 for children and 0.64 +/- 0.07, 0.69 +/- 0.06, and 0.72 +/- 0.06 for infants, respectively. SE, RE, and BIS values were inversely proportionally related to the end-tidal concentration of sevoflurane for children, but for infants, the correlation was much less clear. No significant correlations were found between SE, RE, or BIS values and the hemodynamic values.     

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.     

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.     

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.     

Entropy and bispectral index during anaesthesia in children

Entropy is a new EEG based technology developed as a measure of depth of anaesthesia. The Entropy algorithm quantifies the degree of disorder in the EEG. During anaesthesia the disorder of the EEG, or entropy, falls. Entropy is independent of absolute frequency or amplitude of the EEG. This may make it suitable for paediatric anaesthesia. In this prospective observational blinded study we recorded the Entropy and Bispectral Index in 23 children undergoing general anaesthesia with isoflurane and nitrous oxide, supplemented with peripheral nerve blockade. We recorded Entropy at several times during anaesthesia, pre-awakening and 1-minute post-awakening. Entropy pre-awakening and 1 minute after awakening was compared to a value during anaesthesia in three age groups; less than one-year-old (infants), one to five years (toddlers) and five to twelve years (children). The correlation between BIS and Entropy was also calculated. Entropy post-awakening was higher than during anaesthesia for all age groups. Entropy pre-awakening was higher than during anaesthesia for the children and toddlers. This was not as apparent in infants. There was a strong correlation between BIS and Entropy for children and toddlers. The correlation was less for infants. This study demonstrates that, in children, Entropy is lower during anaesthesia when compared to awake values. Further evaluation in the paediatric population is worthwhile.     

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.