Sevoflurane decreases bispectral index values more than does halothane at equal MAC multiples

At the minimum alveolar concentration (MAC) of inhaled anesthetics, 50% of subjects move in response to noxious stimulation. Similarly, at MAC-awake, 50% of subjects respond appropriately to command. The bispectral index (BIS) nominally measures the effect of anesthetics on wakefulness or consciousness. We postulated that the use of halothane with a larger MAC-awake/MAC ratio than sevoflurane would produce higher BIS values at comparable levels of MAC. We studied 33 unpremedicated patients anesthetized by inhalation, 18 with sevoflurane and 15 with halothane. We measured BIS before and during anesthesia at 1 MAC, both before and after tracheal intubation facilitated by fentanyl and rocuronium and then at 1.5 MAC. BIS measurements were made after meeting steady-state conditions. No surgery was performed during this study. BIS values in awake patients did not differ between the sevoflurane and halothane groups (96 +/- 2 and 96 +/- 2, mean +/- sd, respectively). At 1 MAC without and with neuromuscular blockade and at 1.5 MAC, BIS values for patients anesthetized with halothane (54 +/- 7, 56 +/- 7, and 49 +/- 7, respectively) exceeded those for patients anesthetized with sevoflurane (34 +/- 6, 34 +/- 6, and 29 +/- 5, respectively) (P < 0.0001). This finding adds to other evidence indicating that BIS is drug specific.     

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.     

异氟醚麻醉深度的多指标微机实时判断

目的：编制一套多指标监测、微机统计和评分程序，用于术中随时判断麻醉深度。方法：手术病人３２例，１５项指标同时监测，当需要判断麻醉深度时，输入全部指标值，微机计算出总分值（Ｍ），根据Ｍ的增减来判断麻醉深度的相对变化。为验证Ｍ的可靠性，测定血浆环磷酸腺苷浓度，计算二者的相关性。结果：其中２２例的Ｍ与ｃＡＭＰ的个体相关系数（ｒ）的均值为０．８１±０．０８，有显著意义（Ｐ＜０．０５）。结论：本研究拟订的评分法能在７０％的病人中较准确地判断麻醉深度，尤其显示微机判断的实时性。     

Cardiac rhythm and left ventricular function of infants at 1 MAC sevoflurane and halothane

BACKGROUND: The implementation of sevoflurane in pediatric anesthesia practice led to a decrease in the incidence of cardiac arrest previously reported with halothane. Nevertheless, the effects of sevoflurane on cardiac rhythm and function have not been systematically investigated in infants. Thus, we compared cardiac rhythm and left ventricular function at 1 MAC sevoflurane and halothane anesthesia and investigated the potential benefit effect of atropine. METHODS: Twenty infants ASA physical status I or II were randomly assigned to have anesthesia induced with either sevoflurane (up to 5%) or halothane (up to 1.5%). After insertion of an i.v. line, anesthesia was maintained at 1 MAC sevoflurane (group S) or 1 MAC halothane (group H) with infants breathing spontaneously in 100% oxygen. Cardiac output and contractility were measured by transthoracic echocardiography. Three sets of hemodynamic parameters were averaged prior to and after administration of 20 microg x kg(-1) of i.v. atropine. RESULTS: Infants breathing spontaneously 1 MAC halothane or 1 MAC sevoflurane were found to have comparable hemodynamic parameters. After atropine administration, heart rate and cardiac index (CI) increased significantly in both groups (19.6 +/- 7.6% in group H and 21.3 +/- 13.1% in group S, 18.6 +/- 8.8% in group H and 17.7 +/- 12% in group S respectively). Moreover, atropine induced an increase in left ventricular shortening fraction with no difference between groups. In contrast, only infants in group S presented a significant increase in ejection fraction. CONCLUSIONS: Indices of left ventricular function were comparable between groups with no clinically significant change following atropine administration. The present study confirms the favorable hemodynamic profile of sevoflurane in infants breathing spontaneously at 1 MAC concentration.     

七氟醚与异氟醚苏醒期熵指数和听觉诱发电位指数的相关性

目的观察七氟醚和异氟醚苏醒期熵指数(RE和SE)与听觉诱发电位指数(AAI)的变化和相关性。方法择期行腹腔镜下胆囊或子宫附件切除术患者30例,随机均分为七氟醚组(S组)和异氟醚组(I组),分别持续吸入2%～3%七氟醚和异氟醚维持麻醉。吸入麻醉药停止后,20min内每隔1分钟记录RE、SE与AAI,并分析其相关性。结果苏醒期RE、SE与AAI均呈逐渐上升趋势,Ⅰ组相关系数分别为0.89和0.91(P<0.05);S组相关系数分别为0.93和0.91(P<0.05)。结论熵指数和AAI均能反映七氟醚和异氟醚苏醒期麻醉深度的变化,两者相关性良好。     

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。     

麻醉深度对老年肠癌患者术中血流动力学和麻醉复苏的影响

目的 探讨Narcotrend监测下3种不同麻醉深度对老年肠癌根治手术患者血流动力学和麻醉复苏的影响.方法 全身麻醉下行腹腔镜肠癌根治术的老年患者150例,60岁～92岁,美国麻醉医师协会(ASA)分级Ⅰ～Ⅲ级,根据随机数字表法将患者随机均分为3组(每组50例):A组[维持麻醉深度Narcotrend指数(narcotrend index,NI)在D0]、B组(NI维持在D2)和C组(NI维持在E1).术中根据Narcotrend监测结果调整麻醉用药,使各组麻醉深度维持在预设定目标水平.观察并记录患者不同时点血流动力学变化、麻醉药用量、麻醉复苏情况及副作用. 结果 A组患者心率(heart rate,HR)和平均动脉压(mean artery pressure,MAP)在气管插管后即刻、气腹后2 min、手术结束和拔管时明显增加(P＜0.05),3组患者的MAP在麻醉诱导后和气腹前均比基础值明显降低(P＜0.05或P＜0.01);C组患者MAP在麻醉诱导后和气腹前明显低于A组和B组(P＜0.05).A组患者高血压的发生率为31.3％(15/48),明显高于B组的14.6％(7/48)和C组的l2.2％(6/49)(P＜0.05);C组低血压的发生率为40.8％(20/49),明显高于A组的12.5％(6/48)和B组的18.8％(9/48) (P＜0.01).C组丙泊酚用量明显多于A组和B组[分别为(1 136±378)、(1 217±366)、(1 637±423) mg](P＜0.05),C组睁眼时间和拔管时间[(14.8±1.3)、(19.2±4.8) min]较A组[(7.2±1.4)、(10.0±3.3) min]和B组[(8.1±1.1)、(11.8±2.6) min]明显延长(P＜0.01). 结论 老年肠癌患者术中麻醉深度维持在D2最为理想,该麻醉深度不增加麻醉用药和麻醉复苏时间,且更有利于维持血流动力学的稳定.     

利多卡因对丙泊酚靶控输注时不同意识状态下效应部位浓度及熵指数的影响

目的 探讨静脉输注利多卡因对丙泊酚靶控输注时不同意识状态的预测效应部位浓度及熵指数的影响.方法 择期全麻下骨科下肢手术患者60例,ASAⅠ或Ⅱ级,年龄18～60岁,随机均分为利多卡因1.0 mg/kg组(L1组)、利多卡因1.5 mg/kg组(L2组)和对照组(C组).麻醉开始前L1组、L2组分别给予利多卡因1.0 mg/kg和1.5 mg/kg,C组给予等容量的生理盐水,1min后采用靶控输注丙泊酚行全麻诱导.观察入室安静后10 min(T1)、靶控输注前(T2)、插管前即刻(T3)、插管后即刻(T4)、插管后3 min(T5)、插管后5min(T6)时熵指数、MAP、HR、SpO2、OAA/S评分.记录靶控输注期间语言反应消失时(LVC)、意识消失时(LOC)即刻的熵指数和丙泊酚的预测效应部位浓度.结果 与T1、T2时比较,C组T3、T5、T6时和L1、L2组T3～T6时MAP均明显降低(P＜0.01);与T1、T2时比较,三组T3～T6时RE和SE均明显降低(P＜0.01);与T3时比较,C组T4时MAP、HR、RE和SE明显升高(P＜0.01或P＜0.05),而L1、L2组差异无统计学意义.三组患者在LVC、LOC时的熵指数和丙泊酚的预测效应部位浓度差异无统计学意义.结论 静注利多卡因1.0 mg/kg或1.5 mg/kg,对不同意识状态时丙泊酚靶控输注的预测效应部位浓度和熵指数并无显著的影响,但可减轻气管插管时的应激反应,并抑制气管插管刺激时的熵指数升高.     

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.     

不同浓度的异氟醚对听觉诱发电位指数和数量化脑电图的影响

目的　观察异氟醚对听觉诱发电位指数 (AAI)、数量化脑电图 (QEEG)各参数和血液动力学的影响 ,评价AAI判断异氟醚麻醉深度的可行性。方法　选择A患者SAⅠ～Ⅱ级行下腹部手术的患者 30例 ,在丙泊酚、维库溴铵诱导插管后分别吸入 0 8、1 0、1 3MAC的异氟醚 ,每种浓度维持 2 0min。记录BP、HR、AAI、双频谱指数 (BIS)、95 %边缘频率 (95 %SEF)和中间频率 (MF)的值。结果　随呼末异氟醚浓度的增高 ,AAI、QEEG各参数 (BIS、95 %SEF和MF)均显著降低。以上改变与呼末异氟醚浓度呈线性相关 (R =0 818～ 0 92 4 ,P <0 0 1)。结论　在 0 8～ 1 3MAC的范围内 ,AAI、BIS、95 %SEF和MF与呼末异氟醚浓度呈线性相关。AAI、BIS、95 %SEF和MF均可作为异氟醚麻醉深度的监测指标     

舒芬太尼在七氟醚稳态吸入下对BIS和Narcotrend值的影响

目的观察在七氟醚稳态吸入下,不同剂量舒芬太尼在无伤害性刺激时对脑电双频指数(BIS)、Narcotrend指数的影响。方法 48例全麻下行择期腹腔镜妇科手术患者,ASAⅠ或Ⅱ级,随机均分为四组。七氟醚吸入诱导,气管插管后调整七氟醚呼气末浓度为1.0MAC,维持15min后,A、B、C三组分别静注舒芬太尼0.25、0.5、1.0μg/kg,待BIS、Narcotrend值降低至最低点后,观察5min结束试验。D组给予生理盐水2ml。结果四组患者意识消失(LOC)、七氟醚达到稳态吸入(SS)时的BIS、Narcotrend值及舒芬太尼tmax比较差异均无统计学意义。与LOC时比较,SS时四组患者BIS、Narcotrend值均明显降低(P0.01)。与给予舒芬太尼时(0min)比较,A、B、C三组BIS、Narcotrend值在给予舒芬太尼后均明显下降(P0.05)。结论七氟醚麻醉下(1.0MAC),在无伤害性刺激时,舒芬太尼可降低BIS、Narcotrend值,且降低程度与剂量无关。     

A comparison of the SNAP II and BIS XP indices during sevoflurane and nitrous oxide anaesthesia at 1 and 1.5 MAC and at awakening

Background. Monitoring level of consciousness during anaesthesia,with the ability to predict the intentional or unintentionalreturn to consciousness, is desirable. The purpose of this studywas to compare two processed electroencephalographic depth ofanaesthesia monitors (SNAP II^TM and BIS XP^TM) during sevofluraneand sevoflurane/nitrous oxide anaesthesia. Methods. In total, 42 subjects received an interscalene block,followed by general anaesthesia with sevoflurane or sevoflurane/nitrousoxide. The indices were recorded at baseline, at 1.5 and 1.0minimum alveolar concentration (MAC) equivalents, and duringemergence. Results. The SNAP and BIS indices decreased from baseline at1.5 and 1.0 MAC equivalents, but there was no difference withingroups between subjects who received nitrous oxide and thosewho did not. The SNAP index returned to baseline by 1 min beforeawakening and was higher than baseline at eye opening, but theBIS index remained below baseline at awakening. There was abias of –1 (95% CI: –3 to 1) between the SNAP andBIS at baseline; this increased to 21 (95% CI: 19–23)during maintenance of anaesthesia and was 6 (95% CI: 4–8)at awakening. Conclusions. The SNAP index tracks loss of consciousness andemergence from sevoflurane and sevoflurane/nitrous oxide anaesthesia.There is significant bias between the SNAP and BIS indices andtherefore, the indices are not interchangeable. The SNAP indexreturns to baseline before awakening, whereas the BIS indexremains below baseline at awakening, suggesting that the SNAPindex may be more sensitive to unintentional awareness.