Auditory evoked potentials index versus bispectral index during propofol sedation in spinal anesthesia

Purpose  It is still controversial whether an electroencephalogram could be a useful monitor of sedation levels. The present study was performed to compare the bispectral index (BIS) and the auditory evoked potentials index (AAI) during light sedation with propofol infusion in spinal anesthesia. Methods  Eighty patients, aged 20 to 70 years, scheduled for surgery of the lower extremities under spinal anesthesia were assigned to one of four groups (20 patients each). Patients in the AAI propofol and BIS propofol groups were sedated with propofol infusion at an initial rate of 2 mg·kg⁻¹·h⁻¹. Propofol infusion was controlled to try to keep the observer’s assessment of alertness/sedation (OAAS) scale at 3 or 4. Patients in the AAI control and BIS control groups did not receive propofol. Results  The OAAS scales and the AAI or BIS decreased significantly in all groups during surgery, while the decrease was larger in the AAI propofol and BIS propofol groups. The AAI was significantly lower along with lower OAAS scales. There was no overlap in the AAI between OAAS scale 3 and scale 5 in the AAI propofol group, while in the BIS propofol group, no difference was observed in the BIS among OAAS scales 2, 3, 4, and 5. Conclusion  The AAI, but not the BIS, could discriminate slight changes of consciousness during light sedation with propofol infusion in patients with spinal anesthesia. This work was done at the Department of Anesthesiology, Ofuna Chuo Hospital, Kanagawa, Japan.     

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.     

Auditory steady-state response and bispectral index for assessing level of consciousness during propofol sedation and hypnosis

We assessed the effect of propofol on the auditory steady-state response (ASSR), bispectral (BIS) index, and level of consciousness in two experiments. In Experiment 1, propofol was infused in 11 subjects to obtain effect-site concentrations of 1, 2, 3, and 4 microg/mL. The ASSR and BIS index were recorded during baseline and at each concentration. The ASSR was evoked by monaural stimuli. Propofol caused a concentration-dependent decrease of the ASSR and BIS index values (r(2) = 0.76 and 0.93, respectively; P<0.0001). The prediction probability for loss of consciousness was 0.89, 0.96, and 0.94 for ASSR, BIS, and arterial blood concentration of propofol, respectively. In Experiment 2, we compared the effects of binaural versus monaural stimulus delivery on the ASSR in six subjects during awake baseline and propofol-induced unconsciousness. During baseline, the ASSR amplitude with binaural stimulation (0.47+/-0.13 microV, mean +/- SD) was significantly (P<0.002) larger than with monaural stimulation (0.35+/-0.11 microV). During unconsciousness, the amplitude was 0.09+/-0.09 microV with monaural and 0.06+/-0.04 microV with binaural stimulation (NS). The prediction probability for loss of consciousness was 0.97 (0.04 SE) for monaural and 1.00 (0.00 SE) for binaural delivery. We conclude that the ASSR and BIS index are attenuated in a concentration-dependent manner by propofol and provide a useful measure of its sedative and hypnotic effect. BIS was easier to use and slightly more sensitive. The ASSR should be recorded with binaural stimulation. The ASSR and BIS index are both useful for assessing the level of consciousness during sedation and hypnosis with propofol. However, the BIS index was simpler to use and provided a more sensitive measure of sedation. Implications: We have compared two methods for predicting whether the amount of propofol given to a human subject is sufficient to cause unconsciousness, defined as failure to respond to a simple verbal command. The two methods studied are the auditory steady-state response, which measures the electrical response of the brain to sound, and the bispectral index, which is a number derived from the electroencephalogram. The results showed that both methods are very good predictors of the level of consciousness; however, bispectral was easier to use.     

The effect of noise on the bispectral index during propofol sedation.

Because noise in the operating room has been alleged to interfere with the ability to sedate patients before surgery, we evaluated the effect of noise on the Bispectral index (BIS) value during propofol sedation. Thirty unpremedicated patients were studied before the start of surgery while receiving propofol sedation on two separate occasions according to a randomized, crossover protocol design. After achieving a stable baseline BIS value of either 75 or 80 with a target-controlled infusion of propofol, an external sound source administered noise at 50, 80, 110, and 120 dB. The changes in the BIS value were recorded over a 1-min interval at each noise level. In the BIS 75 group, increasing levels of noise did not significantly alter the BIS value. However, in the BIS 80 group, the BIS values at 80, 110, and 120 dB were significantly higher compared to the value at 50 dB. In conclusion, experimental noise increases the BIS and appears to have a greater effect on the BIS value at "lighter" levels of propofol sedation. IMPLICATIONS: Experimental noise levels can increase the Bispectral index (BIS) values during propofol sedation in the operating room. However, the magnitude of the BIS response is influenced by the depth of sedation.     

Validation of the bispectral index monitor during conscious and deep sedation in children

In this study, we tested the validity of the bispectral index (BIS) monitor during conscious and deep sedation of children by comparing it with the University of Michigan Sedation Scale (UMSS), a validated observational pediatric sedation scale. Eighty-six children <12 yr of age were enrolled in this observational study. The subjects underwent conscious or deep sedation administered by non-anesthesiologists for diagnostic or therapeutic procedures in four departments in a children's hospital. Sedation medications varied among departments and were not controlled by the study protocol. An independent observer derived a UMSS score at 10-min intervals for 1 h during sedation; personnel administering sedation medications and performing the procedures were blinded to the BIS and UMSS scores. Significant correlation between BIS scores and UMSS scores was found (r = -0.704, P < 0.0001), including in subjects <6 mo of age (n = 6) (r = -0.761, P < 0.001). Poor correlation was found when ketamine or an oral combination of chloral hydrate, hydroxyzine, and meperidine were used for sedation. We conclude that BIS correlates well with UMSS scores and may be a valid measure of conscious and deep sedation in children. IMPLICATIONS: We compared bispectral index scores with a validated observational scale of conscious and deep sedation in children and found significant correlation. We conclude that the bispectral index may be a valid measurement of depth of sedation in children.     

Validation of the bispectral index monitor for measuring the depth of sedation in children

The Bispectral Index (BIS) is an empirically calibrated number derived from adult electroencephalograph data that correlates with the depth of sedation in adults. We tested the hypothesis that the BIS score is a valid measure of the depth of pediatric sedation in a study designed to avoid limitations of a previously published report. BIS values from 96 healthy ASA physical status I-II children aged 1-12 yr undergoing sedation were continually recorded and electronically transferred to a computer. Two independent observers blinded as to BIS score evaluated sedation using the Observer's Assessment of Alertness/Sedation (OAA/S) and the University of Michigan Sedation Scale (UMSS) at 3-5 min intervals. There was a significant correlation between BIS and UMSS and between BIS and OAA/S by both the Spearman's rank correlation test and by prediction probability (P < 0.001). In children <6 yr, there was a significant correlation between BIS and the clinical sedation scores for subgroups undergoing invasive and noninvasive procedures (P < 0.001). There was also good agreement between the 2 independent observers who assessed clinical sedation scores (kappa = 0.51, P < 0.001). We conclude that the BIS monitor is a quantitative, nondisruptive and easy to use depth of sedation monitor in children.     

Comparison of a new composite index based on midlatency auditory evoked potentials and electroencephalographic parameters with bispectral index (BIS) during moderate propofol sedation

BACKGROUND AND OBJECTIVE: Derived parameters of the electroencephalogram and auditory evoked potentials can be used to determine depth of anaesthesia and sedation. However, it is not known whether any parameter can identify the occurrence of awareness in individual patients. We have compared the performance of bispectral index and a new composite index derived from auditory evoked potentials and the electroencephalogram (AAI 1.61) in predicting consciousness, explicit and implicit memory during moderate sedation with propofol. METHODS: Twenty-one patients with spinal anaesthesia received intraoperatively propofol at the age-corrected C(50) for loss of consciousness and were presented test words via headphones. Bispectral index and AAI 1.61 (auditory evoked potentials, AEP-Monitor2) were recorded in parallel as well as the Observer's Assessment of Alertness/Sedation-score. Postoperatively, testing for explicit and implicit memory formation was performed. RESULTS: Bispectral index and AAI 1.61 correlated well with loss of consciousness defined by an Observer's Assessment of Alertness/Sedation-score of 2 (identical P(K) of 0.87), but did not allow a prediction of postoperative explicit or implicit recall. CONCLUSIONS: Both bispectral index and AAI may be indices of depth of sedation rather than indicators of memory formation, which persists during propofol sedation even after loss of consciousness.     

靶控异丙酚镇静时脑电双频指数和听觉诱发电位指数监测意识状态的比较

目的 在靶控输注异丙酚镇静时比较脑电双频指数（BIS）和听觉诱发电位指数（AEPindex)监测意识状态的准确性。方法 16例病人在全麻诱导前用异丙酚靶控输注镇静，同时监测BIS和AEPindex，用逻辑回归、ROC曲线（Receiver Operating Characteristic)过程、以及灵敏度和特异性比较两种方法监测意识状态的准确性。结果 BIS和AEPindex均能很好的反映病人镇静时的意识状态（P＝0．01），AEPindex的ROC曲线下面积与BIS的ROC曲线下面积相比，差异无统计学意义（P＞0．05），镇静警醒评分（OAA／S）从2恢复到3时AEPindex从42急剧上升至67（P＞0．01），而BIS则从64逐渐上升至72（P＞0．05），提示AEPindex对患者意识状态的差别力更好。OAA／S与BIS、AEPindex和靶控浓度有显著相关性（r分别是0．781、0．684和－0．580，P均＜0．01）。结论 AEPindex和BIS均能正确反映靶控输注异丙酚镇静时的镇静深度，AEPindex对意识（有／无）的鉴别更佳，而BIS能很好的反映意识恢复的渐进性过程。     

听觉诱发电位指数及脑电双频谱指数与芬太尼复合异丙酚镇静深度的相关性

目的 分析听觉诱发电位指数（AAI）及脑电双频谱指数（BIS）与芬太尼复合异丙酚镇静深度的相关性。方法拟在全麻下行腹部手术病人45例，年龄40-55岁，随机分为3组（n=15）：异丙酚组（P组）、芬太尼2μg／kg复合异丙酚组（FP2组）以及芬太尼5μg／kg复合异丙酚组（FP5组）。P组、FP2组、FP5组分别静脉注射生理盐水5ml、芬太尼2、5μg／kg麻醉诱导。4min后以血浆靶浓度（Cp）1．0μg／ml TCI异丙酚，以后每3分钟递增0．2μg／ml，直至警觉，清醒评分（OAA／S评分）达到1分。分别于病人人室平卧10min（基础值）、注射芬太尼后4min、每次调整异丙酚Cp前即刻记录AAI、BIS、平均动脉压（MAP）、心率（HR）、脉搏血氧饱和度（SpO2）、Cp、效应室浓度（Ce），并进行OAA／S评分，对AAI及BIS与OAA／S评分间进行等级相关分析。结果P组、FP2组、FP5组AAI及BIS与OAA／S评分间均呈正相关。三组间BIS与OAA／S评分间相关程度逐渐降低（P〈0．05），而组间AAI与OAA／S评分间相关程度比较差异无统计学意义。在病人对呼唤反应消失时，随着芬太尼剂量的增加，BIS逐渐升高，而AAI差异无统计学意义。结论AAI可以监测芬太尼复合异丙酚的镇静深度，而BIS则不能。     

BIS和AEPI监测镇静深度的评价

目的比较脑电双频指数（BIS）和听觉诱发电位指数（AEPI）在丙酚靶控镇静深度的临床价值.方法45例腰-硬联合麻醉术中需丙泊酚镇静病人,ASA I级,腰麻平面确定后开始丙泊酚靶控输注镇静.结果（1）丙泊酚镇静期BIS、AEPI逐渐降低,苏醒期逐渐升高（P＜0.01）,而AEPI则在意识转换过程中变化更敏感（P＜0.01）.（2）在丙泊酚镇静期和苏醒期BIS、AEPI与丙泊酚EC密切相关.（3）在丙泊酚镇静期,联合监测当BIS≤63和AEPI≤30时敏感度即可达100%.结论BIS和AEPI是监测麻醉镇静深度的良好指标,BIS和AEPI联合监测提高了诊断的敏感度.     

Automated responsiveness test and bispectral index monitoring during propofol and propofol/N2O sedation

BACKGROUND: Sedation practice, especially when non-anaesthesia personnel are involved, requires efficient anaesthetic depth monitoring. Therefore, we used prediction probability (PK) to evaluate the performance of the bispectral index (BIS) of the EEG and automated responsiveness test (ART) to predict sedation depth and loss of subject's responsiveness during propofol sedation, with and without N2O. METHODS: Twenty volunteers were studied during propofol administration with (N2O) and without (Air) N2O. The protocol consisted of sequential 15-min cycles. After a control period, propofol was infused to a target effect-site concentration of 0.25 microg/ml (N2O) or 1.5 microg/ml (Air), which was subsequently increased by 0.25 or 0.5 microg/ml, respectively, until loss of responsiveness was detected by loss of response to command [observer's assessment of alertness/sedation (OAA/S) score 相似文献   

Cerebral state index during propofol anesthesia: a comparison with the bispectral index and the A-line ARX index

BACKGROUND: The objective of this study was to prospectively test the Cerebral State Index designed for measuring the depth of anesthesia. The Cerebral State Index is calculated using a fuzzy logic combination of four subparameters of the electroencephalographic signal. The performance of the Cerebral State Index was compared with that of the Bispectral Index and the A-Line ARX Index. METHODS: This study applied raw data from two previously published clinical protocols. The patients in protocol 1 were given a continuous propofol infusion, 300 ml/h, until 80% of burst suppression occurred. In protocol 2, a stepwise increased target-controlled infusion of propofol was administered to patients until loss of response to noxious stimuli while the Observer's Assessment of Alertness and Sedation was registered every 4 min. The Cerebral State Index was calculated off-line from the recorded electroencephalographic data. The Spearman rank correlation coefficient between electronic indices and the effect site concentration of propofol was calculated along with the prediction probability of each index to predict the Observer's Assessment of Alertness and Sedation level. RESULTS: The Spearman rank correlation coefficients between the Cerebral State Index, Bispectral Index, and A-Line ARX Index and the propofol effect site concentration were -0.94, -0.89, and -0.82, respectively, in protocol 1, whereas the prediction probability values between the Cerebral State Index, Bispectral Index, and A-Line ARX Index and the Observer's Assessment of Alertness and Sedation score in protocol 2 were 0.92, 0.93, and 0.91, respectively. CONCLUSION: The Cerebral State Index detects well the graduated levels of propofol anesthesia when compared with the propofol effect site concentration and the Observer's Assessment of Alertness and Sedation score.     

罗库溴铵对不同丙泊酚镇静水平脑电双频指数和脑状态指数的影响

目的 观察罗库溴铵对丙泊酚不同镇静水平脑电双频指数(BIS)和脑状态指数(CSI)的影响.方法 选择ASA Ⅰ或Ⅱ级气管插管全麻行择期手术患者70例.分为罗库溴铵组(L1、L2 组,n=20)和生理盐水组(C1、C2组,n=15),L1、C1组效应室浓度(Ce)设定为2.5～g/ml,L2、C2组Ce设定为4.0μg/ml.比较麻醉诱导前(To)、气管插管前(T1)、气管插管即刻(T2)、气管插管后3 min(T3)、5 min(T4)、注射罗库溴铵/生理盐水前(T5)、注射罗库溴铵/生理盐水后最大作用强度时(T6)及肌颤搐恢复时(T7)的HR、MAP,并记录T5～T7时的BIS、CSI.结果 L1组BIS、CSI T6时较T5、T7时下降(P<0.05).结论 丙泊酚Ce为2.5～μg/ml时,罗库溴铵会导致BIS、CSI 下降.     

Addition of epinephrine to intrathecal tetracaine augments depression of the bispectral index during intraoperative propofol sedation

Purpose Epinephrine added to local anesthetic agents for spinal anesthesia is frequently used to prolong the duration of anesthesia. Epinephrine stimulates the -adrenoceptor, and it is known that the 2-adrenoceptor agonists have a central inhibitory effect. We investigated the effect of intrathecal epinephrine during propofol sedation with spinal anesthesia, using a bispectral index (BIS) monitor.Methods Twenty adult patients, scheduled for spinal anesthesia, were allocated to the control group (n = 10) or epinephrine group (n = 10). Patients in the control group received 14mg of tetracaine, whereas the epinephrine group received 14mg of tetracaine and 0.2mg of epinephrine. Immediately after the pinprick test, propofol was administered at 0.5mg·kg^–1 by infusion for the initial dose, then continuously at 2mg·kg^–1·h^–1 in both groups. BIS scores were recorded before subarachnoid block, and then every 5min for 90min after subarachnoid block.Results There were significant differences in the BIS score between the two groups at 45–55min and at 60–70min after subarachnoid block.Conclusion Intrathecal epinephrine augments the sedative effect of propofol during spinal anesthesia.     

Randomized placebo-controlled trial to assess the effect of remifentanil and propofol on bispectral index and sedation

The effect of the combination of opiates and hypnotics on bispectral index (BIS) is unclear. This double-blind placebo-controlled trial investigated the effect on BIS and sedation of different infusion doses of remifentanil combined with a steady infusion of propofol. Forty patients initially received a target-controlled infusion of propofol 2 micrograms ml-1 for 15 min. They were then randomized to receive either placebo, 0.01, 0.05 or 0.1 microgram kg-1 min-1 remifentanil for a further 15 min. We found a significant correlation between the dose of remifentanil and the change of BIS after 15 min of infusion. The correlation between all the sedation scores and their corresponding BIS was also significant. We concluded that remifentanil, in combination with propofol, reduces BIS when used for sedation.      

The correlation of the bispectral index monitor with clinical sedation scores during mechanical ventilation in the pediatric intensive care unit

In patients who are mechanically ventilated in the pediatric intensive care unit (PICU), sedative and/or analgesic medications are routinely provided and titrated to effect based on clinical assessment of the patient. The bispectral index (BIS) monitor uses a modified electroencephalogram to quantify the effects of central nervous system-acting drugs on the level of consciousness. To evaluate the usefulness of the BIS monitor to predict clinical sedation levels in the PICU, we compared BIS values with simultaneously obtained clinical sedation scores in 24 mechanically ventilated pediatric patients aged 5.7 plus minus 6.1 yr. For each sedation scale used, the BIS value correlated with increasing depth of sedation (P < 0.0001) and was independent of the drug(s) used for sedation. To differentiate adequate from inadequate sedation, a BIS value <70 had a sensitivity of 0.87--0.89 and a positive predictive value of 0.68--0.84. To differentiate adequate from excessive sedation, a BIS value <50 had a sensitivity of 0.67--0.75 and a positive predictive value of 0.07--0.52. We conclude that the BIS monitor may be a useful adjunct for the assessment of sedation in PICU patients. IMPLICATIONS: We demonstrate the usefulness of the bispectral index monitor for assessing sedation in pediatric intensive care unit patients. The bispectral index monitor correlated with clinically assessed sedation levels and was useful for differentiating adequate from inadequate sedation, which would be of value when the clinical examination is unavailable.     

老年人脑电双频指数、咪达唑仑血药浓度与镇静深度的相关性研究

目的 探讨老年人手术病人椎管内麻醉后用咪达唑仑镇静,脑电双频谱指数、咪达唑仑血药浓度和镇静深度间的相关关系。方法 44例ASAⅠ-Ⅱ级择期手术病人,不用术前药。分为老年组（61－82岁）和年轻组（19－43岁）,每组22例。为尽快达到稳态血药浓度,采用靶控输注. 咪达唑仑靶浓度从50ng/ml起渐增,直至病人对轻推无反应（意识消失）,每个浓度维持15min。连续记录EEG参数,在每一稳态血药浓度末,记录BIS、95％SEF,桡动脉取血（高效液相色谱法测定咪达唑仑血药浓度,并评定镇静深度（OAA／S评分法）。用Spearman’s等级相关进行相关分析,并计算预测概率（Pk）值。结果 两组BIS（r=0.935-0.955)与镇静水平的相关性优于血药浓度（r=-0.849～-0.870）和95％SEF（(r=0.503-0.571).BIS的Pk值高（0．942－0．972）。在同一镇静评分(OAA/S4-1时）,老年组BIS值明显高于年轻组（P＜0．01）,而血药浓度低于年轻组。结论 BIS在监测咪达唑仑镇静水平及预测意识消失方面有重要价值。在同一镇静评分时,老年人BIS值高于年轻人。     

麻醉深度指数与脑电双频谱指数测定靶控输注异丙酚患者镇静时镇静深度的比较

目的对异丙酚靶控输注(TCI)镇静的患者,比较麻醉深度指数(CSI)与脑电双频谱指数(BIS)在无手术刺激条件下监测镇静深度的准确性。方法 ASA Ⅰ或Ⅱ级患者20例,手术种类不限,诱导插管前以异丙酚TCI镇静,靶浓度从0．5 μg/ml开始,输注5 min后递增,递增梯度为0．5 μg/ml, 直至改良清醒镇静评分(OAA/S)为0分后5 min停止,试验中监测并记录患者CSI及BIS,每间隔20 s 行改良OAA/S评分,记录TCI系统预测效应部位浓度值每变化0．1 μg/ml时的数值及时间。计算CSI 及BIS预测不同改良OAA/S评分的预测概率(Pk)。结果 CSI及BIS与改良OAA/S评分均有较好的相关性,患者在不同改良OAA/S评分时的镇静深度均表现出较高的Pk值(Pk>0．9),且二者比较差异无统计学意义。语言反应消失时的BIS05与CSI05、BIS50与CSI50、BIS95与CSI95分别为79．2与74．9、69．2 与65．9、59．2与56．8。意识消失时的BIS05与CSI05、BIS50与CSI50、BIS95与CSI95分别为73．6与65．2、57．1 与54．8、40．6与44．3。结论异丙酚TCI镇静时CSI同BIS一样能够较好的反映患者的镇静深度变化,CSI监测用于观察患者语言反应消失和意识消失的能力优于BIS监测。     

The use of bispectral analysis to monitor outpatient sedation.

The bispectral (BIS) index has been used to interpret partial EEG recordings to predict the level of sedation and loss of consciousness in patients undergoing general anesthesia. The author has evaluated BIS technology in determining the level of sedation in patients undergoing outpatient deep sedation. These experiences are outlined in this review article. Initially, the correlation of the BIS index with traditional subjective patient evaluation using the Observer's Assessment of Alertness and Sedation (OAA/S) scale was performed in 25 subjects. In a second study, the recovery profile of 39 patients where the BIS was used to monitor sedation was compared with a control group where the monitor was not used. A strong positive relationship between the BIS and OAA/S readings was found in the initial subjects. From the recovery study, it appears that use of the BIS monitor may help titrate the level of sedation so that less drugs are used to maintain the desired level of sedation. A trend to earlier return of motor function in BIS-monitored patients was also demonstrated. BIS technology offers an objective, ordinal means of assessing the depth of sedation. This can be invaluable in comparing studies of techniques. The BIS index provides additional information to standard monitoring techniques that helps guide the administration of sedative-hypnotic agents. The trend to earlier return of motor function in BIS-monitored patients warrants further investigation.