脑电双频指数监测临床应用进展

脑电双频指数（BIS）是将脑电信号处理后得到的一个量化参数,主要用于监测麻醉深度。近年来的临床应用研究表明在BIS监测下调控麻醉深度能够为患者术后恢复提供更多的益处．而且BIS还可用于指导闭环靶控麻醉、监测脑缺血、预测心肺复苏的结局等。     

脑电双频指数监测与术后转归关系的研究进展

背景 脑电双频指数（bispectral index,BIS）使用脑电图数据监测麻醉过程中的镇静深度,其与患者术后转归的联系越来越受到国内外学者的关注.目的 对BIS监测与术后转归之间关系的研究进展作一综述.内容 探究BIS监测与患者术后死亡率、术中知晓、术后认知功能障碍（postoperative cognitive dysfunction,POCD）及术后谵妄之间的关联性.趋向 BIS监测可能用于预测患者术后转归,为改善手术患者预后提供了一个新的方法.     

监测脑电双频谱指数预防全麻患者术中知晓的效果:meta分析

目的 采用meta分析评价脑电双频谱指数(BIS)监测用于预防全麻患者术中知晓的效果.方法 检索Cochrane Central Register of Controlled Trials (Central)、Pubmed、Medline、EMBASE等数据库有关BIS监测与未应用BIS监测全麻患者术中知晓效果的临床、随机、对照研究.应用Cochrane协作网系统评价法对纳入文献质量进行评价和资料提取,评价指标为术中知晓发生率.采用RevMan5.1软件进行meta分析.结果 共纳入5项研究,包括34181例患者,其中应用BIS监测患者17432例,术中知晓发生率0.132％;未应用BIS监测患者16749例,术中知晓发生率0.245％,BIS监测组与未应用BIS监测组术中知晓发生率比较差异无统计学意义(P＞0.05)；根据麻醉方式不同进一步分析:在吸入麻醉中,应用BIS监测患者13288例,术中知晓发生率0.128％,未应用BIS监测患者13202例,术中知晓发生率0.113％,BIS监测组与未应用BIS监测组术中知晓发生率比较差异无统计学意义(P＞0.05)；在全凭静脉麻醉中,应用BIS监测患者4144例,术中知晓发生率0.145％,未应用BIS监测患者3547例,术中知晓发生率0.733％,BIS监测组术中知晓发生率明显低于未应用BIS监测组(P＜0.01).结论 监测BIS可预防全凭静脉麻醉患者术中知晓的发生,但不能预防吸入麻醉患者术中知晓的发生.     

非体外循环冠脉旁路移植术中BIS及HRV-PSA变化

目的　调查非体外循环冠状动脉旁路移植术(OPCAB)术中知晓的发生,研究其与脑电双频指数(BIS)、心率变异功率分析(HRV- PSA)监测结果的关系。方法　89 例 OPCAB患者,在麻醉医师不了解BIS情况下实施麻醉,术中有专人(非麻醉者)监测并记录平均动脉压(MAP)、心率(HR)、BIS和HRV PSA各参数值,并负责随访患者有无知晓发生。结果　全组与诱导后相比气管插管、切皮、锯胸骨及关胸时BIS显著增高(P<0 .01),但整个手术过程低频高频比(LF/HF)平稳。89例中有8例发生术中知晓。8例患者发生知晓时的BIS值均在 73 以上,而其余 81 例无知晓者术中无一例BIS高于 70。结论　(1)无 BIS监测下凭经验和血液动力学变化实施 OPCAB麻醉,术中知晓发生率高,表现为发生知晓者BIS偏高;(2)以 BIS作为麻醉深度的指标,可减少或防止术中知晓的发生;联合应用HRV PSA监测,可更加合理地评价麻醉深度。     

肌松药对脑电双频指数监测麻醉深度的影响

脑电双频指数(bispectral index,BIS)是基于原始脑电图的一种麻醉深度监测指标,近年来已广泛用于临床.术中监测麻醉深度能提高麻醉质量和手术安全性,通过合理调控麻醉深度,减少麻醉用药量和避免麻醉并发症的发生.但是.关于BIS监测在临床麻醉中应用的实际意义或价值以及BIS值判读准确性及可能的影响因素仍是人们一直关心的热点问题,结合近期国内外有关文献,现就肌松药对BIS监测麻醉深度的影响及相关临床应用情况作一综述.     

脑电双频指数在麻醉中的应用

麻醉深度的监测有利于调控麻醉药的用量,实现用最少的麻醉药物达到最好的麻醉效果,不仅可以防止麻醉药物过量所造成的危险,缩短苏醒过程,还可以避免术中知晓。脑电双频指数(bispectral index,BIS)作为一种麻醉深度的监测工具,能较好地监测大脑皮质功能状态及其变化,对预测体动、术中知晓以及意识的消失和恢复都具有较好的灵敏度,同时,还可减少麻醉药物用量,已成为麻醉深度监测的重要手段。本文对BIS在临床应用的进展进行综述。     

脑电双频指数的临床矛盾性评价

背景 1996年10月,美国食品药品管理局批准BIS监护仪用于临床监测镇静效应.BIS的临床使用减少了术中知晓,改善了患者术后恢复,提高了围手术期安全性,但临床应用发现,BIS数值和变化与临床表现有时并非一致(即矛盾性). 目的 对引起BIS矛盾性变化的原因进行阐述,以指导临床应用. 内容 原因可能与全身麻醉药的药理特点、作用部位、频谱干扰、特殊病理生理状态(包括低血糖、脑缺血、低血容量、神经功能障碍等)及年龄、手术方式、血管活性药物等诸多因素有关. 趋向 鉴于BIS的矛盾性,如何利用BIS监测或联合其他监测手段加强特殊人群麻醉管理,是需要积极思考的问题.     

依托咪酯和丙泊酚诱导插管期间SNAP指数的变化

准确监测麻醉深度、避免术中知晓是现代临床麻醉学亟待解决的一大问题.目前认为脑电双频指数（BIS）是唯一通过美国食品药品监督管理局（FDA）认可的监测麻醉镇静程度的可靠指标,由于它具有客观、连续、简单、效果好,提供量化指标,且与多种麻醉药之间线性关系明确,可指导合理用药和正确预测麻醉效果.SNAPTM为美国VIASYS公司生产的新型BIS监测仪.BIS值能很好的反映麻醉意识深度,预防麻醉药物用量不足或过量,避免术中知晓和循环波动.BIS预测全麻药镇静深度的报道常见,SNAP却鲜有报道.本研究观察依托咪酯和丙泊酚诱导插管期间SNAP指数与镇静程度之间关系及血压和心率变化,旨在为临床选择麻醉诱导用药提供理论基础.     

体外循环心脏手术对脑电双频指数变化的影响

体外循环(CPB)期间术中知晓以及术后中枢神经系统并发症仍是影响心脏外科手术预后的重要因素之一。脑电双频指数(BIS)是能直观的监测麻醉深度和大脑皮质功能状态的方法。本研究拟对CPB心脏直视手术患儿进行动态BIS监测，就CPB中诸多可能影响BIS的因素进行分析。     

听觉诱发电位对麻醉深度监测的研究进展

准确监测麻醉深度、避免术中知晓是现代临床麻醉学中急待解决的老问题,本文就听觉诱发电位在麻醉深度监测中的研究进展作一综述。     

The use of bispectral index during a cardiopulmonary arrest: a potential predictor of cerebral perfusion

A 62-year-old male underwent off-pump coronary artery grafting surgery while cerebral function was monitored with bispectral index (BIS). The BIS monitoring was continued into the immediate postoperative period, during which time the patient experienced a cardiopulmonary arrest. The changes in the BIS values helped the resuscitating team in assessing the cerebral response to the cardiopulmonary resuscitation.     

Bispectral index: clinical effectiveness and role in reducing anesthetic drug consumption

A numeric value derived from bispectral analysis of EEG, the bispectral index (BIS), has been recently introduced as a monitor of the hypnotic component of anaesthesia. Application of BIS monitoring in anaesthesia appears extremely interesting to drugs titration and drugs economy, and in the evaluation of time for discharge in a one day surgery regimen. In this prospective study ASA I-II patients for Day-Surgery were enrolled in three groups: subaracnoid anaesthesia (SA), general anaesthesia (GA) with BIS and GA without BIS monitoring. At present 35 patients for DS operative hysteroscopy were enrolled. No significant differences were measured between the GA groups. A longer time of recovery was necessary in the SA group. A greater amount of anaesthetic in BIS group could be attributed to a better monitoring of sedation which prevents intraoperative awakening.     

Bispectral Index (BIS) may not predict awareness reaction to intubation in surgical patients.

Bispectral Index (BIS) has been marketed as a measure of the hypnotic component of anesthesia and is recommended as a guide for the administration of hypnotic drugs during anesthesia. BIS values between 40 and 60 are recommended for surgery under general anesthesia. This study investigates whether a BIS baseline between 50 and 60 prevents awareness reaction to endotracheal intubation. After approval by the university's Ethics Committee, 20 consenting patients were enrolled in the study. Midazolam (0.1 mg/kg PO) was given 30 minutes before induction. Anesthesia was induced with alfentanil (10 mcg/kg, followed by 2 mcg/kg(-1) x min(-1)) and propofol infusion was adjusted to a BIS target level between 50 and 60. Propofol infusion rate was maintained constant for 5 minutes with constant BIS. Prior to intubation, patients were tested in one-minute intervals for awareness using Tunstall's isolated forearm technique. Three minutes after endotracheal intubation, the study period ended and surgery was performed. After intubation, 8 of 20 patients showed an awareness reaction, squeezing the investigator's hand in response to a command. No patient had recall. Comparison of patients with and without awareness reaction revealed no differences in BIS before or after intubation. This study shows that a BIS value between 50 and 60 prior to intubation is inadequate to prevent an awareness reaction to endotracheal intubation during propofol/alfentanil anesthesia. Because BIS cannot differentiate between patients with and without awareness reaction, its value as a monitor for awareness and a measurement of the hypnotic component of anesthesia must be questioned.     

Narkosetiefe bei Intubation

In order to study the depth of anaesthesia during endotracheal intubation, 30 patients received either thiopentone or propofol for anaesthesia induction. The BIS value as a parameter for the depth of anaesthesia and the rate pressure product (RPP) were aquired online. Patients who received thiopentone for anaesthesia induction showed significantly higher BIS values at the moment of intubation and reached BIS values >60 significantly more frequently than patients receiving propofol. The RPP in the propofol group lay significantly below that of the thiopentone patients. For all patients there was an mean increase in BIS values of 8 index points and an increase in the RPP. Therefore, BIS values around 50 should be achieved before intubation in order to avoid the critical BIS value for awareness of >60 despite the increase caused by the intubation procedure. Within 24 h of intubation all patients were interviewed for possible signs of awareness. None of the patients was able to remember the intubation or reported other experiences that indicated an unconscious awareness. Nevertheless, the progress of BIS values in a standardized intubation as performed in the normal clinical routine, shows that the use of thiopentone for initiating anaesthesia results in a very flat level of anaesthesia during intubation. The risk for patients to experience awareness should therefore, not be underestimated. Therefore, when using thiopentone it is recommended to also use a rapid acting muscle relaxant or to select a high ED95 to compensate for the flat level of anaesthesia. Alternatively, repetetive boluses of the hypnotic shortly before intubation should be considered or to revert to propofol. The dosage and pharmacokinetics of the analgesic should also be taken into consideration because an insufficient analgesia leads to a faster flattening of the depth of anaesthesia.     

¿Contamos actualmente con un método fiable para detectar el momento de pérdida de consciencia durante la inducción de la anestesia?

This review aims to give an overview of the current state of monitoring depth of anaesthesia and detecting the moment of loss of consciousness, from the first clinical signs involved in anaesthesia to the latest technologies used in this area. Such techniques are extremely important for the development of automatic systems for anaesthesia control, including preventing intraoperative awareness episodes and overdoses. A search in the databases Pubmed and IEEE Xplore was performed using terms such anaesthetic monitoring, depth of anaesthesia, loss of consciousness, as well as anaesthesia indexes, namely BIS. Despite the several methods capable of monitoring the hypnotic state of anaesthesia, there is still no methodology to accurate detect the moment of loss of consciousness during induction of general anaesthesia.     

Brain monitoring with electroencephalography and the electroencephalogram-derived bispectral index during cardiac surgery

Cardiac surgery presents particular challenges for the anesthesiologist. In addition to standard and advanced monitors typically used during cardiac surgery, anesthesiologists may consider monitoring the brain with raw or processed electroencephalography (EEG). There is strong evidence that a protocol incorporating the processed EEG bispectral index (BIS) decreases the incidence intraoperative awareness in comparison with standard practice. However, there is conflicting evidence that incorporating the BIS into cardiac anesthesia practice improves "fast-tracking," decreases anesthetic drug use, or detects cerebral ischemia. Recent research, including many cardiac surgical patients, shows that a protocol based on BIS monitoring is not superior to a protocol based on end-tidal anesthetic concentration monitoring in preventing awareness. There has been a resurgence of interest in the anesthesia literature in limited montage EEG monitoring, including nonproprietary processed indices. This has been accompanied by research showing that with structured training, anesthesiologists can glean useful information from the raw EEG trace. In this review, we discuss both the hypothesized benefits and limitations of BIS and frontal channel EEG monitoring in the cardiac surgical population.     

Bispectral index monitoring is useful to reduce total amount of propofol and to obtain immediate recovery after propofol anesthesia

Bispectral index (BIS) is a processed EEG parameter for assessment of hypnotic effects of anesthetics. We studied whether BIS monitoring can improve recovery from propofol anesthesia and decrease the total amount of propofol needed. Forty-six patients without hypertension and obesity were studied. In the BIS group (n = 20), propofol infusion rate was adjusted to achieve a target BIS value between 40-60, increasing to 65 during the final 10 min of the surgical procedure. In the control group (n = 19), propofol infusion rate was adjusted based only on standard clinical signs. Compared with the control group, patients in the BIS group required lower propofol infusion rates(4.3 +/- 1.1 vs 4.9 +/- 0.8 mg.kg-1.h-1; P < 0.05), and the total amount of propofol decreased significantly (709 +/- 210 vs 914 +/- 326 mg; P < 0.05). BIS monitoring led to immediate recovery after propofol anesthesia. There were no significant differences in the incidence of intraoperative responses between the two groups. BIS monitoring decreased the total amount of propofol and led to immediate recovery after propofol anesthesia. These findings indicate that the use of BIS monitoring may be useful in controlling the infusion rate of propofol during surgery.     

Predicting ischemic brain injury after intraoperative cardiac arrest during cardiac surgery using the BIS monitor

Two patients in whom the bispectral index (BIS) decreased to zero following cardiac arrest during cardiothoracic surgery are described. The BIS value decreased to zero after cardiac arrest, and the value remained low for the remainder of the anesthetic despite successful cardiopulmonary resuscitation. Both patients were found to have severe brain injuries in the postoperative period.     

Auditory information processing during adequate propofol anesthesia monitored by electroencephalogram bispectral index

Memory for intraoperative events may arise from inadequate anesthesia when the hypnotic state is not continuously monitored. Electroencephalogram bispectral index (BIS) enables monitoring of the hypnotic state and titration of anesthesia to an adequate level (BIS 40 to 60). At this level, preserved memory function has been observed in trauma patients. We investigated memory formation in elective surgical outpatients during target-controlled propofol anesthesia supplemented with alfentanil. While BIS remained between 40 and 60, patients listened to a tape with either familiar instances (exemplars) from two categories (Experimental [E] group, n = 41) or bird sounds (Control [C] group, n = 41). After recovery, memory was tested directly and indirectly. BIS during audio presentation was on average (+/- SD) 44 +/- 5 and 46 +/- 5 for Groups E and C, respectively. No patient consciously recalled the intraoperative period, nor were presented words recognized reliably (Group E, 0.9 +/- 0.8 hits; Group C, 0.8 +/- 0.8 hits) (P = 0.7). When asked to generate category exemplars, Group E named 2.10 +/- 1.0 hits versus 1.98 +/- 1.0 in Group C (P = 0.9). We found no explicit or implicit memory effect of familiar words presented during adequate propofol anesthesia at BIS levels between 40 and 60 in elective surgical patients. IMPLICATIONS: This study suggests that stable levels of adequate hypnosis may prevent information processing and memory formation during general anesthesia and supports the feasibility of electroencephalogram bispectral index as a monitor of adequate anesthesia.     

心脏手术中的脑电图（EEG）及脑电双频指数（BIS）监测

心脏手术对于麻醉医生来说存在特别的挑战。术中除了基本的和高级的监测措施，麻醉医生会考虑应用普通的或经过处理的脑电图（electroencephalography，EEG）监测患者的脑功能状态。有力证据显示，与普通监测相比，术中合并经处理的EEG电双频指数（bispectralindex，BIS）监测可有效降低术中知晓的发生率。也有与之冲突的证据显示，心脏手术麻醉应用BIS可改善“快通道麻醉”，减少麻醉药的使用和及早发现脑缺血。最近一项大样本研究显示，对于预防术中知晓，BIS监测并不优于呼气末麻醉药浓度监测。目前有众多麻醉学文献关注综合EEG监测，包括一些非专用的处理后的指数。研究表明，通过专业训练，麻醉医生可以从普通的EEG轨迹采集到有用的数据。本综述中，我们对心脏手术人群术中BIS和额叶EEG监测的优势和局限性加以阐述。