Comparison of bispectral index and end-tidal anaesthetic concentration monitoring on recovery profile of desflurane in patients undergoing lumbar spine surgery

Effectiveness Assessment of Bispectral Index Monitoring Compared with Conventional Monitoring in General Anesthesia: A Systematic Review and Meta-Analysis

Background and Objective. The Bispectral Index (BIS) is utilized to guide the depth of anesthesia monitoring during surgical procedures. However, conflicting results regarding the benefits of BIS for depth of anesthesia monitoring have been reported in numerous studies. The purpose of this meta-analysis and systematic review was to assess the effectiveness of BIS for depth of anesthesia monitoring. Search Methods. A systematic search of Ovid-MEDLINE, Cochrane, and PubMed was conducted from inception to April 20, 2023. Clinical trial registers and grey literature were also searched, and reference lists of included studies, as well as related review articles, were manually reviewed. Selection Criteria. The inclusion criteria were randomized controlled trials without gender or age restrictions. The control groups used conventional monitoring, while the intervention groups utilized BIS monitoring. The exclusion criteria included duplicates, reviews, animal studies, unclear outcomes, and incomplete data. Data Collection and Analysis. Two independent reviewers screened the literature, extracted data, and assessed methodological quality, with analyses conducted using R 4.0 software. Main Results. Forty studies were included. In comparison to the conventional depth of anesthesia monitoring, BIS monitoring reduced the postoperative cognitive dysfunction risk (RR = 0.85, 95% CI: 0.73∼0.99, P = 0.04), shortened the eye-opening time (MD = -1.34, 95% CI: -2.06∼-0.61, P < 0.01), orientation recovery time (MD = -1.99, 95% CI: -3.62∼-0.36, P = 0.02), extubation time (MD = -2.54, 95% CI: -3.50∼-1.58, P < 0.01), and postanesthesia care unit stay time (MD = -7.11, 95% CI: -12.67∼-1.55, P = 0.01) and lowered the anesthesia drug dosage (SMD = -0.39, 95% CI: -0.63∼-0.15, P < 0.01). Conclusion. BIS can be used to effectively monitor the depth of anesthesia. Its use in general anesthesia enhances the effectiveness of both patient care and surgical procedures.

Prevention of accidental awareness under general anaesthesia: A regional service evaluation

The United Kingdom's Fifth National Audit Project investigated the incidence and causes of accidental awareness during general anaesthesia. Subsequently, guidelines produced by the Association of Anaesthetists of Great Britain and Ireland provide key recommendations to minimise awareness. These include using processed electroencephalogram for patients receiving total intravenous anaesthesia while paralysed and using audible low end-tidal anaesthetic concentration alarms. The Southcoast Perioperative Audit and Research Collaboration undertook a five-day regional service evaluation, assessing the measures in place to minimise awareness and conducting a practitioner survey. Eight hospitals participated with 382 theatre attendances were analysed. Processed electroencephalograph monitoring for patients receiving total intravenous anaesthesia with neuromuscular blockade has been widely adopted into regional practice, from 23% of cases in the Fifth National Audit Project, to 85% in this snapshot. During volatile anaesthesia, age-adjusted low end-tidal anaesthetic concentration alarms were used in 34% cases. The range was 0-97% at different hospitals, suggesting heterogeneity in practice. Seventy-six per cent of anaesthetists rarely alter the default anaesthetic machine alarm settings. Therefore, instigating default low end-tidal anaesthetic concentration alarms could improve compliance with guidelines and reduce the risk of awareness for patients.

Guidelines on perioperative optimization protocol for the adult patient 2023

OBJECTIVE

The French Society of Anesthesiology and Intensive Care Medicine [Société Française d'Anesthésie et de Réanimation (SFAR)] aimed at providing guidelines for the implementation of perioperative optimization programs.

DESIGN

A consensus committee of 29 experts from the SFAR was convened. A formal conflict-of-interest policy was developed at the outset of the process and enforced throughout. The entire guidelines process was conducted independently of any industry funding. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence.

METHODS

Four fields were defined: 1) Generalities on perioperative optimization programs; 2) Preoperative measures; 3) Intraoperative measures and; 4) Postoperative measures. For each field, the objective of the recommendations was to answer a number of questions formulated according to the PICO model (population, intervention, comparison, and outcomes). Based on these questions, an extensive bibliographic search was carried out using predefined keywords according to PRISMA guidelines and analyzed using the GRADE® methodology. The recommendations were formulated according to the GRADE® methodology and then voted on by all the experts according to the GRADE grid method. As the GRADE® methodology could have been fully applied for the vast majority of questions, the recommendations were formulated using a "formalized expert recommendations" format.

RESULTS

The experts' work on synthesis and application of the GRADE® method resulted in 30 recommendations. Among the formalized recommendations, 19 were found to have a high level of evidence (GRADE 1±) and ten a low level of evidence (GRADE 2±). For one recommendation, the GRADE methodology could not be fully applied, resulting in an expert opinion. Two questions did not find any response in the literature. After two rounds of rating and several amendments, strong agreement was reached for all the recommendations.

CONCLUSIONS

Strong agreement among the experts was obtained to provide 30 recommendations for the elaboration and/or implementation of perioperative optimization programs in the highest number of surgical fields.

Abstract No.: ABS0888: BIS (Bispectral Index) The current tool for monitoring of unintended awareness and depth of anaesthesia

Background & Aims:

Awareness under general anaesthesia is an unpleasant phenomenon which often goes unnoticed and neglected. Numerous incidences of intraoperative awareness are not reported. Our aim was to evaluate intraoperative awareness during general anaesthesia and titrate amount of anaesthetic agents according toBispectral Index ( BIS).

Methods:

This randomised, prospective comparative study was conducted in 100 adult patients, randomly divided equally in to 2 groups: BIS and NON BIS. After obtaining written informed consent,patients belonging to American Society of Anesthesiologists (ASA) grade 1and 2, aged 20-60 years, weighing 40-75 kg posted for elective surgical procedures in various specialties under general anaesthesia were included. Patients with ASA 3 & 4, psychiatric illness on medication, language barrier, pregnancy or known allergy to propofol were excluded. Postoperatively intraoperative awareness was assessed by modified form of Brice questionnaire at various time intervals. Hemodynamic parameters were monitored and total propofol consumption was calculated.

Results:

Intra-operative awareness reported was 2% in BIS group and 8% in NON-BIS group. Total propofol consumption in BIS group was significantly less as compared to NON BIS group respectively 8.25±1.7 mg vs 11.15±2.5 mg (P value <0.0001).

Conclusion:

BIS serves as an excellent tool for awareness monitoring and titration of anaesthetic drugs perioperatively

AWARENESS IN BOTH GROUPS.

Depth of Anesthesia Monitoring

The electroencephalogram (EEG) can be analyzed in its raw form for characteristic drug-induced patterns of change or summarized using mathematical parameters as a processed electroencephalogram (pEEG). In this article we aim to summarize the contemporary literature pertaining to the commonly available pEEG monitors including the effects of commonly used anesthetic drugs on the EEG and pEEG parameters, pEEG monitor pitfalls, and the clinical implications of pEEG monitoring for anesthesia, pediatrics, and intensive care.

Comparison of End-Tidal Anesthetic Gas Concentration versus Bispectral Index-Guided Protocol as Directing Tool on Time to Tracheal Extubation for Sevoflurane-Based General Anesthesia

Background:

Modalities for titrating anesthetic drug-like bispectral index (BIS) and end-tidal anesthetic gas (ETAG) concentration in predicting early extubation had been studied with old anesthetic agents such as isoflurane.

Aim:

The aim of this study is to compare the effect of ETAG concentration versus BIS-guided protocol as directing tool on time to tracheal extubation for sevoflurane-based general anesthesia.

Materials and Methods:

This prospective, randomized, double-blind trial studied sixty patients with American Society of Anesthesiologists physical status classes I and II who received sevoflurane-based general anesthesia and were allocated to either BIS–guided anesthesia group (n = 30) or ETAG–guided anesthesia group (n = 30). Time to tracheal extubation was measured. BIS value was kept between 40 and 60 in BIS group, whereas minimum alveolar concentration value was kept between 0.7 and 1.3 in ETAG group. The two groups were compared using Student's t-test, and P < 0.05 was considered statistically significant. The statistical analysis was performed using the open source “R” programming language.

Results:

Mean time to tracheal extubation was significantly shorter in BIS group (308.77 ± 20.48 s) as compared to ETAG group (377.90 ± 25.06 s) (P < 0.001). The sevoflurane concentration used was also significantly less in group BIS than group ETAG at multiple time intervals (P = 0.001).

Conclusion:

Prediction of extubation was significantly early with BIS monitoring as compared to ETAG monitoring in sevoflurane-based general anesthesia.

Bispectral index monitoring of the clinical effects of propofol closed-loop target-controlled infusion: Systematic review and meta-analysis of randomized controlled trials

BACKGROUND

To investigate whether closed-loop systems under bispectral index anesthesia depth monitoring can reduce the intraoperative propofol dosage.

METHODS

All randomized controlled trials (RCTs) on reducing propofol dosage under closed-loop systems were collected, and the literature was screened out, the abstracts and full texts were carefully read, and the references were tracked, data extraction and quality evaluation were conducted on the included research, and the RevMan5.3 software was used for meta-analysis. The main results were propofol and the incidence of adverse reactions such as hypertensive hypotension and postoperative cognitive dysfunction. A total of 879 cases were included in 8 articles, including 450 occurrences in the closed-loop system group and 429 cases in the open-loop system group.

RESULTS

Compared with manual control, closed-loop systems under bispectral index anesthesia depth monitoring reduced the dose of propofol (MD: -0.62, 95% CI: -1.08--0.16, P = .008), with heterogeneity (I2 = 80%). Closed-loop systems significantly reduced the incidence of abnormal blood pressure (MD: -0.02, 95%CI: -0.05-0.01, P = .15, I2 = 74%) and postoperative cognitive dysfunction (MD: -0.08, 95% CI: -0.14 -0.01, P = .02, I2 = 94%).

CONCLUSION

Bispectral index monitoring of propofol closed-loop target-controlled infusion system can reduce the amount of propofol, reduce the incidence of adverse reactions such as hypertensive or hypotension and postoperative cognitive dysfunction.

Desflurane anesthesia compared with total intravenous anesthesia on anesthesia-controlled operating room time in ambulatory surgery following strabotomy: a randomized controlled study

BACKGROUND

Ophthalmic ambulatory surgery is preferred to be performed under general anesthesia either by total intravenous anesthesia (TIVA) or by inhalational anesthesia to increase the patient comfort. However, anesthesia-controlled time (ACT) can cause increased non-operative operating room (OR) time which may adversely affect the ORs efficiency. This study was aimed to compare the ACT of desflurane with that of propofol-remifentanil in strabismus ambulatory surgery.

METHODS

From November 2016 to December 2017, a total of 200 strabismus patients (aged 18-60 years old, and scheduled for elective ambulatory surgery at Zhongshan Ophthalmic Center) were randomly assigned to receive either propofol-based TIVA (group TIVA) or desflurane anesthesia (group DES) for maintenance of anesthesia. The primary outcome was the extubation time. Secondary outcomes included surgical time, anesthetic time, OR exit time, and Phase I and II recovery time. The intraoperative incidences of hypotension, bradycardia and oculocardiac reflex (OCR), and the incidences of any post-operative complications were recorded. Mann-Whitney U test and Chi-square or Fisher exact tests were used to compare the two groups.

RESULTS

We found that the extubation time (5.5 [3.9-7.0] vs. 9.7 [8.5-11.4] min, P < 0.001) and the incidence of prolonged time to extubation (0 vs. 6%, P = 0.029) in the DES group were significantly decreased compared with those in the TIVA group. The patients in the DES group displayed shorter OR exit time as compared with that in the TIVA group (7.3 [5.5-8.7] vs. 10.8 [9.3-12.3] min, P < 0.001). The patients using desflurane exhibited more stable hemodynamics during surgery than the patients using propofol-based TIVA, as demonstrated by lower incidences of hypotension (1% vs. 22%, P < 0.001), bradycardia (2% vs. 13%, P = 0.002), and OCR (17% vs. 44%, P < 0.001).

CONCLUSION

DES enhanced the ophthalmic OR efficiency by reducing the extubation time and OR exit time, and provided more stable hemodynamics intra-operatively than TIVA in patients undergoing strabismus ambulatory surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, No. NCT02922660; https://clinicaltrials.gov/ct2/show/NCT02922660?id=NCT02922660&draw=2&rank=1.

Substitution of propofol for dexmedetomidine in the anaesthetic regimen does not ameliorate the post-operative cognitive decline in elderly patients

Background and Aims:

Post-operative cognitive dysfunction (POCD) is a poorly understood complication particularly observed in elderly patients, with long-term poor outcome. The randomised study was to compare the incidence of POCD in elderly with bispectral index (BIS)-guided intra-operative use of either dexmedetomidine or propofol with sevoflurane.

Methods:

Eighty-seven patients, planned for non-cardiac surgery under general anaesthesia, were included between June 2017 and March 2018. After exclusion of 7 patients, remaining 80 patients were randomised into dexmedetomidine group and propofol group with 40 patients each. In both the groups, BIS-guided anaesthesia was provided. Cognitive function was assessed by an anaesthesiologist using a battery of neuropsychological tests at baseline pre-operatively, third and seventh day after surgery. The data were entered into a Microsoft Excel spreadsheet and analysis was performed using Statistical Package for Social Sciences (SPSS) version 21.

Results:

Propofol group had a non-significant lower incidence of POCD on third day and dexmedetomidine group showed decreased incidence of POCD on seventh day, accompanied by lower anaesthetic requirement (inhalational as well as intravenous) concomitant with delayed emergence with an acceptable BIS value.

Conclusion:

Dexmedetomidine appeared to be anaesthetic sparing as compared to propofol. BIS monitoring for titrating depth of anaesthesia and hence the anaesthetic exposure is an invaluable tool as compared to routine care anaesthesia for reducing POCD. The patients in both groups did not develop significant POCD until the seventh post-operative day.

Bispectral index for improving intraoperative awareness and early postoperative recovery in adults

BACKGROUND

The use of clinical signs, or end-tidal anaesthetic gas (ETAG), may not be reliable in measuring the hypnotic component of anaesthesia and may lead to either overdosage or underdosage resulting in adverse effects because of too deep or too light anaesthesia. Intraoperative awareness, whilst uncommon, may lead to serious psychological disturbance, and alternative methods to monitor the depth of anaesthesia may reduce the incidence of serious events. Bispectral index (BIS) is a numerical scale based on electrical activity in the brain. Using a BIS monitor to guide the dose of anaesthetic may have advantages over clinical signs or ETAG. This is an update of a review last published in 2014.

OBJECTIVES

To assess the effectiveness of BIS to reduce the risk of intraoperative awareness and early recovery times from general anaesthesia in adults undergoing surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and Web of Science on 26 March 2019. We searched clinical trial registers and grey literature, and handsearched reference lists of included studies and related reviews.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs in which BIS was used to guide anaesthesia compared with standard practice which was either clinical signs or end-tidal anaesthetic gas (ETAG) to guide the anaesthetic dose. We included adult participants undergoing any type of surgery under general anaesthesia regardless of whether included participants had a high risk of intraoperative awareness. We included only studies in which investigators aimed to evaluate the effectiveness of BIS for its role in monitoring intraoperative depth of anaesthesia or potential improvements in early recovery times from anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We assessed the certainty of evidence with GRADE.

MAIN RESULTS

We included 52 studies with 41,331 participants; two studies were quasi-randomized and the remaining studies were RCTs. All studies included participants undergoing surgery under general anaesthesia. Three studies recruited only participants who were at high risk of intraoperative awareness, whilst two studies specifically recruited an unselected participant group. We analysed the data according to two comparison groups: BIS versus clinical signs; and BIS versus ETAG. Forty-eight studies used clinical signs as a comparison method, which included titration of anaesthesia according to criteria such as blood pressure or heart rate and, six studies used ETAG to guide anaesthesia. Whilst BIS target values differed between studies, all were within a range of values between 40 to 60.BIS versus clinical signsWe found low-certainty evidence that BIS-guided anaesthesia may reduce the risk of intraoperative awareness in a surgical population that were unselected or at high risk of awareness (Peto odds ratio (OR) 0.36, 95% CI 0.21 to 0.60; I2 = 61%; 27 studies; 9765 participants). However, events were rare with only five of 27 studies with reported incidences; we found that incidences of intraoperative awareness when BIS was used were three per 1000 (95% CI 2 to 6 per 1000) compared to nine per 1000 when anaesthesia was guided by clinical signs. Of the five studies with event data, one included participants at high risk of awareness and one included unselected participants, four used a structured questionnaire for assessment, and two used an adjudication process to identify confirmed or definite awareness.Early recovery times were also improved when BIS was used. We found low-certainty evidence that BIS may reduce the time to eye opening by mean difference (MD) 1.78 minutes (95% CI -2.53 to -1.03 minutes; 22 studies; 1494 participants), the time to orientation by MD 3.18 minutes (95% CI -4.03 to -2.33 minutes; 6 studies; 273 participants), and the time to discharge from the postanaesthesia care unit (PACU) by MD 6.86 minutes (95% CI -11.72 to -2 minutes; 13 studies; 930 participants).BIS versus ETAGAgain, events of intraoperative awareness were extremely rare, and we found no evidence of a difference in incidences of intraoperative awareness according to whether anaesthesia was guided by BIS or by ETAG in a surgical population at unselected or at high risk of awareness (Peto OR 1.13, 95% CI 0.56 to 2.26; I2 = 37%; 5 studies; 26,572 participants; low-certainty evidence). Incidences of intraoperative awareness were one per 1000 in both groups. Only three of five studies reported events, two included participants at high risk of awareness and one included unselected participants, all used a structured questionnaire for assessment and an adjudication process to identify confirmed or definite awareness.One large study (9376 participants) reported a reduced time to discharge from the PACU by a median of three minutes less, and we judged the certainty of this evidence to be low. No studies measured or reported the time to eye opening and the time to orientation.Certainty of the evidenceWe used GRADE to downgrade the evidence for all outcomes to low certainty. The incidence of intraoperative awareness is so infrequent such that, despite the inclusion of some large multi-centre studies in analyses, we believed that the effect estimates were imprecise. In addition, analyses included studies that we judged to have limitations owing to some assessments of high or unclear bias and in all studies, it was not possible to blind anaesthetists to the different methods of monitoring depth of anaesthesia.Studies often did not report a clear definition of intraoperative awareness. Time points of measurement differed, and methods used to identify intraoperative awareness also differed and we expected that some assessment tools were more comprehensive than others.

AUTHORS' CONCLUSIONS

Intraoperative awareness is infrequent and, despite identifying a large number of eligible studies, evidence for the effectiveness of using BIS to guide anaesthetic depth is imprecise. We found that BIS-guided anaesthesia compared to clinical signs may reduce the risk of intraoperative awareness and improve early recovery times in people undergoing surgery under general anaesthesia but we found no evidence of a difference between BIS-guided anaesthesia and ETAG-guided anaesthesia. We found six studies awaiting classification and two ongoing studies; inclusion of these studies in future updates may increase the certainty of the evidence.