Postoperative Recovery with Bispectral Index versus Anesthetic Concentration–guided Protocols

Pharmacokinetics and pharmacodynamics of ciprofol after continuous infusion in elderly patients

BACKGROUND

Ciprofol, a novel intravenous anesthetic, which has primarily been used for the induction and maintenance of general anesthesia in adults, is characterized by rapid onset, short duration of action, and quick and smooth recovery. However, the pharmacokinetic characteristics of continuous infusions and the correlation between the plasma concentration and the bispectral index (BIS) in elderly patients are still unknown.

METHOD

In this randomized, controlled study, thirty elderly patients (62-78 years old) undergoing elective gastrointestinal tumor resection were treated with propofol (N = 15) or ciprofol (N = 15) as sedatives during anesthesia. After induction, ciprofol/propofol was continuously infused intravenously until the end of the operation. Perioperative vital signs, injection pain, adverse events (AEs), BIS values, eyelid reflex disappearance times, and recovery times were recorded. The plasma concentrations of ciprofol and propofol were measured by liquid chromatography tandem mass spectrometry (LC‒MS/MS) and the pharmacokinetics were determined by noncompartmental analysis.

RESULTS

Both drugs caused a decrease in blood pressure and heart rate after induction. Eight cases (53. 3%) of hypotension and 3 cases (20%) of bradycardia occurred in the propofol group, while 8 cases (53. 3%) of hypotension and 5 cases (33. 3%) of bradycardia occurred in the ciprofol group. At intubation, the ciprofol group experienced fewer fluctuations in blood pressure than the propofol group. Ciprofol resulted in only one case (6.7%) of mild injection pain, less than that produced by propofol (10/15, 66.7%) (P < 0.05). Anesthesia induction was successfully completed with both drugs, and there were no significant differences in eyelash reflex disappearance or recovery time between the two groups. The plasma concentrations during maintenance were relatively stable in both groups (propofol 1.78 ± 0.67 μg/mL, ciprofol 0.71 ± 0.23 μg/mL), and a suitable depth of sedation was achieved with a BIS of 40-60. The pharmacokinetic (PK) parameters for ciprofol are listed as follows: Maximum Plasma Concentration (Cmax) 6.02 ± 2.13 μg/ml; Time to Maximum Concentration (Tmax) 0.18 ± 0.62 min; Apparent Volume of Distribution (Vz) 3.96 ± 0.84 L/kg; Total Clearance (CL) 0.83 ± 0.14 L/h/kg; Half-life (t½) 3.47 ± 1.85 h; Area Under the Curve (AUC) 5000 ± 900 L/h/kg; Terminal Elimination Rate Constant (λz) 0.23 ± 0.07 1/h. Similar to propofol, the plasma concentration of ciprofol was linearly correlated with the BIS.

CONCLUSION

Ciprofol, a novel intravenous anesthetic, can be safely and effectively used in elderly patient continuous infusion with minimal injection pain. Plasma concentrations of ciprofol correlate well with BIS values, helping control sedation depth. For elderly patients undergoing gastrointestinal tumor surgery, an optimal maintenance dose of 0.8 mg/kg/h is recommended.

TRIAL REGISTRATION

This clinical trial (registration No: ChiCTR2100047580, https://www.chictr.org.cn . The pre-registration date was June 20, 2021, and the review approval and official case solicitation began in December 2021; Retrospectively registered) was conducted in accordance with the World Medical Congress Declaration of Helsinki and Good Clinical Practice guidelines. All study subjects provided written informed consent.

A study of the relationship between Bispectral index and age-adjusted minimum alveolar concentration during the maintenance phase of general anesthesia in elective surgery

Background and Aims

Bispectral index (BIS) and minimum alveolar concentration (MAC) are commonly used to monitor the depth of anesthesia. The objective was to study the correlation between BIS and age-adjusted minimum alveolar concentration (aaMAC) during the maintenance phase of anesthesia. The influence of variables affecting BIS and or aaMAC was studied to determine an equation between BIS and aaMAC.

Material and Methods

This prospective observational study was carried out after institutional ethical approval in adult patients 18-60 years of either sex, ASA I and II posted for elective surgery under general anesthesia. Five minutes after airway management, BIS values and aaMAC equivalents were noted during the maintenance phase of anesthesia. aaMAC and corresponding BIS values were recorded every minute for periods, where the anesthetic agent concentration had remained the same during preceding 5 minutes till the switching off of the anesthetic agent. Age, sex, ASA status, use of nitrous oxide, inhalational agent, dose of midazolam, and opioid used were also recorded.

Results

BIS/aaMAC showed an inverse correlation. Increasing age, ASA II status, morphine equivalent >5, and use of nitrous oxide, sevoflurane, or isoflurane were associated with a higher BIS at equivalent aaMAC. Using the exchangeable correlation structure, a generalized estimation equation was obtained as the best predictor.

Conclusion

Factors affecting both aaMAC and BIS affect the relationship between the two, and although there are wide variations, BIS and aaMAC can be equated and values of either can be calculated if one is known using a generalized estimates equation.

Effects of different anesthetic depth during propofol anesthesia on postoperative recovery 24 h after arthroscopic day surgery: A randomized clinical trial

Background: This study aimed to compare the effects of different depths of sedation during propofol anesthesia on postoperative recovery 24 h after knee arthroscopy day surgery in adult patients.

Methods: This prospective randomized controlled trial involved 126 patients (ASA physical status 1–2) who were scheduled to undergo arthroscopic day surgery. Patients were randomly divided into two groups: the light-sedation (L-Group) or deep-sedation (D-Group). In the L-group, the bispectral index values were kept in the range of 50–59; in the D-group, the bispectral index values were maintained in the range of 40–49. The Quality of Recovery-15 (QoR-15) score assessed 24 h postoperatively using a 15-item questionnaire was the primary outcome. Secondary outcomes included Athens Insomnia Scale scores, postoperative pain scores, nausea or vomiting.

Results: The total QoR-15 score 24 h postoperatively was similar in the two groups (L-group median:130, IQR [127–132] vs. D-group median:131, IQR [126–135], p = 0.089). But among the five dimensions of the QoR-15, physiological comfort was significantly better in the D-group than L-group (p < 0.001). The time to open eyes (p < 0.001), follow the command (p < 0.001) and to extubation (p < 0.001) after surgery in the L-group were shorter than the D-group. The Athens Insomnia Scale scores (p < 0.001) and incidence of dreaming (p = 0.041) at the first postoperative night in the L-group was significantly higher than those in the D-group. Propofol consumption in the L-group was less than D-group (p < 0.001).

Conclusion: For patients undergoing arthroscopic day surgery, general anesthesia with high-bispectral-index (50–59) cannot improve the total QoR-15 score 24 h postoperatively after surgery, but can lessen propofol consumption, reduce the time of extubation and anesthesia recovery period, compared with low-bispectral-index (40–49). Patients exposed to general anesthesia with low-bispectral-index values (40–49) may have better quality sleep and physical comfort than those with high-bispectral-index values (50–59).

Clinical Trial Registration:http://www.chictr.org.cn/showproj.aspx?proj=126526, identifier ChiCTR2100046340

A survey of current practices, attitudes and demands of anaesthesiologists regarding the depth of anaesthesia monitoring in China

Background

In this study, we aimed to analyse survey data to explore two different hypotheses; and for this purpose, we distributed an online survey to Chinese anaesthesiologists. The hypothetical questions in this survey include: (1) Chinese anaesthesiologists mainly use the depth of anaesthesia (DoA) monitors to prevent intraoperative awareness and (2) the accuracy of these monitors is the most crucial performance factor during the clinical daily practice of Chinese anaesthesiologists.

Methods

We collected and statistically analysed the response of a total of 12,750 anesthesiologists who were invited to participate in an anonymous online survey. The Chinese Society of Anaesthesiologists (CSA) trial group provided the email address of each anaesthesiologist, and the selection of respondents was random from the computerized system.

Results

The overall response rate was 32.0% (4037 respondents). Only 9.1% (95% confidence interval, 8.2-10.0%) of the respondents routinely used DoA monitors. Academic respondents (91.5, 90.3-92.7%) most frequently used DoA monitoring to prevent awareness, whereas nonacademic respondents (88.8, 87.4-90.2%) most frequently used DoA monitoring to guide the delivery of anaesthetic agents. In total, the number of respondents who did not use a DoA monitor and whose patients experienced awareness (61.7, 57.8-65.6%) was significantly greater than those who used one or several DoA monitors (51.5, 49.8-53.2%). Overall, the crucial performance factor during DoA monitoring was considered by 61.9% (60.4-63.4%) of the respondents to be accuracy. However, most respondents (95.7, 95.1-96.3%) demanded improvements in the accuracy of the monitors for DoA monitoring. In addition, broad application in patients of all ages (86.3, 85.2-87.4%), analgesia monitoring (80.4, 79.2-81.6%), and all types of anaesthetic agents (75.6, 74.3-76.9%) was reported. In total, 65.0% (63.6-66.5%) of the respondents believed that DoA monitors should be combined with EEG and vital sign monitoring, and 53.7% (52.1-55.2%) believed that advanced DoA monitors should include artificial intelligence.

Conclusions

Academic anaesthesiologists primarily use DoA monitoring to prevent awareness, whereas nonacademic anaesthesiologists use DoA monitoring to guide the delivery of anaesthetics. Anaesthesiologists demand high-accuracy DoA monitors incorporating EEG signals, multiple vital signs, and antinociceptive indicators. DoA monitors with artificial intelligence may represent a new direction for future research on DoA monitoring.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01510-7.

The Use of Bispectral Index Monitoring Does Not Change Intraoperative Exposure to Volatile Anesthetics in Children

The exposure of infants and children to volatile anesthetics, such as sevoflurane, has been a topic of concern with respect to the potential risk for long term neurocognitive effects. The primary objective of this study was to determine whether the perioperative utilization of Bispectral Index (BIS) monitoring alters the sevoflurane delivery and exposure to children. This is a prospective randomized trial of two groups of healthy ambulatory day surgery patients (2 to 12 years). The patients in both groups had the BIS applied soon after the induction of general anesthesia, but only the anesthesiologists in the group randomized to BIS visible were able to see the BIS values. All of the patients received general anesthesia with sevoflurane. This study found no difference in the overall exposure to sevoflurane between both groups (mean end-tidal sevoflurane level of 1.8 in both groups, P = 084). The duration of time in the recovery room, the time to meet discharge criteria, the Pediatric Agitation Emergence Delirium (PAED) scores and the Face, Legs, Activity, Cry, Consolability (FLACC) scores were not statistically different between the groups. The application and utilization of intraoperative BIS monitoring does not alter the sevoflurane administration nor the discharge readiness nor the recovery profile in healthy ambulatory children.

Variations in Values of State, Response Entropy and Haemodynamic Parameters Associated with Development of Different Epileptiform Patterns during Volatile Induction of General Anaesthesia with Two Different Anaesthetic Regimens Using Sevoflurane in Comparison with Intravenous Induct: A Comparative Study

BACKGROUND AND OBJECTIVES

Raw electroencephalographic (EEG) signals are rarely used to monitor the depth of volatile induction of general anaesthesia (VIGA) with sevoflurane, even though EEG-based indices may show aberrant values. We aimed to identify whether response (RE) and state entropy (SE) variations reliably reflect the actual depth of general anaesthesia in the presence of different types of epileptiform patterns (EPs) in EEGs during induction of general anaesthesia.

MATERIALS AND METHODS

A randomized, prospective clinical study was performed with 60 patients receiving VIGA using sevoflurane with the increasing concentrations (group VIMA) or the vital capacity (group VCRII) technique or an intravenous single dose of propofol (group PROP). Facial electromyography (fEMG), fraction of inspired sevoflurane (FiAA), fraction of expired sevoflurane (FeAA), minimal alveolar concentration (MAC) of sevoflurane, RE and SE, and standard electroencephalographic evaluations were performed in these patients.

RESULTS

In contrast to periodic epileptiform discharges, erroneous SE and RE values in the patients' EEGs were associated with the presence of polyspikes (PS) and rhythmic polyspikes (PSR), which were more likely to indicate toxic depth rather than false emergence from anaesthesia with no changes in the FiAA, FeAA, and MAC of sevoflurane.

CONCLUSION

Calculated RE and SE values may be misleading during VIGA when EPs are present in patients' EEGs. During VIGA with sevoflurane, we recommend monitoring raw EEG data in scientific studies to correlate it with potentially erroneous RE and SE values and the end-tidal concentration of sevoflurane in everyday clinical practice, when monitoring raw EEG is not available, because they can mislead anaesthesiologists to reduce sevoflurane levels in the ventilation gas and result in unintentional true emergence from anaesthesia. Further studies are required to investigate the behaviour of EEG-based indices during rapid changes in sevoflurane concentrations at different stages of VIGA and the influence of polyspikes and rhythmic polyspikes on the transformation of EEG signals into a digital form.

Clinical and pharmacogenetics associated with recovery time from general anesthesia

AIM

Delayed recovery from general anesthesia is a well-known complication that requires predictive tools and approaches. This study aimed to determine significant factors associated with postanesthesia recovery and to develop an algorithm for estimating recovery time from general anesthesia.

MATERIALS & METHODS

The genotypes of patients were determined by SNaPshot or ARMS-qPCR. The algorithm was developed via machine-learning and tested by the worm plot.

RESULTS

Results showed that OPRM1 rs1799971 (p = 0.006) and ABCG2 rs2231142 (p = 0.041) were significantly associated with recovery time. Ten factors after random forest and stepwise selection were associated with recovery time. Ten factors after random forest and stepwise selection were associated with recovery time. Meanwhile, seven factors were associated with delayed recovery.

CONCLUSION

This study demonstrated that both clinical and pharmacogenetic data are significantly associated with recovery from general anesthesia and provide the basis for pre-emptive prediction tools.

An investigation into the effect of depth of anesthesia on postoperative pain in laparoscopic cholecystectomy surgery: a double-blind clinical trial

Backgrounds and objective

Some studies have shown that deeper anesthesia is more effective on postoperative analgesia and reduces the need for sedative drugs. This study sought to investigate the effect of depth of anesthesia on postoperative pain in laparoscopic cholecystectomy.

Materials and methods

In this double-blind clinical trial, 60 patients undergoing laparoscopic cholecystectomy were randomly divided into two groups: low bispectral index (L-BIS=35–44) and high bispectral index (H-BIS=45–55). Anesthesia protocol was the same for both groups (propofol and remifentanil). The pain intensity (at rest and during cough) was evaluated based on the visual analog scale scores in recovery and at 8, 16 and 24 hours after surgery.

Results

The mean pain score was significantly lower in patients in the L-BIS group at all examined times at rest and during cough than that in the H-BIS group. The number of patients in need of additional sedative drug in the H-BIS group in recovery was significantly more than that in the L-BIS group (27 vs 18 patients, P=0.007). The incidence of nausea in the recovery room 8 hours after the surgery was significantly less in the L-BIS group than that in the H-BIS group, while at 16 and 24 hours, no case of nausea was reported in the two groups.

Conclusion

Given the results of this study, it seems that general anesthesia with propofol and remifentanil with L-BIS causes less need for additional analgesic drug and less nausea and vomiting compared to anesthesia with H-BIS.

Protocol for an observational study of delirium in the post-anaesthesia care unit (PACU) as a potential predictor of subsequent postoperative delirium

INTRODUCTION

Postoperative delirium can be a serious consequence of major surgery, associated with longer hospital stays, readmission, cognitive and functional deterioration and mortality. Delirium is an acute, reversible disorder characterised by fluctuating course, inattention, disorganised thinking and altered level of consciousness. Delirium occurring in the hours immediately following anaesthesia and delirium occurring in the postoperative period of 1-5 days have been described as distinct clinical entities. This protocol describes an observational study with the aim of determining if delirium in the first hour following tracheal tube removal is a predictor of delirium in the 5 subsequent postoperative days. Improved understanding regarding the development of postoperative delirium would improve patient care and allow more effective implementation of delirium prevention measures.

METHODS AND ANALYSIS

Patients enrolled to the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) randomised controlled trial will be eligible for this substudy. A validated delirium assessment method, the 3-min Diagnostic Confusion Assessment Method and the Richmond Agitation and Sedation Scale will be used to assess 100 patients for delirium at 30 min and 60 min following tracheal tube removal. Patients will also be assessed for delirium over postoperative days 1-5 using three validated methods, the Confusion Assessment Method (CAM), CAM for the Intensive Care Unit and structured chart review. Logistic regression analysis will then be performed to test whether immediately postoperative delirium independently predicts subsequent postoperative delirium.

ETHICS AND DISSEMINATION

This observational substudy of ENGAGES has been approved by the ethics board of Washington University School of Medicine. Enrolment began in June 2016 and will continue until June 2017. Dissemination plans include presentations at scientific conferences and scientific publications.

TRIAL REGISTRATION NUMBER

NCT02241655.

Protocol for the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) study: a pragmatic, randomised clinical trial

INTRODUCTION

Postoperative delirium, arbitrarily defined as occurring within 5 days of surgery, affects up to 50% of patients older than 60 after a major operation. This geriatric syndrome is associated with longer intensive care unit and hospital stay, readmission, persistent cognitive deterioration and mortality. No effective preventive methods have been identified, but preliminary evidence suggests that EEG monitoring during general anaesthesia, by facilitating reduced anaesthetic exposure and EEG suppression, might decrease incident postoperative delirium. This study hypothesises that EEG-guidance of anaesthetic administration prevents postoperative delirium and downstream sequelae, including falls and decreased quality of life.

METHODS AND ANALYSIS

This is a 1232 patient, block-randomised, double-blinded, comparative effectiveness trial. Patients older than 60, undergoing volatile agent-based general anaesthesia for major surgery, are eligible. Patients are randomised to 1 of 2 anaesthetic approaches. One group receives general anaesthesia with clinicians blinded to EEG monitoring. The other group receives EEG-guidance of anaesthetic agent administration. The outcomes of postoperative delirium (≤5 days), falls at 1 and 12 months and health-related quality of life at 1 and 12 months will be compared between groups. Postoperative delirium is assessed with the confusion assessment method, falls with ProFaNE consensus questions and quality of life with the Veteran's RAND 12-item Health Survey. The intention-to-treat principle will be followed for all analyses. Differences between groups will be presented with 95% CIs and will be considered statistically significant at a two-sided p<0.05.

ETHICS AND DISSEMINATION

Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) is approved by the ethics board at Washington University. Recruitment began in January 2015. Dissemination plans include presentations at scientific conferences, scientific publications, internet-based educational materials and mass media.

TRIAL REGISTRATION NUMBER

NCT02241655; Pre-results.

Benefit of general anesthesia monitored by bispectral index compared with monitoring guided only by clinical parameters. Systematic review and meta-analysis

BACKGROUND

The bispectral index parameter is used to guide the titration of general anesthesia; however, many studies have shown conflicting results regarding the benefits of bispectral index monitoring. The objective of this systematic review with meta-analysis is to evaluate the clinical impact of monitoring with the bispectral index parameter.

METHODS

The search for evidence in scientific information sources was conducted during December 2013 to January 2015, the following primary databases: Medline/PubMed, LILACS, Cochrane, CINAHL, Ovid, SCOPUS and TESES. The criteria for inclusion in the study were randomized controlled trials, comparing general anesthesia monitored, with bispectral index parameter with anesthesia guided solely by clinical parameters, and patients aged over 18 years. The criteria for exclusion were studies involving anesthesia or sedation for diagnostic procedures, and intraoperative wake-up test for surgery of the spine.

RESULTS

The use of monitoring with the bispectral index has shown benefits reducing time to extubation, orientation in time and place, and discharge from both the operating room and post anesthetic care unit. The risk of nausea and vomiting after surgery was reduced by 12% in patients monitored with bispectral index. Occurred a reduction of 3% in the risk of cognitive impairment postoperatively at 3 months postoperatively and 6% reduction in the risk of postoperative delirium in patients monitored with bispectral index. Furthermore, the risk of intraoperative memory has been reduced by 1%.

CONCLUSION

Clinically, anesthesia monitoring with the BIS can be justified because it allows advantages from reducing the recovery time after waking, mainly by reducing the administration of general anesthetics as well as the risk of adverse events.

Associations Between Age and Dosing of Volatile Anesthetics in 2 Academic Hospitals

BACKGROUND

The inverse relationship between age and dose requirement for potent volatile anesthetics is well established, but the question of whether anesthetic providers consider this relationship in practice remains unanswered. We sought to determine whether there is an association between patient age and the mean dose of volatile anesthetic delivered during maintenance of anesthesia.

METHODS

This was a retrospective cross-sectional study of patients receiving a single potent volatile anesthetic at 2 academic hospitals using data recorded in an anesthesia information management system. Multivariate linear models were constructed at each hospital to examine the relationship between age and mean minimum alveolar concentration (MAC) fraction delivered during the maintenance of anesthesia.

RESULTS

A total of 7878 cases at the 2 hospitals were included for analysis. For patients aged <65 years, we observed decreasing doses of volatile anesthetics as age increased. Per decade, mean delivered MAC fraction decreased by an estimated 1.8% (95% confidence interval, 1.5-2.2, P < 0.0001), smaller than the 6.7% decrease suggested by previous studies of human anesthetic requirements. At age >65 years, the magnitude of the inverse association between age and MAC fraction was higher (3.8% decrease per decade; 95% confidence interval, 2.9-4.7).

CONCLUSIONS

Increasing age is associated with decreased absolute doses of potent volatile anesthetics, an association that seems to strengthen as patients enter the geriatric age range. The observed decreases in absolute anesthetic dose were less than those predicted by previous research and therefore represent an overall increase in "age-adjusted dose" as patients grow older.

Intraoperative awareness risk, anesthetic sensitivity, and anesthetic management for patients with natural red hair: a matched cohort study

PURPOSE

The red-hair phenotype, which is often produced by mutations in the melanocortin-1 receptor gene, has been associated with an increase in sedative, anesthetic, and analgesic requirements in both animal and human studies. Nevertheless, the clinical implications of this phenomenon in red-haired patients undergoing surgery are currently unknown.

METHODS

In a secondary analysis of a prospective trial of intraoperative awareness, red-haired patients were identified and matched with five control patients, and the relative risk for intraoperative awareness was determined. Overall anesthetic management between groups was compared using Hotelling's T(2) statistic. Inhaled anesthetic requirements were compared between cohorts by evaluating the relationship between end-tidal anesthetic concentration and the bispectral index with a linear mixed-effects model. Time to recovery was compared using Kaplan-Meier analysis, and differences in postoperative pain and nausea/vomiting were evaluated with Chi square tests.

RESULTS

A cohort of 319 red-haired patients was matched with 1,595 control patients for a sample size of 1,914. There were no significant differences in the relative risk of intraoperative awareness (relative risk = 1.67; 95% confidence interval 0.34 to 8.22), anesthetic management, recovery times, or postoperative pain between red-haired patients and control patients. The relationship between pharmacokinetically stable volatile anesthetic concentrations and bispectral index values differed significantly between red-haired patients and controls (P < 0.001), but without clinical implications.

CONCLUSION

There were no demonstrable differences between red-haired patients and controls in response to anesthetic and analgesic agents or in recovery parameters. These findings suggest that perioperative anesthetic and analgesic management should not be altered based on self-reported red-hair phenotype.

Intraoperative bispectral index monitoring and time to extubation after cardiac surgery: secondary analysis of a randomized controlled trial

BACKGROUND

Fast track recovery is a care process goal after cardiac surgery. Intraoperative anesthetic depth may impact recovery, but the impact of brain monitoring on time to extubation and intensive care unit (ICU) length of stay after cardiac surgery has not been extensively studied. Our goal was to determine if BIS-guided anesthesia improves time to extubation compared to MAC-guided anesthesia in a cardiac surgery population.

METHODS

In this secondary outcome analysis of a randomized controlled study, we analyzed 294 patients undergoing elective coronary bypass grafting, valve replacements, and bypass plus valve replacements at a single tertiary referral center between February 1, 2009 and April 30, 2010. We analyzed cardiac surgery patients that had been randomized to BIS-guided anesthesia alerts (n = 131) or MAC-guided anesthesia alerts (n = 163). The primary outcome measure was time to extubation in the BIS-guided and anesthetic concentration-guided groups. Secondary outcomes were length of stay in the ICU and total postoperative hospital length of stay.

RESULTS

Valid extubation time data were available for 247 of 294 patients. The median [IQR] time to extubation was 307 [215 to 771] minutes in the BIS group and 323 [196 to 730] minutes in the anesthetic concentration group (p = 0.61). The median [IQR] ICU length of stay was 54 [29 to 97] hours versus 70 [44 to 99] hours (p = 0.11). In terms of postoperative hospital length of stay, there was no difference between the groups with median [IQR] times of 6 [5-8] days (p = 0.69) in each group.

CONCLUSIONS

The use of intraoperative BIS monitoring during cardiac surgery did not change time to extubation, ICU length of stay or hospital length of stay. Data regarding BIS monitoring and recovery in an exclusively cardiac surgery population are consistent with recent effectiveness studies in the general surgical population.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT00689091.

Bispectral index for improving anaesthetic delivery and postoperative recovery

BACKGROUND

The use of clinical signs may not be reliable in measuring the hypnotic component of anaesthesia. The use of bispectral index (BIS) to guide the dose of anaesthetic may have certain advantages over clinical signs. This is the second update of a review originally published in 2007.

OBJECTIVES

The primary objective of this review focused on whether the incorporation of BIS into the standard practice for management of anaesthesia can reduce the risk of intraoperative awareness, consumption of anaesthetic agents, recovery time and total cost of anaesthesia in surgical patients undergoing general anaesthesia.

SEARCH METHODS

In this updated version, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 1), MEDLINE (1990 to 31 January 2013), EMBASE (1990 to 31 January 2013) and reference lists of articles. Previously, we searched to May 2009.

SELECTION CRITERIA

We included randomized controlled trials comparing BIS with standard practice criteria for titration of anaesthetic agents.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality, extracted data and analysed the data. We contacted study authors for further details.

MAIN RESULTS

We included 36 trials. In studies using clinical signs as standard practice, the results demonstrated a significant effect of the BIS-guided anaesthesia in reducing the risk of intraoperative awareness among surgical patients at high risk for awareness (7761 participants; odds ratio (OR) 0.24, 95% confidence interval (CI) 0.12 to 0.48). This effect was not demonstrated in studies using end tidal anaesthetic gas (ETAG) monitoring as standard practice (26,530 participants; OR 1.13, 95% CI 0.56 to 2.26). BIS-guided anaesthesia reduced the requirement for propofol by 1.32 mg/kg/hr (672 participants; 95% CI -1.91 to -0.73) and for volatile anaesthetics (desflurane, sevoflurane, isoflurane) by 0.65 minimal alveolar concentration equivalents (MAC) (95% CI -1.01 to -0.28) in 985 participants. Irrespective of the anaesthetics used, BIS reduced the following recovery times: time for eye opening (2557 participants; by 1.93 min, 95% CI -2.70 to -1.16), response to verbal command (777 participants; by 2.73 min, 95% CI -3.92 to -1.54), time to extubation (1501 participants; by 2.62 min, 95% CI -3.46 to -1.78), and time to orientation (373 participants; by 3.06 min, 95% CI -3.63 to -2.50). BIS shortened the duration of postanaesthesia care unit stay by 6.75 min (1953 participants; 95% CI -11.20 to -2.31) but did not significantly reduce the time to home readiness (329 participants; -7.01 min, 95% CI -30.11 to 16.09).

AUTHORS' CONCLUSIONS

BIS-guided anaesthesia can reduce the risk of intraoperative awareness in surgical patients at high risk for awareness in comparison to using clinical signs as a guide for anaesthetic depth. BIS-guided anaesthesia and ETAG-guided anaesthesia may be equivalent in protection against intraoperative awareness but the evidence for this is inconclusive. In addition, anaesthesia guided by BIS kept within the recommended range improves anaesthetic delivery and postoperative recovery from relatively deep anaesthesia.

Monitoring of anesthetic depth during surgical correction of acquired valvular disorders: single center, randomized trial

OBJECTIVE

The authors' primary objective was to test the hypothesis that Cerebral State Index (CSI)-guided control of anesthetic depth might reduce the consumption of anesthetics and shorten the duration of ICU and hospital stays after surgical correction of combined valve disorders.

DESIGN

Single center, randomized trial.

SETTING

City Hospital Number 1 of Arkhangelsk, Russian Federation.

PARTICIPANTS

Fifty adult patients with combined valve disorders requiring surgical correction.

INTERVENTIONS

The patients were randomized into 2 groups. In the CSI group, anesthetic depth was monitored, and the rate of infusion of propofol was titrated to maintain the depth of anesthesia corresponding to a CSI of 40-60. In the control group, the depth of anesthesia was monitored clinically, and the dosage of propofol was administered according to the recommendations of the manufacturer.

MEASUREMENTS AND MAIN RESULTS

All patients received standard perioperative monitoring. Consumption of anesthetics and length of ICU and hospital stays were recorded. Preoperative patient characteristics did not differ significantly between the groups. In the CSI group, average intraoperative doses of midazolam and propofol were reduced by 41% and 19%, respectively (p<0.01). Maintenance of anesthesia guided by CSI shortened the time until fit for ICU discharge by 50% and reduced the lengths of ICU and postoperative hospital stays by 35% and 25%, respectively (p< 0.05).

CONCLUSIONS

Monitoring of anesthetic depth reduces the requirements for midazolam and propofol, resulting in a faster recovery and a shorter postoperative ICU and hospital stay after surgical correction of combined valve disorders.