Recovery from bispectral index-guided anaesthesia in a large randomized controlled trial of patients at high risk of awareness. The effect of cerebral monitoring on recovery after general anesthesia: a comparison of the auditory evoked potential and bispectral index devices with standard clinical practice. Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial. Anesthesia awareness and the bispectral index. Bispectral index-guided general anesthesia in combination with thoracic epidural analgesia reduces recovery time in fast-track colon surgery. Bispectral index-guided anaesthesia for off-pump coronary artery bypass grafting. Does the use of electroencephalographic bispectral index or auditory evoked potential index monitoring facilitate recovery after desflurane anesthesia in the ambulatory setting? Bispectral index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. BIS Utility Study Group. [The utility of bispectral index monitoring in general anesthesia].
Electroencephalographic monitors of anaesthetic depth are reported to assist anaesthetists in reducing recovery times. We explored the effect of bispectral index (BIS) monitoring on recovery times in a double-blind, randomized controlled trial of 2,463 patients at high risk of awareness. Patients were randomized to BIS-guided anaesthesia or routine care. In the BIS group, anaesthesia was adjusted to maintain a BIS value of 40-60 from the commencement of laryngoscopy to the start of wound closure, and 55-70 during wound closure. In the routine care group, anaesthesia was adjusted according to traditional clinical signs. In multivariate models, BIS monitoring, female gender, lower American Society of Anesthesiologists' physical status and shorter duration of anaesthesia predicted faster time to eye-opening after anaesthesia, and faster time to post-anaesthesia care unit discharge. BIS monitoring did not affect times to tracheal extubation among patients admitted to the intensive care unit. We conclude that BIS monitoring has statistically significant, but clinically modest, effects on recovery times in high risk surgical patients. The use of cerebral monitoring may improve the ability of anesthesiologists to titrate anesthetic drugs. However, there is controversy regarding the impact of the alleged anesthetic-sparing effects of cerebral monitoring on the recovery process and patient outcome. We designed this prospective double-blinded, sham-controlled study to evaluate the impact of intraoperative monitoring with the electroencephalogram bispectral index (BIS) or auditory evoked potential (AEP) device on the usage of desflurane and the time to discharge from the recovery room, as well as on patient satisfaction with their anesthetic experience and recovery. Ninety healthy patients undergoing laparoscopic general surgery procedures using a standardized anesthetic technique were randomly assigned to one of three monitoring groups: standard clinical practice (control), BIS-guided, or AEP-guided. Both the BIS and AEP monitors were connected to all patients before induction of general anesthesia. In the control group, the anesthesiologists were not permitted to observe the BIS or AEP index values during the intraoperative period. In the BIS-guided group, the volatile anesthetic was titrated to maintain a BIS value in the range of 45-55. In the AEP-guided group, the targeted AEP index range was 15-20. The BIS and AEP indices, as well as end-tidal desflurane concentration, were recorded at 3-5 min intervals. Recovery times to awakening, tracheal extubation, fast-track score >or=12, and postanesthesia care unit (PACU) discharge criteria were recorded at 1-10 min intervals. In addition, patient satisfaction with anesthesia and quality of recovery were evaluated on 100- and 18-point scales, respectively, at 24 h after surgery. The AEP- and BIS-guided groups were administered significantly smaller average end-tidal desflurane concentrations than the control group (3.8 +/- 0.9 and 3.9 +/- 0.6 versus 4.7 +/- 1.7, respectively) (P < 0.01). Although the emergence times to eye opening, tracheal extubation, and obeying commands were consistently shorter in the AEP and BIS groups (6 +/- 4 and 6 +/- 5 versus 8 +/- 8 min; 6 +/- 5 and 6 +/- 4 versus 11 +/- 10 min; and 8 +/- 4 and 7 +/- 4 versus 12 +/- 9 min, respectively), only the extubation times were significantly different from the control group (P < 0.05). More importantly, the length of the PACU stay was significantly shorter in both the AEP- and BIS-guided groups (79 +/- 43 and 80 +/- 47 versus 108 +/- 58 min, respectively) (P < 0.05). The patients' quality of recovery was also significantly higher in the two monitored groups (15 +/- 2 versus 13 +/- 3 in the control group, P < 0.05). We concluded that cerebral monitoring with either the BIS or AEP devices reduced the maintenance anesthetic (desflurane) requirement, resulting in a shorter length of stay in the PACU and improved quality of recovery after laparoscopic surgery. However, there were no significant outcome differences between the two cerebral monitored groups.
                Compared with standard monitoring practices, use of an auditory evoked potential or bispectral index monitor to titrate the volatile anesthetic led to a significant reduction in the anesthetic requirement. The anesthetic-sparing effect of cerebral monitoring resulted in a shorter postanesthesia care unit stay and improved quality of recovery from the patient's perspective. Awareness is an uncommon complication of anaesthesia, affecting 0.1-0.2% of all surgical patients. Bispectral index (BIS) monitoring measures the depth of anaesthesia and facilitates anaesthetic titration. In this trial we determined whether BIS-guided anaesthesia reduced the incidence of awareness during surgery in adults.
                We did a prospective, randomised, double-blind, multicentre trial. Adult patients at high risk of awareness were randomly allocated to BIS-guided anaesthesia or routine care. Patients were assessed by a blinded observer for awareness at 2-6 h, 24-36 h, and 30 days after surgery. An independent committee, blinded to group identity, assessed every report of awareness. The primary outcome measure was confirmed awareness under anaesthesia at any time.
                Of 2463 eligible and consenting patients, 1225 were assigned to the BIS group and 1238 to the routine care group. There were two reports of awareness in the BIS-guided group and 11 reports in the routine care group (p=0.022). BIS-guided anaesthesia reduced the risk of awareness by 82% (95% CI 17-98%).
                BIS-guided anaesthesia reduces the risk of awareness in at-risk adult surgical patients undergoing relaxant general anaesthesia. With a cost of routine BIS monitoring at US16 dollars per use in Australia and a number needed to treat of 138, the cost of preventing one case of awareness in high-risk patients is about 2200 dollars. Awareness during anesthesia is a serious complication with potential long-term psychological consequences. Use of the bispectral index (BIS), developed from a processed electroencephalogram, has been reported to decrease the incidence of anesthesia awareness when the BIS value is maintained below 60. In this trial, we sought to determine whether a BIS-based protocol is better than a protocol based on a measurement of end-tidal anesthetic gas (ETAG) for decreasing anesthesia awareness in patients at high risk for this complication.
                We randomly assigned 2000 patients to BIS-guided anesthesia (target BIS range, 40 to 60) or ETAG-guided anesthesia (target ETAG range, 0.7 to 1.3 minimum alveolar concentration [MAC]). Postoperatively, patients were assessed for anesthesia awareness at three intervals (0 to 24 hours, 24 to 72 hours, and 30 days after extubation).
                We assessed 967 and 974 patients from the BIS and ETAG groups, respectively. Two cases of definite anesthesia awareness occurred in each group (absolute difference, 0%; 95% confidence interval [CI], -0.56 to 0.57%). The BIS value was greater than 60 in one case of definite anesthesia awareness, and the ETAG concentrations were less than 0.7 MAC in three cases. For all patients, the mean (+/-SD) time-averaged ETAG concentration was 0.81+/-0.25 MAC in the BIS group and 0.82+/-0.23 MAC in the ETAG group (P=0.10; 95% CI for the difference between the BIS and ETAG groups, -0.04 to 0.01 MAC).
                We did not reproduce the results of previous studies that reported a lower incidence of anesthesia awareness with BIS monitoring, and the use of the BIS protocol was not associated with reduced administration of volatile anesthetic gases. Anesthesia awareness occurred even when BIS values and ETAG concentrations were within the target ranges. Our findings do not support routine BIS monitoring as part of standard practice. (ClinicalTrials.gov number, NCT00281489 [ClinicalTrials.gov].).
                Copyright 2008 Massachusetts Medical Society. The impact of bispectral index (BIS)-guided general anesthesia on recovery from general anesthesia has been evaluated in different patient populations. The benefit of using BIS has been inconsistent. We designed this study to examine the value of BIS-guided anesthesia in a fast-track setting where the goal is rapid recovery.
                Forty-four patients undergoing open colon resection were randomly assigned to receive either BIS-guided (BIS group, n = 22) or clinically guided (standard care group, n = 22) total IV anesthesia with propofol after placing a thoracic epidural catheter. Duration of postanesthesia care unit stay, time to tracheal extubation, direct drug cost, the incidence of hemodynamic abnormalities, ability of ambulation on the day of surgery, and patient satisfaction with anesthetic management were assessed.
                In the BIS-guided group, tracheal extubation was achieved significantly earlier (7.6 vs. 15.4 min, P < 0.01) and the postanesthesia care unit stay was significantly shorter (51 vs. 85 min, P < 0.01). Total anesthetic drug cost was reduced by 23% and the incidence of hypotension requiring treatment was significantly lower in the BIS group. Early ambulation, patient satisfaction, and incidence of adverse events were not significantly different between the groups.
                BIS-guided IV anesthesia in combination with thoracic epidural analgesia facilitates rapid recovery and reduces the overall cost of care in patients undergoing fast-track colon surgery. Bispectral index (BIS) monitoring may assist reduction in utilisation of anaesthetic agents during general surgical procedures. This study was designed to test whether the use of BIS monitoring reduces the anaesthetic requirements during off-pump coronary artery bypass grafting (CABG). This prospective - clinical trial was conducted on 40 adult patients undergoing elective off-pump CABG. Patients received either isoflurane or propofol anaesthesia. BIS monitoring, which guided the dose of anaesthetic, was carried out in 50 percent of the patients. The amount of anaesthetic agent (isoflurane or propofol) administered from the start of anaesthesia to the end of surgical procedure was calculated and were compared in four groups of patients - namely Group A (I-no BIS) received isoflurane; end tidal concentration was maintained at 1-1.2% in a low flow technique throughout the procedure, Group B (I-BIS) received isoflurane in a low flow technique; inspired concentration was dictated by BIS value maintained at 50; Group C (P-no BIS) received propofol at a dose range of 4-8 mg/kg/hr and in Group D(P-BIS) the propofol infusion rate was dictated by BIS value maintained at 50. The quantity of isoflurane was significantly less for Group B (I-BIS) as compared with Group A (I-no BIS) (37 +/- 4 vs. 24 +/- 4 ml; p< 0.05) and similarly the amount of propofol infused was significantly less in Group D (P-BIS) as compared with Group C (P-no BIS) (176 +/- 9 vs. 120 +/- 6 ml; p< 0.05). BIS guided anaesthesia reduces the anaesthetic agent required for the performance of off-pump CABG. This can be extrapolated in terms of saving agent and reduced cardiac depression during off-pump CABG. Analogous to the Bispectral Index (BIS) monitor, the auditory evoked potential monitor provides an electroencephalographic-derived index (AAI), which is alleged to correlate with the central nervous system depressant effects of anesthetic drugs. This clinical study was designed to test the hypothesis that intraoperative cerebral monitoring guided by either the BIS or the AAI value would facilitate recovery from general anesthesia compared with standard clinical monitoring practices alone in the ambulatory setting.
                Sixty consenting outpatients undergoing gynecologic laparoscopic surgery were randomly assigned to one of three study groups: (1) control (standard practice), (2) BIS guided, or (3) AAI guided. Anesthesia was induced with 1.5-2.5 mg/kg propofol and 1-1.5 microg/kg fentanyl given intravenously. Desflurane, 3%, in combination with 60% nitrous oxide in oxygen was administered for maintenance of general anesthesia. In the control group, the inspired desflurane concentration was varied based on standard clinical signs. In the BIS- and AAI-guided groups, the inspired desflurane concentrations were titrated to maintain BIS and AAI values in targeted ranges of 50-60 and 15-25, respectively. BIS and AAI values, hemodynamic variables, and the end-tidal desflurane concentration were recorded at 5-min intervals during the maintenance period. The emergence times and recovery times to achieve specific clinical endpoints were recorded at 1- to 10-min intervals. The White fast-track and modified Aldrete recovery scores were assessed on arrival in the PACU, and the quality of recovery score was evaluated at the time of discharge home.
                A positive correlation was found between the AAI and BIS values during the maintenance period. The average BIS and AAI values (mean +/- SD) during the maintenance period were significantly lower in the control group (BIS, 41 +/- 10; AAI, 11 +/- 6) compared with the BIS-guided (BIS, 57 +/- 14; AAI, +/- 11) and AAI-guided (BIS, 55 +/- 12; AAI, 20 +/- 10) groups. The end-tidal desflurane concentration was significantly reduced in the BIS-guided (2.7 +/- 0.9%) and AAI-guided (2.6 +/- 0.9%) groups compared with the control group (3.6 +/- 1.5%). The awakening (eye-opening) and discharge times were significantly shorter in the BIS-guided (7 +/- 3 and 132 +/- 39 min, respectively) and AAI-guided (6 +/- 2 and 128 +/- 39 min, respectively) groups compared with the control group (9 +/- 4 and 195 +/- 57 min, respectively). More importantly, the median [range] quality of recovery scores was significantly higher in the BIS-guided (18 [17-18]) and AAI-guided (18 [17-18]) groups when compared with the control group (16 [10-18]).
                Compared with standard anesthesia monitoring practice, adjunctive use of auditory evoked potential and BIS monitoring can improve titration of desflurane during general anesthesia, leading to an improved recovery profile after ambulatory surgery. The bispectral index (BIS), a parameter derived from the electroencephalograph (EEG), has been shown to correlate with increasing sedation and loss of consciousness. This study determined whether addition of BIS monitoring to standard anesthetic practice results in improvements in the conduct of anesthesia or in patient outcomes.
                Three hundred two patients receiving a propofol-alfentanil-nitrous oxide anesthetic were studied at four institutions. Thirty-four patients were initially enrolled to determine preexisting anesthetic practice and patient outcomes at each institution. Subsequent patients were randomized to either standard clinical practice (SP group), or standard practice plus BIS monitoring (BIS group). In all patients, the anesthesiologist attempted to provide a stable anesthetic with the fastest possible recovery. BIS was recorded for all patients, but viewed only in the BIS group. In the BIS group, propofol infusions were adjusted to achieve a target BIS between 45-60, increasing to 60-75 during the final 15 min of the case. In the SP group, propofol dose adjustments were made based only on standard clinical signs. Drug use, intraoperative responses, and patient recovery parameters were recorded.
                Demographics were similar between groups. Compared with the SP group, patients in the BIS group required lower normalized propofol infusion rates (134 vs. 116 microg x kg[-1] x min[-1]; P < 0.001), were extubated sooner (11.22 vs. 7.25 min; P < 0.003), had a higher percentage of patients oriented on arrival to PACU (43% vs. 23%; P < 0.02), had better postanesthesia care unit (PACU) nursing assessments (P < 0.001), and became eligible for discharge sooner (37.77 vs. 31.70 min; P <0.04). There was no significant difference in the incidence of intraoperative responses between the groups.
                Titrating propofol with BIS monitoring during balanced anesthesia decreased propofol use and significantly improved recovery. Intraoperative course was not changed. These findings indicate that the use of BIS may be valuable in guiding the administration of propofol intraoperatively. The Bispectral Index (BIS), a parameter derived from the electroencephalograph, has been shown to correlate with increasing sedation and loss of consciousness. This study was designed to investigate whether using BIS would improve anaesthetic drug management and immediate recovery after anaesthesia.
                160 patients undergoing abdominal surgery were studied. The patients were randomised to receive either propofol or sevoflurane anaesthesia. In each group 40 patients were anaesthetised with BIS monitoring and 40 without BIS. In BIS groups, propofol and sevoflurane dose was adjusted to achieve a target BIS values between 40-60 during the whole procedure. Drug consumption, intraoperative responses, times of recovery after anaesthesia and a "Clinical Quality Scale of Recovery" score were recorded from blinded observators.
                Demographic data were similar between groups. BIS monitoring improved the immediate recovery after propofol anaesthesia, while no significant differences were observed in patients receiving sevoflurane. The consumption of both propofol and sevoflurane significantly decreased (30 and 40%, respectively). There was no significant differences in the incidence of intraoperative responses between groups. The BIS groups had a higher percentage of patients with better ICU assessments.
                BIS monitoring decreased the consumption of both propofol and sevoflurane and facilitated the immediate recovery after propofol anaesthesia. Intraoperative course was not changed. These findings indicate that the use of BIS may be a valuable guide of the intraoperatively administration of propofol and sevoflurane.
BIS-guided anaesthesia could reduce the risk of intraoperative recall in surgical patients with high risk of awareness in studies using clinical signs as a guide to anaesthetic practice but not in studies using end tidal anaesthetic gases as a guide. In addition, anaesthesia guided by the BIS within the recommended range could improve anaesthetic delivery and postoperative recovery from relatively deep anaesthesia.