Bispectral index-guided anesthesia in patients undergoing aortocoronary bypass grafting

Fast-track cardiac care for adult cardiac surgical patients

BACKGROUND

Fast-track cardiac care is a complex intervention involving several components of care during cardiac anaesthesia and in the postoperative period, with the ultimate aim of early extubation after surgery, to reduce length of stay in the intensive care unit and in the hospital. Safe and effective fast-track cardiac care may reduce hospital costs. This is an update of a Cochrane review first published in 2003, updated in 2012 and updated now in 2016.

OBJECTIVES

To determine the safety and effectiveness of fast-track cardiac care compared with conventional (not fast-track) care in adult patients undergoing cardiac surgery. Fast-track cardiac care intervention includes administration of low-dose opioid-based general anaesthesia or use of a time-directed extubation protocol, or both.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 5), MEDLINE (January 2012 to May 2015), Embase (January 2012 to May 2015), the Cumulative Index to Nursing and Allied Health Literature (CINAHL; January 2012 to May 2015) and the Institute for Scientific Information (ISI) Web of Science (January 2012 to May 2015), along with reference lists of articles, to identify additional trials. We applied no language restrictions.

SELECTION CRITERIA

We included all randomized controlled trials of adult cardiac surgical patients (coronary artery bypass grafts, aortic valve replacement, mitral valve replacement) that compared fast-track cardiac care and conventional (not fast-track) care groups. We focused on the following fast-track interventions, which were designed for early extubation after surgery: administration of low-dose opioid-based general anaesthesia during cardiac surgery and use of a time-directed extubation protocol after surgery. The primary outcome was risk of mortality. Secondary outcomes included postoperative complications, reintubation within 24 hours of surgery, time to extubation, length of stay in the intensive care unit and in the hospital, quality of life after surgery and hospital costs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted study data. We contacted study authors for additional information. We calculated a Peto odds ratio (OR) for risk of mortality and used a random-effects model to report risk ratio (RR), mean difference (MD) and 95% confidence intervals (95% CIs) for all secondary outcomes.

MAIN RESULTS

We included 28 trials (4438 participants) in the updated review. We considered most participants to be at low to moderate risk of death after surgery. We assessed two studies as having low risk of bias and 11 studies high risk of bias. Investigators reported no differences in risk of mortality within the first year after surgery between low-dose versus high-dose opioid-based general anaesthesia groups (OR 0.53, 95% CI 0.25 to 1.12; eight trials, 1994 participants, low level of evidence) and between a time-directed extubation protocol versus usual care (OR 0.80, 95% CI 0.45 to 1.45; 10 trials, 1802 participants, low level of evidence).Researchers noted no significant differences between low-dose and high-dose opioid-based anaesthesia groups in the following postoperative complications: myocardial infarction (RR 0.98, 95% CI 0.48 to 1.99; eight trials, 1683 participants, low level of evidence), stroke (RR 1.17, 95% CI 0.36 to 3.78; five trials, 562 participants, low level of evidence) and tracheal reintubation (RR 1.77, 95% CI 0.38 to 8.27; five trials, 594 participants, low level of evidence).Comparisons with usual care revealed no significant differences in the risk of postoperative complications associated with a time-directed extubation protocol: myocardial infarction (RR 0.59, 95% CI 0.27 to 1.31; eight trials, 1378 participants, low level of evidence), stroke (RR 0.85, 95% CI 0.33 to 2.16; 11 trials, 1646 participants, low level of evidence) and tracheal reintubation (RR 1.34, 95% CI 0.74 to 2.41; 12 trials, 1261 participants, low level of evidence).Although levels of heterogeneity were high, low-dose opioid anaesthesia was associated with reduced time to extubation (reduction of 4.3 to 10.5 hours, 14 trials, 2486 participants, low level of evidence) and length of stay in the intensive care unit (reduction of 0.4 to 7.0 hours, 12 trials, 1394 participants, low level of evidence). Use of a time-directed extubation protocol was associated with reduced time to extubation (reduction of 3.7 to 8.8 hours, 16 trials, 2024 participants, low level of evidence) and length of stay in the intensive care unit (reduction of 3.9 to 10.5 hours, 13 trials, 1888 participants, low level of evidence). However, these two fast-track care interventions were not associated with reduced total length of stay in the hospital (low level of evidence).

AUTHORS' CONCLUSIONS

Low-dose opioid-based general anaesthesia and time-directed extubation protocols for fast-track interventions have risks of mortality and major postoperative complications similar to those of conventional (not fast-track) care, and therefore appear to be safe for use in patients considered to be at low to moderate risk. These fast-track interventions reduced time to extubation and shortened length of stay in the intensive care unit but did not reduce length of stay in the hospital.

Bispectral index and lower margin amplitude of the amplitude-integrated electroencephalogram in neonates

BACKGROUND

The lower margin amplitude (LMA) of the amplitude-integrated electroencephalogram (aEEG) is suppressed in neonates during deep sedation, a feature that is attributed to the bispectral index (BIS) in adults.

OBJECTIVE

We compare the BIS and the LMA of the aEEG in neonates.

METHODS

Thirty neurologically healthy neonates between 37 and 44 weeks postmenstrual age were included in this study. Twenty patients received sedoanalgesic therapy for various reasons. BIS and aEEG recordings were performed simultaneously. The digital data were imported in the numerical software environment Matlab®. The LMA of the aEEG was computed on a 1-min time scale and synchronized with the BIS data. The correlation between the time-dependent variables BIS and LMA was estimated using the Spearman rank correlation index.

RESULTS

The median correlation between BIS and LMA was 0.3. Inclusion of recordings of high signal quality only into analysis improved the median correlation index to 0.6.

CONCLUSIONS

We found a light-to-moderate correlation between BIS and LMA in our study cohort and a good correlation in the subgroup with high signal quality.

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.

Prognostic evaluation of bispectral index in patients following cardiopulmonary resuscitation

The aim of this study was to evaluate the prognosis of patients following cardiopulmonary resuscitation in an intensive care unit (ICU) using bispectral index (BIS) monitoring. The study was a prospective comparative study performed at the academic department of an ICU. A total of 33 adults who received cardiopulmonary resuscitation were enrolled and divided into the surviving and non-surviving groups according to their 7-day survival status. During their stay in the ICU, the BIS and arterial oxygen saturation (SaO₂) levels of all the patients were continuously monitored. The neurological condition of the patients was measured according to the Glasgow coma scale (GCS). Acute physiological and chronic diseases were measured according to the acute physiology and chronic health evaluation II (APACHE II). SaO₂ was monitored in all patients. The jugular bulb venous oxygen saturation (SjO₂) levels were continuously monitored in 23 patients and the difference between the SaO₂ and SjO₂ values was used to indicate oxygen metabolism in the brain. The variables in the present study were compared between the 2 groups. The correlations between BIS values and GCS or APACHE II scores were analyzed. The BIS values were significantly higher in the surviving group than in the non-surviving group (P<0.01). The difference between the SaO₂ and SjO₂ was significant (P<0.01). There was a positive correlation between BIS values and GCS scores (r=0.821, P<0.01) and between BIS values and APACHE II scores (r=0.434, P<0.05). BIS values may be used to predict the post-resuscitative outcome of patients following cardiopulmonary resuscitation.

The effect of landiolol on cerebral blood flow in patients undergoing off-pump coronary artery bypass surgery

PURPOSE

To examine the effect of landiolol on cerebral blood flow in patients with normal or deteriorated cardiac function.

METHODS

Thirty adult patients who were diagnosed with angina pectoris and who underwent elective off-pump coronary artery bypass surgery were studied. Patients were divided into two groups, one with a preoperative left ventricular ejection fraction (EF) of 50% or higher (normal EF group; n = 15) and the other with an EF of less than 50% (low EF group; n = 15). The mean cerebral blood flow velocity (Vmca) and pulsatility index (PI) in the middle cerebral artery were recorded using transcranial Doppler ultrasonography (TCD). Individual hemodynamic data were obtained using a pulmonary arterial catheter.

RESULTS

In both groups, landiolol produced a significant decrease in heart rate (HR), which then returned to baseline 15 min after administration was completed. A significant decrease in mean arterial pressure occurred in the low EF group, but the decrease was within 30% of the baseline. In the normal EF group, there was no decrease in cardiac index (CI), whereas in the low EF group, CI significantly decreased along with the decrease in HR. There were no significant differences in Vmca and PI between the two groups.

CONCLUSION

Continuous administration of landiolol at a dose of 0.04 mg/kg/min after 1 min rapid i.v. administration at a dose of 0.125 mg/kg/min decreases HR without causing aggravation of CBF during treatment of intraoperative tachycardia in patients with normal and deteriorated cardiac function.

Comparison of the EEG-based SNAP index and the Bispectral (BIS) index during sevoflurane-nitrous oxide anaesthesia

The BIS monitor (Aspect Medical Inc, Newton, USA) was the first electroencephalogram (EEG)-based monitor of the hypnotic effect reflected by a dimensionless figure ranging from 100 (awake state) to 0 (flat line EEG). Its widespread use makes it the most-studied and the best-known among same intended devices. Its algorithm processes low-frequency EEG oscillations in order to provide the Bispectral index. A BIS index ranging from 40 to 60 has been established as the proper for surgical performance. The BIS monitor permits a closer approach to the hypnotic component of anaesthesia beyond clinical signs and may reduce the probability of intraoperative awareness; therefore, it has become a recommended monitoring tool in routine practice. The SNAP monitor (Nicolet Biomedical, Madison WI, USA) is also intended for monitoring the hypnotic effect of anaesthetics, which is in turn displayed as an index ranging from 100 to 0, with 100 meaning a fully awake state and 0 meaning no brain activity. The algorithm of the SNAP monitor is featured by its additional processing of ultra-high EEG frequencies, which seem to be involved in the formation of consciousness. The use of these frequencies would theoretically improve responsiveness during increased brain activity. We studied its behaviour patterns and capability to monitor the hypnotic effect induced by sevoflurane-nitrous oxide by comparison with the BIS index. Seventy patients ASA I-III were induced with propofol, fentanyl and rocuronium, and maintained with sevoflurane-N(2)O. BIS and SNAP indices were simultaneously recorded before induction, after intubation, after incision, at the following 10, 30 and 50 minutes, awakening and extubation time points, together with heart rate and blood pressure. The Pearson correlation was R(2) = 0.68 (p < .05). The Bland and Altman test showed a bias of 14.3 for SNAP index values with respect to BIS index values. We concluded that the SNAP index correlates with variations in the hypnotic effect induced by sevoflurane-nitrous oxide anaesthesia when compared with the BIS index. In this context, a SNAP index ranging from 58 to 70 would be equivalent to the BIS index range 40 to 60 and, therefore, the accurate for surgical performance.

Bispectral Index Monitoring in the Intensive Care Unit Provides More Signal Than Noise

The bispectral index (BIS) is processed electroencephalographic technology used in concert with clinical evaluations to objectively evaluate a patient's level of consciousness and probability of recall. Although the BIS has been extensively studied in the operating room setting, differences in patient populations, goals of treatment, and the environments themselves necessitate the development of BIS data specific to the intensive care unit. Data have evolved over the last several years, but for many reasons, the results and conclusions have varied. Yet within the data are important consistencies that help define the usefulness of BIS in patients who cannot be evaluated with subjective assessment tools such as the Sedation-Agitation Scale or the Richmond Agitation-Sedation Scale. Some of these patients cannot be evaluated with such tools because they lack motor responsiveness due to therapeutic paralysis or because they are receiving deep sedation. Bispectral index scores that are higher than expected in clinically sedated patients can often be traced to electromyographic activity or to the possibility of inadequate sedation and analgesia. The BIS must not be regarded as the sole indicator of level of consciousness, but should be used as part of an integrated approach to the evaluation of carefully selected patients with critical illness.