Processed electroencephalogram and evoked potential techniques for amelioration of postoperative delirium and cognitive dysfunction following non-cardiac and non-neurosurgical procedures in adults

Early processed electroencephalography for the monitoring of deeply sedated mechanically ventilated critically ill patients

BACKGROUND

Deep sedation may be indicated in the intensive care unit (ICU) for the management of acute organ failure, but leads to sedative-induced delirium. Whether processed electroencephalography (p-EEG) is useful in this setting is unclear.

AIM

To describe the PSI index in deeply sedated critically ill patients with acute organ failure, and to examine a potential association between low PSI values and ICU delirium. [Correction added on 16 October 2024, after first online publication: Aim subsection in Abstract has been added on this version.] METHODS: We conducted a single-centre observational study of non-neurological ICU patients sedated according to a standardized guideline of deep sedation (Richmond Agitation Sedation Scale [RASS] between -5 and -4) during the acute phase of respiratory and/or cardio-circulatory failure. The SedLine (Masimo Incorporated, Irvine, California) was used to monitor the Patient State Index (PSI) (ranging from 0 to 100, <25 = very deep sedation and >50 = light sedation to full awareness) during the first 72 h of care. Delirium was assessed with the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU).

RESULTS

The median duration of PSI monitoring was 43 h. Patients spent 49% in median of the total PSI monitoring duration with a PSI <25. Patients with delirium (n = 41/97, 42%) spent a higher percentage of total monitored time with PSI <25 (median 67% [19-91] vs. 47% [12.2-78.9]) in non-delirious patients (p .047). After adjusting for the cumulative dose of analgesia and sedation, increased time spent with PSI <25 was associated with higher delirium (odds ratio 1.014; 95% CI 1.001-1.027, p = .036).

CONCLUSIONS

A clinical protocol of deep sedation targeted to RASS at the acute ICU phase may be associated with prolonged EEG suppression and increased delirium. Whether PSI-targeted sedation may help reducing sedative dose and delirium deserves further clinical investigation.

RELEVANCE TO CLINICAL PRACTICE

Patients requiring deep sedation are at high risk of being over-sedated and developing delirium despite the application of an evidence-based sedation guideline. Development of early objective measures are essential to improve sedation management in these critically ill patients.

Bispectral Index Monitoring Effect on Delirium Occurrence and Nursing Quality Improvement in Post-anesthesia Care Unit Patients Recovering From General Anesthesia: A Randomized Controlled Trial

BACKGROUND

The effect of intraoperative anesthesia depth monitoring on delirium occurrence and improvement of nursing quality in the post-anesthesia care unit (PACU) remains unclear. We aimed to explore the effect of intraoperative anesthesia bispectral index (BIS) monitoring on delirium occurrence and improvement of nursing quality in the PACU for patients recovering from general anesthesia.

METHODS

 This randomized controlled trial included 120 patients, aged 20-80 years, classified as grades I-III according to the American Society of Anesthesiologists. The BIS-guided group (group B) underwent intraoperative monitoring of BIS anesthesia depth (maintained within the anesthetic range (40-60)). The depth of anesthesia was not monitored in the non-BIS-guided group (group C). The patient's vital signs were recorded at the beginning of the operation (T0), upon entering the PACU (T1), 15 min after extubation (T2), and after leaving the PACU (T3). Delirium score, emergence period (extubation and PACU observation times), and adverse events in the PACU were monitored. The nursing activity score (NAS) was used to evaluate the quality of care.

RESULTS

Group B exhibited significantly lower heart rate and mean arterial pressure at T1 and T2, shorter time to extubation and PACU observation time, and a significantly lower incidence of adverse events than group C. Group B had significantly lower Ricker sedation-agitation scores and a lower incidence of delirium than group C. The NAS was significantly lower for group B than for group C. Patients aged 60-80 years in group C experienced agitation, requiring 30% more frequent assistance from one or two nurses than those in group B.

CONCLUSION

Intraoperative BIS monitoring can reduce the incidence of adverse events in the PACU, diminish the incidence of delirium during the recovery period in elderly patients, lessen the nursing workload, improve nursing quality, and promote patient rehabilitation, thus meriting clinical application.

Electroencephalography-Guided Anesthesia and Delirium in Older Adults After Cardiac Surgery: The ENGAGES-Canada Randomized Clinical Trial

Importance

Intraoperative electroencephalogram (EEG) waveform suppression, suggesting excessive general anesthesia, has been associated with postoperative delirium.

Objective

To assess whether EEG-guided anesthesia decreases the incidence of delirium after cardiac surgery.

Design, Setting, and Participants

Randomized, parallel-group clinical trial of 1140 adults 60 years or older undergoing cardiac surgery at 4 Canadian hospitals. Recruitment was from December 2016 to February 2022, with follow-up until February 2023.

Interventions

Patients were randomized in a 1:1 ratio (stratified by hospital) to receive EEG-guided anesthesia (n = 567) or usual care (n = 573). Patients and those assessing outcomes were blinded to group assignment.

Main Outcomes and Measures

The primary outcome was delirium during postoperative days 1 through 5. Intraoperative measures included anesthetic concentration and EEG suppression time. Secondary outcomes included intensive care and hospital length of stay. Serious adverse events included intraoperative awareness, medical complications, and 30-day mortality.

Results

Of 1140 randomized patients (median [IQR] age, 70 [65-75] years; 282 [24.7%] women), 1131 (99.2%) were assessed for the primary outcome. Delirium during postoperative days 1 to 5 occurred in 102 of 562 patients (18.15%) in the EEG-guided group and 103 of 569 patients (18.10%) in the usual care group (difference, 0.05% [95% CI, -4.57% to 4.67%]). In the EEG-guided group compared with the usual care group, the median volatile anesthetic minimum alveolar concentration was 0.14 (95% CI, 0.15 to 0.13) lower (0.66 vs 0.80) and there was a 7.7-minute (95% CI, 10.6 to 4.7) decrease in the median total time spent with EEG suppression (4.0 vs 11.7 min). There were no significant differences between groups in median length of intensive care unit (difference, 0 days [95% CI, -0.31 to 0.31]) or hospital stay (difference, 0 days [95% CI, -0.94 to 0.94]). No patients reported intraoperative awareness. Medical complications occurred in 64 of 567 patients (11.3%) in the EEG-guided group and 73 of 573 (12.7%) in the usual care group. Thirty-day mortality occurred in 8 of 567 patients (1.4%) in the EEG-guided group and 13 of 573 (2.3%) in the usual care group.

Conclusions and Relevance

Among older adults undergoing cardiac surgery, EEG-guided anesthetic administration to minimize EEG suppression, compared with usual care, did not decrease the incidence of postoperative delirium. This finding does not support EEG-guided anesthesia for this indication.

Trial Registration

ClinicalTrials.gov Identifier: NCT02692300.

Potential increased propofol sensitivity in cognitively impaired elderly: a controlled, double-blind study

Background

Cognitive impairment in the elderly may lead to potential increased sensitivity to anesthetic agents targeting receptors associated with cognition. This study aimed to explore the effect of cognitive status on propofol consumption during surgery in elderly patients.

Methods

Sixty elderly patients scheduled for laparoscopic radical prostatectomy were allocated to either a cognitively normal [CogN, Montreal Cognitive Assessment (MoCA) score ≥26] or cognitively impaired (CogI, MoCA <26) group. Propofol was administered via target-controlled infusion to maintain a bispectral index (BIS) between 55-65 during surgery. Propofol consumption was recorded at three time points: T1 (abolished eyelash reflex), T2 (BIS = 50), T3 (extubation). BIS values at eyelash reflex abolition were also recorded. Postoperative MoCA, Visual Analogue Scale (VAS) scores, and remifentanil/sufentanil consumption were assessed.

Results

BIS values before induction were similar between CogN and CogI groups. However, at eyelash reflex abolition, BIS was significantly higher in CogI than CogN (mean ± SD: 65.3 ± 7.2 vs. 61.1 ± 6.8, p = 0.031). Propofol requirement to reach BIS 50 was lower in CogI vs. CogN (1.24 ± 0.19 mg/kg vs. 1.46 ± 0.12 mg/kg, p = 0.003). Postoperative MoCA, VAS scores, and remifentanil/sufentanil consumption did not differ significantly between groups.

Conclusion

Compared to cognitively intact elderly, those with cognitive impairment exhibited higher BIS at eyelash reflex abolition and required lower propofol doses to achieve the same BIS level, suggesting increased propofol sensitivity. Cognitive status may impact anesthetic medication requirements in the elderly.

Effect of bispectral index on intra-operative awareness: A meta-analysis of randomized controlled studies

Background

Randomized controlled trials (RCTs) investigating the efficacy of bispectral index (BIS) to reduce intra-operative awareness (IOA) have reported conflicting results. The purpose of this meta-analysis is to consolidate results from RCTs to assess the efficacy of BIS in reducing IOA when compared to controls. Secondary outcomes included time to extubation, time to spontaneous and/or verbal eye opening, PACU discharge time, and utilization of inhaled anesthetics.

Methods

RCTs which reported on one of the primary and/or secondary outcomes were included. Literature search utilized keywords "randomized control trial" and "intraoperative awareness." Meta-analysis was performed using RevMan 5.

Results

Twenty-seven RCTs were included in the study with a total of 35,585 patients, with 18,146 patients in the BIS and 17,439 in the control group. Eighteen of 14,062 patients (0.12%) and 42 of 16,765 (0.25%) reported definite IOA in the BIS and control group, respectively, with no statistically significant difference. BIS was effective in reducing the time to spontaneous eye opening by an average of 1.3 minutes and the time to extubation by an average of 1.97 minutes. There was no difference in PACU discharge times among the groups. There was a significant decrease in consumption of sevoflurane but no difference in desflurane and propofol compared to the control group.

Conclusion

While BIS monitoring results in decreased incidence of intra-operative awareness by half, it was not statistically significant. BIS provides modest benefits with regard to reducing the time to extubation, the time to spontaneous eye opening, and consumption of sevoflurane.Level of evidence: I.

Electroencephalography Monitoring for Preventing Postoperative Delirium and Postoperative Cognitive Decline in Patients Undergoing Cardiothoracic Surgery: A Meta-Analysis

Background

Patients undergoing cardiothoracic surgery frequently encounter perioperative neurocognitive disorders (PND), which can include postoperative delirium (POD) and postoperative cognitive decline (POCD). Currently, there is not enough evidence to support the use of electroencephalograms (EEGs) in preventing POD and POCD among cardiothoracic surgery patients. This meta-analysis examined the importance of EEG monitoring in POD and POCD.

Methods

Cochrane Library, PubMed, and EMBASE databases were searched to obtain the relevant literature. This analysis identified trials based on the inclusion and exclusion criteria. The Cochrane tool was used to evaluate the methodological quality of the included studies. Review Manager software (version 5.3) was applied to analyze the data.

Results

Four randomized controlled trials (RCTs) were included in this meta-analysis, with 1096 participants. Our results found no correlation between EEG monitoring and lower POD risk (relative risk (RR): 0.81; 95% CI: 0.55-1.18; p = 0.270). There was also no statistically significant difference between the EEG group and the control group in the red cell transfusions (RR: 0.86; 95% CI: 0.51-1.46; p = 0.590), intensive care unit (ICU) stay (mean deviation (MD): -0.46; 95% CI: -1.53-0.62; p = 0.410), hospital stay (MD: -0.27; 95% CI: -2.00-1.47; p = 0.760), and mortality (RR: 0.33; 95% CI: 0.03-3.59; p = 0.360). Only one trial reported an incidence of POCD, meaning we did not conduct data analysis on POCD risk.

Conclusions

This meta-analysis did not find evidence supporting EEG monitoring as a potential method to reduce POD incidence in cardiothoracic surgery patients. In the future, more high-quality RCTs with larger sample sizes are needed to validate the relationship between EEG monitoring and POD/POCD further.

Postoperative cognitive dysfunction after beach chair positioning compared to supine position in orthopaedic surgery in the elderly

INTRODUCTION

Postoperative cognitive dysfunction (POCD) occurs in up to 26% of patients older than 60 years 1 week after non-cardiac surgery. Intraoperative beach chair positioning (BCP) is advantageous for some types of shoulder surgery. However, this kind of positioning leads to a downward bound redistribution of blood volume, with possible hypoperfusion of the brain. We hypothesized that patients > 60 years undergoing orthopaedic shoulder surgery in a BCP might experience more POCD than patients operated in the supine position (SP).

MATERIAL AND METHODS

A single-centre, prospective observational trial of 114 orthopaedic patients was performed. Study groups were established according to the type of intraoperative positioning. Anaesthesiological management was carried out similarly in both groups, including types of anaesthetics and blood pressure levels. POCD was evaluated using the Trail Making Test, the Letter-Number Span and the Regensburger Word Fluency Test. The frequency of POCD 1 week after surgery was considered primary outcome.

RESULTS

Baseline characteristics, including duration of surgery, were comparable in both groups. POCD after 1 week occurred in 10.5% of SP patients and in 21.1% of BCP patients (p = 0.123; hazard ratio 2.0 (CI 95% 0.794-5.038)). After 4 weeks, the incidence of POCD decreased (SP: 8.8% vs. BCP: 5.3%; p = 0.463). 12/18 patients with POCD showed changes in their Word Fluency Tests. Near-infrared spectroscopy (NIRS) values were not lower in patients with POCD compared to those without POCD (54% (50/61) vs. 57% (51/61); p = 0.671).

CONCLUSION

POCD at 1 week after surgery tended to occur more often in patients operated in beach chair position compared to patients in supine position without being statistically significant.

Preoperative mild cognitive impairment as a risk factor of postoperative cognitive dysfunction in elderly patients undergoing spine surgery

Introduction

Any persistent degree of cognitive impairment in older adults is a concern as it can progress to dementia. This study aimed to determine the incidence and risk factors for early postoperative cognitive dysfunction (POCD) in elderly patients undergoing spine surgery.

Methods

Patients were enrolled from a previous prospective observational study after screening for normal cognitive function using the Mini Mental State Examination (MMSE). Cognitive function was evaluated before surgery and at 1 week, month, and year post-surgery using MMSE and Montreal Cognitive Assessment scores (MoCA). Mild cognitive impairment (MCI) was determined using the MoCA scores adjusted for age. POCD was defined as a drop of three or more points on the MMSE 1 week post-surgery. Multivariate logistic analysis was performed to identify POCD risk factors.

Results

A total of 427 patients were included. Eighty-five (20%) had pre-existing MCI. The MCI group showed lower MoCA scores at each time point (baseline, 1 week after surgery, 1 month after surgery, 1 year after surgery) compared to the non-MCI group. Those in the MCI group had a higher rate of admission to intensive care unit after surgery, postoperative delirium, and POCD 1 week post-surgery, than those in the non-MCI group (16.5% vs. 6.7%, p = 0.008; 27.1% vs. 15.8%, p = 0.024; and 18.8% vs. 8.2%, p < 0.001, respectively). Among them, 10.3% were assessed for POCD on postoperative day 7 and self-reported poor social roles and physical functioning 1 week postoperatively.

Conclusion

Preoperative MCI was seen in ~20% of surgical patients aged >70 years. POCD was seen in ~20% of patients with pre-existing MCI, and ~ 10% of those without. Benzodiazepine use, significant comorbidities, pre-existing MCI, and depressive tendencies were risk factors for POCD.

The effect of anesthetic depth on postoperative delirium in older adults: a systematic review and meta-analysis

BACKGROUND

Postoperative delirium (POD) is an important complication for older patients and recent randomised controlled trials have showed a conflicting result of the effect of deep and light anesthesia.

METHODS

We included randomised controlled trials including older adults that evaluated the effect of anesthetic depth on postoperative delirium from PubMed, Embase, Web of Science and Cochrane Library. We considered deep anesthesia as observer's assessment of the alertness/ sedation scale (OAA/S) of 0-2 or targeted bispectral (BIS) < 45 and the light anesthesia was considered OAA/S 3-5 or targeted BIS > 50. The primary outcome was incidence of POD within 7 days after surgery. And the secondary outcomes were mortality and cognitive function 3 months or more after surgery. The quality of evidence was assessed via the grading of recommendations assessment, development, and evaluation approach.

RESULTS

We included 6 studies represented 7736 patients aged 60 years and older. We observed that the deep anesthesia would not increase incidence of POD when compared with the light anesthesia when 4 related studies were pooled (OR, 1.40; 95% CI, 0.63-3.08, P = 0.41, I2 = 82%, low certainty). And no significant was found in mortality (OR, 1.12; 95% CI, 0.93-1.35, P = 0.23, I2 = 0%, high certainty) and cognitive function (OR, 1.13; 95% CI, 0.67-1.91, P = 0.64, I2 = 13%, high certainty) 3 months or more after surgery between deep anesthesia and light anesthesia.

CONCLUSIONS

Low-quality evidence suggests that light general anesthesia was not associated with lower POD incidence than deep general anesthesia. And High-quality evidence showed that anesthetic depth did not affect the long-term mortality and cognitive function.

SYSTEMATIC REVIEW REGISTRATION

CRD42022300829 (PROSPERO).

Incidence change of postoperative delirium after implementation of processed electroencephalography monitoring during surgery: a retrospective evaluation study

BACKGROUND

Postoperative delirium (POD) is a common complication in the elderly, which is associated with poor outcomes after surgery. Recognized as predisposing factors for POD, anesthetic exposure and burst suppression during general anesthesia can be minimized with intraoperative processed electroencephalography (pEEG) monitoring. In this study, we aimed to evaluate whether implementation of intraoperative pEEG-guided anesthesia is associated with incidence change of POD.

METHODS

In this retrospective evaluation study, we analyzed intravenous patient-controlled analgesia (IVPCA) dataset from 2013 to 2017. There were 7425 patients using IVPCA after a noncardiac procedure under general anesthesia. Patients incapable of operating the device independently, such as cognitive dysfunction or prolonged sedation, were declined and not involved in the dataset. After excluding patients who opted out within three days (N = 110) and those with missing data (N = 24), 7318 eligible participants were enrolled. Intraoperative pEEG has been implemented since July 2015. Participants having surgery after this time point had intraoperative pEEG applied before induction until full recovery. All related staff had been trained in the application of pEEG-guided anesthesia and the assessment of POD. Patients were screened twice daily for POD within 3 days after surgery by staff in the pain management team. In the first part of this study, we compared the incidence of POD and its trend from 2013 January-2015 July with 2015 July-2017 December. In the second part, we estimated odds ratios of risk factors for POD using multivariable logistic regression in case-control setting.

RESULTS

The incidence of POD decreased from 1.18 to 0.41% after the administration of intraoperative pEEG. For the age group ≧ 75 years, POD incidence decreased from 5.1 to 1.56%. Further analysis showed that patients with pEEG-guided anesthesia were associated with a lower odd of POD (aOR 0.33; 95% CI 0.18-0.60) than those without after adjusting for other covariates.

CONCLUSIONS

Implementation of intraoperative pEEG was associated with a lower incidence of POD within 3 days after surgery, particularly in the elderly. Intraoperative pEEG might be reasonably considered as part of the strategy to prevent POD in the elder population.

TRIAL REGISTRATION

Not applicable.

Post-Operative Cognitive Dysfunction in Elderly Patients Receiving Propofol Sedation for Gastrointestinal Endoscopies: An Observational Study Utilizing Processed Electroencephalography

BACKGROUND

Propofol sedation is commonly administered during gastrointestinal (GI) procedures. The Patient State Index (PSI) is a processed electroencephalography (EEG) parameter obtained with the SedLine® Sedation Monitoring system (Masimo Corporation, Irvine, CA). When used to objectively assess the patient's level of consciousness, PSI may provide a more effective, safer titration of sedation during GI procedures. We hypothesize that having more or longer episodes of deep sedation as assessed by PSI (i.e., PSI<26) would correlate with developing new-onset or worsening post-operative cognitive dysfunction (POCD).

METHODS

This was a pragmatic, double-blinded observational study of 400 patients aged ≥65 years undergoing upper GI endoscopy, lower GI endoscopy, or a combined procedure utilizing propofol sedation at a tertiary-care [A1] academic medical center. The patients were monitored with the SedLine® Brain Function Monitor, software version 2 (Masimo Corporation, Irvine, CA), throughout the case, starting at baseline (i.e., before administration of propofol) and stopping at case end. We assessed the subjects' cognitive function via an in-person interview at baseline (pre-procedure) and telephone interviews at 1, 7 (±1), and 90 days after study enrollment. Cognitive function was assessed by administering the short blessed test (SBT), which is a validated brief cognitive screening appropriate for in-person and telephone administration.

RESULTS

The correlations between the change in SBT score and the pre-defined parameters of PSI were not significant (all p-values >5%). There was a significant drop in SBT scores on day seven. Higher age was also significantly associated with a drop in SBT from baseline. Deep sedation, as evidenced by the number of times PSI was lower than 26, was not predictive of the change in SBT, nor was gender, total propofol dose, or vasoactive drug use during the procedure.

CONCLUSIONS

The observed incidence of POCD after GI procedures with propofol sedation was low (1.3% at seven days and 2.95% at 90 days) and lower than at the baseline. Age was associated with a greater average decline in SBT score, although the absolute change was small (-0.067 per year of age increase). Deeper sedation, as documented by the PSI score, was not associated with a change in POCD measured with the SBT.

[Processed EEG for personalized dosing of anesthetics during general anesthesia]

Electroencephalogram (EEG)-guided anesthesia is indispensable in modern operating rooms and has become established as the standard form of monitoring. Many anesthesiologists rely on processed EEG indices in the hope of averting anesthesia-related complications, such as intraoperative awareness, postoperative delirium and other cognitive complications in their patients. This educational review aims to provide information on the five most prevalent monitors used to guide depth of sedation during general anesthesia. This article elucidates the principles underpinning the application of these monitors where known, which are generally based on power in various EEG frequency bands and on the burst suppression pattern. Convinced that EEG-guided anesthesia has the potential of benefitting many surgical patients, it is felt that many basic principles and shortcomings of processed EEG indices need to be better understood in the clinical practice. After discussing the different monitors and clinically relevant data from the literature, the article gives a short practical guidance on how to critically interpret processed EEG information and troubleshooting of confounded indices in the context of clinical situations.

Sevoflurane and desflurane effects on early cognitive function after low-risk surgery: A randomized clinical trial

BACKGROUND AND OBJECTIVES

Deleterious effects on short-term and long-term quality of life have been associated with the development of postoperative cognitive dysfunction (POCD) after general anesthesia. Yet, the progress in the field is still required. Most of the studies investigate POCD after major surgery, so scarce evidence exists about the incidence and effect different anesthetics have on POCD development after minor procedures. In this study, we compared early postoperative cognitive function of the sevoflurane and desflurane patients who experienced a low-risk surgery of thyroid gland.

MATERIALS AND METHODS

Eighty-two patients, 40 years and over, with no previous severe cognitive, neurological, or psychiatric disorders, appointed for thyroid surgery under general anesthesia, were included in the study. In a random manner, the patients were allocated to either sevoflurane or desflurane study arms. Cognitive tests assessing memory, attention, and logical reasoning were performed twice: the day before the surgery and 24 h after the procedure. Primary outcome, magnitude of change in cognitive testing, results from baseline. POCD was diagnosed if postoperative score decreased by at least 20%.

RESULTS

Median change from baseline cognitive results did not differ between the sevoflurane and desflurane groups (-2.63%, IQR 19.3 vs. 1.13%, IQR 11.0; p = .222). POCD was detected in one patient (1.22%) of the sevoflurane group. Age, duration of anesthesia, postoperative pain, or patient satisfaction did not correlate with test scores. Intraoperative temperature negatively correlated with total postoperative score (r = -0.35, p = .007).

CONCLUSIONS

Both volatile agents proved to be equivalent in terms of the early cognitive functioning after low-risk thyroid surgery. Intraoperative body temperature may influence postoperative cognitive performance.

Depth of anesthesia, temperature, and postoperative delirium in children and adolescents undergoing cardiac surgery

BACKGROUND

After pediatric cardiosurgical interventions, postoperative delirium can occur, which can be associated with undesirable consequences during and after the hospital stay. It is therefore important to avoid any factors causing delirium as far as possible. Electroencephalogram (EEG) monitoring can be used during anesthesia to individually adjust dosages of hypnotically acting drugs. It is necessary to gain knowledge about the relationship between intraoperative EEG and postoperative delirium in children.

METHODS

In a dataset comprising 89 children (53 male, 36 female; median age: 0.99 (interquartile range: 0.51, 4.89) years) undergoing cardiac surgery involving use of a heart-lung machine, relationships between depth of anesthesia as measured by EEG (EEG index: Narcotrend Index (NI)), sevoflurane dosage, and body temperature were analyzed. A Cornell Assessment of Pediatric Delirium (CAP-D) score ≥ 9 indicated delirium.

RESULTS

The EEG could be used in patients of all age groups for patient monitoring during anesthesia. In the context of induced hypothermia, EEG monitoring supported individually adjusted sevoflurane dosing. The NI was significantly correlated with the body temperature; decreasing temperature was accompanied by a decreasing NI. A CAP-D score ≥ 9 was documented in 61 patients (68.5%); 28 patients (31.5%) had a CAP-D < 9. Delirious patients with an intubation time ≤ 24 h showed a moderate negative correlation between minimum NI (NImin) and CAP-D (rho = -0.41, 95% CI: -0.70 - -0.01, p = 0.046), i.e., CAP-D decreased with increasing NImin. In the analysis of all patients' data, NImin and CAP-D showed a weak negative correlation (rho = -0.21, 95% CI: -0.40 - 0.01, p = 0.064). On average, the youngest patients had the highest CAP-D scores (p = 0.002). Patients with burst suppression / suppression EEG had a longer median intubation time in the intensive care unit than patients without such EEG (p = 0.023). There was no relationship between minimum temperature and CAP-D score.

CONCLUSIONS

The EEG can be used to individually adjust sevoflurane dosing during hypothermia. Of the patients extubated within 24 h and classified as delirious, patients with deeper levels of anesthesia had more severe delirium symptoms than patients with lighter levels of anesthesia.

Performance of the bispectral index and electroencephalograph derived parameters of anesthetic depth during emergence from xenon and sevoflurane anesthesia

Many processed EEG monitors (pEEG) are unreliable when non-GABAergic anesthetic agents are used. The primary aim of the study was to compare the response of the Bispectral Index (BIS) during emergence from anesthesia maintained by xenon and sevoflurane. To better understand the variation in response of pEEG to these agents, we also compared several EEG derived parameters relevant to pEEG monitoring during emergence. Twenty-four participants scheduled for lithotripsy were randomized to receive xenon or sevoflurane anesthesia. Participants were monitored with the BIS and had simultaneous raw EEG collected. BIS index values were compared at three key emergence timepoints: first response, eyes open and removal of airway. Two sets of EEG derived parameters, three related to the BIS: relative beta ratio, SynchFastSlow and SynchFastSlow biocoherence, and two unrelated to the BIS: spectral edge frequency and the composite cortical state, were calculated for comparison. BIS index values were significantly lower in the xenon group than the sevoflurane group at each emergence timepoint. The relative beta ratio parameter increased significantly during emergence in the sevoflurane group but not in the xenon group. The spectral edge frequency and composite cortical state parameters increased significantly in both groups during emergence. The BIS index is lower at equivalent stages of behavioural response during emergence from xenon anesthesia when compared to sevoflurane anesthesia, most likely due to differences in how these two agents influence the relative beta ratio. The spectral edge frequency and composite cortical state might better reflect emergence from xenon anaesthesia.Clinical trial number and registry Australia New Zealand Clinical Trials Registry Number: ACTRN12618000916246.

Desflurane is risk factor for postoperative delirium in older patients' independent from intraoperative burst suppression duration

Background

Postoperative Delirium (POD) is the most frequent neurocognitive complication after general anesthesia in older patients. The development of POD is associated with prolonged periods of burst suppression activity in the intraoperative electroencephalogram (EEG). The risk to present burst suppression activity depends not only on the age of the patient but is also more frequent during propofol anesthesia as compared to inhalative anesthesia. The aim of our study is to determine, if the risk to develop POD differs depending on the anesthetic agent given and if this correlates with a longer duration of intraoperative burst suppression.

Methods

In this secondary analysis of the SuDoCo trail [ISRCTN 36437985] 1277 patients, older than 60 years undergoing general anesthesia were included. We preprocessed and analyzed the raw EEG files from each patient and evaluated the intraoperative burst suppression duration. In a logistic regression analysis, we assessed the impact of burst suppression duration and anesthetic agent used for maintenance on the risk to develop POD.

Results

18.7% of patients developed POD. Burst suppression duration was prolonged in POD patients (POD 27.5 min ± 21.3 min vs. NoPOD 21.4 ± 16.2 min, p < 0.001), for each minute of prolonged intraoperative burst suppression activity the risk to develop POD increased by 1.1% (OR 1.011, CI 95% 1.000-1.022, p =  0.046). Burst suppression duration was prolonged under propofol anesthesia as compared to sevoflurane and desflurane anesthesia (propofol 32.5 ± 20.3 min, sevoflurane 17.1 ± 12.6 min and desflurane 20.1 ± 16.0 min, p < 0.001). However, patients receiving desflurane anesthesia had a 1.8fold higher risk to develop POD, as compared to propofol anesthesia (OR 1.766, CI 95% 1.049-2.974, p =  0.032).

Conclusion

We found a significantly increased risk to develop POD after desflurane anesthesia in older patients, even though burst suppression duration was shorter under desflurane anesthesia as compared to propofol anesthesia. Our finding might help to explain some discrepancies in studies analyzing the impact of burst suppression duration and EEG-guided anesthesia on the risk to develop POD.

Protocol for the electroencephalography guidance of anesthesia to alleviate geriatric syndromes (ENGAGES-Canada) study: A pragmatic, randomized clinical trial

Background:  There is some evidence that electroencephalography guidance of general anesthesia can decrease postoperative delirium after non-cardiac surgery.  There is limited evidence in this regard for cardiac surgery.  A suppressed electroencephalogram pattern, occurring with deep anesthesia, is associated with increased incidence of postoperative delirium (POD) and death.  However, it is not yet clear whether this electroencephalographic pattern reflects an underlying vulnerability associated with increased incidence of delirium and mortality, or whether it is a modifiable risk factor for these adverse outcomes. Methods:  The Electroe ncephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes ( ENGAGES-Canada) is an ongoing pragmatic 1200 patient trial at four Canadian sites.  The study compares the effect of two anesthetic management approaches on the incidence of POD after cardiac surgery.  One approach is based on current standard anesthetic practice and the other on electroencephalography guidance to reduce POD. In the guided arm, clinicians are encouraged to decrease anesthetic administration, primarily if there is electroencephalogram suppression and secondarily if the EEG index is lower than the manufacturers recommended value (bispectral index (BIS) or WAVcns below 40 or Patient State Index below 25).  The aim in the guided group is to administer the minimum concentration of anesthetic considered safe for individual patients.  The primary outcome of the study is the incidence of POD, detected using the confusion assessment method or the confusion assessment method for the intensive care unit; coupled with structured delirium chart review.  Secondary outcomes include unexpected intraoperative movement, awareness, length of intensive care unit and hospital stay, delirium severity and duration, quality of life, falls, and predictors and outcomes of perioperative distress and dissociation. Discussion:  The ENGAGES-Canada trial will help to clarify whether or not using the electroencephalogram to guide anesthetic administration during cardiac surgery decreases the incidence, severity, and duration of POD. Registration: ClinicalTrials.gov ( NCT02692300) 26/02/2016.

Protocol for the electroencephalography guidance of anesthesia to alleviate geriatric syndromes (ENGAGES-Canada) study: A pragmatic, randomized clinical trial

Background:  There is some evidence that electroencephalography guidance of general anesthesia can decrease postoperative delirium after non-cardiac surgery.  There is limited evidence in this regard for cardiac surgery.  A suppressed electroencephalogram pattern, occurring with deep anesthesia, is associated with increased incidence of postoperative delirium (POD) and death.  However, it is not yet clear whether this electroencephalographic pattern reflects an underlying vulnerability associated with increased incidence of delirium and mortality, or whether it is a modifiable risk factor for these adverse outcomes. Methods:  The Electroe ncephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes ( ENGAGES-Canada) is an ongoing pragmatic 1200 patient trial at four Canadian sites.  The study compares the effect of two anesthetic management approaches on the incidence of POD after cardiac surgery.  One approach is based on current standard anesthetic practice and the other on electroencephalography guidance to reduce POD. In the guided arm, clinicians are encouraged to decrease anesthetic administration, primarily if there is electroencephalogram suppression and secondarily if the EEG index is lower than the manufacturers recommended value (bispectral index (BIS) or WAVcns below 40 or Patient State Index below 25).  The aim in the guided group is to administer the minimum concentration of anesthetic considered safe for individual patients.  The primary outcome of the study is the incidence of POD, detected using the confusion assessment method or the confusion assessment method for the intensive care unit; coupled with structured delirium chart review.  Secondary outcomes include unexpected intraoperative movement, awareness, length of intensive care unit and hospital stay, delirium severity and duration, quality of life, falls, and predictors and outcomes of perioperative distress and dissociation. Discussion:  The ENGAGES-Canada trial will help to clarify whether or not using the electroencephalogram to guide anesthetic administration during cardiac surgery decreases the incidence, severity, and duration of POD. Registration: ClinicalTrials.gov ( NCT02692300) 26/02/2016.

Association of volatile anesthesia exposure and depth with emergence agitation and delirium in children: Prospective observational cohort study

Background

Sevoflurane anesthesia is widely used in pediatric ambulatory surgery. However, emergency agitation (EA) and emergency delirium (ED), as major complications following sevoflurane anesthesia in children, pose risks to surgery and prognosis. Identifying the high risk of EA/ED, especially anesthesia exposure and the depth of anesthesia, may allow preemptive treatment.

Methods

A total of 137 patients were prospectively enrolled in this single-center observational cohort study to assess the incidence of EA or ED. Multivariable logistic regression analyses were used to test the association between volatile anesthesia exposure and depth with EA or ED. The Richmond Agitation and Sedation Scale (RASS), Pediatric Anesthesia Emergence Delirium Scale (PAED) and Face, Legs, Activity, Cry, and Consolability (FLACC) behavioural pain scale was used to assess the severity of EA or ED severity and pain. Bispectral index (BIS) to monitor the depth of anesthesia, as well as Time_LOW-BIS/Time_ANES %, EtSevo (%) and EtSevo-time AUC were included in the multivariate logistic regression model as independent variables to analyze their association with EA or ED.

Results

The overall prevalence of EA and ED was 73/137 (53.3%) and 75/137 (54.7%) respectively, where 48/137 (35.0%), 19/137 (13.9%), and 6/137 (4.4%) had mild, moderate, and severe EA. When the recovery period was lengthened, the prevalence of ED and extent of FLACC decreased and finally normalized within 30 min in recovered period. Multivariable logistic regression demonstrated that intraoperative agitation [2.84 (1.08, 7.47) p = 0.034], peak FLACC [2.56 (1.70, 3.85) p < 0.001] and adverse event (respiratory complications) [0.03 (0.00, 0.29) p = 0.003] were independently associated with higher odds of EA. Taking EtSevo-time AUC ≤ 2,000 as a reference, the incidence of EA were [15.84 (2.15, 116.98) p = 0.002] times and 16.59 (2.42, 113.83) p = 0.009] times for EtSevo-time AUC 2,500-3,000 and EtSevo-time AUC > 3,000, respectively. Peak FLACC [3.46 (2.13, 5.62) p < 0.001] and intraoperative agitation [5.61 (1.99, 15.86) p = 0.001] were independently associated with higher odds of developing ED. EtSevo (%), intraoperative BIS value and the percentage of the duration of anesthesia at different depths of anesthesia (BIS ≤ 40, BIS ≤ 30, BIS ≤ 20) were not associated with EA and ED.

Conclusions

For pediatrics undergoing ambulatory surgery where sevoflurane anesthesia was administered, EA was associated with surgical time, peak FLACC, respiratory complications, and "EtSevo-time AUC" with a dose-response relationship; ED was associated with peak FLACC and intraoperative agitation.

miR-182-5p Delivered by Plasma Exosomes Promotes Sevoflurane-Induced Neuroinflammation and Cognitive Dysfunction in Aged Rats with Postoperative Cognitive Dysfunction by Targeting Brain-Derived Neurotrophic Factor and Activating NF-κB Pathway

The objective of this study was to discuss the possible mechanism and effect of miR-182-5p delivered by plasma exosomes on sevoflurane-induced neuroinflammation and cognitive disorder in aged rats with postoperative cognitive dysfunction (POCD). Firstly, aged POCD rat models were constructed by sevoflurane anesthesia and superior mesenteric artery occlusion. Subsequently, exosomes and miR-182-5p were inhibited by injection of GW4869 and miR-182-5p-sponge, respectively. Then, exosomes were extracted from the plasma of rats in each group, followed by the determination of the morphology and diameters of exosomes as well as the expression of exosome markers CD63 and CD81 by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot. Besides, the Morris water maze (MWM) and fear conditioning test were used to evaluate the learning and memory ability of rats; Western blot to detect the expression levels of neurotrophic factors (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) as well as NF-κB pathway-related proteins (p65 and p-p65) in rat hippocampal tissues or PC-12 cells; qRT-PCR to assess the expression levels of miR-182-5p and BDNF in rat plasma, plasma exosomes, hippocampal tissues, and PC-12 cells; ELISA to evaluate the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in rat hippocampal tissues; and dual-luciferase reporter assay to verify the targeting relationship between miR-182-5p and BDNF. After examination, the results were obtained as follows. miR-182-5p expression was up-regulated in POCD rats and could be delivered by plasma exosomes. Inhibition of plasma exosomes or miR-182-5p could significantly ameliorate learning and memory disorders; decrease the levels of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β; increase the expression of BDNF and NGF; and inhibit the activity of NF-κB signaling pathway in POCD rat hippocampus. In addition, miR-182-5p could also target and inhibit BDNF. All in all, miR-182-5p delivered by plasma exosomes promotes sevoflurane-induced neuroinflammation and cognitive dysfunction in aged POCD rats by targeting BDNF and activating the NF-κB pathway.

Influence of Narcotrend-Assisted Anesthesia In-Depth Monitor on Cognitive Impairment of Elderly Patients under General Anesthesia

Objective

This research is designed to probe into the influence of Narcotrend- (NT-) assisted anesthesia in-depth monitor on cognitive impairment of elderly patients under general anesthesia (GA).

Methods

One hundred and forty-four elderly patients with GA in our hospital from October 2020 to April 2021 were randomized into two groups, namely, NT group (supervised anesthesia under NT monitoring) and group C (anesthesia according to doctors' experience). The heart rate (HR), mean arterial pressure (MAP), and central venous pressure (CVP) were recorded before surgery (T0), at the beginning of surgery (T1), at the end of surgery (T2), and 1 day after surgery (T3). Serum of patients was obtained at these four time points for measurements of C-reactive protein (CRP), interleukin-6 (IL-6), and cortisol (Cor) levels using the enzyme-linked immunosorbent assay (ELISA). The alterations in cognitive function pre- and post-anesthesia were assessed using the mini-mental state examination (MMSE), and adverse events (AEs) during anesthesia recovery, postoperative recovery, and dosage of anesthetics were recorded.

Results

At T1 and T2, MAP was higher and CVP was lower in NT group, versus group C. NT group presented higher CRP, IL-6, and Cor than group C at T1-T3. MMSE scores were higher in TN group than in group C at 12, 24, and 48 h after surgery. The incidence rates of postoperative cognitive dysfunction (POCD) and total AEs in group C were noticeably higher than those in NT group. Compared with group C, the time of anesthesia recovery, extubation, and postanesthesia care unit (PACU) residence in NT group reduced remarkably.

Conclusions

NT has little effect on the physical condition of elderly patients under GA, and can reduce the dosage of narcotic drugs and promote the recovery of patients from anesthesia, which has high clinical value.

Postoperative Delirium in Neurosurgical Patients: Recent Insights into the Pathogenesis

Postoperative delirium (POD) is a complication characterized by disturbances in attention, awareness, and cognitive function that occur shortly after surgery or emergence from anesthesia. Since it occurs prevalently in neurosurgical patients and poses great threats to the well-being of patients, much emphasis is placed on POD in neurosurgical units. However, there are intricate theories about its pathogenesis and limited pharmacological interventions for POD. In this study, we review the recent insights into its pathogenesis, mainly based on studies within five years, and the five dominant pathological theories that account for the development of POD, with the intention of furthering our understanding and boosting its clinical management.

Processed intraoperative burst suppression and postoperative cognitive dysfunction in a cohort of older noncardiac surgery patients

Postoperative cognitive dysfunction (POCD) is a decline in cognitive test performance which persists months after surgery. There has been great interest in the anesthesia community regarding whether variables generated by commercially available processed EEG monitors originally marketed to prevent awareness under anesthesia can be used to guide intraoperative anesthetic management to prevent POCD. Processed EEG monitors represent an opportunity for anesthesiologists to directly monitor the brain even if they have not been trained to interpret EEG waveforms. There is continued equipoise regarding whether any of the variables generated by the machines' interpretation of raw data are associated with POCD. Most literature has focused on the depth of anesthesia number, however recent studies have shown that processed depth may not be accurate in older age groups due to reduced alpha band power. Burst suppression is an encephalographic pattern of high voltage activity alternating with periods of electrical silence and is another marker of depth which can be obtained from commercial processed EEG monitors. We performed a prospective cohort study to determine whether burst suppression and burst suppression ratio as measured by the BIS Monitor (Bispectral Index, BIS Medtronic, Boulder CO), is associated with cognitive dysfunction 3 months after surgery. We recruited 167 elective surgery patients, 65 years of age and older, anticipated to require at least 2 day inpatient admission. Our main outcome measure was cognitive decline in composite z-score on the Alzheimer's Disease Research Center UDS Battery of at least 1 standard deviation 3 months after surgery relative to preoperative baseline. 14% experienced POCD, this group was older (72 [70, 74] versus 70 [67, 75] years), and had frailty scores as measured by the FRAIL Scale (2 [0, 3] versus 1 [0, 2]) and lower baseline z-scores (- 0.2 [- 0.6, 0.5] versus 0.1 [- 0.3, 0.5]). There was a univariable association between suppression ratio > 10 (SR > 10) and POCD (4.8 [0, 37.3] versus 15.4 [4.0-142.4] min), p = .038. However, after adjustment this relationship did not persist, only anesthetic technique, age, and pain remained in the model. In our cohort of older elective noncardiac surgery patients we found a marginal association between processed burst suppression (total burst suppression p = .067, SR > 5 p = .052, SR > 10.038) which did not persist in a multivariable model. Patients with POCD had almost twice the number of minutes of burst suppression, and three times the amount of time for SR > 5 and > 10. Our finding may be a limitation of the monitor's ability to detect burst suppression. The consistent trend towards more intraoperative burst suppression in patients who developed POCD suggests that future studies are needed to investigate the relationship of raw intraoperative burst suppression and POCD.Trial registry Clinical trial number and registry URL: Optimizing Postoperative Cognitive Dysfunction in the Elderly-PRESERVE, Clinical Trials Gov# NCT02650687; https://clinicaltrials.gov/ct2/show/NCT02650687 .

Risk factors and a nomogram model for postoperative delirium in elderly gastric cancer patients after laparoscopic gastrectomy

Background

To evaluate the risk factors of postoperative delirium (POD) in elderly gastric cancer (GC) patients after laparoscopic gastrectomy and construct a predictive model.

Methods

Elderly GC patients undergoing laparoscopic gastrectomy were enrolled and grouped based on the status of POD development within postoperative 7 days. Independent risk factors were selected out by univariate and multivariate logistic regression analyses and then enrolled in the nomogram prediction model.

Results

A total of 270 elderly GC patients were enrolled, and POD occurred in 74 (27.4%) patients within postoperative 7 days. The results of multivariate regression analysis indicated that age (OR: 3.30, 95% CI: 1.41–6.85, P < 0.001), sleeping pills (OR: 1.87, 95% CI: 1.12–3.09, P = 0.012), duration of ICU stay (OR: 1.55, 95% CI: 1.02–2.37, P = 0.029), albumin/fibrinogen ratio (AFR) (OR: 1.74, 95% CI: 1.03–2.76, P = 0.019), and neutrophils/lymphocytes ratio (NLR) (OR: 2.12, 95% CI: 1.11–4.01, P = 0.016) were five independent risk factors for POD in elderly GC patients. The AUC of the constructed nomogram model based on these five factors was 0.807.

Conclusions

This study highlighted that age, AFR, NLR, sleeping pills taking, and duration of ICU stay were independent risk factors for POD, and the nomogram model based on these factors could effectively predict POD in elderly GC patients.

Electroencephalogram Features of Perioperative Neurocognitive Disorders in Elderly Patients: A Narrative Review of the Clinical Literature

Postoperative neurocognitive disorder (PND) is a common postoperative complication, particularly in older patients. Electroencephalogram (EEG) monitoring, a non-invasive technique with a high spatial-temporal resolution, can accurately characterize the dynamic changes in brain function during the perioperative period. Current clinical studies have confirmed that the power density of alpha oscillation during general anesthesia decreased with age, which was considered to be associated with increased susceptibility to PND in the elderly. However, evidence on whether general anesthesia under EEG guidance results in a lower morbidity of PND is still contradictory. This is one of the reasons that common indicators of the depth of anesthesia were limitedly derived from EEG signals in the frontal lobe. The variation of multi-channel EEG features during the perioperative period has the potential to highlight the occult structural and functional abnormalities of the subcortical-cortical neurocircuit. Therefore, we present a review of the application of multi-channel EEG monitoring to predict the incidence of PND in older patients. The data confirmed that the abnormal variation in EEG power and functional connectivity between distant brain regions was closely related to the incidence and long-term poor outcomes of PND in older adults.

The Efficacy and Safety of Remimazolam Tosilate Versus Dexmedetomidine in Outpatients Undergoing Flexible Bronchoscopy: A Prospective, Randomized, Blind, Non-Inferiority Trial

Purpose: This study aimed to compare the efficacy and safety of remimazolam tosilate-remifentanil (RT-RF) vs dexmedetomidine-remifentanil (Dex-RF) for outpatients undergoing fiberoptic bronchoscopy (FB).

Patients and methods: We conducted a double-blind, randomized, prospective study involving a total of 146 outpatients undergoing FB divided into two groups. The RT-RF (RR) group (n = 73) received an initial dose of 12 mg/kg/h of RT for 10 min followed by a maintenance dose of 1–2 mg/kg/h, while the Dex-RF (DR) group (n = 73) received an initial dose of 0.5 μg/kg of Dex for 10 min followed by a maintenance dose of 0.2–0.7 μg/kg/h. All outpatients also received 0.05–0.2 μg/kg/min RF to maintain the Modified Observer’s Assessment of Alertness and Sedation (MOAA/S) scale <3. The primary outcome was rate of successful FB completed. Secondary outcomes were time metrics, hemodynamics, intubating conditions, oxygen saturation, coughing severity, number of remedies, total dose of fentanyl, RF, RT, and Dex, incidence of dreaming, patient and bronchoscopist satisfaction, willingness to repeat bronchoscopy, and adverse events.

Results: The FB successful completion rate was 94.52% (95% CI: 89.20–99.90) in the RR group and 91.78% (95% CI: 85.30–98.20) in the DR group. Compared with patients in the DR group, the onset time, time to fully alert, and hospital discharge were all significantly shorter in the RR group (p < 0.01), and hemodynamics were more stable in the RR group. Intubating conditions, clinically acceptable intubating conditions, lowest oxygen saturation, coughing severity, consumption of fentanyl and RF, number of remedies, and patient and bronchoscopist satisfaction were similar between the groups (p > 0.05), as were demographic characteristics, incidence of dreaming, willingness to repeat bronchoscopy, and adverse events (p > 0.05).

Conclusion: RT-RF has non-inferior efficacy, better time metrics and hemodynamic stability for outpatients undergoing FB than Dex-RF.

Systematic Review Registration: [http://www.chictr.org.cn/showproj.aspx?proj=66673], identifier [ChiCTR2000041524].

Anaesthetic Approach to Enhanced Recovery after Surgery for Kidney Transplantation: A Narrative Review

Enhanced recovery after surgery (ERAS) protocols are designed to reduce medical complications, the length of hospital stays (LoS), and healthcare costs. ERAS is considered safe and effective for kidney transplant (KTx) surgery. KTx recipients are often frail with multiple comorbidities. As these patients follow an extensive diagnostic pathway preoperatively, the ERAS protocol can ideally be implemented at this stage. Small singular changes in a long perioperative pathway can result in significant positive outcomes. We have investigated the current evidence for an ERAS pathway related to anaesthetic considerations in renal transplant surgery for adult recipients.

Can we improve delirium prevention and treatment in the emergency department? A systematic review

BACKGROUND

This systematic review was conducted to evaluate any interventions to prevent incident delirium, or shorten the duration of prevalent delirium, in older adults presenting to the emergency department (ED).

METHODS

Health sciences librarian designed electronic searches were conducted from database inception through September 2021. Two authors reviewed studies, and included studies that evaluated interventions for the prevention and/or treatment of delirium and excluded non-ED studies. The risk of bias (ROB) was evaluated by the Cochrane ROB tool or the Newcastle-Ottawa (NOS) scale. Meta-analysis was conducted to estimate a pooled effect of multifactorial programs on delirium prevention.

RESULTS

Our search strategy yielded 11,900 studies of which 10 met study inclusion criteria. Two RCTs evaluated pharmacologic interventions for delirium prevention; three non-RCTs employed a multi-factorial delirium prevention program; three non-RCTs evaluated regional anesthesia for hip fractures; and one study evaluated the use of Foley catheter, medication exposure, and risk of delirium. Only four studies demonstrated a significant impact on delirium incidence or duration of delirium-one RCT of melatonin reduced the incidence of delirium (OR 0.19, 95% CI 0.06 to 0.62), one non-RCT study on a multi-factorial program decreased inpatient delirium prevalence (41% to 19%) and the other reduced incident delirium (RR 0.37, 95% CI 0.22 to 0.61). One case-control study on the use of ED Foley catheters in the ED increased the duration of delirium (proportional OR 3.1, 95% CI 1.3 to 7.4). A pooled odds ratio for three multifactorial programs on delirium prevention was 0.46 (95% CI 0.31-0.68, I2  = 0).

CONCLUSION

Few interventions initiated in the ED were found to consistently reduce the incidence or duration of delirium. Delirium prevention and treatment trials in the ED are still rare and should be prioritized for future research.

Delirium in Older Adults: What a Surgeon Needs to Know

Delirium remains a challenging clinical problem in hospitalized older adults, especially for postoperative patients. This complication, with a high risk of postoperative mortality and an increased length of stay, frequently occurs in older adult patients. This brief narrative paper aims to review the recent literature regarding delirium and its most recent update. We also offer physicians a brief and essential clinical practice guide to managing this acute and common disease.

Burst Suppression During General Anesthesia and Postoperative Outcomes: Mini Review

In the last decade, burst suppression has been increasingly studied by many to examine whether it is a mechanism leading to postoperative cognitive impairment. Despite a lack of consensus across trials, the current state of research suggests that electroencephalogram (EEG) burst suppression, duration and EEG emergence trajectory may predict postoperative delirium (POD). A mini literature review regarding evidence about burst suppression impact and susceptibilities was conducted, resulting in conflicting studies. Primarily, studies have used different algorithm values to replace visual burst suppression examination, although many studies have since emerged showing that algorithms underestimate burst suppression duration. As these methods may not be interchangeable with visual analysis of raw data, it is a potential factor for the current heterogeneity between data. Even though additional research trials incorporating the use of raw EEG data are necessary, the data currently show that monitoring with commercial intraoperative EEG machines that use EEG indices to estimate burst suppression may help physicians identify burst suppression and guide anesthetic titration during surgery. These modifications in anesthetics could lead to preventing unfavorable outcomes. Furthermore, some studies suggest that brain age, baseline impairment, and certain medications are risk factors for burst suppression and postoperative delirium. These patient characteristics, in conjunction with intraoperative EEG monitoring, could be used for individualized patient care. Future studies on the feasibility of raw EEG monitoring, new technologies for anesthetic monitoring and titration, and patient-associated risk factors are crucial to our continued understanding of burst suppression and postoperative delirium.

Awareness and Perspectives among Asian Anesthesiologists on Postoperative Delirium: A Multinational Survey

Postoperative delirium (POD) is a common perioperative complication. Although POD is preventable in up to 40% of patients, it is frequently overlooked. The objective of the survey is to determine the level of knowledge and clinical practices related to POD among anesthesiologists in different Asian countries. A questionnaire of 22 questions was designed by members of the Asian focus group for the study of POD, and it was sent to anesthesiologists in Singapore, Thailand, and South Korea from 1 April 2019 through 17 September 2019. In total, 531 anesthesiologists (Singapore: 224, Thailand: 124, Korea: 183) responded to the survey. Half the respondents estimated the incidence of POD to be 11–30% and believed that it typically occurs in the first 48 h after surgery. Among eight important postoperative complications, POD was ranked fifth. While 51.4% did not perform any test for POD, only 13.7% monitored the depth of anesthesia in all their patients. However, 83.8% preferred depth of anesthesia monitoring if they underwent surgery themselves. The results suggest that Asian anesthesiologists underestimate the incidence and relevance of POD. Because it increases perioperative mortality and morbidity, there is an urgent need to educate anesthesiologists regarding the recognition, prevention, detection, and management of POD.

[Intraoperative Neuromonitoring: Electroencephalography]

Intraoperative neuromonitoring using electroencephalography (EEG) enables anaesthesiologists to monitor the depth of anaesthesia. It is intended to reduce the occurrence of intraoperative wakefulness, postoperative delirium and postoperative cognitive deficits and to shorten process times in the operating room. This article shows how to interpret the raw EEG, spectrograms and processed indices for different age groups and anaesthetics and summarizes the resulting clinical benefits. While propofol and volatile anesthetics produce characteristic frontal EEG signatures with a high activity of coherent α- and δ-waves, ketamine triggers an increase in rapid γ-waves, which leads to incorrectly high indices (BIS, PSI, NI) despite deep anaesthetic levels.In children, frontal α-waves do not appear until the age of approx. 6 months and valid indices (BIS, PSI, NI) can only be derived starting at an age of approx. 12 months. Furthermore, children of preschool and elementary school age often show epileptiform discharges in the EEG during induction of anaesthesia, what is linked to emergence delirium. In adults, the intraoperative frontal α-power decreases significantly with increasing age and older patients tend to have an increased occurrence of burst suppression patterns during anaesthesia. Clinical benefits of EEG-based neuromonitoring comprise reduced doses of anaesthesia, shorter wake-up times after surgery and a lower incidence of intraoperative awareness during total intravenous anaesthesia. Moreover, anaesthesia guided by processed EEG indices can reduce the incidence of postoperative delirium and postoperative cognitive deficits in older patients. In-depth knowledge about intraoperative EEG changes that go beyond the interpretation of processed indices could lead to a further reduction in intra- and postoperative complications in the future.

Cerebral hemorrhagic infarction was diagnosed subsequently after high-amplitude slow waves detected on processed electroencephalogram during sedation: a case report

Background

Continuous electroencephalogram (EEG) monitoring is useful for assessing the level of sedation and detecting non-convulsive epileptic seizures and cerebral ischemia in the intensive care unit. This report describes a case of cerebral hemorrhagic infarction diagnosed after the detection of high-amplitude slow waves on processed EEG during sedation.

Case presentation

A 68-year-old man who underwent cardiac surgery was sedated in the intensive care unit following an invasive procedure. High-amplitude slow waves appeared on processed EEG monitoring before the detection of anisocoria. Computed tomography revealed a cerebral hemorrhagic infarction.

Conclusions

In the management of critically ill patients, continuous EEG monitoring with forehead electrodes may be useful in the early detection of brain lesions.

Intracranial electroencephalography features of young and old mice under midazolam administration

Understanding the electroencephalography features of young and old patients treated with anesthetic drugs is important to allow accurate drug use in elderly patients. This study aimed to monitor the intracranial electroencephalography (in the cortex and hippocampus) in free-moving young and old mice under midazolam administration. Behavioral assessment revealed that compared with young mice, old mice had a longer immobility time with a similar midazolam dose. In both young and old mice, midazolam significantly suppressed the total, δ (0.5-4 Hz), θ (4-8 Hz), and α (8-12 Hz) power, and thus induced an increase in the relative β (12-30 Hz) and γ (30-140 Hz) power. Age had a main effect on the γ frequency; specifically, under normal conditions, old mice had a lower γ power than young mice. After midazolam administration, the relative power of high γ frequency (50-140 Hz) remained lower in old mice than in young mice. Our findings suggest that a lower γ power is indicative of an aging brain.

Clemastine Ameliorates Perioperative Neurocognitive Disorder in Aged Mice Caused by Anesthesia and Surgery

Perioperative neurocognitive disorder (PND) leads to progressive deterioration of cognitive function, especially in aged patients. Demyelination is closely associated with cognitive dysfunction. However, the relationship between PND and demyelination remains unclear. Here we showed that demyelination was related to the pathogenesis of PND. Clemastine, an antihistamine with potency in remyelination, was predicted to have a potential therapeutic effect on PND by next-generation sequencing and bioinformatics in our previous study. In the present study, it was given at 10 mg/kg per day for 2 weeks to evaluate the effects on PND in aged mice. We found that clemastine ameliorated PND and reduced the expression levels of inflammatory factors such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β). Further investigation suggested clemastine increased the expression of oligodendrocyte transcription factor 2 (OLIG2) and myelin basic protein (MBP) to enhance remyelination by inhibiting the overactivation of the WNT/β-catenin pathway. At the same time, the expression of post-synaptic density protein 95 (PSD95, or DLG4), brain-derived neurotrophic factor (BDNF), synaptosomal-associated protein 25 (SNAP25) and neuronal nuclei (NEUN) were also improved. Our results suggested that clemastine might be a therapy for PND caused by anesthetic and surgical factors in aged patients.

Related Factors and Treatment of Postoperative Delirium in Old Adult Patients: An Integrative Review

“Postoperative delirium” is defined as delirium occurring in the hospital up to one week after a procedure or before discharge (whichever occurs first) that meets the DSM-5 diagnostic criteria. Objectives: To describe the risk factors related to this pathology and identify effective non-pharmacological forms of treatment. An integrative review of the available literature was performed. The search results considered included all quantitative studies published between 2011 and 2019 in both English and Spanish. A total of 117 studies were selected. Advanced age was identified as the principal risk factor for postoperative delirium. Nursing interventions appear to be the key to preventing or reducing the seriousness of delirium after an anaesthetic episode. The aetiology of postoperative delirium remains unknown, and no treatment exists to eliminate this pathology. The role of nursing staff is fundamental in the prevention, diagnosis, and management of the pathology.

The raw and processed electroencephalogram in modern anesthesia practice: a brief primer on select clinical applications

The evidence supporting the intraoperative use of processed electroencephalography (pEEG) monitoring to guide anesthetic delivery is growing rapidly. This article reviews the key features of electroencephalography (EEG) waveforms and their clinical implications in select patient populations and anesthetic techniques. The first patient topic reviewed is the vulnerable brain. This term has emerged as a description of patients who may exhibit increased sensitivity to anesthetics and/or may develop adverse neurocognitive effects following anesthesia. pEEG monitoring of patients who are known to have or are suspected of having vulnerable brains, with focused attention on the suppression ratio, alpha band power, and pEEG indices, may prove useful. Second, pEEG monitoring along with vigilant attention to anesthetic delivery may minimize the risk of intraoperative awareness when administering a total intravenous anesthesia in combination with a neuromuscular blockade. Third, we suggest that processed EEG monitoring may play a role in anesthetic and resuscitative management when adverse changes in blood pressure occur. Fourth, pEEG monitoring can be used to better identify anesthesia requirements and guide anesthetic titration in patients with known or suspected substance use.

Processed Multiparameter Electroencephalogram-Guided General Anesthesia Management Can Reduce Postoperative Delirium Following Carotid Endarterectomy: A Randomized Clinical Trial

Background: Patients undergoing carotid endarterectomy (CEA) for severe carotid stenosis are vulnerable to postoperative delirium, a complication frequently associated with poor outcome. This study investigated the impact of processed electroencephalogram (EEG)-guided anesthesia management on the incidence of postoperative delirium in patients undergoing CEA. Methods: This single-center, prospective, randomized clinical trial on 255 patients receiving CEA under general anesthesia compared the outcomes of patient state index (PSI) monitoring [SEDLine Brain Function Monitor (Masimo, Inc, Irvine, CA)] (standard group, n = 128) with PSI combined with density spectral array(DSA) -guided monitoring (intervention group, n = 127) to reduce the risk of intraoperative EEG burst suppression. All patients were monitored by continuous transcranial Doppler ultrasound (TCD) and near-infrared spectroscopy (NIRS) to avoid perioperative cerebral hypoperfusion or hyperperfusion. According to the surgical process, EEG suppression time was calculated separately for three stages: S1 (from anesthesia induction to carotid artery clamping), S2 (from clamping to declamping), and S3 (from declamping to the end of surgery). The primary outcome was incidence of postoperative delirium according to the Confusion Assessment Method algorithm during the first 3 days post-surgery, and secondary outcomes were other neurologic complications and length of hospital stay. Results: There were no episodes of cerebral hypoperfusion or hyperperfusion according to TCD and NIRS monitoring in either group during surgery. The incidence of postoperative delirium within 3 days post-surgery was significantly lower in the intervention group than the standard group (7.87 vs. 28.91%, P < 0.01). In the intervention group, the total EEG suppression time and the EEG suppression time during S2 and S3 were shorter (Total, 0 "0" vs. 0 "1.17" min, P = 0.04; S2, 0 "0" vs. 0 "0.1" min, P < 0.01; S3, 0 "0" vs. 0 "0" min, P = 0.02). There were no group differences in incidence of neurologic complications and length of postoperative hospital stay. Conclusion: Processed electroencephalogram-guided general anesthesia management, consisting of PSI combined with DSA monitoring, can significantly reduce the risk of postoperative delirium in patients undergoing CEA. Patients, especially those exhibiting hemodynamic fluctuations or receiving surgical procedures that disrupt cerebral perfusion, may benefit from the monitoring of multiple EEG parameters during surgery. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03622515.

Recommendations for standards of monitoring during anaesthesia and recovery 2021: Guideline from the Association of Anaesthetists

This guideline updates and replaces the 5th edition of the Standards of Monitoring published in 2015. The aim of this document is to provide guidance on the minimum standards for monitoring of any patient undergoing anaesthesia or sedation under the care of an anaesthetist. The recommendations are primarily aimed at anaesthetists practising in the UK and Ireland, but it is recognised that these guidelines may also be of use in other areas of the world. Minimum standards for monitoring patients during anaesthesia and in the recovery phase are included. There is also guidance on monitoring patients undergoing sedation and during transfer. There are new sections specifically discussing capnography, sedation and regional anaesthesia. In addition, the indications for processed electroencephalogram and neuromuscular monitoring have been updated.

Update on the SedLine® algorithm for calculating the Patient State Index of older individuals during general anesthesia: a randomized controlled trial

BACKGROUND

The SedLine^® sensor processes (Masimo Corporation; Irvine, CA, USA) raw electroencephalogram (EEG) signals and displays the depth of sedation as a Patient State Index (PSi). Reliance on standard processed EEG data and failure to recognize age-related effects can lead to an erroneous interpretation that low-amplitude EEG findings in an older patient signify an insufficient depth of anesthesia presented as abnormally high PSi values (AHPSi). We hypothesized that the incidence of AHPSi would decrease with the use of the recently-updated version of the SedLine^® sensor, in which the Bispectral Index (BIS) values were used to titrate anesthesia.

METHODS

Thirty-three patients undergoing sevoflurane-remifentanil anesthesia were randomized into two groups. SedLine^® sensors designed based on an old (v.1203) or updated (v.2000) algorithms were used. The BIS (v.4.1) and absolute index of total EEG power (TP) were simultaneously recorded. The attending anesthesiologists titrated the anesthetics, and BIS was maintained at 40-60. The incidence of AHPSi (PSi>50 with BIS 40-60) was calculated during the first 30 min after the start of surgery.

RESULTS

Compared to the old algorithm group, the incidence of AHPSi was significantly lower in the updated algorithm group (26.7% vs. 4.2%, P<0.001). Lower TP values and the use of the old algorithm have significant effect on increased PSi values (P<0.001).

CONCLUSIONS

The incidence of AHPSi decreased with the use of the updated version of the SedLine^® algorithm.

Post-operative delirium in older hip fracture patients: a new onset or was it already there?

PURPOSE

Hip fractures are a worldwide health issue primarily for older patients, conditioning major morbidity and mortality. An experienced multidisciplinary team is essential to manage surgery and peri-operative implications, to enable rapid functional and cognitive recovery. Delirium is a recognizable problem associated with negative outcomes. Our study aims to determine the influence of pre-operative delirium in the incidence of post-operative delirium, and to evaluate the association between other known peri-operative risk factors with both conditions.

METHODS

A single-center, retrospective cohort study, conducted at a Level II trauma center over a 14-month period, included 241 patients with 65 years of age or older submitted to hip fracture surgery. Peri-operative data were gathered regarding baseline characteristics (sociodemographic, functional and cognitive status), intra-operative events (anesthesia technique, surgery duration, blood loss) and post-operative outcomes (delirium occurrence).

RESULTS

Statistical analysis evidenced a female (75.5%) and elderly population (83.9 ± 7.8 years old) with significant comorbidities (cognitive impairment in 51.9%, ASA ≥ III in 79.7%, mean CIRS-G 8.83 ± 4.69) that underwent surgical fracture repair, mostly under 4 h (96.3%) and under regional anesthesia (63.1%). Pre- and post-operative delirium incidence was 18.3% and 12.9%, respectively, displaying increased presence according to cognitive impairment severity.

CONCLUSION

Post-operative delirium was almost inexistent when it was absent pre-operatively. Moreover, pre-operative cognitive status was associated with the development of pre- and post-operative delirium. Careful cognitive assessment, implementation of preventive strategies and avoidance of peri-operative pro-delirium factors are crucial for comprehensive geriatric care.

BIS index monitoring and perioperative neurocognitive disorders in older adults: a systematic review and meta-analysis

BACKGROUND AND AIMS

Perioperative neurocognitive disorders (PND) are common in elderly patients after surgery. It has been reported that BIS-guided anesthesia potentially influenced the occurrence of PND. Therefore, we conducted this systematic review and meta-analysis to explore the associations between bispectral index (BIS) monitoring and PND.

METHODS

Two researchers independently searched for relevant randomized controlled trials (RCTs) in PubMed, EMBASE, and the Cochrane Library (CENTRAL) using keywords related to the BIS and PND from inception to April 22, 2019. Odds ratios (OR) with 95% CI were calculated using a random effects model.

RESULTS

Nine RCTs involving 4023 participants aged 60 years or older were included into this meta-analysis. BIS-guided anesthesia was not associated with lower incidence of POD (random effects; OR: 0.69; 95% CI 0.48, 1.01), delayed neurocognitive recovery (DNR) at 1 day, 7 days (random effects; OR: 0.14; 95% CI 0.02, 1.23; random effects; OR: 0.97; 95% CI 0.57, 1.63), and postoperative neurocognitive disorder (NCD) at 90 days and 1 year after surgery in older adults (random effects; OR:0.72; 95% CI 0.52, 1.00; random effects; OR: 0.26; 95% CI 0.03, 2.47).

CONCLUSIONS

No definite evidence demonstrated that BIS-guided anesthesia decreased the incidence of POD, DNR and postoperative NCD in older patients. More homogeneous RCTs assessing the efficacy of BIS monitoring on reducing the occurrence of these perioperative cognitive disorders are needed.

Does electroencephalographic burst suppression still play a role in the perioperative setting?

With the widespread use of electroencephalogram [EEG] monitoring during surgery or in the Intensive Care Unit [ICU], clinicians can sometimes face the pattern of burst suppression [BS]. The BS pattern corresponds to the continuous quasi-periodic alternation between high-voltage slow waves [the bursts] and periods of low voltage or even isoelectricity of the EEG signal [the suppression] and is extremely rare outside ICU and the operative room. BS can be secondary to increased anesthetic depth or a marker of cerebral damage, as a therapeutic endpoint [i.e., refractory status epilepticus or refractory intracranial hypertension]. In this review, we report the neurophysiological features of BS to better define its role during intraoperative and critical care settings.

Recommendations from the Italian intersociety consensus on Perioperative Anesthesa Care in Thoracic surgery (PACTS) part 2: intraoperative and postoperative care

Introduction

Anesthetic care in patients undergoing thoracic surgery presents specific challenges that require a multidisciplinary approach to management. There remains a need for standardized, evidence-based, continuously updated guidelines for perioperative care in these patients.

Methods

A multidisciplinary expert group, the Perioperative Anesthesia in Thoracic Surgery (PACTS) group, was established to develop recommendations for anesthesia practice in patients undergoing elective lung resection for lung cancer. The project addressed three key areas: preoperative patient assessment and preparation, intraoperative management (surgical and anesthesiologic care), and postoperative care and discharge. A series of clinical questions was developed, and literature searches were performed to inform discussions around these areas, leading to the development of 69 recommendations. The quality of evidence and strength of recommendations were graded using the United States Preventive Services Task Force criteria.

Results

Recommendations for intraoperative care focus on airway management, and monitoring of vital signs, hemodynamics, blood gases, neuromuscular blockade, and depth of anesthesia. Recommendations for postoperative care focus on the provision of multimodal analgesia, intensive care unit (ICU) care, and specific measures such as chest drainage, mobilization, noninvasive ventilation, and atrial fibrillation prophylaxis.

Conclusions

These recommendations should help clinicians to improve intraoperative and postoperative management, and thereby achieve better postoperative outcomes in thoracic surgery patients. Further refinement of the recommendations can be anticipated as the literature continues to evolve.