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

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.

Use of Processed Electroencephalography in the Clinical Setting

Purpose of Review

Processed electroencephalography (pEEG) is widely used in clinical practice. Few clinicians utilize the full potential of these devices. This brief review will address the improvements in patient management available from the utilization of all pEEG data.

Recent Findings

Anesthesiologists easily learn to recognize raw pEEG patterns that are consistent with an appropriate level of hypnotic effect. Power distribution within the waveform can be displayed in a visual format that identifies signatures of the principal anesthetic hypnotics. Opinion on the benefit of pEEG data in the mitigation of postoperative neurological impairment remains divided.

Summary

Looking beyond the index number can aid clinical decision making and improve confidence in the benefits of this monitoring modality.

Delirium prevention and treatment in the emergency department (ED): a systematic review protocol

INTRODUCTION

Delirium is a dangerous syndrome of acute brain dysfunction that is common in the emergency department (ED), especially among the geriatric population. Most systematic reviews of interventions for delirium prevention and treatment have focused on inpatient settings. Best practices of effective delirium care in ED settings have not been established. The primary objective of this study is to identify pharmacologic and non-pharmacologic interventions as applied by physicians, nursing staff, pharmacists and other ED personnel to prevent incident delirium and to shorten the severity and duration of prevalent delirium in a geriatric population within the ED.

METHODS AND ANALYSIS

Searches using subject headings and keywords will be conducted from database inception through June 2020 in MEDLINE, EMBASE, Web of Science, PsychINFO, CINAHL, ProQuest Dissertations and Theses Global and Cochrane CENTRAL as well as grey literature. Database searches will not be limited by date or language. Two reviewers will identify studies describing any interventions for delirium prevention and/or treatment in the ED. Disagreements will be settled by a third reviewer. Pooled data analysis will be performed where possible using Review Manager. Risk ratios and weighted difference of means will be used for incidence of delirium and other binary outcomes related to delirium, delirium severity or duration of symptoms, along with 95% CIs. Heterogeneity will be measured by calculating I², and a forest plot will be created. If significant heterogeneity is identified, metaregression is planned using OpenMeta to identify possible sources of heterogeneity.

ETHICS AND DISSEMINATION

This is a systematic review of previously conducted research; accordingly, it does not constitute human subjects research needing ethics review. This review will be prepared as a manuscript and submitted for publication to a peer-reviewed journal, and the results will be presented at conferences.

PROSPERO TRIAL REGISTRATION NUMBER

CRD42020169654.

Effects of electroencephalography and regional cerebral oxygen saturation monitoring on perioperative neurocognitive disorders: a systematic review and meta-analysis

BACKGROUND

Perioperative neurocognitive disorders (PND) is a common postoperative complication including postoperative delirium (POD), postoperative cognitive decline (POCD) or delayed neurocognitive recovery. It is still controversial whether the use of intraoperative cerebral function monitoring can decrease the incidence of PND. The purpose of this study was to evaluate the effects of different cerebral function monitoring (electroencephalography (EEG) and regional cerebral oxygen saturation (rSO2) monitoring) on PND based on the data from randomized controlled trials (RCTs).

METHODS

The electronic databases of Ovid MEDLINE, PubMed, EMBASE, Cochrane Library database were systematically searched using the indicated keywords from their inception to April 2020. The odds ratio (OR) or mean difference (MD) with 95% confidence interval (CI) were employed to analyze the data. Heterogeneity across analyzed studies was assessed with chi-square test and I2 test.

RESULTS

Twenty two RCTs with 6356 patients were included in the final analysis. Data from 12 studies including 4976 patients were analyzed to assess the association between the EEG-guided anesthesia and PND. The results showed that EEG-guided anesthesia could reduce the incidence of POD in patients undergoing non-cardiac surgery (OR: 0.73; 95% CI: 0.57-0.95; P = 0.02), but had no effect on patients undergoing cardiac surgery (OR: 0.44; 95% CI: 0.05-3.54; P = 0.44). The use of intraoperative EEG monitoring reduced the incidence of POCD up to 3 months after the surgery (OR: 0.69; 95% CI: 0.49-0.96; P = 0.03), but the incidence of early POCD remained unaffected (OR: 0.61; 95% CI: 0.35-1.07; P = 0.09). The remaining 10 studies compared the effect of rSO2 monitoring to routine care in a total of 1380 participants on the incidence of PND. The results indicated that intraoperative monitoring of rSO2 could reduce the incidence of POCD (OR 0.53, 95% CI 0.39-0.73; P < 0.0001), whereas no significant difference was found regarding the incidence of POD (OR: 0.74; 95% CI: 0.48-1.14; P = 0.17).

CONCLUSIONS

The findings in the present study indicated that intraoperative use of EEG or/and rSO2 monitor could decrease the risk of PND.

TRIAL REGISTRATION

PROSPREO registration number: CRD42019130512 .

Postoperative neurocognitive disorders

A decline in cognitive function is a frequent complication of major surgery. Postoperative cognitive impairments have generally been divided into short- (postoperative delirium) and long-term disturbances (postoperative cognitive dysfunction [POCD]). Long-term impairments are often subtle and overlooked. They need to be objectively assessed using neuropsychological tests to be diagnosed. Although POCD has been the subject of considerable research over the past decades, it remains uncertain why some patients do not return to preoperative levels of cognitive function. Surgery and anesthesia have both been implicated to play a role in POCD development, and certain patient-related factors, such as advanced age and low preoperative baseline cognitive function, have consistently been found to predict postoperative cognitive decline. This article will present an overview of POCD and its etiology and provide advice on possible strategies on its prevention.

[Study of functional connectivity during anesthesia based on sparse partial least squares]

Anesthesia consciousness monitoring is an important issue in basic neuroscience and clinical applications, which has received extensive attention. In this study, in order to find the indicators for monitoring the state of clinical anesthesia, a total of 14 patients undergoing general anesthesia were collected for 5 minutes resting electroencephalogram data under three states of consciousness (awake, moderate and deep anesthesia). Sparse partial least squares (SPLS) and traditional synchronized likelihood (SL) are used to calculate brain functional connectivity, and the three conscious states before and after anesthesia were distinguished by the connection features. The results show that through the whole brain network analysis, SPLS and traditional SL method have the same trend of network parameters in different states of consciousness, and the results obtained by SPLS method are statistically significant ( P<0.05). The connection features obtained by the SPLS method are classified by the support vector machine, and the classification accuracy is 87.93%, which is 7.69% higher than that of the connection feature classification obtained by SL method. The results of this study show that the functional connectivity based on the SPLS method has better performance in distinguishing three kinds of consciousness states, and may provides a new idea for clinical anesthesia monitoring.

Electroencephalography: Clinical Applications During the Perioperative Period

Electroencephalography (EEG) monitoring has become technically feasible in daily clinical anesthesia practice. EEG is a sensitive method for detecting neurophysiological changes in the brain and represents an important frontier in the monitoring and treatment of patients in the perioperative period. In this review, we briefly introduce the essential principles of EEG. We review EEG application during anesthesia practice in the operating room, including the use of processed EEG in depth of anesthesia assessment, raw EEG monitoring in recognizing brain states under different anesthetic agents, the use of EEG in the prevention of perioperative neurocognitive disorders and detection of cerebral ischemia. We then discuss EEG utilization in the intensive care units, including the use of EEG in sedative level titration and prognostication of clinical outcomes. Existing literature provides insight into both the advances and challenges of the clinical applications of EEG. Future study is clearly needed to elucidate the precise EEG features that can reliably optimize perioperative care for individual patients.

Anesthetic Management Using Multiple Closed-loop Systems and Delayed Neurocognitive Recovery: A Randomized Controlled Trial

BACKGROUND

Cognitive changes after anesthesia and surgery represent a significant public health concern. We tested the hypothesis that, in patients 60 yr or older scheduled for noncardiac surgery, automated management of anesthetic depth, cardiac blood flow, and protective lung ventilation using three independent controllers would outperform manual control of these variables. Additionally, as a result of the improved management, patients in the automated group would experience less postoperative neurocognitive impairment compared to patients having standard, manually adjusted anesthesia.

METHODS

In this single-center, patient-and-evaluator-blinded, two-arm, parallel, randomized controlled, superiority study, 90 patients having noncardiac surgery under general anesthesia were randomly assigned to one of two groups. In the control group, anesthesia management was performed manually while in the closed-loop group, the titration of anesthesia, analgesia, fluids, and ventilation was performed by three independent controllers. The primary outcome was a change in a cognition score (the 30-item Montreal Cognitive Assessment) from preoperative values to those measures 1 week postsurgery. Secondary outcomes included a battery of neurocognitive tests completed at both 1 week and 3 months postsurgery as well as 30-day postsurgical outcomes.

RESULTS

Forty-three controls and 44 closed-loop patients were assessed for the primary outcome. There was a difference in the cognition score compared to baseline in the control group versus the closed-loop group 1 week postsurgery (-1 [-2 to 0] vs. 0 [-1 to 1]; difference 1 [95% CI, 0 to 3], P = 0.033). Patients in the closed-loop group spent less time during surgery with a Bispectral Index less than 40, had less end-tidal hypocapnia, and had a lower fluid balance compared to the control group.

CONCLUSIONS

Automated anesthetic management using the combination of three controllers outperforms manual control and may have an impact on delayed neurocognitive recovery. However, given the study design, it is not possible to determine the relative contribution of each controller on the cognition score.

Apprenticeship Learning for a Predictive State Representation of Anesthesia

OBJECTIVE

In this paper, we present an original decision support algorithm to assist the anesthesiologists delivery of drugs to maintain the optimal Depth of Anesthesia (DoA).

METHODS

Derived from a Transform Predictive State Representation algorithm (TPSR), our model learned by observing anesthesiologists in practice. This framework, known as apprenticeship learning, is particularly useful in the medical field as it is not based on an exploratory process - a prohibitive behavior in healthcare. The model only relied on the four commonly monitored variables: Heart Rate (HR), the Mean Blood Pressure (MBP), the Respiratory Rate (RR) and the concentration of anesthetic drug (AAFi).

RESULTS

Thirty-one patients have been included. The performances of the model is analyzed with metrics derived from the Hamming distance and cross entropy. They demonstrated that low rank dynamical system had the best performances on both predictions and simulations. Then, a confrontation of our agent to a panel of six real anesthesiologists demonstrated that 95.7% of the actions were valid.

CONCLUSION

These results strongly support the hypothesis that TPSR based models convincingly embed the behavior of anesthesiologists including only four variables that are commonly assessed to predict the DoA.

SIGNIFICANCE

The proposed novel approach could be of great help for clinicians by improving the fine tuning of the DoA. Furthermore, the possibility to predict the evolutions of the variables would help preventing side effects such as low blood pressure. A tool that could autonomously help the anesthesiologist would thus improve safety-level in the surgical room.

Processed EEG monitoring for anesthesia and intensive care practice

Individual response to sedatives and hypnotics is characterized by high variability and the identification of a personalized dose during anesthesia in the operating room and during sedation in the intensive care unit may have beneficial effects. Although the brain is the main target of general intravenous and inhaled anesthetic agents, electroencephalography (EEG) is not routinely utilized to explore cerebral response to sedation and anesthesia probably because EEG trace reading is complex and requires encephalographers' skills. Automated processing algorithms (processed EEG, pEEG) of raw EEG traces provide easy-to-use indices that can be utilized to optimize anesthetic management. A large number of high-quality studies and the recommendations of international scientific societies have confirmed the deleterious consequences of inadequate or excessively deep anesthesia (and sedation) level. In this context, anesthesia in the operating rooms and moderate/deep sedation in intensive care units driven by pEEG monitors could become a standard practice in the near future. The aim of the present review was to provide an overview of current knowledge and debate on available technologies for pEEG monitoring and their role in clinical practice for anesthesia and sedation.

Postoperative Cognitive Dysfunction

Cognitive dysfunction is a common complication in primary or metastatic brain tumors and can be correlated to disease itself or various treatment modalities. The symptoms of cognitive deficits may include problems with memory, attention and information processing. Primary brain tumors are highly associated with neurocognitive deficit and poor quality of life. This review discusses the pathophysiology, risk factors and assessment of cognitive dysfunction. It also gives an overview of the effect of anesthetics on postoperative cognitive dysfunction and its management.

[Dynamics of brain CD68+ and stabilin-1+ macrophage infiltration in patients with myocardial infarction]

Te aim of the study was to evaluate the temporal dynamics of brain CD68+ and stabilin-1+ macrophage infltration in patients with fatal myocardial infarction (MI) type 1.

MATERIALS AND METHODS

Te study included 31 patients with fatal MI type I. Te control group comprised 10 patients of 18-40 age group who died from injuries incompatible with life. Patients with MI were divided into two groups. Group 1 comprised patients who died during the frst 72 hours of MI, group 2 comprised patients who died on days 4‒28. Macrophage infltration in the brain was assessed by immunohistochemical analysis. We used CD68 as a marker for the cells of the macrophage lineage and stabilin-1 as an M2-like macrophage biomarker.

RESULTS

In group 1 the number of brain CD68+ macrophages was signifcantly higher than in the control group. In group 2 the intensity of brain CD68+ cells infltration was lower than in group 1 and higher than in the control group. Tere was a small amount of stabilin-1+ macrophages in the brain of healthy people, as well as of patients who died from MI. Tere were no signifcant differences in the number of stabilin-1+ cells between group 1 and group 2. Correlation analysis revealed the presence of positive correlation between the number of CD68 + macrophages in the infarct, peri-infarct, and non-infarct areas of the myocardium and the number of CD68+ macrophages in the brain in patients with MI. Tere were not correlations between the number of CD68 + and stabilin-1+ cells and the presence of diabetes mellitus, history of stroke, history of MI, and pre-infarction angina.

CONCLUSION

Te number of brain CD68+ macrophages signifcantly increased during the frst three days of MI. Te number of brain stabilin-1+ macrophages did not increase and did not differ from the control values. We observed a positive correlation between the number of CD68+ macrophages in the brain and myocardium.

Effect of Electroencephalography-Guided Anesthetic Administration on Postoperative Delirium Among Older Adults Undergoing Major Surgery: The ENGAGES Randomized Clinical Trial

IMPORTANCE

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

OBJECTIVE

To assess whether EEG-guided anesthetic administration decreases the incidence of postoperative delirium.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial of 1232 adults aged 60 years and older undergoing major surgery and receiving general anesthesia at Barnes-Jewish Hospital in St Louis. Recruitment was from January 2015 to May 2018, with follow-up until July 2018.

INTERVENTIONS

Patients were randomized 1:1 (stratified by cardiac vs noncardiac surgery and positive vs negative recent fall history) to receive EEG-guided anesthetic administration (n = 614) or usual anesthetic care (n = 618).

MAIN OUTCOMES AND MEASURES

The primary outcome was incident delirium during postoperative days 1 through 5. Intraoperative measures included anesthetic concentration, EEG suppression, and hypotension. Adverse events included undesirable intraoperative movement, intraoperative awareness with recall, postoperative nausea and vomiting, medical complications, and death.

RESULTS

Of the 1232 randomized patients (median age, 69 years [range, 60 to 95]; 563 women [45.7%]), 1213 (98.5%) were assessed for the primary outcome. Delirium during postoperative days 1 to 5 occurred in 157 of 604 patients (26.0%) in the guided group and 140 of 609 patients (23.0%) in the usual care group (difference, 3.0% [95% CI, -2.0% to 8.0%]; P = .22). Median end-tidal volatile anesthetic concentration was significantly lower in the guided group than the usual care group (0.69 vs 0.80 minimum alveolar concentration; difference, -0.11 [95% CI, -0.13 to -0.10), and median cumulative time with EEG suppression was significantly less (7 vs 13 minutes; difference, -6.0 [95% CI, -9.9 to -2.1]). There was no significant difference between groups in the median cumulative time with mean arterial pressure below 60 mm Hg (7 vs 7 minutes; difference, 0.0 [95% CI, -1.7 to 1.7]). Undesirable movement occurred in 137 patients (22.3%) in the guided and 95 (15.4%) in the usual care group. No patients reported intraoperative awareness. Postoperative nausea and vomiting was reported in 48 patients (7.8%) in the guided and 55 patients (8.9%) in the usual care group. Serious adverse events were reported in 124 patients (20.2%) in the guided and 130 (21.0%) in the usual care group. Within 30 days of surgery, 4 patients (0.65%) in the guided group and 19 (3.07%) in the usual care group died.

CONCLUSIONS AND RELEVANCE

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

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02241655.

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

BACKGROUND

Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) may complicate a patient's postoperative recovery in several ways. Monitoring of processed electroencephalogram (EEG) or evoked potential (EP) indices may prevent or minimize POD and POCD, probably through optimization of anaesthetic doses.

OBJECTIVES

To assess whether the use of processed EEG or auditory evoked potential (AEP) indices (bispectral index (BIS), narcotrend index, cerebral state index, state entropy and response entropy, patient state index, index of consciousness, A-line autoregressive index, and auditory evoked potentials (AEP index)) as guides to anaesthetic delivery can reduce the risk of POD and POCD in non-cardiac surgical or non-neurosurgical adult patients undergoing general anaesthesia compared with standard practice where only clinical signs are used.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and clinical trial registry databases up to 28 March 2017. We updated this search in February 2018, but these results have not been incorporated in the review.

SELECTION CRITERIA

We included randomized or quasi-randomized controlled trials comparing any method of processed EEG or evoked potential techniques (entropy, BIS, AEP etc.) against a control group where clinical signs were used to guide doses of anaesthetics in adults aged 18 years or over undergoing general anaesthesia for non-cardiac or non-neurosurgical elective operations.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcomes were: occurrence of POD; and occurrence of POCD. Secondary outcomes included: all-cause mortality; any postoperative complications; and postoperative length of stay. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included six randomized controlled trials (RCTs) with 2929 participants comparing processed EEG or EP indices-guided anaesthesia with clinical signs-guided anaesthesia. There are five ongoing studies and one study awaiting classification.Anaesthesia administration guided by the indices from a processed EEG (bispectral index) probably reduces the risk of POD within seven days after surgery with risk ratio (RR) of 0.71 (95% CI 0.59 to 0.85; number needed to treat for an additional beneficial outcome (NNTB) of 17, 95% CI 11 to 34; 2197 participants; 3 RCTs; moderate quality of evidence). Three trials also showed the lower rate of POCD at 12 weeks after surgery (RR 0.71, 95% CI 0.53 to 0.96; NNTB 38, 95% CI 21 to 289; 2051 participants; moderate-quality evidence), but it is uncertain whether processed EEG indices reduce POCD at one week (RR 0.84, 95% CI 0.69 to 1.02; 3 trials; 1989 participants; moderate-quality evidence), and at 52 weeks (RR 0.30, 95% CI 0.05 to 1.80; 1 trial; 59 participants; very low quality of evidence). There may be little or no effect on all-cause mortality (RR 1.01, 95% CI 0.62 to 1.64; 1 trial; 1155 participants; low-quality evidence). One trial suggested a lower risk of any postoperative complications with processed EEG (RR 0.51, 95% CI 0.37 to 0.71; 902 participants, moderate-quality evidence). There may be little or no effect on reduced postoperative length of stay (mean difference -0.2 days, 95% CI -2.02 to 1.62; 1155 participants; low-quality evidence).

AUTHORS' CONCLUSIONS

There is moderate-quality evidence that optimized anaesthesia guided by processed EEG indices could reduce the risk of postoperative delirium in patients aged 60 years or over undergoing non-cardiac surgical and non-neurosurgical procedures. We found moderate-quality evidence that postoperative cognitive dysfunction at three months could be reduced in these patients. The effect on POCD at one week and over one year after surgery is uncertain. There are no data available for patients under 60 years. Further blinded randomized controlled trials are needed to elucidate strategies for the amelioration of postoperative delirium and postoperative cognitive dysfunction, and their consequences such as dementia (including Alzheimer's disease (AD)) in both non-elderly (below 60 years) and elderly (60 years or over) adult patients. The one study awaiting classification and five ongoing studies may alter the conclusions of the review once assessed.