The association of bispectral index values and metrics of cerebral perfusion during cardiopulmonary bypass

Association between intraoperative electroencephalograph complexity index and postoperative delirium in elderly patients undergoing orthopedic surgery: a prospective cohort study

PURPOSE

The primary method for predicting POD (postoperative confusion) relies on the analysis of clinical features. Brain activity complexity is a promising factor associated with the state of consciousness. The aim of this study was to investigate the role of EEG (electroencephalography) complexity changes in predicting POD in elderly patients undergoing orthopedic surgery.

METHODS

From January 2024 to August 2024, 289 elderly patients undergoing orthopedic surgery were recruited at the Second Affiliated Hospital of Nanjing Medical University. Intraoperative EEG data from patients were collected and then EEG nonlinear features were extracted by MATLAB custom scripts. The logistic regression and CNN (convolutional neural networks) were used to explore the predictive effect of nonlinear features on POD from both static and dynamic perspectives.

RESULTS

Low permutation Lempel-Ziv complexity (PLZC) among the EEG nonlinear features emerged as an independent risk factor for POD [OR = 0.210; 95% CI (0.050-0.850); p = 0.029]. Receiver operating characteristic curve (ROC) analysis revealed a poor area under the curve of 0.615 (95% CI 0.517-0.711) for PLZC in predicting POD. After the inclusion of temporal factors, the ROC analysis indicated that the EEG nonlinear indices had a moderate predictive effect on POD [AUC = 0.701; (95% CI 0.541-0.862)].

CONCLUSIONS

EEG nonlinear feature indices may be effective biomarkers for POD and could help predict POD in elderly patients undergoing orthopedic surgery.

Associations between oral frailty, oral microbiota composition, and postoperative delirium in older adult patients

BACKGROUND

Poor oral health, prevalent among the older adults, can undermine overall health and contribute to frailty. Older adults experiencing oral frailty and dysbiosis potentially face an elevated risk of postoperative delirium. This study aims to explore the influence of oral frailty and changes in oral microbiota composition on occurrence of postoperative delirium in older adult patients undergoing non-cardiac surgery.

METHODS

A total of 303 older adult patients undergoing non-cardiac surgeries were recruited in the Second Affiliated Hospital of Nanjing Medical University from July 2023 to December 2023. Oral swabs for oral microbiota analyses were collected before surgery. Subsequently, after propensity score matching, 21 samples from patients with postoperative delirium and 21 samples from patients without postoperative delirium were analyzed for oral microbiota. Our primary objective was to determine the association between oral frailty, changes in oral microbiota composition, and the occurrence of postoperative delirium.

RESULTS

Oral frailty emerged as an independent risk factor for postoperative delirium [HR = 1.75; 95% CI = (1.04-2.96); p = 0.035]. Additionally, patients with postoperative delirium demonstrated lower oral microbiota diversity, as indicated by a reduced Chao index compared with those without postoperative delirium (p = 0.034). A significant association was also found between the dysbiosis index and postoperative delirium (p < 0.001). ROC analysis revealed a pronounced area under the curve of 0.95 (95% CI: 0.88-1.00) for the dysbiosis index in predicting postoperative delirium. Subsequent Principal Coordinates and Kaplan-Meier analyses affirmed that both beta diversity and the dysbiosis index were significantly correlated with incidence of postoperative delirium, with p-values of 0.002 and <0.001, respectively. Furthermore, the interaction analysis through Cox proportional hazards regression suggested a combined effect of oral frailty and the dysbiosis index on the likelihood of developing postoperative delirium (p = 0.004).

CONCLUSIONS

Oral frailty and changes in oral microbiota among older adult patients undergoing non-cardiac surgery may influence the incidence of postoperative delirium.

The Role of Processed Electroencephalography in the Detection and Management of Acute Cerebral Ischemia: A Scoping Review

Processed electroencephalography (pEEG) is increasingly used to titrate the depth of anesthesia. Whether such intra-procedural pEEG monitoring can offer additional information on cerebral perfusion or acute focal or global cerebral ischemia is unknown. This scoping review aimed to provide a narrative analysis of the current literature reporting the potential role of pEEG in adults with acute cerebral ischemia. In keeping with the scoping review methodology, a broad search strategy was defined, including descriptions of encephalography in acute ischemic stroke, carotid endarterectomy, cardiac surgery, and cardiac arrest. Additional screening of citations was conducted by 2 independent assessors. From 310 records, 28 full-text articles met inclusion criteria. Most identified studies were observational in design, and described the diagnostic ability of pEEG to identify cerebral hypoperfusion or its prognostic sensitivity after stroke or carotid surgery. No studies were identified that evaluated pEEG in the specific setting of endovascular therapy for acute ischemic stroke. Low sensitivity associations between pEEG indices and cerebral blood flow were highlighted, which may be influenced by cerebral autoregulatory thresholds. Despite the associations reported in observational studies, this review identified significant uncertainty in the role of pEEG during cerebral ischemia. There is a paucity of high-level observational (cohort or case-control) or randomized trial research examining the possible role of pEEG for the detection and management of cerebral ischemia during acute stroke, including during endovascular therapy, or in other common scenarios of acute cerebral ischemia.

Association between EEG metrics and continuous cerebrovascular autoregulation assessment: a scoping review

OBJECTIVE

Cerebrovascular autoregulation is defined as the capacity of cerebral blood vessels to maintain stable cerebral blood flow despite changing blood pressure. It is assessed using the pressure reactivity index (the correlation coefficient between mean arterial blood pressure and intracranial pressure). The objective of this scoping review is to describe the existing evidence concerning the association of EEG and cerebrovascular autoregulation in order to identify key concepts and detect gaps in the current knowledge.

METHODS

Embase, MEDLINE, SCOPUS, and Web of Science were searched considering articles between their inception up to September 2023. Inclusion criteria were human (paediatric and adult) and animal studies describing correlations between continuous EEG and cerebrovascular autoregulation assessments.

RESULTS

Ten studies describing 481 human subjects (67% adult, 59% critically ill) were identified. Seven studies assessed qualitative (e.g. seizures, epileptiform potentials) and five evaluated quantitative (e.g. bispectral index, alpha-delta ratio) EEG metrics. Cerebrovascular autoregulation was evaluated based on intracranial pressure, transcranial Doppler, or near infrared spectroscopy. Specific combinations of cerebrovascular autoregulation and EEG metrics were evaluated by a maximum of two studies. Seizures, highly malignant patterns or burst suppression, alpha peak frequency, and bispectral index were associated with cerebrovascular autoregulation. The other metrics showed either no or inconsistent associations.

CONCLUSION

There is a paucity of studies evaluating the link between EEG and cerebrovascular autoregulation. The studies identified included a variety of EEG and cerebrovascular autoregulation acquisition methods, age groups, and diseases allowing for few overarching conclusions. However, the preliminary evidence for the presence of an association between EEG metrics and cerebrovascular autoregulation prompts further in-depth investigations.

Risk factors for postoperative delirium in frail elderly patients undergoing on-pump cardiac surgery and development of a prediction model-a prospective observational study

Background

To identify the risk factors for postoperative delirium (POD) after cardiac surgery in frail elderly patients and develop a receiver operating characteristic (ROC) prediction model to confirm the effectiveness.

Methods

This was a prospective observational study, patients were assessed preoperatively according to the frailty index (FI) scale. Cerebral (SctO2) was assessed at different time points using near-infrared spectroscopy (NIRS). On the basis of the occurrence of POD within 7 days after surgery, patients were divided into POD and non-POD groups. Risk factors were analyzed using logistic regression analysis, while their predictive values were evaluated using the receiver operating characteristic curve analysis.

Results

POD was significantly associated with frailty, lower preoperative MMSE scores, hyperlipidemia, diabetes, cerebrovascular disease, lower hemoglobin level, lower albumin level, longer operation time, longer CPB time, lower SctO2 at T5, and lower SctO2baseline (P < 0.05). SrtO2 and SmtO2 did not differ significantly between groups. FI, preoperative MMSE score, and operation time as independent risk factors (P < 0.05). Significant predictive value was demonstrated in all 3 variables (P < 0.001; respectively). Among them, high sensitivity and specificity were observed with the FI (cut-off value 0.27, sensitivity 75%, specificity 73.5%) and operation time (cut-off value 237.5, sensitivity 62.5%, specificity 78.6%).

Conclusions

The FI, preoperative MMSE score, and operation time were independent risk factors for POD in elderly patients after cardiac surgery, with high predictive value observed with the FI and operation time. Cerebral oxygen saturation was associated with POD but was not an independent risk factor.

Clinical Trial Registration

Chinese Clinical Trail Registry, No: chictr2200056038.

Update of the European Society of Anaesthesiology and Intensive Care Medicine evidence-based and consensus-based guideline on postoperative delirium in adult patients

Postoperative delirium (POD) remains a common, dangerous and resource-consuming adverse event but is often preventable. The whole peri-operative team can play a key role in its management. This update to the 2017 ESAIC Guideline on the prevention of POD is evidence-based and consensus-based and considers the literature between 01 April 2015, and 28 February 2022. The search terms of the broad literature search were identical to those used in the first version of the guideline published in 2017. POD was defined in accordance with the DSM-5 criteria. POD had to be measured with a validated POD screening tool, at least once per day for at least 3 days starting in the recovery room or postanaesthesia care unit on the day of surgery or, at latest, on postoperative day 1. Recent literature confirmed the pathogenic role of surgery-induced inflammation, and this concept reinforces the positive role of multicomponent strategies aimed to reduce the surgical stress response. Although some putative precipitating risk factors are not modifiable (length of surgery, surgical site), others (such as depth of anaesthesia, appropriate analgesia and haemodynamic stability) are under the control of the anaesthesiologists. Multicomponent preoperative, intra-operative and postoperative preventive measures showed potential to reduce the incidence and duration of POD, confirming the pivotal role of a comprehensive and team-based approach to improve patients' clinical and functional status.

Delirium after Cardiac Surgery-A Narrative Review

Postoperative delirium (POD) after cardiac surgery is a well-known phenomenon which carries a higher risk of morbidity and mortality. Multiple patient-specific risk factors and pathophysiologic mechanisms have been identified and therapies have been proposed to mitigate risk of delirium development postoperatively. Notably, cardiac surgery frequently involves the use of an intraoperative cardiopulmonary bypass (CPB), which may contribute to the mechanisms responsible for POD. Despite our greater understanding of these causative factors, a substantial reduction in the incidence of POD remains high among cardiac surgical patients. Multiple therapeutic interventions have been implemented intraoperatively and postoperatively, many with conflicting results. This review article will highlight the incidence and impact of POD in cardiac surgical patients. It will describe some of the primary risk factors associated with POD, as well as anesthetic management and therapies postoperatively that may help to reduce delirium.

Age-dependent neurovascular coupling characteristics in children and adults during general anesthesia

General anesthesia is an indispensable procedure in clinical practice. Anesthetic drugs induce dramatic changes in neuronal activity and cerebral metabolism. However, the age-related changes in neurophysiology and hemodynamics during general anesthesia remain unclear. Therefore, the objective of this study was to explore the neurovascular coupling between neurophysiology and hemodynamics in children and adults during general anesthesia. We analyzed frontal electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS) signals recorded from children (6-12 years old, n = 17) and adults (18-60 years old, n = 25) during propofol-induced and sevoflurane-maintained general anesthesia. The neurovascular coupling was evaluated in wakefulness, maintenance of a surgical state of anesthesia (MOSSA), and recovery by using correlation, coherence and Granger-causality (GC) between the EEG indices [EEG power in different bands and permutation entropy (PE)], and hemodynamic responses the oxyhemoglobin (Δ[HbO]) and deoxy-hemoglobin (Δ[Hb]) from fNIRS in the frequency band in 0.01-0.1 Hz. The PE and Δ[Hb] performed well in distinguishing the anesthesia state (p > 0.001). The correlation between PE and Δ[Hb] was higher than those of other indices in the two age groups. The coherence significantly increased during MOSSA (p < 0.05) compared with wakefulness, and the coherences between theta, alpha and gamma, and hemodynamic activities of children are significantly stronger than that of adults' bands. The GC from neuronal activities to hemodynamic responses decreased during MOSSA, and can better distinguish anesthesia state in adults. Propofol-induced and sevoflurane-maintained combination exhibited age-dependent neuronal activities, hemodynamics, and neurovascular coupling, which suggests the need for separate rules for children's and adults' brain states monitoring during general anesthesia.

Effect of combined use of cerebral oximetry and electroencephalogram monitoring on the incidence of perioperative neurocognitive disorders in adult cardiac and non-cardiac surgery: A systematic review of randomized and non-randomized trials

Background: There is insufficient evidence to recommend using either intraoperative cerebral oximetry or (processed) electroencephalogram (EEG) alone for preventing perioperative neurocognitive disorders (PNDs). Objective: To evaluate the effectiveness of combined use of cerebral oximetry and electroencephalogram-guided anesthesia on the incidence of PNDs in adult patients undergoing cardiac and non-cardiac interventions. Methods: A PICOS - based systematic review of English articles using Pubmed and Embase (from inception to August 2022) was performed. There were no exclusion criteria regarding the type of the study. Abstract proceedings and new study protocols or ongoing studies were not included. Review articles were analyzed in search of eligible references. All possible terms that were illustrative of PNDs were used. Results: Among the 63 full manuscripts that were analyzed in detail, 15 met the inclusion criteria. We found 2 retrospective, 8 prospective observational and 5 randomized controlled trials of which 1 did not evaluate the use of neuromonitoring in the randomization process. The definition and the methods used to diagnose PNDs were very heterogeneous. Only 8 studies used an algorithm to avoid/treat cerebral oxygen desaturation and/or to treat EEG abnormalities. Overall, there was a tendency towards less PNDs in studies where such an algorithm was used. Conclusions: Our results suggest that integrating information obtained from cerebral oximetry and an EEG monitor may reduce the incidence of PNDs whenever an adapted algorithm is used to improve brain function.

Nomogram for Prediction of Postoperative Delirium after Deep Brain Stimulation of Subthalamic Nucleus in Parkinson’s Disease under General Anesthesia

Introduction. Postoperative delirium can increase cognitive impairment and mortality in patients with Parkinson’s disease. The purpose of this study was to develop and internally validate a clinical prediction model of delirium after deep brain stimulation of the subthalamic nucleus in Parkinson’s disease under general anesthesia. Methods. We conducted a retrospective observational cohort study on the data of 240 patients with Parkinson’s disease who underwent deep brain stimulation of the subthalamic nucleus under general anesthesia. Demographic characteristics, clinical evaluation, imaging data, laboratory data, and surgical anesthesia information were collected. Multivariate logistic regression was used to develop the prediction model for postoperative delirium. Results. A total of 159 patients were included in the cohort, of which 38 (23.90%) had postoperative delirium. Smoking (OR 4.51, 95% CI 1.56–13.02, $p<0.01$ ) was the most important risk factor; other independent predictors were orthostatic hypotension (OR 3.42, 95% CI 0.90–13.06, $p=0.07$ ), inhibitors of type-B monoamine oxidase (OR 3.07, 95% CI 1.17–8.04, $p=0.02$ ), preoperative MRI with silent brain ischemia or infarction (OR 2.36, 95% CI 0.90–6.14, $p=0.08$ ), Hamilton anxiety scale score (OR 2.12, 95% CI 1.28–3.50, $p<0.01$ ), and apolipoprotein E level in plasma (OR 1.48, 95% CI 0.95–2.29, $p=0.08$ ). The area under the receiver operating characteristic curve (AUC) was 0.76 (95% CI 0.66–0.86). A nomogram was established and showed good calibration and clinical predictive capacity. After bootstrap for internal verification, the AUC was 0.74 (95% CI 0.66–0.83). Conclusion. This study provides evidence for the independent inducing factors of delirium after deep brain stimulation of the subthalamic nucleus in Parkinson’s disease under general anesthesia. By predicting the development of delirium, our model may identify high-risk groups that can benefit from early or preventive intervention.