Identification of individuals at risk for postoperative cognitive dysfunction (POCD)

Perioperative cognition in association with malnutrition and frailty: a narrative review

Postoperative delirium (POD) is a prevalent clinical entity characterized by reversible fluctuating altered mental status and cognitive impairment with acute and rapid onset a few days after major surgery. Postoperative cognitive decline (POCD) is a more permanent extension of POD characterized by prolonged global cognitive impairment for several months to years after surgery and anesthesia. Both syndromes have been shown to increase morbidity and mortality in postoperative patients making their multiple risk factors targets for optimization. In particular, nutrition imparts a significant and potentially reversible risk factor. Malnutrition and frailty have been linked as risk factors and predictive indicators for POD and less so for POCD. This review aims to outline the association between nutrition and perioperative cognitive outcomes as well as potential interventions such as prehabilitation.

Neuroinflammation: The central enabler of postoperative cognitive dysfunction

The proportion of advanced age patients undergoing surgical procedures is on the rise owing to advancements in surgical and anesthesia technologies as well as an overall aging population. As a complication of anesthesia and surgery, older patients frequently suffer from postoperative cognitive dysfunction (POCD), which may persist for weeks, months or even longer. POCD is a complex pathological process involving multiple pathogenic factors, and its mechanism is yet unclear. Potential theories include inflammation, deposition of pathogenic proteins, imbalance of neurotransmitters, and chronic stress. The identification, prevention, and treatment of POCD are still in the exploratory stages owing to the absence of standardized diagnostic criteria. Undoubtedly, comprehending the development of POCD remains crucial in overcoming the illness. Neuroinflammation is the leading hypothesis and a crucial component of the pathological network of POCD and may have complex interactions with other mechanisms. In this review, we discuss the possible ways in which surgery and anesthesia cause neuroinflammation and investigate the connection between neuroinflammation and the development of POCD. Understanding these mechanisms may likely ensure that future treatment options of POCD are more effective.

Spinal anesthesia for L5-S1 interlaminar endoscopic lumbar discectomy: a retrospective study

OBJECTIVE

This study aimed to report our experience with spinal anesthesia (SA) in patients undergoing L5-S1 interlaminar endoscopic lumbar discectomy (IELD) and clarify its advantages and disadvantages.

METHODS

One hundred twelve patients who underwent IELD for an L5-S1 disc herniation under SA were retrospectively analyzed. SA with 0.5% ropivacaine was administered using a 27-gauge fine needle. Intraoperatively, the volume and level of SA, surgical time, blood loss, and cardiopulmonary complications were documented. Postoperative data was collected included the number of patients who ambulated on the day of surgery, incidence of complications and were then statistically analyzed.

RESULTS

Analgesia was complete throughout the entire operation in all patients and no other adjuvant intraoperative analgesic drugs were needed. Mean visual analog scale scores for intraoperative and early postoperative (24 h) pain were 0 and 2.43 ± 1.66. SA was administered at the L3-4 interspace in 34 patients (30.4%) and the L2-3 interspace in 78 (69.6%). Administration was successful with the first attempt in all patients. Mean operation time was 70.12 ± 6.52 min. Mean intraoperative blood loss volume was 20.71 ± 5.26 ml. Ninety-eight patients ambulated on the same day as surgery. Mean length of hospital stay was 24.36 ± 3.64 h. Dural injury without damaging the nerve root occurred in one patient. One patient experienced recurrent disc herniation. Intraoperative hypotension and respiratory distress occurred in five (4.5%) and three (2.7%) patients, respectively. Three patients (2.7%) received postoperative analgesia therapy and two (1.8%) experienced nausea. Two patients (1.8%) developed urinary retention. Spinal headache, cauda equina syndrome, and neurotoxicity did not occur.

CONCLUSION

SA can achieve satisfactory pain control for patients undergoing IELD with a low incidence of adverse events. SA may be a useful alternative to local and general anesthesia for IELD surgery. Future randomized controlled trials are warranted to investigate.

Postsurgery Subjective Cognitive and Short-Term Memory Impairment Among Middle-Aged Chinese Patients

Importance

Perioperative neurocognitive disorder, particularly postoperative cognitive impairment, is common and associated with multiple medical and social adversities, although data from China are lacking.

Objective

To examine the incidence, trajectory, and risk factors for subjective cognitive and short-term memory impairment after surgery in the Chinese population.

Design, Setting, and Participants

This cohort study used data from the China Surgery and Anesthesia Cohort to assess surgical patients aged 40 to 65 years from 2 medical centers between July 15, 2020, and March 31, 2023, with active follow-up within 1 year after the surgery. Of 11 158 patients who were successfully recruited (response rate, 94.4%), 10 149 participants were eligible and available for analysis. From this population, separate cohorts were constructed for analyzing subjective cognitive impairment (8105 noncardiac and 678 cardiac surgery patients) and short-term memory impairment (5246 noncardiac and 454 cardiac surgery patients).

Exposures

Twenty-four potential risk factors regarding comorbidities, preoperative psychological conditions, anesthesia- or surgery-related factors, and postsurgical events were included.

Main Outcomes and Measures

Outcomes included subjective cognitive function measured by the 8-Item Informant Interview to Differentiate Aging and Dementia (AD8; scores range from 0 to 8, with higher scores indicating more severe cognitive impairment) and short-term memory measured by the 3-Word Recall Test (TRT; scores range from 0 to 3, with lower scores indicating more severe short-term memory impairment) at 1, 3, 6, and 12 months after noncardiac and cardiac surgery. Generalized linear mixed models were used to identify risk factors associated with the presence of AD8 (score ≥2) or TRT (score <3) abnormality as well as the aggressively deteriorative trajectories of those cognitive measurements.

Results

For noncardiac surgery patients, the AD8 analysis included 8105 patients (mean [SD] age, 52.3 [7.1] years; 3378 [41.7%] male), and the TRT analysis included 5246 patients (mean [SD] age, 51.4 [7.0] years; 1969 [37.5%] male). The AD8 abnormality incidence rates after noncardiac surgery increased from 2.2% (175 of 8105) at 7 days to 17.1% (1059 of 6191) at 6 months after surgery, before appearing to decrease. In contrast, the TRT abnormality incidence rates followed a U-shaped pattern, with the most pronounced incidence rates seen at 7 days (38.9% [2040 of 5246]) and 12 months (49.0% [1394 of 2845]). Similar patterns were seen among cardiac surgery patients for the AD8 analysis (678 patients; mean [SD] age, 53.2 [6.3] years; 393 [58.0%] male) and TRT analysis (454 patients; mean [SD] age, 52.4 [6.4] years; 248 [54.6%] male). Among noncardiac surgery patients, the top risk factors for aggressively deteriorative AD8 trajectory and for AD8 abnormality, respectively, after surgery were preoperative sleep disturbances (Pittsburgh Sleep Quality Index ≥16 vs 0-5: odds ratios [ORs], 4.04 [95% CI, 2.20-7.40] and 4.54 [95% CI, 2.40-8.59]), intensive care unit stay of 2 days or longer (ORs, 2.43 [95% CI, 1.26-4.67] and 3.07 [95% CI, 1.67-5.65]), and preoperative depressive symptoms (ORs, 1.76 [95% CI, 1.38-2.24] and 2.23 [95% CI, 1.79-2.77]). Analyses for TRT abnormality and trajectory, as well as the analyses conducted among cardiac surgery patients, found fewer associated factors.

Conclusions and Relevance

This cohort study of middle-aged Chinese surgery patients found subjective cognitive and short-term memory impairment within 12 months after both cardiac and noncardiac surgery, with multiple identified risk factors, underscoring the potential of preoperative psychological interventions and optimized perioperative management for postoperative cognitive impairment prevention.

Comparison of Procedural Sedation With Propofol and Dexmedetomidine During Transcatheter Aortic Valve Replacement Using the Transfemoral Approach

OBJECTIVES

Although procedural sedation is an established method of anesthesia for transcatheter aortic valve replacement (TAVR), reliable evidence to guide the choice of a suitable sedative agent remains scarce. Accordingly, this trial aimed to compare the effect of procedural sedation with dexmedetomidine versus propofol on postoperative neurocognitive and related clinical outcomes in patients undergoing TAVR.

DESIGN

Prospective, randomized, double-blind clinical trial.

SETTING

The study was conducted at the University Medical Centre Ljubljana, Slovenia.

PARTICIPANTS

The study enrolled 78 patients who underwent TAVR under procedural sedation between January 2019 and June 2021. Seventy-one patients randomized into the propofol group (n = 34) and dexmedetomidine group (n = 37) were included in the final analysis.

INTERVENTIONS

Patients in the propofol group received sedation with propofol (continuous intravenous infusion of 0.5-2.5 mg/kg/h), whereas patients in the dexmedetomidine group received sedation with dexmedetomidine (loading dose of 0.5 µg/kg over 10 minutes followed by continuous intravenous infusion of 0.2-1.0 µg/kg/h).

MEASUREMENTS AND MAIN RESULTS

Minimental state examination (MMSE) was performed before and 48 hours after TAVR. There was no statistically significant difference in MMSE scores between groups before TAVR (p = 0.253), but the MMSE after the procedure revealed a significantly lower incidence of delayed neurocognitive recovery (p = 0.005) and thus better cognitive outcomes in the dexmedetomidine group (p = 0.022).

CONCLUSIONS

Compared with propofol, procedural sedation with dexmedetomidine in TAVR was associated with a significantly lower incidence of delayed neurocognitive recovery.

Novel Mechanisms of Perioperative Neurocognitive Disorders: Ferroptosis and Pyroptosis

Perioperative neurocognitive disorders (PNDs) are some of the most common postoperative complications among the elderly and susceptible individuals, which significantly worsens the clinical outcome of patients. However, the prevention and treatment strategies of PNDs are difficult to determine and implement since the pathogenesis of PNDs is not well understood. The development of living organisms is associated with active and organized cell death, which is essential for maintaining the homeostasis of life. Ferroptosis is a programmed cell death (different from apoptosis and necrosis) mainly caused by an imbalance in the generation and degradation of intracellular lipid peroxides due to iron overload. Pyroptosis is an inflammatory cell death characterized by the creation of membrane holes mediated by the gasdermin (GSDM) family, followed by cell lysis and the release of pro-inflammatory cytokines. Ferroptosis and pyroptosis are involved in the pathogenesis of various central nervous system (CNS) diseases. Furthermore, ferroptosis and pyroptosis are closely associated with the occurrence and development of PNDs. This review summarizes the main regulatory mechanisms of ferroptosis and pyroptosis and the latest related to PNDs. Based on the available evidence, potential intervention strategies that can alleviate PNDs by inhibiting ferroptosis and pyroptosis have also been provided.

The role of PERK-eIF2α-ATF4-CHOP pathway in sevoflurane induced neuroapoptosis and cognitive dysfunction in aged mice

Postoperative cognitive dysfunction (POCD) is a common surgical complication that causes additional pain in patients and affects their quality of life. To address this problem, emerging studies have focused on the POCD. Recent studies have shown that aging and anesthetic exposure are the two major risk factors for developing POCD. However, few reports described the exact molecular mechanisms underlying POCD in elderly patients. In the previous studies, the endoplasmic reticulum (ER) stress and neuroapoptosis in the hippocampus were associated with inducing POCD; however, no further information on the related signaling pathways could be disclosed. The PERK-eIF2α-ATF4-CHOP pathway is identified as the main regulatory pathway involved in ER stress and cell apoptosis. Therefore, we assume that the occurrence of POCD induced by sevoflurane inhalation may potentially result from ER stress and neuroapoptosis in the hippocampus of aged mice mediated by the PERK-eIF2α-ATF4-CHOP pathway. In our study, we found a relationship between sevoflurane inhalation concentration and memory decline in aged mice, with a 'ceiling effect'. We have confirmed that POCD induced by sevoflurane results from ER stress and neuroapoptosis in the hippocampus of aged mice, which is regulated by the over-expression of PERK-eIF2α-ATF4-CHOP pathway. Furthermore, we also showed that the dephosphorylation inhibitor of eIF2α (salubrinal) could down-regulate PERK-eIF2α-ATF4-CHOP pathway expression to inhibit ER stress and enhance the cognitive function of aged mice. In general, our study has elucidated one of the molecular mechanisms of sevoflurane-related cognitive dysfunction in aged groups and provided new strategies for treating sevoflurane-induced POCD.

Investigation on Awareness of Cognitive Impairment Diseases Among Surgical Practitioners

Objective

In this study, we assessed the awareness of cognitive dysfunction and the reasons for the lack of awareness among surgical practitioners in Jiaxing.

Methods

Questionnaires were distributed to surgical practitioners covering all Class III and Class II hospitals in Jiaxing. Respondents were asked to make selections regarding the demographic data, clinical attitudes and practices of cognitive dysfunction based on Alzheimer's Disease Assessment Scale (ADKS) of the Chinese version.

Results

A total of 180 questionnaires were distributed, 12 of which were incomplete, with 168 being included for analysis. The respondents were generally under 50 years of age (150, 89.3%), predominantly males (146, 86.9%), and surgeons (153, 91.1%). They generally had a bachelor's or master's degrees (165, 98.2%), and served in Class III hospitals (127, 75.6%). The title of the practitioner was found to impact their attention toward their patients' cognitive status during preoperative preparation (P<0.05). Titles and hospital levels were found to influence decisions of surgical practitioners to invite specialist physicians for consultation and assessment when a patient was identified to have cognitive dysfunction (P<0.05). Most surgical practitioners had little knowledge or training about Alzheimer's disease and cognitive dysfunction. Among the 168 respondents, the mean ADKS score was 20.14±2.40, and the awareness rate was 67.1%, indicating that the surgical practitioner's title influenced ADKS score (P<0.001).

Conclusion

Surgical practitioners, especially young physicians and those in Class II hospitals, had lower awareness of cognitive dysfunction, with low ADKS scores; therefore, they needed to be further trained to recognize cognitive dysfunction.

Research progress of postoperative cognitive dysfunction in cardiac surgery under cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is often used in cardiothoracic surgery because its nonphysiological state causes pathophysiological changes in the body, causing multiorgan and multitissue damage to varying degrees. Postoperative cognitive dysfunction (POCD) is a common central nervous system complication after cardiac surgery. The etiology and mechanism of POCD are not clear. Neuroinflammation, brain mitochondrial dysfunction, cerebral embolism, ischemia, hypoxia, and other factors are related to the pathogenesis of POCD. There is a close relationship between CPB and POCD, as CPB can cause inflammation, hypoxia and reperfusion injury, and microemboli formation, all of which can trigger POCD. POCD increases medical costs, seriously affects patients' quality of life, and increases mortality. Currently, there is a lack of effective treatment methods for POCD. Commonly used methods include preoperative health management, reducing inflammation response during surgery, preventing microemboli formation, and implementing individualized rehabilitation programs after surgery. Strengthening preventive measures can minimize the occurrence of POCD and its adverse effects.

Mechanism of the Mongolian medicine Eerdun Wurile basic formula in improving postoperative cognitive dysfunction by inhibiting apoptosis through the SIRT1/p53 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The Mongolian medicine Eerdun Wurile is a commonly used Mongolian in folk medicine used to treat cerebral nervous system diseases such as cerebral hemorrhage, cerebral thrombosis, nerve injury and cognitive function, cardiovascular diseases such as hypertension and coronary heart disease. Eerdun wurile may effect anti-postoperative cognitive function.

AIM OF THE STUDY

To investigate the molecular mechanism of the Mongolian medicine Eerdun Wurile Basic Formula (EWB) in improving postoperative cognitive dysfunction (POCD) based on Network pharmacology, and to confirm involvement of the SIRT1/p53 signal pathway, one of the key signal pathways, by using the POCD mouse model.

MATERIAL AND METHODS

Obtain compounds and disease-related targets through TCMSP, TCMID, PubChem, PharmMapper platforms, GeneCards, and OMIM databases, and screen intersection genes; Use Cytoscape software to build a "drug-ingredient-disease-target" network, and the STRING platform for protein interaction analysis.; R software was used to analyze the function of gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment.; AutoDock Vina software for active components and core targets to Perform molecular docking. The POCD mouse model was prepared by intracerebroventricular injection of lipopolysaccharide (LPS), and the morphological changes of hippocampal tissue were observed by hematoxylin-eosin (HE) staining, Western blot, immunofluorescence and TUNEL were used to verify the results of network pharmacological enrichment analysis.

RESULTS

There were 110 potential targets for improving POCD by EWB, 117 items were enriched by GO, and 113 pathways were enriched by KEGG, among which the SIRT1/p53 signaling pathway was related to the occurrence of POCD. Quercetin, kaempferol, vestitol, β-sitosterol and 7-methoxy-2-methyl isoflavone in EWB can form stable conformations with low binding energy with core target proteins IL-6, CASP3, VEGFA, EGFR and ESR1. Animal experiments showed that compared with the POCD model group, the EWB group could significantly improve the apoptosis in the hippocampus of the mice, and significantly down-regulate the expression of Acetyl-p53 protein (P < 0.05).

CONCLUSION

EWB can improve POCD with the characteristics of multi-component, multi-target, and multi-pathway synergistic effects. Studies have confirmed that EWB can improve the occurrence of POCD by regulating the expression of genes related to the SIRT1/p53 signal pathway, which provides a new target and basis for the treatment of POCD.

Intergenerational Perioperative Neurocognitive Disorder

Accelerated neurocognitive decline after general anesthesia/surgery, also known as perioperative neurocognitive disorder (PND), is a widely recognized public health problem that may affect millions of patients each year. Advanced age, with its increasing prevalence of heightened stress, inflammation, and neurodegenerative alterations, is a consistent contributing factor to the development of PND. Although a strong homeostatic reserve in young adults makes them more resilient to PND, animal data suggest that young adults with pathophysiological conditions characterized by excessive stress and inflammation may be vulnerable to PND, and this altered phenotype may be passed to future offspring (intergenerational PND). The purpose of this narrative review of data in the literature and the authors' own experimental findings in rodents is to draw attention to the possibility of intergenerational PND, a new phenomenon which, if confirmed in humans, may unravel a big new population that may be affected by parental PND. In particular, we discuss the roles of stress, inflammation, and epigenetic alterations in the development of PND. We also discuss experimental findings that demonstrate the effects of surgery, traumatic brain injury, and the general anesthetic sevoflurane that interact to induce persistent dysregulation of the stress response system, inflammation markers, and behavior in young adult male rats and in their future offspring who have neither trauma nor anesthetic exposure (i.e., an animal model of intergenerational PND).

Inhibition of PINK1-Mediated Mitophagy Contributes to Postoperative Cognitive Dysfunction through Activation of Caspase-3/GSDME-Dependent Pyroptosis

PTEN-induced kinase 1 (PINK1)-mediated mitophagy and caspase-1/gasdermin D canonical pyroptosis pathways have been implicated in the pathogenesis of postoperative cognitive dysfunction (POCD). However, gasdermin E (GSDME), another recently identified executioner of pyroptosis that can be specifically cleaved by caspase-3, is highly expressed in the brain and neurons. This study aimed to ascertain whether PINK1-dependent mitophagy governs postoperative cognitive capacity through caspase-3/GSDME. Twelve month old male Sprague-Dawley rats underwent exploratory laparotomy under isoflurane anesthesia. Lipopolysaccharide (LPS)-primed SH-SY5Y cells were used to mimic postsurgical neuroinflammation. For the interventional study, rats were administered with adeno-associated virus serotype 9 (AAV9)-mediated silencing of Pink1 and/or caspase-3 inhibitor Ac-DEVD-CHO (Ac-DC). SH-SY5Y cells were treated with siPINK1 and/or Ac-DC. Cognitive performance was assessed using the Morris water maze test. The mitophagy- and pyroptosis-related parameters were determined in the hippocampus and SH-SY5Y cells. Anesthesia/surgery and LPS caused defective PINK1-mediated mitophagy and activation of caspase-3/GSDME-dependent pyroptosis. AAV-9 mediated Pink1 overexpression mitigated cognitive impairment and caspase-3/GSDME-dependent pyroptosis. Conversely, inhibition of PINK1 aggravates POCD and overactivates neuronal pyroptosis. These abnormalities were rescued by Ac-DC treatment. Collectively, PINK1-mediated mitophagy regulates anesthesia and surgery-induced cognitive impairment by negatively affecting the caspase-3/GSDME pyroptosis pathway, which provides a promising therapeutic target for POCD.

Correlation between neutrophil/lymphocyte ratio, platelet/lymphocyte ratio and postoperative cognitive dysfunction in elderly patients with esophageal cancer

The present study intends to investigate the correlation between neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and postoperative cognitive dysfunction (POCD) in elderly patients with esophageal cancer. Elderly patients >65 years old with esophageal cancer in our department from October 2017 to June 2021 were included in the study. The cognitive function of the patients was assessed by the mini-mental state examination (MMSE) Scale at 1day, 3 days, and 7days after surgery. POCD was considered when the scores were <27 points, and the remaining patients were included in the control group. A total of 104 elderly patients with esophageal cancer were included in this study, and 24 patients developed POCD, with an incidence of 23.1%. The expression of NLR and PLR in both 2 groups was increased on the 1st postoperative day compared with that before surgery. There was no significant difference in the expression of NLR and PLR between the 2 groups before operation, but the expression of both in the POCD group was significantly higher than that in the control group after operation (P < .05). Logistic regression analysis showed that smoking, postoperative NLR and postoperative PLR were independent risk factors for POCD. Spearman test showed that NLR was negatively correlated with MMSE scores at postoperative 1 day and 3 days (P < .05), while PLR was negatively correlated with MMSE scores at postoperative 1 day, 3 days and 7 days (P < .05). The Area Under receiver operating characteristic curve (AUC) of postoperative NLR for predicting POCD in elderly patients with esophageal cancer was 0.656, and the AUC of postoperative PLR was 0.722. After combination of NLR and PLR, the AUC increased to 0.803 with the sensitivity of 66.7% and specificity of 82.5%. The expression level of postoperative NLR and PLR in elderly patients with esophageal cancer combined with POCD is significantly increased, which is associated with postoperative cognitive impairment. Moreover, the combination of NLR and PLR has a good predictive ability for POCD, which could be used as a potential biomarker for early diagnosis of POCD.

Effects of regional cerebral oxygen saturation monitoring on postoperative cognitive dysfunction in older patients: a systematic review and meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is common after surgery and anesthesia, particularly in older patients. It has been reported that regional cerebral oxygen saturation (rSO₂) monitoring potentially influences the occurrence of POCD. However, its role in the prevention of POCD remains controversial in older patients. Additionally, the quality of evidence on this topic is still relatively poor.

METHODS

The electronic databases PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched using the indicated keywords from their inception to June 10, 2022. We limited our meta-analysis to randomized controlled trials (RCTs) that assessed the effects of rSO₂ monitoring on POCD in older patients. Methodological quality and risk of bias were assessed. The primary outcome was the incidence of POCD during hospitalization. The secondary outcomes were postoperative complications and the length of hospital stay (LOS). Odds ratios (OR) and 95% confidence intervals (CI) were calculated to determine the incidence of POCD and postoperative complications. The standardized mean difference (SMD) instead of the raw mean difference and 95% CI were calculated for LOS.

RESULTS

Six RCTs, involving 377 older patients, were included in this meta-analysis. The incidence of POCD ranges from 17 to 89%, with an overall prevalence of 47% in our pooled analysis. Our results demonstrated that rSO₂-guided intervention could reduce the incidence of POCD in older patients undergoing non-cardiac surgery (OR, 0.44; 95% CI, 0.25 to 0.79; P = 0.006) rather than cardiac surgery (OR, 0.69; 95% CI, 0.32 to 1.52; P = 0.36). Intraoperative rSO₂ monitoring was also associated with a significantly shorter LOS in older patients undergoing non-cardiac surgery (SMD, -0.93; 95% CI, -1.75 to -0.11; P = 0.03). Neither the incidence of postoperative cardiovascular (OR, 1.12; 95% CI, 0.40 to 3.17; P = 0.83) nor surgical (OR, 0.78; 95% CI, 0.35 to 1.75; P = 0.54) complications were affected by the use of rSO₂ monitoring.

CONCLUSION

The use of rSO₂ monitoring is associated with a lower risk of POCD and a shorter LOS in older patients undergoing non-cardiac surgery. This may have the potential to prevent POCD in high-risk populations. Further large RCTs are still warranted to support these preliminary findings.