Surgery, neuroinflammation and cognitive impairment

CD33 Ameliorates Surgery-Induced Spatial Learning and Memory Impairments Through TREM2

Neuroinflammation is implicated in the onset of postoperative cognitive dysfunction (POCD), with CD33 and triggering receptor expressed on myeloid cells 2 (TREM2) playing crucial roles in immune response modulation and neuroinflammatory processes. A total of 96 aged male C57/BL6 mice (9-12 months) were randomly assigned to one of four groups, each receiving an siRNA injection into the lateral ventricle. Subsequently, the mice underwent partial hepatectomy under general anesthesia. To assess cognitive function, the Morris water maze tests were conducted both pre- and post-surgery. Following behavioral assessments, hippocampal tissues were swiftly harvested. The regulation of CD33 and TREM2 expression was achieved through siRNA in the BV2 microglia cell line. Expression levels of CD33 and TREM2 were evaluated both in vitro and in vivo using quantitative RT-PCR and western blot analyses. This study explored the impact of CD33 and TREM2 on POCD in aged mice and revealed that surgery and anesthesia increased CD33 expression, leading to spatial learning and memory impairments. Inhibiting CD33 expression via siRNA administration ameliorated cognitive deficits and mitigated the neuroinflammatory response triggered by surgery. Additionally, CD33 inhibition reversed the surgery-induced decrease in synaptic-related proteins, highlighting its role in preserving synaptic integrity. Moreover, our experiments suggest that CD33 may influence neuroinflammation and cognitive function through mechanisms involving TREM2. This is evidenced by the suppression of pro-inflammatory cytokines following CD33 knockdown in microglia and the reversal of these effects when both CD33 and TREM2 are concurrently knocked down. These findings imply that CD33 might promote neuroinflammation by inhibiting TREM2. This study highlights the potential of targeting CD33 as a promising therapeutic strategy for preventing and treating POCD. It provides valuable insights into the intricate mechanisms underlying cognitive dysfunction following surgical procedures.

Prevalence and risk factors of subsyndromal delirium in ICU: A systematic review and meta-analysis

OBJECTIVE

To systematically assess the prevalence and risk factors for subsyndromal delirium (SSD) in the intensive care unit.

DESIGN

A systematic reviewand meta-analysis.

METHODOLOGY

This systematic review and meta-analysis was conducted in eight databases, including PubMed, Web of Science, Ovid,Scopus, China Knowledge Resource Integrated Database, Wanfang Database,Weipu Database and Chinese Biomedical Database. All original observational studies of subsyndromal delirium in the ICU were included, with languages limited to English and Chinese. The methodological quality was assessed by the Newcastle-Ottawa Scale and the Agency for Healthcare Research and Quality recommendation checklist. Meta-analysis was performed using Stata software (version 18.0).

RESULT

A total of 27 studies involving 7,286 participants were included in this review. The pooled prevalence of SSD was 32.4 % (95 %CI: 27.1 %-37.7 %).Fourteen studies reported 34 independent risk factors, and the following ten factors were significantly associated with SSD: older age, higher Acute Physiology and Chronic Health Evaluation II (APACHE II) score, lower Mini-mental Status Examination (MMSE) score, pain, mechanical ventilation, hypoproteinemia, blood transfusion, longer ICU stay, infection, and physical restraint.

CONCLUSION

We conducted a systematic review and meta-analysis to evaluate the prevalence of SSD in the ICU and identified 10 risk factors associated with SSD. However, the studies have significant heterogeneity, future research should be conducted in multicenter with large samples to strengthen the current evidence.

IMPLICATIONS FOR CLINICAL PRACTICE

Subsyndromal delirium is a frequently occurring adverse event in the ICU, so it is recommended that clinicians and nurses incorporate the assessment of SSD into their daily routine. In this study, we also identified ten risk factors associated with SSD, and some of which could be modified or intervened. These findings provide a basis for ICU medical staff to identify patients at high risk of SSD and then implement individualized interventions to reduce the prevalence of SSD.

The immune-inflammatory responses on the hypothalamic-pituitary-adrenal axis and the neurovascular unit in perioperative neurocognitive disorder

Perioperative neurocognitive disorders (PNDs) refer to a wide spectrum of cognitive impairment persisting days to even after a year postoperative with significant morbidity and mortality. However, despite much efforts involving perioperative managements, PNDs are still prevalent with no standard preventative and therapeutic strategy. To overcome PNDs, a better understanding of pathophysiology of PNDs is crucial and a large number of studies have proven that immune-inflammatory responses from surgical stress are involved in the abnormal activation of the hypothalamic-pituitary-adrenal (HPA) axis and destabilization of neurovascular unit (NVU) that lead to PNDs. The HPA axis is one of the key components to maintaining physiological homeostasis in response to stress. Under normal conditions, the HPA axis is involved in multiple roles from memory consolidation to regulating the circadian rhythm by activating adrenal cortex to secret cortisol. However, when overwhelmed with inflammatory response from surgical stress, HPA axis may be abnormally activated to release excessive glucocorticoids to cause PNDs. In addition, NVU, the functional unit of the brain essential for maintaining blood brain barrier and cerebral blood flow, is another possible factor that may lead to PNDs as compromised NVU from inflammatory response can result in disrupted blood brain barrier and impaired brain homeostasis. Therefore, the interaction of immune-inflammatory response with the HPA axis and the NVU seems to play a significant role and therapeutic and/or preventive strategies focused on these interactions may be promising direction for future managements of PNDs.

Remimazolam attenuates lipopolysaccharide-induced neuroinflammation and cognitive dysfunction

OBJECTIVE

Remimazolam, a novel benzodiazepine, is widely used as an anesthetic in endoscopic procedures; however, its effects on cognitive function remain unclear, limiting its broader application in general anaesthesia. Neuroinflammation is a well-established key factor in the etiology and progression of cognitive dysfunction, including conditions such as Alzheimer's disease, Parkinson's disease, postoperative delirium, and postoperative cognitive dysfunction. Preclinical studies have demonstrated that remimazolam exerts anti-inflammatory and neuroprotective effects, and clinical reports indicate a reduced incidence of postoperative delirium in patients treated with remimazolam. Nevertheless, whether remimazolam improves cognitive function through its anti-inflammatory properties remains uncertain. This study aimed to investigate the neuroprotective effects of remimazolam and its underlying mechanism in a lipopolysaccharide (LPS)-induced model of neuroinflammation, neuronal injury, and cognitive dysfunction METHODS: C57BL/6 J male mice were administered LPS intraperitoneally to establish a model of neuroinflammation-induced cognitive impairment. A subset of mice received remimazolam via intraperitoneal injection 30 minutes prior to LPS administration. Cognitive performance was evaluated using behavioural tests, including the Morris Water Maze (MWM), Novel Object Recognition (NOR) test, and Open Field Test (OFT). Hippocampal tissues were analyzed by haematoxylin-eosin (HE) staining to assess structural changes. Inflammatory markers, including Interleukin (IL)-6, IL-1β, and tumor necrosis factor-α, were quantified using enzyme-linked immunosorbent assay (ELISA) and real-time quantitative PCR. Immunofluorescence was used to detect translocator protein (TSPO) and markers of microglia activation (IBA-1, CD16/32, and CD206).

RESULTS

(1) Remimazolam reversed LPS-induced cognitive deficits, as evidenced by shorter spatial exploration latency and increased platform crossings in the MWM, and an elevated recognition index in the NOR test. (2) Remimazolam improved hippocampal morphology, reducing LPS-induced neuronal damage. (3) Remimazolam significantly decreased levels of hippocampal inflammatory cytokines, inhibited microglial activation, promoted M2-type microglia polarization, and increased TSPO expression.

CONCLUSION

Remimazolam demonstrated neuroprotective and anti-neuroinflammatory effects in a mouse model of LPS-induced cognitive impairment. These effects are likely mediated through the regulation of TSPO, which inhibits microglial activation and promotes the polarization of microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype.

Cognitive disorders: Potential astrocyte-based mechanism

Cognitive disorders are a common clinical manifestation, including a deterioration in the patient's memory ability, attention, executive power, language, and other functions. The contributing factors of cognitive disorders are numerous and diverse in nature, including organic diseases and other mental disorders. Neurodegenerative diseases are a common type of organic disease related to the pathology of neuronal death and disruption of glial cell balance, ultimately accompanied with cognitive impairment. Thus, cognitive disorder frequently serves as an extremely critical indicator of neurodegenerative disorders. Cognitive impairments negatively affect patients' daily lives. However, our understanding of the precise pathogenic pathways of cognitive defects remains incomplete. The most prevalent kind of glial cells in the central nervous system are called astrocytes. They have a unique significance in cerebral function because of their wide range of functions in maintaining homeostasis in the central nervous system, regulating synaptic plasticity, and so on. Dysfunction of astrocytes is intimately linked to cognitive disorders, and we are attempting to understand this phenomenon predominantly from those perspectives: neuroinflammation, astrocytic senescence, connexin, Ca2 + signaling, mitochondrial dysfunction, and the glymphatic system.

tsRNA-5006c regulates hippocampal neurons ferroptosis to ameliorate perioperative neurocognitive disorders in aged male mice

The aim of this research is to investigate whether ferroptosis occurs in the pathogenesis of perioperative neurocognitive disorders (PND), and to explore the function and underlying molecular mechanism of tsRNA in the regulation of ferroptosis in PND. A PND aged mice model was established and behavioral changes and ferroptosis occurrence were confirmed. The effect of ferroptosis inhibitor ferrostatin-1 (Fer-1) on PND mice was detected. tsRNA expression profile in PND mice and the effect of tsRNA on ferroptosis in vitro were perfomed. We found that anxious exploration behavior and short-term working memory was declined in PND mice compared with control mice, and the levels of S100β and IL-6 were increased. Meanwhile, hippocampal neurons of PND mice were damaged and accompanied by ferroptosis. Fer-1 can improve cognitive impairment in PND mice, as reflected by improved anxious exploration behavior and short-term working memory, and the levels of S100β and IL-6 were decreased. The expression profile of tsRNA in PND mice is disordered, and the dysregulated tsRNAs were mainly enriched in biologic functions related to neuronal development and ferroptosis. The tsRNA-5006c, identified as a pivotal player, significantly suppressed ferroptosis in primary mice neurons. This study shows for the first time that the pathophysiological process of PND is accompanied by ferroptosis of neurons, and reveals that tsRNA-5006c regulates ferroptosis of hippocampal neurons to ameliorate PND, which is of great significance for the development of new treatment strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04176-3.

Bibliometric Analysis of Neuroinflammation and Postoperative Cognitive Dysfunction

BACKGROUND

The occurrence and development of postoperative cognitive dysfunction (POCD) are closely linked to neuroinflammation. This bibliometric analysis aims to provide novel insights into the research trajectory, key research topics, and potential future development trends in the field of neuroinflammation-induced POCD.

METHODS

The Web of Science Core Collection (WoSCC) database was searched to identify publications from 2012 to 2023 on neuroinflammation-induced POCD. Bibliometric analysis, involving both statistical and visual analyses, was conducted using CiteSpace, VOSviewer, and the R software.

RESULTS

Research on neuroinflammation-induced POCD has exhibited an increasing trend over the past 12 years. China had the highest number of publications, Nanjing Medical University had the most collaboration with other institutions, Zhiyi Zuo was the most published author, and the Journal of Neuroinflammation served as the primary publication in the field of neuroinflammation-induced POCD. The most frequent keyword was POCD. Keyword clustering analysis indicated that the predominant cluster is dexmedetomidine. Burst detection revealed that postoperative delirium (POD), perioperative neurocognitive disorders (PND), apoptosis, and epigenetic modifications were the future research trends.

CONCLUSIONS

Our analysis identified the following key research areas associated with neuroinflammation-induced POCD: anesthesia, surgery, dexmedetomidine, NLRP3 inflammasome, and mechanism of neuroinflammation-induced POCD. The potential future research topics comprise POD, PND, apoptosis, and epigenetic modifications.

Double negative T cells promote surgery-induced neuroinflammation, microglial engulfment and cognitive dysfunction via the IL-17/CEBPβ/C3 pathway in adult mice

CD3(+) CD4(-) CD8(-) double negative T cells (DNTs) manifest themselves in autoimmune diseases and associated inflammation. In the central nervous system, the increased presence of DNTs is associated with the progression of neurological conditions and brain injury. Active DNTs that produce IL-17 have been regarded as a pro-inflammatory phenotype. The IL-17 signaling pathway mediates neuroinflammatory responses by inducing glial activation and producing inflammatory factors. Neuroinflammation is considered integral to the pathogenesis of perioperative neurocognitive disorders (PNDs), commonly developed after surgery in susceptible patients. We and others have demonstrated a significant role for complement C3 in surgery-induced neuroinflammation and cognitive impairment but the regulatory mechanisms for this remain unexplored. We hypothesized that surgery induces DNT infiltration into the CNS that in turn upregulates complement C3 expression and this causes changes that contribute to cognitive impairment. Using an adult murine abdominal surgery model, we investigated perioperative changes in cognitive performance, quantifying the presence of T cell subsets and phenotype, IL-17 signaling pathway activation, glial cell activation and C3 expression in the brain. Postoperative IL-17 specific inhibitor GSK2981278 administration or preoperatively conditional CEBPβ knock-down by AAV9 viral vector were then applied to evaluate the effect of inhibiting IL-17 signaling pathway on postoperative C3 expression and cognitive performance. The results showed an increased hippocampus infiltration of DNTs with augmented IL-17 production, along with C3 upregulation and cognitive impairment. Both inhibition of IL-17 or knock-down of CEBPβ significantly suppressed C3 expression, synaptic engulfment by microglia and attenuated cognitive impairment. These findings indicate that DNTs promote postoperative neuroinflammation and cognitive impairment via the IL-17/CEBPβ/C3 pathway and targeting this IL-17 axis could be a potential therapeutic strategy to ameliorate postoperative neuroinflammation and cognitive impairment.

Hippocampal Nogo66-NgR1 signaling activation restricts postsynaptic assembly in aged mice with postoperative neurocognitive disorders

Postoperative neurocognitive disorders (pNCD) are a common neurological complication, especially in elderly following anesthesia and surgery. Yet, the underlying mechanisms of pNCD remain elusive. This study aimed to investigate the molecular mechanisms that compromise synaptic metaplasticity in pNCD development with a focus on the involvement of Nogo-66 receptor 1 (NgR1) in the pathogenesis of pNCD in aged mice. Aged mice subjected to anesthesia and laparotomy surgery exhibited anxiety-like behavior and contextual fear memory impairment. Moreover, the procedure significantly increased NogoA and NgR1 expressions, particularly in the hippocampal CA1 and CA3 regions. This increase led to the depolymerization of F-actin, attributed to the activation of the RhoA-GTPase, resulting in a reduction of dendritic spines and changes in their morphology. Additionally, these changes hindered the efficient postsynaptic delivery of the subunit GluA1 and GluA2 of AMPA receptors (AMPARs), consequently diminishing excitatory neurotransmission in the hippocampus. Importantly, administering the competitive NgR1 antagonist peptide NEP1-40 (Nogo-A extracellular peptide residues 1-40 amino acids of Nogo-66) and Fasudil (a Rho-kinase inhibitor) effectively mitigated synaptic impairments and reversed neurocognitive deficits in aged mice following anesthesia and surgery. Our work indicates that high hippocampal Nogo66-NgR1 signaling disrupts postsynaptic AMPA receptor surface delivery due to F-actin depolymerization in the pathophysiology of pNCD.

Quantitative electroencephalography predicts postoperative delirium in adult cardiac surgical patients from a prospective observational study

The diagnostic and prognostic value of quantitative electroencephalogram (qEEG) in the the onset of postoperative delirium (POD) remains an area of inquiry. We aim to determine whether qEEG could assist in the diagnosis of early POD in cardiac surgery patients. We prospectively studied a cohort of cardiac surgery patients undergoing qEEG for evaluation of altered mental status. Delirium was assessed with the Confusion Assessment Method for the intensive care unit (CAM-ICU). The qEEG were interpreted by clinician, and reports were reviewed to identify features such as amplitude-integrated EEG (aEEG), relative band energy in ɑ/β/θ/δ frequencies, α variability and spectral entropy. The raw EEG was also preprocessed offline for nonlinear analysis including Multi-scale Entropy analysis (MSE) and Detrended Fluctuation Analysis (DFA). Linear regression was performed to quantify associations among EEG findings, delirium, and clinical outcomes. Receiver operating characteristic (ROC) analysis was used to assess the accuracy of the qEEG as POD prediction index. Meanwhile, a comprehensive comparison of dynamic complexity across time scales and DFA exponent α was conducted between the non-delirium and delirium groups. Among those recruited initially (n = 64), 60 patients were evaluated and 29 patients (48.3%) met delirium criteria. When comparing delirious and non-delirious participants, significant differences were found in terms of age (p = 0.03), APACHE II scores (p = 0.004), lactate (p = 0.03), and hospital days (p = 0.048). Multivariate regression analysis revealed that the first quartile (Q1) and fourth quartile (Q4) of peak or valley value of F3-P3/F4-P4 derivation (for example, Q1 of peak value for F3-P3 derivation: OR 12.4, 95% CI 1.72-89.76, p = 0.012) showed a higher association with the incidence of POD. ROC analysis demonstrated qEEG could predict POD with high sensitivity and specificity, yielding an overall good accuracy. For instance, the peak value of F3-P3 derivation (the area under the curve of 0.81), as a predictor of POD showed a sensitivity of 90% and specificity pf 72% (p < 0.001). Furthermore, the MSE curves indicated that the non-delirium group exhibited higher complexity values at fine scales, while the delirium group had significantly higher complexity at coarse scales. The DFA comparison results revealed that long-term fractal exponent alpha2 values were higher in delirium patients than in non-delirium patients, with significant differences observed at the F4-P4 electrodes (p = 0.04). The qEEG can reliably predict delirium after heart cardiac surgery. It is helpful for clinicians to early diagnose and manage these patients.Trial registration: Clinical Trials.gov Identifier, NCT03351985. Registered 1 December 2017.

Efficacy of repetitive transcranial magnetic stimulation in preventing postoperative delirium in elderly patients undergoing major abdominal surgery: A randomized controlled trial

BACKGROUND

Postoperative delirium (POD) is a serious complication in elderly patients after major surgery, associated with high morbidity and mortality. Treatment and prevention methods are limited. Repetitive transcranial magnetic stimulation (rTMS) shows potential in enhancing cognitive function and improving consciousness.

OBJECTIVE

To evaluate whether early postoperative rTMS has a protective effect against POD and to explore its potential mechanisms.

METHODS

Patients aged 60 years or older, scheduled for major abdominal surgery, were randomly assigned to receive rTMS at 100 % RMT, 10 Hz, with 2000 pulses targeting the DLPFC after extubation in PACU, either as active rTMS(n = 61) or sham rTMS (n = 61). The primary outcome was the incidence of POD during the first 3 postoperative days.

RESULTS

In the modified intention-to-treat analysis of 122 patients (mean [SD] age, 70.2 [4.1] years; 53.3 % women), POD incidence was lower in the rTMS group (11.5 %) compared to the sham rTMS group (29.5 %) (relative risk, .39; 95 % CI, .18 to .86; P = .01). rTMS patients had higher BDNF (8.47 [2.68] vs. 5.76 [1.42] ng/mL; P < .001) and lower NfL (.05 [.04] vs. .06 [.04] ng/mL; P = .02) levels. Mediation analysis suggests that rTMS may reduce POD by increasing brain-derived neurotrophic factor (z = -3.72, P < .001) rather than decreasing neurofilament light (z = 1.92, P = .06).

CONCLUSIONS

Immediate postoperative rTMS can reduce the incidence of POD in elderly patients undergoing major abdominal surgery, probably by upregulating brain-derived neurotrophic factor levels.

Effects of remimazolam and surgery on cognition in a tibia fracture mouse model

BACKGROUND

To investigate the effects of remimazolam and surgery on cognitive function and neuropathology.

METHODS

We performed intramedullary pin fixation of tibial fractures in wild-type male (12-13-week-old) C57BL/6J mice under intraperitoneal anesthesia with remimazolam. Age-matched wild-type control mice received either saline or remimazolam without surgery. Training was performed 1 h before surgery, and the open field test was performed on the third postoperative day, in addition to trace fear conditioning on the third versus the seventh day and the Y maze test on the fourth versus the eighth day. Phosphorylated tau (P-TAU) protein levels in hippocampal tissue, microglial activation, dendritic spine density in neuronal cells, and interleukin-6 (IL-6) levels were determined.

RESULTS

We detected no significant differences in locomotor ability among the three groups in the open field test on the third postoperative day; however, on the conditioned fear test or in the Y-maze, the cognitive related performance of the mice in the surgery group was significantly worse than that of the control group and the remimazolam group. However, there were no differences among the three groups in the behavioural experiments on the seventh and eighth days. In addition, mice in the surgery group had higher levels of P-TAU in their hippocampal tissue, more microglial activation, more significant changes in neuronal dendritic spine density, and higher levels of IL-6 in their hippocampal tissue compared with mice in the other two groups.

CONCLUSIONS

The cognitive dysfunction and neuropathological changes produced by remimazolam-based surgery are mainly of surgical origin and are not related to the use of remimazolam, a general anesthetic agent.

Current Progress on Postoperative Cognitive Dysfunction: An Update

Postoperative cognitive dysfunction (POCD) represents a significant clinical concern, particularly among elderly surgical patients. It is characterized by a decline in cognitive performance, affecting memory, attention, coordination, orientation, verbal fluency, and executive function. This decline in cognitive abilities leads to longer hospital stays and increased mortality. This review provides a comprehensive overview of the current progress in understanding the relevant pathogenic factors, possible pathogenic mechanisms, diagnosing, prevention and treatment of POCD, as well as suggesting future research directions. It discusses neuronal damage, susceptible genes, central cholinergic system, central nervous system (CNS) inflammation, stress response and glucocorticoids, and oxidative stress in the development of POCD, aiming to uncover the pathological mechanism and develop effective treatment strategies for POCD.

Cardiac surgery with valve replacement temporarily disrupts the hippocampal memory network

BACKGROUND

Systemic inflammation after heart valve replacement surgery commonly results in complications including cognitive impairment. This study was designed to investigate whether valvular heart disease itself and inflammation after valve replacement surgery affects cognition and the related functional connectivity (FC) of the hippocampal memory network.

METHODS

Forty-three patients with valvular heart disease were screened for recruitment and assessed with cognition function tests, blood inflammatory cytokine measurements, and functional magnetic resonance imaging scans before surgery and on postoperative day 7 and 30. Age- and sex-matched healthy controls (n=30) were recruited for comparison. The brain FC networks using the hippocampus as a seed were analysed. Bivariate correlation and structural equation model analyses were carried out to investigate the association between altered FC, memory, and inflammation.

RESULTS

Thirty-five patients and 29 healthy controls completed the study, and their data were finally analysed and reported. Compared with healthy controls, the surgery group had increased FC in the bilateral precuneus and middle cingulate and paracingulate gyri before surgery. They exhibited impaired memory, increased plasma concentrations of proinflammatory cytokines, and decreased hippocampal FC at postoperative day 7. At 30 days after surgery, the FC abnormalities seen before surgery and at postoperative day 7 were restored to the level comparable with the healthy controls. High systemic inflammation was significantly associated with worse memory and lower FC in the hippocampal memory network.

CONCLUSIONS

Valve replacement surgery temporarily disrupts the hippocampal memory network with transient associated memory decline.

CLINICAL TRIAL REGISTRATION

ChiCTR2300069614.

Progress and Frontiers of Research on Dexmedetomidine in Perioperative Medicine: A Bibliometric Analysis

Background

Dexmedetomidine has received increasing attention for its sedative, analgesic, anxiolytic, anti-inflammatory and anti-stress effects in perioperative medicine. Numerous studies have been carried out to explore its influence on perioperative patients.

Objective

This study aimed to identify the most influential literature, trends and hotspots in dexmedetomidine research by bibliometric analysis.

Methods

Articles and reviews related to dexmedetomidine in perioperative medicine were collected from Web of Science Core Collection. VOSviewer and Citespace software were used for bibliometric analysis and data visualization.

Results

A total of 1652 suitable publications were extracted from the database for analysis, including 1,497 articles and 155 reviews. The number of publications in the field of dexmedetomidine research has increased markedly since 2013, with China being the major contributor, followed by United States. BMC Anesthesiology published the highest number of papers on this topic. Anesthesiology ranked first in terms of average citations per paper and co-citation journal. Ji Fuhai was the most prolific author, and Ma Daqing was the most cited authors. The main hotspots during this period were "elderly patients", "postoperative cognitive dysfunction", "injury" and "risk factors".

Conclusion

This study presents an overview of the development related to dexmedetomidine in perioperative medicine using bibliometric analysis. Dexmedetomidine research is thriving and expanding rapidly around the world. The effect of dexmedetomidine on cognitive function has been the latest research hotspot. To advance research in this field, more rigorous and scientific multi-center studies should be designed and further cooperation and academic exchange should be strengthened.

The NF-κB pathway: Key players in neurocognitive functions and related disorders

Perioperative neurocognitive disorder (PND) is a common complication of surgical anesthesia, yet its precise etiology remains unclear. Neuroinflammation is a key feature of PND, influenced by both patient -related and surgical variables. The nuclear factor-κB (NF-κB) transcription factor family plays a critical role in regulating the body's immunological proinflammatory response, which is pivotal in the development of PND. Surgery and anesthesia trigger the activation of the NF-κB signaling pathway, leading to the initiation of inflammatory cascades, disruption of the blood-brain barrier, and neuronal injury. Immune cells and glial cells are central to these pathological processes in PND. Furthermore, this study explores the interactions between NF-κB and various signaling molecules, including Tlr4, P2X, α7-nAChR, ROS, HIF-1α, PI3K/Ak, MicroRNA, Circular RNA, and histone deacetylases, within the context of PND. Targeting NF-κB as a therapeutic approach for PND shows promise as a potential treatment strategy.

Acute changes in hippocampal metabolism after anesthesia and surgery: Implications for perioperative neurocognitive disorder

BACKGROUND

The risk of developing dementia is higher in individuals who suffer from perioperative neurocognitive disorder (PND), including postoperative cognitive dysfunction (POCD) and delirium. Recent studies have indicated correlations between anesthesia, surgery and PND. Acute metabolic changes induced by anesthesia and surgery may be related to cognitive impairments. Despite a paucity of research on acute metabolic changes in the hippocampus during surgery, there are conflicting about specific metabolites.

METHODS

We developed a mouse model of cognitive impairment induced by isoflurane anesthesia and unilateral nephrectomy. Cognition was evaluated by Y maze and fear conditioning test (FCT). The hippocampus was harvested after the surgery. LC-MS (liquid chromatography-mass spectrometry) was performed. The differential metabolites involved in lipid, amino acid, nucleotide, carbohydrate metabolism were analyzed.

RESULTS

Anesthesia and surgery exposure induced cognition decline. A total of 49 metabolites were significantly up-regulated and 122 down-regulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of the metabolites identified purine, glutathione, nicotinate and nicotinamide metabolism. Metabolites involved in lipid, amino acid, nucleotide, carbohydrate metabolism were identified including nicotinamide adenine dinucleotide (NAD), 1-Methylnicotinamide, propionic acid, histidine, adenosine, and guanosine cyclic monophosphate. Some metabolites exhibited a consistent change trend in the hippocampus of aging mice.

CONCLUSIONS

The study indicates that anesthesia and surgery can induce acute alterations in hippocampal metabolomics, including metabolites involved in lipid, amino acid, nucleotide, and carbohydrate metabolism. These metabolites may play a role in modulating PND through the regulation of neuroinflammation, oxidative stress, blood-brain barrier (BBB) permeability.

An immune signature of postoperative cognitive decline: a prospective cohort study

BACKGROUND

Postoperative cognitive decline (POCD) is the predominant complication affecting patients over 60 years old following major surgery, yet its prediction and prevention remain challenging. Understanding the biological processes underlying the pathogenesis of POCD is essential for identifying mechanistic biomarkers to advance diagnostics and therapeutics. This study aimed to provide a comprehensive analysis of immune cell trajectories differentiating patients with and without POCD and to derive a predictive score enabling the identification of high-risk patients during the preoperative period.

MATERIAL AND METHODS

Twenty-six patients aged 60 years old and older undergoing elective major orthopedic surgery were enrolled in a prospective longitudinal study, and the occurrence of POCD was assessed 7 days after surgery. Serial samples collected before surgery, and 1, 7, and 90 days after surgery were analyzed using a combined single-cell mass cytometry and plasma proteomic approach. Unsupervised clustering of the high-dimensional mass cytometry data was employed to characterize time-dependent trajectories of all major innate and adaptive immune cell frequencies and signaling responses. Sparse machine learning coupled with data-driven feature selection was applied to the presurgery immunological dataset to classify patients at risk for POCD.

RESULTS

The analysis identified cell-type and signaling-specific immune trajectories differentiating patients with and without POCD. The most prominent trajectory features revealed early exacerbation of JAK/STAT and dampening of inhibitory κB and nuclear factor-κB immune signaling responses in patients with POCD. Further analyses integrating immunological and clinical data collected before surgery identified a preoperative predictive model comprising one plasma protein and 10 immune cell features that classified patients at risk for POCD with excellent accuracy (AUC=0.80, P =2.21e-02 U -test).

CONCLUSION

Immune system-wide monitoring of patients over 60 years old undergoing surgery unveiled a peripheral immune signature of POCD. A predictive model built on immunological data collected before surgery demonstrated greater accuracy in predicting POCD compared to known clinical preoperative risk factors, offering a concise list of biomarker candidates to personalize perioperative management.

Improvement of Isolated Abducens Nerve Palsy with Hydrocephalus after CSF Diversion: A Possible Evaluative Role of Retroclival-pontomedullary Distance

Isolated abducens nerve palsy (IANP), caused by secondary communicating hydrocephalus, has been rarely documented; in addition, its mechanism and appropriate treatment are not understood well. This study presents a case of bilateral IANP with hydrocephalus in a 62-year-old man who was successfully treated with cerebrospinal fluid (CSF) diversion to correct an enlarged retroclival space during the follow-up of recurrent brain tumor in the right parieto-occipital lobe. The patient was treated with three resections, temozolomide, and irradiation before developing IANP. Magnetic resonance imaging (MRI) revealed a recurrent tumor and ventriculomegaly with an expanded retroclival cisternal space. The patient underwent subtotal tumor resection and external ventricular drain placement in the anterior horn of the lateral ventricle. His bilateral IANP persisted for 4 days after surgery but gradually improved and disappeared by Day 7. Four weeks later, the patient underwent ventriculoperitoneal (VP) shunt surgery to establish a permanent CSF diversion that continued to control the symptoms. Retrospective MRI review revealed the distance between the clivus and pontomedullary junction on the sagittal section (retroclival-pontomedullary distance; RPD) of 9.0, 12.8, 10.7, and 10.6 mm before IANP, on IANP onset, on postoperative Day 4, and post VP shunt surgery, respectively. In conclusion, VP shunt surgery was an appropriate approach for IANP with communicating hydrocephalus to correct the enlarged retroclival cisternal space. RPD thus may be used as one of possible evaluation methods for IANP with hydrocephalus, which can be caused by various factors.

Preoperative Exposure to Fine Particulate Matter and Risk of Postoperative Complications: A Single Center Observational Cohort Bayesian Analysis

Background

While exposure to fine particulate matter air pollution (PM 2.5 ) is known to cause adverse health effects, its impact on postoperative outcomes in US adults remains understudied. Perioperative exposure to PM 2.5 may induce inflammation that interacts insidiously with the surgical stress response, leading to higher postoperative complications.

Methods

We conducted a single center, retrospective cohort study using data from 49,615 surgical patients living along Utah's Wasatch Front and who underwent elective surgical procedures at a single academic medical center from 2016-2018. Patients' addresses were geocoded and linked to daily Census-tract level PM 2.5 estimates. We hypothesized that elevated PM 2.5 concentrations in the week prior to surgery would be associated with an increase in a bundle of major postoperative complications. A hierarchical Bayesians regression model was fit adjusting for age, sex, season, neighborhood disadvantage, and the Elixhauser index of comorbidities.

Results

Postoperative complications increased in a dose-dependent manner with higher concentrations of PM 2.5 exposure, with a relative increase of 8% in the odds of complications (OR=1.082) for every 10ug/m 3 increase in the highest single-day 24-hr PM 2.5 exposure during the 7 days prior to surgery. For a 30 fold increase in PM 2.5 (1 ug/m 3 to 30ug/m 3 ) the odds of complication rose to over 27% (95%CI: 4%-55%). The association persisted after controlling for comorbidities and confounders; our inferences were robust to modeling choices and sensitivity analysis.

Conclusions

In this large Utah cohort, exposure to elevated PM 2.5 concentrations in the week before surgery was associated with a dose-dependent increase in postoperative complications, suggesting a potential impact of air pollution on surgical outcomes. These findings merit replication in larger datasets to identify populations at risk and define the interaction and impact of different pollutants. PM 2.5 exposure is a potential perioperative risk factor and, given the unmitigated air pollution in urban areas, a global health concern.

Asthma and cognitive dysfunction in older adults: the mediating role of systemic immune-inflammation index

Asthma and cognitive dysfunction represent significant public health challenges. Our study aimed to investigate the relationship between asthma and cognitive dysfunction in adults aged ≥ 60 years, and explore the role of systemic immune inflammation index (SII) in asthma - cognitive dysfunction link. The retrospective cross-sectional study included 2,579 participants aged ≥ 60 years from the 2011-2014 National Health and Nutrition Examination Survey (NHANES) cycles. Asthma diagnosis was confirmed using the MCQ010 questionnaire, cognitive function assessed through the Digit Symbol Substitution Test (DSST). SII was calculated using the formula: (platelet count × neutrophil count)/lymphocyte count. Controlling for demographic variables including sex, age, race and/ethnicity, poverty-to-income ratio (PIR) and education level, a negative association was found between asthma and DSST scores (β = -1.75, 95% CI: -3.38, -0.120, P = 0.037). This association persisted even after further adjustments for body mass index (BMI) and diabetes (β = -1.72, 95% CI: -3.38, -0.057, P = 0.043). Moreover, subgroup analysis showed no significant association of sex, age, race/ethnicity, BMI or diabetes with the relationship between asthma and cognitive function. Mediation analysis indicated SII was a mediator of asthma-induced cognitive impairment, a notable Average Causal Mediated Effect (ACME) (P = 0.004) between SII and cognitive dysfunction. Our investigation indicated that elderly asthma (aged ≥ 60 years) was predisposed to cognitive dysfunction, independent of sex, age, race/ethnicity, BMI and diabetes. Furthermore, mediation analysis suggested that asthma might contribute to cognitive dysfunction through the involvement of SII.

Astrocytic phagocytosis in the medial prefrontal cortex jeopardises postoperative memory consolidation in mice

Memory impairment is one of the main characteristics of postoperative cognitive dysfunction. It remains elusive how postoperative pathological changes of the brain link to the memory impairment. The clinical setting of perioperation was mimicked via partial hepatectomy under sevoflurane anaesthesia together with preoperative restraint stress (Hep-Sev-stress) in mice. Memory changes were assessed with fear conditioning. The medial prefrontal cortex (mPFC)-dorsal hippocampus connectivity was evaluated with injecting neurotracer 28 days before surgery. Astrocytic activation was limited via injecting AAV-GFAP-hM4Di-eGFP into the mPFC. Astrocytic and microglial phagocytosis of synapses were visualised with co-labelling hippocampal neuronal axon terminals with PSD-95 and S100β or Iba1. Neuroinflammation and oxidative stress status were also detected. Hep-Sev-stress impaired the memory consolidation (mean [standard error], 49.91 [2.55]% vs. 35.40 [3.97]% in the contextual memory, p = 0.007; 40.72 [2.78]% vs. 27.77 [2.22]% in cued memory, p = 0.002) and the cued memory retrieval (39.00 [3.08]% vs. 24.11 [2.06]%, p = 0.001) in mice when compared with these in the naïve controls. Hep-Sev-stress damaged the connectivity from the dorsal hippocampus to mPFC but not from the mPFC to the dorsal hippocampus and increased the astrocytic but not microglial phagocytosis of hippocampal neuronal axon terminals in the mPFC. The intervention also induced neuroinflammation and oxidative stress in the dorsal hippocampus and the mPFC in a regional-dependent manner. Limiting astrocyte activation in the mPFC alleviated memory consolidation impairment induced by Hep-Sev-stress. Postoperative memory consolidation was impaired due to astrocytic phagocytosis-induced connectivity injury from the dorsal hippocampus to the medial prefrontal cortex.

Fecal microbiota transplantation alleviates cognitive impairment by improving gut microbiome composition and barrier function in male rats of traumatic brain injury following gas explosion

Background

Dysbiosis of gut microbiota (GM) is intricately linked with cognitive impairment and the incidence of traumatic brain injury (TBI) in both animal models and human subjects. However, there is limited understanding of the impact and mechanisms of fecal microbiota transplantation (FMT) on brain and gut barrier function in the treatment of TBI induced by gas explosion (GE).

Methods

We have employed FMT technology to establish models of gut microbiota dysbiosis in male rats, and subsequently conducted non-targeted metabolomics and microbiota diversity analysis to explore the bacteria with potential functional roles.

Results

Hematoxylin-eosin and transmission electron microscopy revealed that GE induced significant pathological damage and inflammation responses, as well as varying degrees of mitochondrial impairment in neuronal cells in the brains of rats, which was associated with cognitive decline. Furthermore, GE markedly elevated the levels of regulatory T cell (Tregs)-related factors interleukin-10, programmed death 1, and fork head box protein P3 in the brains of rats. Similar changes in these indicators were also observed in the colon; however, these alterations were reversed upon transfer of normal flora into the GE-exposed rats. Combined microbiome and metabolome analysis indicated up-regulation of Clostridium_T and Allobaculum, along with activation of fatty acid biosynthesis after FMT. Correlation network analysis indirectly suggested a causal relationship between FMT and alleviation of GE-induced TBI. FMT improved intestinal structure and up-regulated expression of tight junction proteins Claudin-1, Occludin, and ZO-1, potentially contributing to its protective effects on both brain and gut.

Conclusion

Transplantation of gut microbiota from healthy rats significantly enhanced cognitive function in male rats with traumatic brain injury caused by a gas explosion, through the modulation of gut microbiome composition and the improvement of both gut and brain barrier integrity via the gut-brain axis. These findings may offer a scientific foundation for potential clinical interventions targeting gas explosion-induced TBI using FMT.

Low blood S-methyl-5-thioadenosine is associated with postoperative delayed neurocognitive recovery

Elderly individuals display metabolite alterations that may contribute to development of cognitive impairment following surgery and anesthesia. However, these relationships remain largely unexplored. The study aims to assess the S-methyl-5-thioadenosine (MTA) is associated with postoperative delayed neurocognitive recovery (dNCR). We assess altered metabolites following anesthesia/surgery in both mice and patients to identify blood biomarkers of dNCR. Preoperative and postoperative plasma metabolites are determined by widely targeted metabolomics. The brains of mice with anesthesia/surgery show decreased MTA and activated MTA phosphorylase. Mice also show that preoperative administration of MTA can prevent inflammation and cognitive decline. In clinical patients, we detect lower preoperative serum MTA levels in those who developed dNCR. Both low preoperative and postoperative blood MTA levels are associated with increased risk of postoperative dNCR. These results suggest that anesthesia/surgery induces cognitive decline through methionine synthesis pathways and that MTA could be a perioperative predictor of dNCR.

Remimazolam ameliorates postoperative cognitive dysfunction after deep hypothermic circulatory arrest through HMGB1-TLR4-NF-κB pathway

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a complication of deep hypothermic circulatory arrest (DHCA). Various amounts of neurologic dysfunctions have been shown after DHCA, which has often been attributed to systemic inflammatory response syndrome and cerebral ischemia/reperfusion injury. Remimazolam is one of the commonly used anesthetic drugs with protective actions against inflammatory diseases, such as sepsis and cerebral ischemia/reperfusion injury. Here, we determined the protective effect and potential mechanism of action of remimazolam against neuronal damage after DHCA.

METHODS

A rat model of DHCA was established, and a gradient dosage of remimazolam was administered during cardiopulmonary bypass (CPB). The cognitive function of rats was evaluated by Morris water maze. Hematoxylin and eosin and TUNEL staining were performed to assess hippocampus tissue injury and neuronal apoptosis. Inflammatory cytokines concentration were analyzed by enzyme-linked immunosorbent assay. The protein expression was analyzed using automated electrophoresis western analysis and immunohistochemical analysis.

RESULTS

The appropriate dosage of remimazolam reduced histologic injury, neuronal apoptosis, microglia activation, and secondary inflammatory cascades, as well as the downregulation of the expression of the HMGB1-TLR4-NF-κB pathway after DHCA, improved the memory and learning abilities in DHCA rats. Further, administration of a TLR4 antagonist TAK-242 had a similar effect to remimazolam, while the TLR4 agonist LPS attenuated the effect of remimazolam.

CONCLUSIONS

Remimazolam could ameliorate POCD after DHCA through the HMGB1-TLR4-NF-κB signaling pathway.

PDTC improves cognitive impairment in LPS-induced ARDS by regulating miR-181c/NF-κB axis-mediated neuroinflammation

BACKGROUND

Cognitive impairment is a severe complication of acute respiratory distress syndrome (ARDS). Emerging studies have revealed the effects of pyrrolidine dithiocarbamate (PDTC) on improving surgery-induced cognitive impairment. The major aim of the study was to investigate whether PDTC protected against ARDS-induced cognitive dysfunction and to identify the underlying mechanisms involved.

METHODS

The rat model of ARDS was established by intratracheal instillation of lipopolysaccharide (LPS), followed by treatment with PDTC. The cognitive function of rats was analyzed by the Morris Water Maze, and pro-inflammatory cytokines were assessed by quantitative real-time PCR, enzyme-linked immunosorbent assay, and western blot assays. A dual-luciferase reporter gene assay was performed to identify the relationship between miR-181c and its target gene, TAK1 binding protein 2 (TAB2).

RESULTS

The results showed that PDTC improved cognitive impairment and alleviated neuroinflammation in the hippocampus in LPS-induced ARDS model. Furthermore, we demonstrated that miR-181c expression was downregulated in the hippocampus of the ARDS rats, which was restored by PDTC treatment. In vitro studies showed that miR-181c alleviated LPS-induced pro-inflammatory response by inhibiting TAB2, a critical molecule in the nuclear factor (NF)-κB signaling pathway.

CONCLUSION

PDTC improves cognitive impairment in LPS-induced ARDS by regulating miR-181c/NF-κB axis-mediated neuroinflammation, providing a potential opportunity for the treatment of this disease.

Perioperative research into memory (PRiMe), part 2: Adult burns intensive care patients show altered structure and function of the default mode network

BACKGROUND

Long-term cognitive impairment (LTCI) is experienced by up to two thirds of patients discharged from burns intensive care units (BICUs), however little is known about its neurobiological basis. This study investigated if patients previously admitted to BICU showed structural and functional MRI changes of the Default Mode Network (DMN).

METHODS

Fifteen patients previously admitted to BICU with a significant burns injury, and 15 matched volunteers, underwent structural and functional MRI scans. Functional connectivity, fractional anisotropy and cortical thickness of the main DMN subdivisions (anterior DMN (aDMN), posterior DMN (pDMN) and right (rTPJ) and left (lTPJ) temporo-parietal junctions) were compared between patients and volunteers, with differences correlated against cognitive performance.

RESULTS

Functional connectivity between rTPJ and pDMN (t = 2.91, p = 0.011) and between rTPJ and lTPJ (t = 3.18, p = 0.008) was lower in patients compared to volunteers. Functional connectivity between rTPJ and pDMN correlated with cognitive performance (r2 =0.33, p < 0.001). Mean fractional anisotropy of rTPJ (t = 2.70, p = 0.008) and lTPJ (T = 2.39, p = 0.015) was lower in patients but there was no difference in cortical thickness.

CONCLUSIONS

Patients previously admitted to BICU show structural and functional disruption of the DMN. Since functional changes correlate with cognitive performance, this should direct further research into intensive-care-related cognitive impairment.

Gut Microbiota and Probiotics in Perioperative Management: A Narrative Review

The human gut is the abode of several complex and diverse microbes. It is a fact that the human brain is interconnected with the spinal cord and sense organs; however, there is also a possibility of a connection between the brain and the gut microbiome. The human gut can be altered in various ways, the principal method being the intake of prebiotics, probiotics and synbiotics. Can this alteration in the gut microbiome be clinically utilised in the perioperative period? We conducted a literature search related to this topic using databases and search engines (Medical Literature Analysis and Retrieval System Online {MEDLINE}, Embase, Scopus, PubMed and Google Scholar). The search revealed some preclinical and clinical studies in animals and humans that demonstrate the alteration of the gut microbiome with the use of anxiolysis, probiotics/prebiotics and other perioperative factors including opioids, anaesthetics and perioperative stress. The significant effects of this alteration have been seen on preoperative anxiety and postoperative delirium/cognitive dysfunction/pain. These effects are described in this narrative review, which opens up newer vistas for high-quality research related to the gut microbiome, gut-brain axis, the related signaling pathways and their clinical application in the perioperative period.

Blood-brain barrier disruption: a culprit of cognitive decline?

Cognitive decline covers a broad spectrum of disorders, not only resulting from brain diseases but also from systemic diseases, which seriously influence the quality of life and life expectancy of patients. As a highly selective anatomical and functional interface between the brain and systemic circulation, the blood-brain barrier (BBB) plays a pivotal role in maintaining brain homeostasis and normal function. The pathogenesis underlying cognitive decline may vary, nevertheless, accumulating evidences support the role of BBB disruption as the most prevalent contributing factor. This may mainly be attributed to inflammation, metabolic dysfunction, cell senescence, oxidative/nitrosative stress and excitotoxicity. However, direct evidence showing that BBB disruption causes cognitive decline is scarce, and interestingly, manipulation of the BBB opening alone may exert beneficial or detrimental neurological effects. A broad overview of the present literature shows a close relationship between BBB disruption and cognitive decline, the risk factors of BBB disruption, as well as the cellular and molecular mechanisms underlying BBB disruption. Additionally, we discussed the possible causes leading to cognitive decline by BBB disruption and potential therapeutic strategies to prevent BBB disruption or enhance BBB repair. This review aims to foster more investigations on early diagnosis, effective therapeutics, and rapid restoration against BBB disruption, which would yield better cognitive outcomes in patients with dysregulated BBB function, although their causative relationship has not yet been completely established.

Esketamine Prevents Postoperative Emotional and Cognitive Dysfunction by Suppressing Microglial M1 Polarization and Regulating the BDNF-TrkB Pathway in Ageing Rats with Preoperative Sleep Disturbance

Postoperative depression (POD) and postoperative cognitive dysfunction (POCD) have placed heavy burden on patients' physical and mental health in recent years. Sleep disturbance before surgery is a common phenomenon that has been increasingly believed to affect patients' recovery, especially in aged patients, while little attention has been paid to sleep disruption before surgery and the potential mechanism remains ambiguous. Ketamine has been reported to attenuate POCD after cardiac surgery and elicit rapid-acting and sustained antidepressant actions. The present study aimed to clarify the effect of esketamine's (the S-enantiomer of ketamine) protective effects and possible mechanisms of action in POCD and POD. Our results showed that sleep disturbance before surgery exacerbated microglial M1 polarization and microglial BDNF-TrkB signalling dysfunction induced by surgery, resulting in postoperative emotional changes and cognitive impairments. Notably, treatment with esketamine reversed the behavioural abnormalities through inhibiting the M1 polarization of microglia and the inflammatory response thus improving BDNF-TrkB signalling in vivo and vitro. In addition, esketamine administration also reversed the impaired hippocampal synaptic plasticity which has been perturbed by sleep disturbance and surgery. These findings warrant further investigations into the interplay of esketamine and may provide novel ideas for the implication of preoperative preparations and the prevention of postoperative brain-related complications.

Preoperative ketamine administration for prevention of postoperative neurocognitive disorders after major orthopedic surgery in elderly patients: A multicenter randomized blinded placebo-controlled trial

BACKGROUND

Preventive anesthetic impact on the high rates of postoperative neurocognitive disorders in elderly patients is debated. The Prevention of postOperative Cognitive dysfunction by Ketamine (POCK) study aimed to assess the effect of ketamine on this condition.

METHODS

This is a multicenter, randomized, double-blind, interventional study. Patients ≥60 years undergoing major orthopedic surgery were randomly assigned in a 1:1 ratio to receive preoperative ketamine 0.5 mg/kg as an intravenous bolus (n = 152) or placebo (n = 149) in random blocks stratified according to the study site, preoperative cognitive status and age. The primary outcome was the proportion of objective delayed neurocognitive recovery (dNR) defined as a decline of one or more neuropsychological assessment standard deviations on postoperative day 7. Secondary outcomes included a three-month incidence of objective postoperative neurocognitive disorder (POND), as well as delirium, anxiety, and symptoms of depression seven days and three months after surgery.

RESULTS

Among 301 patients included, 292 (97%) completed the trial. Objective dNR occurred in 50 (38.8%) patients in the ketamine group and 54 (40.9%) patients in the placebo group (OR [95% CI] 0.92 [0.56; 1.51], p = 0.73) on postoperative day 7. Incidence of objective POND three months after surgery did not differ significantly between the two groups nor did incidence of delirium, anxiety, apathy, and fatigue. Symptoms of depression were less frequent in the ketamine group three months after surgery (OR [95% CI] 0.34 [0.13-0.86]).

CONCLUSIONS

A single preoperative bolus of intravenous ketamine does not prevent the occurrence of dNR or POND in elderly patients scheduled for major orthopedic surgery. (Clinicaltrials.gov NCT02892916).

Electrophysiological activity pattern of mouse hippocampal CA1 and dentate gyrus under isoflurane anesthesia

General anesthesia can impact a patient's memory and cognition by influencing hippocampal function. The CA1 and dentate gyrus (DG), serving as the primary efferent and gateway of the hippocampal trisynaptic circuit facilitating cognitive learning and memory functions, exhibit significant differences in cellular composition, molecular makeup, and responses to various stimuli. However, the effects of isoflurane-induced general anesthesia on CA1 and DG neuronal activity in mice are not well understood. In this study, utilizing electrophysiological recordings, we examined neuronal population dynamics and single-unit activity (SUA) of CA1 and DG in freely behaving mice during natural sleep and general anesthesia. Our findings reveal that isoflurane anesthesia shifts local field potential (LFP) to delta frequency and reduces the firing rate of SUA in both CA1 and DG, compared to wakefulness. Additionally, the firing rates of DG neurons are significantly lower than CA1 neurons during isoflurane anesthesia, and the recovery of theta power is slower in DG than in CA1 during the transition from anesthesia to wakefulness, indicating a stronger and more prolonged impact of isoflurane anesthesia on DG. This work presents a suitable approach for studying brain activities during general anesthesia and provides evidence for distinct effects of isoflurane anesthesia on hippocampal subregions.

Mendelian randomization of stroke risk after total hip and knee replacements

Objective

Previous epidemiological studies have indicated an increased risk of neurovascular diseases in patients following total hip and knee replacements. However, definitive conclusions regarding the increased risk of stroke post-replacement remain elusive. Therefore, we conducted a two-sample Mendelian randomization study to investigate the causal relationship between total hip and knee replacements and stroke.

Methods

We utilized summary data from publicly available genome-wide association studies (GWAS). Data concerning total hip replacements (THR, N = 319,037) and total knee replacements (TKR, N = 252,041) were sourced from the Genetics of Osteoarthritis (GO) Consortium. Stroke-related data were obtained from the International Stroke Genetics Consortium, encompassing any stroke (AS), any ischemic stroke (AIS), large vessel ischemic stroke (LV-IS), cardioembolic ischemic stroke (CE-IS), and small vessel ischemic stroke (SV-IS). Our primary causal inference method was the inverse variance weighted (IVW) approach, supplemented by weighted median and MR-Egger regression as secondary inference methods. We utilized the MR-PRESSO global test for outlier detection, Cochran's Q statistic to assess heterogeneity, and assessed the multiplicity and stability of our findings using p-values from MR-PRESSO and MR-Egger regressions, and the leave-one-out method, respectively.

Results

We identified significant genetic associations between THR and both AS (IVW p = 0.0001, OR = 1.08, 95% CI = 1.04-1.12) and AIS (IVW p = 0.0016, OR = 1.07, 95% CI = 1.03-1.12). Significant associations were also observed between TKR and AS (IVW p = 0.0002, OR = 1.08, 95% CI = 1.04-1.12), as well as AIS (IVW p = 0.0005, OR = 1.15, 95% CI = 1.06-1.24).

Conclusion

Our findings genetically support an increased risk of stroke following total hip and knee replacements. However, further studies are necessary to elucidate the specific mechanisms underlying stroke episodes post-replacement.

Nutritional Status and Post-Cardiac Surgery Outcomes: An Updated Review with Emphasis on Cognitive Function

Background/Objectives: Nutritional status significantly influences cardiac surgery outcomes, with malnutrition contributing to poorer results and increased complications. This study addresses the critical gap in understanding by exploring the relationship between pre-operative nutritional status and post-operative cognitive dysfunction (POCD) in adult cardiac patients. Methods: A comprehensive search across key databases investigates the prevalence of malnutrition in pre-operative cardiac surgery patients, its effects, and its association with POCD. Factors exacerbating malnutrition, such as chronic illnesses and reduced functionality, are considered. The study also examines the incidence of POCD, its primary association with CABG procedures, and the impact of malnutrition on complications like inflammation, pulmonary and cardiac failure, and renal injury. Discussions: Findings reveal that 46.4% of pre-operative cardiac surgery patients experience malnutrition, linked to chronic illnesses and reduced functionality. Malnutrition significantly contributes to inflammation and complications, including POCD, with an incidence ranging from 15 to 50%. CABG procedures are particularly associated with POCD, and malnutrition prolongs intensive care stays while increasing vulnerability to surgical stress. Conclusions: The review underscores the crucial role of nutrition in recovery and advocates for a universally recognized nutrition assessment tool tailored to diverse cardiac surgery patients. Emphasizing pre-operative enhanced nutrition as a potential strategy to mitigate inflammation and improve cognitive function, the review highlights the need for integrating nutrition screening into clinical practice to optimize outcomes for high-risk cardiac surgery patients. However, to date, most data came from observational studies; hence, there is a need for future interventional studies to test the hypothesis that pre-operative enhanced nutrition can mitigate inflammation and improve cognitive function in this patient population.

Cognitive Impairment Induced by Gestational Diabetes: The Role of Oxidative Stress

BACKGROUND

Cognitive impairment is defined as a neurological condition that alters multiple cerebral functions such as reasoning, memory, concentration, and association, among others. It has found to be widely correlated with several factors such as oxidative stress. The latter could be induced by numerous pathological conditions characterized by increased levels of free radicals and decreased levels of antioxidants. Pregnancy is a period when women undergo a physiological state of oxidative stress due to hormonal changes and increased oxygen requirements to maintain pregnancy. However, when oxidative stress exceeds antioxidant capacity, this leads to cellular damage that promotes a diabetogenic state. Recent studies suggest a possible association between gestational diabetes and cognitive impairment, but the underlying mechanisms remain unclear.

AIMS

We aim to explore the pathophysiological relationship between cognitive impairment and oxidative stress, focusing on the possible involvement of oxidative stress as the inducing mechanism.

METHODS

We performed a comprehensive literature review through PubMed and Google Scholar. Our keywords were "neuroinflammation", "cognitive impairment", "gestational diabetes", "oxidative stress", "antioxidants", and "free radicals".

RESULTS

From the initial 400 records identified, a total of 78 studies were analyzed and included in our study.

CONCLUSION

Oxidative stress plays a fundamental role in the development of cognitive impairment. Understanding this correlation is essential to the development of targeted medical interventions and, ultimately, promote research and prevention that will benefit the mother-child binomial in the short and long term.

Association of preoperative neutrophil-to-lymphocyte ratio with the risk of postoperative delirium in elderly patients undergoing noncardiac surgery: a systematic review and meta-analysis

To assess the correlation between preoperative neutrophil-to-lymphocyte ratio (NLR) and risk of postoperative delirium (POD) in older patients undergoing noncardiac surgery. PubMed, Web of Science, Embase, and Scopus were systematically retrieved from inception until February 2023. Two authors independently conducted the selection of literature, data extraction and statistical analysis. In this meta-analysis, Review Manager 5.4 was used for statistical analysis, and the mean difference (MD) and 95% confidence intervals (CIs) of preoperative NLR between the POD group and non-POD group were calculated. We utilised the Newcastle-Ottawa Scale (NOS) to evaluate the quality of literature. Further, our meta-analysis used a random-effects model, and publication bias was evaluated by conducting a funnel plot. The correlation between preoperative NLR and POD was the primary outcome, and the secondary outcome was the association of other prognostic factors with the risk of POD. This meta-analysis included seven studies with 2424 patients, of whom 403 were diagnosed with POD with an incidence of 16.63%. Results indicated a positive correlation between preoperative NLR and the risk of POD (MD = 1.06, 95% CI: 0.64-1.49; P < 0.001). Further, our results found that neutrophil counts, advanced age, longer surgery time, diabetes, and elevated C-reactive protein were significantly associated with POD (MD = 0.98, 95% CI: 0.40-1.56; P = 0.001; MD = 4.20, 95% CI: 2.90-5.51; P < 0.001; MD = 0.15, 95% CI: 0.05-0.25; P < 0.01; OR = 1.42, 95% CI: 1.08-1.86; P = 0.01; MD = 1.26, 95% CI: 0.36-2.16; P < 0.01). Other factors including lymphocyte counts, hypertension and male gender were not significantly associated with POD (MD = -0.11, 95% CI: -0.27 to 0.05; P > 0.05; OR = 1.20, 95% CI: 0.91-1.58, P > 0.05; OR = 1.28, 95% CI: 1.00-1.63; P = 0.05). Our meta-analysis indicated a positive correlation between preoperative NLR and the risk of POD in older noncardiac surgery patients.

Insulin attenuates LPS-induced cognitive impairment and ferroptosis through regulation of glucose metabolism in hippocampus

AIMS

Neuroinflammation is a recognized contributor to cognitive disorders like Alzheimer's disease, with ferroptosis emerging as a novel mechanism underlying cognitive dysfunction associated with neuroinflammation. Insulin, pivotal in the central nervous system, holds promise for cognitive function enhancement. This study aimed to establish a cognitive impairment model through intracerebroventricular injection of lipopolysaccharide (LPS) and explore the impact of intracerebroventricular insulin injection on cognitive function in mice.

METHODS

We employed diverse experimental techniques, including animal behavior testing, molecular assays, targeted metabolomics, nuclear medicine, and electron microscopy, to assess neurodegenerative changes, brain insulin resistance (IR), glucose uptake and metabolism, and ferroptosis. The model of cognitive impairment was induced via intracerebroventricular injection of LPS, followed by intracerebroventricular administration of insulin to evaluate its effects.

RESULTS

Insulin treatment effectively mitigated LPS-induced cognitive decline and safeguarded against neuronal degeneration. Furthermore, insulin alleviated LPS-induced insulin resistance, enhanced glucose uptake in the hippocampus, and promoted the Pentose Phosphate Pathway (PPP) and nicotinamide adenine dinucleotide phosphate (NADPH) production. Additionally, insulin activated the glutathione (GSH)-glutathione peroxidase 4 (GPX4) pathway, reducing lipid peroxidation, and mitochondrial damage characteristic of LPS-induced ferroptosis in the hippocampus.

CONCLUSION

Our findings underscore the therapeutic potential of insulin in alleviating LPS-induced cognitive impairment and ferroptosis by modulating glucose metabolism. This study offers a promising avenue for future interventions targeting cognitive decline.

C8-ceramide modulates microglia BDNF expression to alleviate postoperative cognition dysfunction via PKCδ/NF-κB signaling pathway

Postoperative cognitive dysfunction (POCD) is a kind of serious postoperative complication in surgery with general anesthesia and it may affect patients' normal lives. Activated microglia are thought to be one of the key factors in the regulation of POCD process. Once activated, resident microglia change their phenotype and secrete kinds of cytokines to regulate inflammatory response in tissues. Among these secretory factors, brain-derived neurotrophic factor (BDNF) is considered to be able to inhibit inflammation response and protect nervous system. Therefore, the enhancement of BDNF expression derived from resident microglia is suggested to be potential treatment for POCD. In our study, we focused on the role of C8-ceramide (a kind of interventional drug) and assessed its regulatory effect on improving the expression of BDNF secreted from microglia to treat POCD. According to the results of our study, we observed that C8-ceramide stimulated primary microglia to up-regulate the expression of BDNF mRNA after being treated with lipopolysaccharide (LPS) in vitro. We proved that C8-ceramide had ability to effectively improve POCD of mice after being accepted carotid artery exposure and their abnormal behavior recovered better than that of mice from the surgery group. Furthermore, we also demonstrated that C8-ceramide enhanced the cognitive function of mice via the PKCδ/NF-κB signaling pathway. In general, our study has confirmed a potential molecular mechanism that led to the occurrence of POCD caused by surgery and provided a new clinical strategy to treat POCD.

High-frequency repetitive transcranial magnetic stimulation ameliorates memory impairment by inhibiting neuroinflammation in the chronic cerebral hypoperfusion mice

BACKGROUND

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has been found to ameliorate cognitive impairment. However, the effects of HF-rTMS remain unknown in chronic cerebral hypoperfusion (CCH).

AIM

To investigate the effects of HF-rTMS on cognitive improvement and its potential mechanisms in CCH mice.

MATERIALS AND METHODS

Daily HF-rTMS therapy was delivered after bilateral carotid stenosis (BCAS) and continued for 14 days. The mice were randomly assigned to three groups: the sham group, the model group, and the HF-rTMS group. The Y maze and the new object recognition test were used to assess cognitive function. The expressions of MAP-2, synapsis, Myelin basic protein(MBP), and brain-derived growth factors (BDNF) were analyzed by immunofluorescence staining and western blot to evaluate neuronal plasticity and white matter myelin regeneration. Nissl staining and the expression of caspase-3, Bax, and Bcl-2 were used to observe neuronal apoptosis. In addition, the activation of microglia and astrocytes were evaluated by fluorescence staining. The inflammation levels of IL-1β, IL-6, and Tumor Necrosis Factor(TNF)-α were detected by qPCR in the hippocampus of mice in each group.

RESULTS

Via behavioral tests, the BCAS mice showed reduced a rate of new object preference and decreased a rate of spontaneous alternations, while HF-rTMS significantly improved hippocampal learning and memory deficits. In addition, the mice in the model group showed decreased levels of MAP-2, synapsis, MBP, and BDNF, while HF-rTMS treatment reversed these effects. As expected, activated microglia and astrocytes increased in the model group, but HF-rTMS treatment suppressed these changes. HF-rTMS decreased BCAS-induced neuronal apoptosis and the expression of pro-apoptotic protein (Caspase-3 and Bax) and increased the expression of anti-apoptotic protein (Bcl-2). In addition, HF-rTMS inhibited the expression of inflammatory cytokines (IL-1β, IL-6, and TNF-α).

CONCLUSIONS

HF-rTMS alleviates cognitive impairment in CCH mice by enhancing neuronal plasticity and inhibiting inflammation, thus serving as a potential method for vascular cognitive impairment.

Perioperative Immunosuppressive Factors during Cancer Surgery: An Updated Review

Surgical excision of the primary tumor represents the most frequent and curative procedure for solid malignancies. Compelling evidence suggests that, despite its beneficial effects, surgery may impair immunosurveillance by triggering an immunosuppressive inflammatory stress response and favor recurrence by stimulating minimal residual disease. In addition, many factors interfere with the immune effectors before and after cancer procedures, such as malnutrition, anemia, or subsequent transfusion. Thus, the perioperative period plays a key role in determining oncological outcomes and represents a short phase to circumvent anesthetic and surgical deleterious factors by supporting the immune system through the use of synergistic pharmacological and non-pharmacological approaches. In line with this, accumulating studies indicate that anesthetic agents could drive both protumor or antitumor signaling pathways during or after cancer surgery. While preclinical investigations focusing on anesthetics' impact on the behavior of cancer cells are quite convincing, limited clinical trials studying the consequences on survival and recurrences remain inconclusive. Herein, we highlight the main factors occurring during the perioperative period of cancer surgery and their potential impact on immunomodulation and cancer progression. We also discuss patient management prior to and during surgery, taking into consideration the latest advances in the literature.

Potential mechanism of Taohong Siwu Decoction in preventing and treating postoperative delirium in intertrochanteric fracture patients based on retrospective analysis and network pharmacology

OBJECTIVE

Elderly patients with hip fractures are at a greater risk of developing postoperative delirium (POD), which significantly impacts their recovery and overall quality of life. Neuroinflammation is a pathogenic mechanism of POD. Taohong Siwu Decoction (THSWD), known for its ability to promote blood circulation and remove blood stasis, can effectively reduce inflammation in the nervous system. Therefore, the objective of this article is to provide a comprehensive summary of the clinical efficacy of THSWD in the prevention of POD. Additionally, it aims to investigate the underlying mechanism of THSWD in the prevention and treatment of POD using network pharmacology and molecular docking.

METHODS

We conducted a retrospective analysis of patients with intertrochanteric fractures between January 2016 and October 2021. The patients were divided into two groups: the control and THSWD group. We performed a comparative analysis of hemoglobin (HB), albumin (ALB), C-reactive protein (CRP), blood urea nitrogen (BUN), and the blood urea nitrogen to creatinine ratio (BCR) on two different time points: the day before surgery (D0) and the third day after surgery (D3). Furthermore, we examined the incidence and duration of delirium, as well as the Harris Hip Score (HHS) at 3 months and 12 months post-surgery. Network pharmacology was employed to identify the primary targets and mechanisms of THSWD in the management of delirium. Molecular docking was employed to confirm the interaction between active ingredients and COX-2. Inflammatory cytokines, including cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor- (TNF-α), were measured using the enzyme-linked immunosorbent assay (ELISA). The cognitive status of the patients was assessed using the Mini-Mental State Examination (MMSE) scoring system.

RESULTS

Regardless of whether it is in D0 or D3, THSWD treatment can increase HB levels while decreasing BCR. In D3, the THSWD group demonstrated a significant reduction in the expression of CRP and BUN when compared to the control group. However, there were no significant differences in ABL levels, surgery duration, and blood loss between the two groups. Additionally, THSWD treatment requires fewer blood transfusions and can reduce the incidence and duration of POD. The results of the logistic analysis suggest that both CRP levels and BCR independently contribute to the risk of POD. Network pharmacology analysis indicates that THSWD has the potential to prevent and treat POD possibly through inflammatory pathways such as IL-17 signaling pathways and NF-kappa B signaling pathways. Molecular docking validated the interaction between the active ingredient of THSWD and COX-2. Furthermore, THSWD treatment can reduce the levels of COX-2, IL-1β, IL-6, TNF-α, BUN and CRP in the blood of patients with POD, increase HB levels, and enhance MMSE scores. The expression of COX-2 is positively associated with other inflammatory markers (IL-1β, IL-6, TNF-α, and CRP), and inversely associated with MMSE.

CONCLUSION

THSWD has been found to have a preventive and therapeutic effect on POD in intertrochanteric fracture patients possibly through inflammatory pathways. This effect may be attributed to its ability to increase hemoglobin levels and reduce the levels of certain detrimental factors, such as blood urea nitrogen and inflammatory factors.

Total Joint Arthroplasty and Sleep: The State of the Evidence

Background

As the number of total hip and knee arthroplasties (TJA) performed increases, there is heightened interest in perioperative optimization to improve outcomes. Sleep is perhaps one of the least understood perioperative factors that affects TJA outcomes. The purpose of this article is to review the current body of knowledge regarding sleep and TJA and the tools available to optimize sleep perioperatively.

Methods

A manual search was performed using PubMed for articles with information about sleep in the perioperative period. Articles were selected that examined: sleep and pain in the perioperative period; the effect of surgery on sleep postoperatively; the relationship between sleep and TJA outcomes; risk factors for perioperative sleep disturbance; the effect of anesthesia on sleep; and the efficacy of interventions to optimize sleep perioperatively.

Results

Sleep and pain are intimately associated; poor sleep is associated with increased pain sensitivity. Enhanced sleep is associated with improved surgical outcomes, although transient sleep disturbances are normal postoperatively. Risk factors for perioperative sleep disturbance include increasing age, pre-existing sleep disorders, medical comorbidities, and type of anesthesia used. Interventions to improve sleep include optimizing medical comorbidities preoperatively, increasing sleep time perioperatively, appropriating sleep hygiene, using cognitive behavioral therapy, utilizing meditation and mindfulness interventions, and using pharmacologic sleep aids.

Conclusions

Sleep is one of many factors that affect TJA. As we better understand the interplay between sleep, risk factors for suboptimal sleep, and interventions that can be used to optimize sleep, we will be able to provide better care and improved outcomes for patients.

Association of postoperative delirium with serum and cerebrospinal fluid proteomic profiles: a prospective cohort study in older hip fracture patients

Postoperative delirium (POD) is a common neuropsychiatric complication in geriatric inpatients after hip fracture surgery and its occurrence is associated with poor outcomes. The purpose of this study was to investigate the relationship between preoperative biomarkers in serum and cerebrospinal fluid (CSF) and the development of POD in older hip fracture patients, exploring the possibility of integrating objective methods into future predictive models of delirium. Sixty hip fracture patients were recruited. Blood and CSF samples were collected at the time of spinal anesthesia when none of the subjects had delirium. Patients were assessed daily using the 4AT scale, and based on these results, they were divided into POD and non-POD groups. The Olink® platform was used to analyze 45 cytokines. Twenty-one patients (35%) developed POD. In the subsample of 30 patients on whom proteomic analyses were performed, a proteomic profile was associated with the incidence of POD. Chemokine (C-X-C motif) ligand 9 (CXCL9) had the strongest correlation between serum and CSF samples in patients with POD (rho = 0.663; p < 0.05). Although several cytokines in serum and CSF were associated with POD after hip fracture surgery in older adults, there was a significant association with lower preoperative levels of CXCL9 in CSF and serum. Despite the small sample size, this study provides preliminary evidence of the potential role of molecular biomarkers in POD, which may provide a basis for the development of new delirium predictive models.

Effect of remimazolam vs propofol on emergence from general anesthesia in patients undergoing cerebral endovascular procedures: A randomized controlled, non-inferiority trial

STUDY OBJECTIVE

This study aimed to compare the time to emergence from general anesthesia with remimazolam versus propofol in patients undergoing cerebral endovascular procedures.

DESIGN

A prospective, double-blind, randomized controlled, non-inferiority trial.

SETTING

An academic hospital.

PATIENTS

Adult patients scheduled for cerebral endovascular procedures.

INTERVENTIONS

Patients were randomized at a 1:1 ratio to undergo surgery under general anesthesia with remimazolam (0.1 mg kg-1 for induction and 0.3-0.7 mg kg-1 h-1 for maintenance) or propofol (1-1.5 mg kg-1 for induction and 4-10 mg kg-1 h-1 for maintenance).

MEASUREMENTS

The primary outcome was the time to emergence from anesthesia. The non-inferiority margin was -2.55 min in group difference. Major secondary outcomes included hypotension during induction, incidence of postoperative delirium and Modified Rankin Scale (mRs) at 30 days and 90 days after surgery.

MAIN RESULTS

Of the 142 randomized patients, 129 completed the trial. In the modified intention-to-treat analysis, the mean time to emergence from anesthesia was 16.1 [10.4] min in the remimazolam group vs. 19.0 [11.2] min in the propofol group. The group difference was -2.9 min [95% CI -6.5, 0.7] (P = 0.003 for non-inferiority). The remimazolam group had lower rate of hypotension during induction (11.3% vs 25.4%, P = 0.03) and use of vasopressors during surgery (29.6% vs 62.0%, P < 0.001). The two groups did not differ in postoperative delirium and mRs at 30 and 90 days after surgery.

CONCLUSIONS

In patients undergoing cerebral endovascular procedures, remimazolam did not increase the time from anesthesia vs propofol.

Association between increased systemic immune-inflammation index and postoperative delirium in older intertrochanteric fracture patients

BACKGROUND AND PURPOSE

The systemic immune-inflammation index (SII), a novel inflammation index derived from the counts of circulating platelets, neutrophils and lymphocytes, has been studied in the treatment of acute cancer and ischemic stroke (AIS). However, the clinical value of the SII in postoperative delirium patients has not been further investigated. The purpose of our research was to study the incidence and preoperative risk factors for postoperative delirium (POD) and verify whether the SII could serve as a potential marker for POD in older intertrochanteric fracture patients. Finally, we created a novel nomogram for predicting POD in older patients with intertrochanteric fractures.

METHODS

We enrolled elderly patients with intertrochanteric fractures who underwent proximal femoral nail antirotation (PFNA) between February 2021 and April 2023. Univariate and multivariate logistic analyses were subsequently performed to confirm the risk factors and construct a nomogram model.Calibration curve and clinical decision curve analysis (DCA) were used to assess the model's fitting performance. The performance of the nomogram was evaluated for discrimination, calibration, and clinical utility.

RESULTS

A total of 293 patients were eligible for inclusion in the study, 25.6% (75/293) of whom had POD. The POD patients had higher SII values than the non-POD patients. The SII was strongly correlated with POD in older intertrochanteric fracture patients, and the optimal cutoff value was 752.6 × 109. Multivariate analysis revealed that age, diabetes, total albumin, SII > 752.6 × 109 and a CRP > 20.25 mg/L were independent risk factors for POD patients. By incorporating these 5 factors, the model achieved a concordance index of 0.745 (95% CI, 0.683-0.808) and had a well-fitted calibration curve and good clinical application value.

CONCLUSION

The SII is a simple and valuable biomarker for POD, and the new nomogram model can be used to accurately predict the occurrence of POD. They can be utilized in clinical practice to identify those at high risk of POD in older intertrochanteric fracture patients.

Liraglutide ameliorates delirium-like behaviors of aged mice undergoing cardiac surgery by mitigating microglia activation via promoting mitophagy

OBJECTIVE

Postoperative delirium (POD) is a prevalent complication in cardiac surgery patients, particularly the elderly, with neuroinflammation posited as a crucial contributing factor. We investigated the prophylactic effects of liraglutide, a GLP-1 analog, on delirium-like behaviors in aged mice undergoing cardiac surgery and explored the underlying mechanisms focusing on neuroinflammation, mitochondrial dysfunction, and synaptic plasticity.

METHODS

Using a cardiac ischemia-reperfusion animal model to mimic cardiac surgery, we assessed delirium-like behaviors, microglial activation, NLRP3 inflammasome activation, mitophagy, synaptic engulfment, and synaptic plasticity.

RESULTS

Cardiac surgery triggered delirium-like behaviors, concomitant with heightened microglial and NLRP3 inflammasome activation and impaired mitochondrial function and synaptic plasticity. Pretreatment with liraglutide ameliorated these adverse outcomes. Mechanistically, liraglutide enhanced mitophagy, thereby inhibiting NLRP3 inflammasome activation and subsequent microglial activation. Furthermore, liraglutide counteracted surgery-induced synaptic loss and impairment of synaptic plasticity.

CONCLUSION

Liraglutide exerts protective effects against delirium-like behaviors in aged mice post-cardiac surgery, potentially through bolstering microglia mitophagy, curtailing neuroinflammation, and preserving synaptic integrity. This highlights the potential of liraglutide as a promising perioperative strategy for delirium prevention in cardiac surgery patients.

Former smoking, but not active smoking, is associated with delirium in postoperative ICU patients: a matched case-control study

Objective

To examine the relationship between current and former smoking and the occurrence of delirium in surgical Intensive Care Unit (ICU) patients.

Methods

We conducted a single center, case-control study involving 244 delirious and 251 non-delirious patients that were admitted to our ICU between 2018 and 2022. Using propensity score analysis, we obtained 115 pairs of delirious and non-delirious patients matched for age and Simplified Acute Physiology Score II (SAPS II). Both groups of patients were further stratified into non-smokers, active smokers and former smokers, and logistic regression was performed to further investigate potential confounders.

Results

Our study revealed a significant association between former smoking and the incidence of delirium in ICU patients, both in unmatched (adjusted odds ratio (OR): 1.82, 95% confidence interval (CI): 1.17-2.83) and matched cohorts (OR: 3.0, CI: 1.53-5.89). Active smoking did not demonstrate a significant difference in delirium incidence compared to non-smokers (unmatched OR = 0.98, CI: 0.62-1.53, matched OR = 1.05, CI: 0.55-2.0). Logistic regression analysis of the matched group confirmed former smoking as an independent risk factor for delirium, irrespective of other variables like surgical history (p = 0.010). Notably, also respiratory and vascular surgeries were associated with increased odds of delirium (respiratory: OR: 4.13, CI: 1.73-9.83; vascular: OR: 2.18, CI: 1.03-4.59). Medication analysis showed that while Ketamine and Midazolam usage did not significantly correlate with delirium, Morphine use was linked to a decreased likelihood (OR: 0.27, 95% CI: 0.13-0.55).

Discussion

Nicotine's complex neuropharmacological impact on the brain is still not fully understood, especially its short-term and long-term implications for critically ill patients. Although our retrospective study cannot establish causality, our findings suggest that smoking may induce structural changes in the brain, potentially heightening the risk of postoperative delirium. Intriguingly, this effect seems to be obscured in active smokers, potentially due to the recognized neuroprotective properties of nicotine. Our results motivate future prospective studies, the results of which hold the potential to substantially impact risk assessment procedures for surgeries.

An immune signature of postoperative cognitive decline in elderly patients

Postoperative cognitive decline (POCD) is the predominant complication affecting elderly patients following major surgery, yet its prediction and prevention remain challenging. Understanding biological processes underlying the pathogenesis of POCD is essential for identifying mechanistic biomarkers to advance diagnostics and therapeutics. This longitudinal study involving 26 elderly patients undergoing orthopedic surgery aimed to characterize the impact of peripheral immune cell responses to surgical trauma on POCD. Trajectory analyses of single-cell mass cytometry data highlighted early JAK/STAT signaling exacerbation and diminished MyD88 signaling post-surgery in patients who developed POCD. Further analyses integrating single-cell and plasma proteomic data collected before surgery with clinical variables yielded a sparse predictive model that accurately identified patients who would develop POCD (AUC = 0.80). The resulting POCD immune signature included one plasma protein and ten immune cell features, offering a concise list of biomarker candidates for developing point-of-care prognostic tests to personalize perioperative management of at-risk patients. The code and the data are documented and available at https://github.com/gregbellan/POCD .

Teaser

Modeling immune cell responses and plasma proteomic data predicts postoperative cognitive decline.

Heart Rate Variability in Surgical Patients Experiencing Live Bedside Music; An Explorative Study

It's known that surgery elicits a stress response involving the autonomic nervous system (ANS) which is important in general recovery but can also have detrimental effects in older patients. Music seems to positively effect postoperative recovery, although the mechanism requires further unravelling. Our objective was to explore the response of the ANS to live bedside music in older surgical patients, by using heart rate variability (HRV) as a proxy. This explorative prospective non-randomized controlled cohort study included 101 older non-cardiac surgical patients, with a median age of 70 (range 60-88 years). HRV was measured in a cohort receiving live bedside music provided by professional musicians and in a control group that did not receive music. HRV was measured pre-intervention, during the intervention, 30 min after the intervention, and again after three hours. Mixed linear modelling was used to assess the effect of the intervention compared to the control group over time. A significant change in both the low and high frequency bands (p = 0.041) and (p = 0.041) respectively, was found over time in the music group compared to the control group indicating relaxation and increased parasympathetic activity in the music group. Other measures revealed a trend but no significant effect was shown. These results provide a first glance and contribute to a better understanding of the effect of music on the recovery of older surgical patients.

Anesthesia and dementia: An up-to-date review of the existing literature

Concerns around the impact of anesthesia on cognitive decline and dementia, including Alzheimer's Disease (AD), have been increasing and recently attracting considerable attention in the research community. One unanswered question is whether anesthesia is a risk factor of dementia, specifically AD type dementia. A large body of evidence, coming from in vivo and in vitro models, suggests that exposure to anesthetic agents may increase the risk of AD through mechanisms of action similar to AD's neuropathology. In terms of clinical studies, our knowledge of the relationship between anesthesia and dementia is based on limited data, with most studies suggesting that there is no association. The aim of this paper was therefore to outline recent clinical studies exploring this controversial relationship and discuss future directions in terms of study design and potential areas of study. As the aging population and the prevalence of dementia and AD increases, we need a better understanding of anesthesia as a risk factor for neurodegeneration through well-designed studies. Despite the controversy, there seems to be little evidence to support that anesthesia itself or other surgical and patient factors can cause or accelerate AD.