Effect of dexmedetomidine on postoperative cognitive dysfunction in elderly patients after general anaesthesia: A meta-analysis

Influence of different intraoperative fluid management on postoperative outcome after abdominal tumours resection

BACKGROUND

Intraoperative fluid management is a crucial aspect of cancer surgery, including colorectal surgery and pancreatoduodenectomy. The study tests if intraoperative multimodal monitoring reduces postoperative morbidity and duration of hospitalisation in patients undergoing major abdominal surgery treated by the same anaesthetic protocols with epidural analgesia.

PATIENTS AND METHODS

A prospective study was conducted in 2 parallel groups. High-risk surgical patients undergoing major abdominal surgery were randomly selected in the control group (CG), where standard monitoring was applied (44 patients), and the protocol group (PG), where cerebral oxygenation and extended hemodynamic monitoring were used with the protocol for intraoperative interventions (44 patients).

RESULTS

There were no differences in the median length of hospital stay, CG 9 days (interquartile range [IQR] 8 days), PG 9 (5.5), p = 0.851. There was no difference in postoperative renal of cardiac impairment. Procalcitonin was significantly higher (highest postoperative value in the first 3 days) in CG, 0.75 mcg/L (IQR 3.19 mcg/L), than in PG, 0.3 mcg/L (0.88 mcg/L), p = 0.001. PG patients received a larger volume of intraoperative fluid; median intraoperative fluid balance +1300 ml (IQR 1063 ml) than CG; +375 ml (IQR 438 ml), p < 0.001.

CONCLUSIONS

There were significant differences in intraoperative fluid management and vasopressor use. The median postoperative value of procalcitonin was significantly higher in CG, suggesting differences in immune response to tissue trauma in different intraoperative fluid status, but there was no difference in postoperative morbidity or hospital stay.

Anesthesia, Anesthetics, and Postoperative Cognitive Dysfunction in Elderly Patients

Postoperative cognitive dysfunction (POCD) remains a major issue that worsens the prognosis of elderly surgery patients. This article reviews the current research on the effect of different anesthesia methods and commonly utilized anesthetics on the incidence of POCD in elderly patients, aiming to provide an understanding of the underlying mechanisms contributing to this condition and facilitate the development of more reasonable anesthesia protocols, ultimately reducing the incidence of POCD in elderly surgery patients.

Cognitive trajectories after surgery: Guideline hints for assessment and treatment

Elderly patients who undergo major surgery (not-neurosurgical) under general anaesthesia frequently complain about cognitive difficulties, especially during the first weeks after surgical "trauma". Although recovery usually occurs within a month, about one out of four patients develops full-blown postoperative Neurocognitive disorders (NCD) which compromise quality of life or daily autonomy. Mild/Major NCD affect approximately 10% of patients from three months to one year after major surgery. Neuroinflammation has emerged to have a critical role in the postoperative NCDs pathogenesis, through microglial activation and the release of pro-inflammatory cytokines which increase blood-brain-barrier permeability, enhance movement of leukocytes into the central nervous system (CNS) and favour the neuronal damage. Moreover, pre-existing Mild Cognitive Impairment, alcohol or drugs consumption, depression and other factors, together with several intraoperative and post-operative sequelae, can exacerbate the severity and duration of NCDs. In this context it is crucial rely on current progresses in serum and CSF biomarker analysis to frame neuroinflammation levels, along with establishing standard protocol for neuropsychological assessment (with specific set of tools) and to apply cognitive training or neuromodulation techniques to reduce the incidence of postoperative NCDs when required. It is recommended to identify those patients who would need such preventive intervention early, by including them in pre-operative and post-operative comprehensive evaluation and prevent the development of a full-blown dementia after surgery. This contribution reports all the recent progresses in the NCDs diagnostic classification, pathogenesis discoveries and possible treatments, with the aim to systematize current evidences and provide guidelines for multidisciplinary care.

Clinical Use of Adrenergic Receptor Ligands in Acute Care Settings

In this chapter, we review how ligands, both agonists and antagonists, for the major classes of adrenoreceptors, are utilized in acute care clinical settings. Adrenergic ligands exert their effects by interacting with the three major classes of adrenoceptors. Adrenoceptor agonists and antagonists have important applications, ranging from treatment of hypotension to asthma, and have proven to be extremely useful in a variety of clinical settings of acute care from the operating room to the critical care environment. Continued research interpreting the mechanisms of adrenoreceptors may help the discovery of new drugs with more desirable clinical profiles.

DEXMEDETOMIDINE AMELIORATES ACUTE BRAIN INJURY INDUCED BY MYOCARDIAL ISCHEMIA-REPERFUSION VIA UPREGULATING THE HIF-1 PATHWAY

ABSTRACT

Objective: Neurological complications after myocardial ischemia/reperfusion (IR) injury remain high and seriously burden patients and their families. Dexmedetomidine (Dex), an α 2 agonist, is endowed with analgesic-sedative and anti-inflammatory effects. Therefore, our study aims to explore the mechanism and effect of Dex on brain damage after myocardial IR injury. Methods C57BL/6 mice were randomly divided into sham, IR, and IR + Dex groups, and myocardial IR models were established. The impact of Dex on brain injury elicited by myocardial IR was assessed via ELISA for inflammatory factors in serum and brain; Evans blue for blood-brain barrier permeability; hematoxylin-eosin staining for pathological injury in brain; immunofluorescence for microglia activation in brain; Morris water maze for cognitive dysfunction; western blot for the expression level of HIF-1α, occludin, cleaved caspase-3, NF-κB p65, and p-NF-κB p65 in the brain. In addition, HIF-1α knockout mice were used to verify whether the neuroprotective function of Dex is associated with the HIF-1 pathway. Results: Dex was capable of reducing myocardial IR-induced brain damage including inflammatory factor secretion, blood-brain barrier disruption, neuronal edema, microglial activation, and acute cognitive dysfunction. However, the protective role of Dex was attenuated in HIF-1α knockout mice. Conclusion: Dex protects against myocardial IR-induced brain injury, and the neuroprotection of Dex is at least partially dependent on the activation of the HIF-1 pathway.

Taming Postoperative Delirium with Dexmedetomidine: A Review of the Therapeutic Agent's Neuroprotective Effects following Surgery

Postoperative delirium (POD) represents a perioperative neurocognitive disorder that has dreaded ramifications on a patient's recovery from surgery. Dexmedetomidine displays multiple mechanisms of neuroprotection to assist in preventing POD as a part of a comprehensive anesthetic care plan. This review will cover dexmedetomidine's pharmacological overlap with the current etiological theories behind POD along with pre-clinical and clinical studies on POD prevention with dexmedetomidine. While the body of evidence surrounding the use of dexmedetomidine for POD prevention still requires further development, promising evidence exists for the use of dexmedetomidine in select dosing and circumstances to enhance recovery from surgery.

Effect of dexmedetomidine on perioperative haemodynamics and early cognitive function in elderly patients undergoing laparoscopic surgery

Introduction

Laparoscopic minimally invasive surgery has been widely used in the diagnosis and treatment of gynaecological diseases.

Aim

To investigate the effect of dexmedetomidine on perioperative haemodynamics and cognitive function in elderly gynaecological patients who underwent laparoscopic surgery.

Material and methods

Clinical baseline characteristics, haemodynamic parameters, renin activity, norepinephrine level, cognitive function, pain level, and sedation were compared between the 2 groups.

Results

At T4 (10 min after extubation) and T5 (1 h after extubation), significant differences were found in systolic blood pressure, diastolic blood pressure, and heart rate between the 2 groups (p < 0.05); renin activity and norepinephrine level were much lower in the dexmedetomidine group than in the control group at T3 (10 min before extubation) and T4 (p < 0.05). One day before surgery, there were no significant differences in Mini-mental state examination (MMSE), visual analogue scale (VAS), and Ramsay scores between the 2 groups (p > 0.05), but the MMSE score 1 day after surgery and the Ramsay score at 12 h after surgery in the dexmedetomidine group were much higher than that in the control group (p < 0.05). Notably, at 2, 4, 12, 24, and 48 h after surgery, the VAS score in the dexmedetomidine group was significantly lower than that in the control group (p < 0.05).

Conclusions

Dexmedetomidine has a better clinical effect in improving perioperative haemodynamics and early cognitive function in elderly gynaecological patients who received laparoscopic surgery.

Neuroprotective effect of dexmedetomidine on autophagy in mice administered intracerebroventricular injections of Aβ25-35

Alzheimer's disease (AD), one of the most prevalent neurodegenerative diseases is associated with pathological autophagy-lysosomal pathway dysfunction. Dexmedetomidine (Dex) has been suggested as an adjuvant to general anesthesia with advantages in reducing the incidence of postoperative cognitive dysfunction in Dex-treated patients with AD and older individuals. Several studies reported that Dex improved memory; however, evidence on the effects of Dex on neuronal autophagy dysfunction in the AD model is lacking. We hypothesized that Dex administration would have neuroprotective effects by improving pathological autophagy dysfunction in mice that received an intracerebroventricular (i.c.v.) injection of amyloid β-protein fragment 25-35 (Aβ25-35) and in an autophagy-deficient cellular model. In the Y-maze test, Dex reversed the decreased activity of Aβ25-35 mice. Additionally, it restored the levels of two memory-related proteins, phosphorylated Ca2+/calmodulin-dependent protein kinase II (p-CaMKII) and postsynaptic density-95 (PSD-95) in Aβ25-35 mice and organotypic hippocampal slice culture (OHSC) with Aβ25-35. Dex administration also resulted in decreased expression of the autophagy-related microtubule-associated proteins light chain 3-II (LC3-II), p62, lysosome-associated membrane protein2 (LAMP2), and cathepsin D in Aβ25-35 mice and OHSC with Aβ25-35. Increased numbers of co-localized puncta of LC3-LAMP2 or LC3-cathepsin D, along with dissociated LC3-p62 immunoreactivity following Dex treatment, were observed. These findings were consistent with the results of western blots and the transformation of double-membrane autophagosomes into single-membraned autolysosomes in ultrastructures. It was evident that Dex treatment alleviated impaired autolysosome formation in Aβ mice. Our study demonstrated the improvement of memory impairment caused by Dex and its neuroprotective mechanism by investigating the role of the autophagy-lysosomal pathway in a murine Aβ25-35 model. These findings suggest that Dex could be used as a potential neuroprotective adjuvant in general anesthesia to prevent cognitive decline.

Comparative evaluation of intraoperative dexmedetomidine versus lidocaine for reducing postoperative cognitive decline in the elderly: a prospective randomized controlled trial

INTRODUCTION

Neuroinflammation, neuronal cytotoxicity, and apoptosis due to exposure to anaesthetic agents are often implicated in postoperative cognitive dysfunction (POCD). Lidocaine and dexmedetomidine have been shown to suppress the neuron-specific markers of inflammation, and we aimed to compare their neuroprotective efficacy in elderly patients.

MATERIAL AND METHODS

This prospective randomized control study compared the incidence of POCD in ASA I/II patients aged 60 to 80 years without any history of substance abuse or any disorder affecting cognition. Dexmedetomidine and lidocaine were administered intraoperatively, and their effects on POCD were correlated with serum levels of IL-1, IL-6, TNF-a, amyloid-β, and S100 on postoperative day 3. POCD was assessed by the Stroop test, Trail making test-B, Porteus Maze test, Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA) on the day before surgery and the third postoperative day, along with blood samples.

RESULTS

Demographic parameters, anaesthesia duration, exposure to anaesthetic gases, intraoperative opioid use, and blood transfusion were similar in the lidocaine ( n = 31) and dexmedetomidine ( n = 29) groups. The incidence of POCD was 29.03% in the lidocaine group and 24.1% in the dexmedetomidine group ( P = 0.77). On postoperative day 3, IL-1 levels increased by 449% with lidocaine and 202% with dexmedetomidine ( P = 0.03). TNF-a, IL-6, and S-100β levels increased similarly in both groups. There was no significant correlation between percentage changes in neuropsychological tests and biomarkers.

CONCLUSIONS

There was no significant difference in the incidence of POCD, but dexmedetomidine had a better anti-inflammatory effect in terms of lesser rise of postoperative IL-1 compared to lidocaine.

Multimodal Analgesia for Accelerated Rehabilitation after Total Knee Arthroplasty: A Randomized, Double-Blind, Controlled Trial on the Effect of the Co-Application of Local Infiltration Analgesia and Femoral Nerve Block Combined with Dexmedetomidine

Background: Multimodal postoperative pain regimens are widely used following total knee arthroplasty (TKA). However, there are few studies on the rehabilitation of the co-application of local infiltration analgesia (LIA) and femoral nerve block (FNB) combined with dexmedetomidine (DEX) for patients undergoing TKA. This study aimed to investigate the effect of LIA plus FNB and co-application of perioperative DEX on TKA outcomes. Methods: 95 patients were randomized into two groups. Patients in group B (n = 48) received a single preoperative FNB and LIA. Patients in group A (n = 47) received FNB and LIA, as well as continuous intravenous injection of DEX starting from the induction of anesthesia to postoperative day 2. All patients were allowed patient-controlled analgesia postoperatively. Visual analog scale (VAS) scores, knee range of motion (ROM) degrees, narcotic consumption, length of hospital stay (LOS), complications, Hospital for Special Surgery (HSS) scores and Montreal Cognitive Assessment-Basic (MoCA-B) Scores were recorded. Results: In group A, the mean VAS scores at rest and during movement were lower, the amount of rescue analgesia was decreased, first time of ambulation was reduced, ROM was improved, MoCA-B Scores were increased, LOS was shorter, HSS scores were higher postoperatively compared with group B (all p < 0.05). Conclusion: Our study indicated multimodal analgesia involving a single FNB and LIA combined with DEX accelerates rehabilitation for patients undergoing TKA.

Dexmedetomidine-mediated sleep phase modulation ameliorates motor and cognitive performance in a chronic blast-injured mouse model

Multiple studies have shown that blast injury is followed by sleep disruption linked to functional sequelae. It is well established that improving sleep ameliorates such functional deficits. However, little is known about longitudinal brain activity changes after blast injury. In addition, the effects of directly modulating the sleep/wake cycle on learning task performance after blast injury remain unclear. We hypothesized that modulation of the sleep phase cycle in our injured mice would improve post-injury task performance. Here, we have demonstrated that excessive sleep electroencephalographic (EEG) patterns are accompanied by prominent motor and cognitive impairment during acute stage after secondary blast injury (SBI) in a mouse model. Over time we observed a transition to more moderate and prolonged sleep/wake cycle disturbances, including changes in theta and alpha power. However, persistent disruptions of the non-rapid eye movement (NREM) spindle amplitude and intra-spindle frequency were associated with lasting motor and cognitive deficits. We, therefore, modulated the sleep phase of injured mice using subcutaneous (SC) dexmedetomidine (Dex), a common, clinically used sedative. Dex acutely improved intra-spindle frequency, theta and alpha power, and motor task execution in chronically injured mice. Moreover, dexmedetomidine ameliorated cognitive deficits a week after injection. Our results suggest that SC Dex might potentially improve impaired motor and cognitive behavior during daily tasks in patients that are chronically impaired by blast-induced injuries.

Influence of dexmedetomidine on postoperative cognitive dysfunction in the elderly: A meta-analysis of randomized controlled trials

INTRODUCTION

Dexmedetomidine (Dex) is suggested to be neuroprotective. However, influence of Dex on postoperative cognitive dysfunction (POCD) in the elderly remains unknown.

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of Dex on POCD. Relevant studies were obtained by search of PubMed, Embase, and Cochrane's Library databases. A random-effect model was used to pool the results.

RESULTS

Fourteen RCTs including 1626 adults of 60 years or older who received surgery with general anesthesia were included. Because methodologically diverse scales were used for POCD, eight RCTs with POCD diagnosed with Mini-Mental State Examination (MMSE) were included in the meta-analysis, while the remaining six RCTs with POCD diagnosed with other scales were qualitative synthesized. Pooled results of RCTs with MMSE showed that Dex significantly reduced the incidence of POCD (risk ratio: 0.47, 95% confidence interval: 0.37-0.60, p < 0.001) with no significant heterogeneity (I2  = 0%) or publication bias (p for Egger's regression test = 0.579). For the remaining six RCTs with POCD diagnosed with other scales, three of them showed that Dex was associated with a significantly lower incidence of POCD, while the other three RCTs did not show a significant difference.

CONCLUSIONS

Dex is associated with a reduced risk of POCD in elderly patients receiving surgeries with general anesthesia, and the results were mainly obtained in studies with POCD diagnosed with MMSE. Based on these findings, Dex may be considered as a preventative measure for POCD in elderly patients.

Dexmedetomidine attenuates hippocampal neuroinflammation in postoperative neurocognitive disorders by inhibiting microRNA-329-3p and activating the CREB1/IL1RA axis

RATIONALE

Due to its anti-inflammatory effect, dexmedetomidine (DEX) can confer neuroprotection in postoperative neurocognitive disorders (NCD). Here, the mechanism responsible for this effect of DEX is rarely ascertained.

OBJECTIVES

Our research was implemented to figure out mechanism governing the protection of DEX against hippocampal neuroinflammation in postoperative NCD.

METHODS

Exploratory laparotomy was applied for generating a postoperative NCD mouse model before bilateral hippocampal injection with microRNA (miR)-329-3p-agomir and intraperitoneal injection with DEX. Cognitive function of mice was evaluated by water maze test and fear conditioning test. Immunofluorescence was performed to assess microglial activation in hippocampus. After cell transfection and DEX treatment, mouse microglial cells (BV-2) were stimulated by lipopolysaccharide (LPS). IL-1β, IL-6, and TNF-α levels and the number of phagocytes were assessed by ELISA and flow cytometry. Dual-luciferase reporter assay was adopted to assess the relationship between miR-329-3p and CREB1.

RESULTS

miR-329-3p expression was reduced in the postoperative NCD mice after DEX treatment. DEX treatment or miR-329-3p downregulation caused attenuated cognitive dysfunction and microglia activation as well as reduced IL-1β, IL-6, and TNF-α levels in the hippocampus of the postoperative NCD mice. Mechanistically, miR-329-3p inversely targeted CREB1 that activated IL1RA in LPS-induced BV-2 cells. DEX treatment, miR-329-3p inhibition, or CREB1 or IL1RA upregulation curtailed the release of proinflammatory proteins and the number of phagocytes in LPS-induced BV-2 cells.

CONCLUSIONS

Collectively, our data provided the novel insight of the neuroprotective mechanism of DEX in postoperative NCD pertaining to the miR-329-3p/CREB1/IL1RA axis.

The Effects of Dexmedetomidine on Perioperative Neurocognitive Outcomes After Cardiac Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

The purpose of this systematic review and meta-analysis is to examine the effect of DEX on delayed dNCR (cognitive dysfunction ≥ 1 week postoperative) after cardiac surgery.

BACKGROUND

DEX has salutary effects on cognitive outcomes following cardiac surgery, however, studies are limited by inconsistent assessment tools, timing, and definitions of dysfunction. It is imperative to identify accurate point estimates of effect of DEX on clinically relevant changes in cognitive function.

METHODS

Randomized trials of adults undergoing cardiac surgery comparing perioperative DEX to placebo or alternate sedation and assessing cognitive function ≥ 1 week postoperative were included. Data was abstracted by three reviewers independently and in parallel according to PRISMA guidelines. The primary outcome is dNCR. To classify as dNCR, cognitive function must decrease by at least the minimal clinically important difference or accepted alternate measure (eg, Reliable Change Index ≥1.96). Bias was assessed with the Cochrane Collaboration tool. Data was pooled using a random effects model.

RESULTS

Nine trials (942 participants) were included in qualitative analysis, of which seven were included in the meta-analysis of dNCR. DEX reduced the incidence of dNCR (OR 0.39, 95% CI 0.25-0.61, P < 0.0001) compared to placebo/no DEX. There was no difference in the incidence of delirium (OR 0.69, 95% CI 0.35-1.34, P = 0.27) or incidence of hemodynamic instability (OR 1.14, 95% CI 0.59-2.18, P = 0.70) associated with perioperative DEX.

CONCLUSIONS

DEX reduced the incidence of dNCR 1 week after cardiac surgery. Although this meta-analysis demonstrates short term cognitive outcomes are improved after cardiac surgery with perioperative DEX, future trials examining long term cognitive outcomes, using robust cognitive assessments, and new perioperative neurocognitive disorders nomenclature with objective diagnostic criteria are necessary.

Neuroinflammation as the Underlying Mechanism of Postoperative Cognitive Dysfunction and Therapeutic Strategies

Postoperative cognitive dysfunction (POCD) is a common neurological complication following surgery and general anesthesia, especially in elderly patients. Severe cases delay patient discharge, affect the patient’s quality of life after surgery, and are heavy burdens to society. In addition, as the population ages, surgery is increasingly used for older patients and those with higher prevalences of complications. This trend presents a huge challenge to the current healthcare system. Although studies on POCD are ongoing, the underlying pathogenesis is still unclear due to conflicting results and lack of evidence. According to existing studies, the occurrence and development of POCD are related to multiple factors. Among them, the pathogenesis of neuroinflammation in POCD has become a focus of research in recent years, and many clinical and preclinical studies have confirmed the correlation between neuroinflammation and POCD. In this article, we reviewed how central nervous system inflammation occurred, and how it could lead to POCD with changes in peripheral circulation and the pathological pathways between peripheral circulation and the central nervous system (CNS). Furthermore, we proposed some potential therapeutic targets, diagnosis and treatment strategies at the cellular and molecular levels, and clinical applications. The goal of this article was to provide a better perspective for understanding the occurrence of POCD, its development, and preventive strategies to help manage these vulnerable geriatric patients.

The Effects of Dexmedetomidine on Perioperative Neurocognitive Outcomes After Noncardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

The purpose of this review is to examine the effect of dexmedetomidine on delayed neurocognitive recovery (dNCR; cognitive dysfunction ≥1 week postoperative) after major noncardiac surgery.

Background

Dexmedetomidine (DEX) effectively reduces delirium in the intensive care unit and reportedly attenuates cognitive decline following major noncardiac surgery. Ascertaining the true effect on postoperative cognition is difficult because studies are limited by suboptimal selection of cognitive assessment tools, timing of testing, and criteria for defining significant cognitive decline.

Methods

Prospective randomized trials comparing perioperative DEX to placebo for major noncardiac surgery assessing cognitive function ≥1 week postoperative were included. Pediatric, nonhuman, and non-English trials, and those where executive function was not assessed were excluded. Data were abstracted by 3 reviewers independently and in parallel according to PRISMA guidelines. The a priori binary primary outcome is dNCR defined as cognitive function declining by the minimal clinically important difference or accepted alternate measure (eg, Reliable Change Index ≥1.96). Bias was assessed with the Cochrane Collaboration tool. Data were pooled using a random effects model.

Results

Among 287 citations identified, 26 (9%) met criteria for full-text retrieval. Eleven randomized trials (1233 participants) were included for qualitative analysis, and 7 trials (616 participants) were included for meta-analysis of dNCR. Dexmedetomidine did not reduce the incidence of dNCR significantly (OR 0.57, 95% CI 0.30-1.10, P = 0.09) compared with placebo. There was no difference in the incidence of delirium (OR 0.94, 95% CI 0.55-1.63, P = 0.83) and a higher incidence of hemodynamic instability (OR 2.11, 95% CI 1.22-3.65, P = 0.008).

Conclusions

Dexmedetomidine does not reduce dNCR 1 week after major noncardiac surgery. This meta-analysis does not yet support the use of perioperative DEX to improve short term cognitive outcomes at this time; trials underway may yet change this conclusion while larger trials are needed to refine the point estimate of effect and examine long-term cognitive outcomes.

Gut-Brain Axis: Possible Role of Gut Microbiota in Perioperative Neurocognitive Disorders

Aging is becoming a severe social phenomenon globally, and the improvements in health care and increased health awareness among the elderly have led to a dramatic increase in the number of surgical procedures. Because of the degenerative changes in the brain structure and function in the elderly, the incidence of perioperative neurocognitive disorders (PND) is much higher in elderly patients than in young people following anesthesia/surgery. PND is attracting more and more attention, though the exact mechanisms remain unknown. A growing body of evidence has shown that the gut microbiota is likely involved. Recent studies have indicated that the gut microbiota may affect postoperative cognitive function via the gut-brain axis. Nonetheless, understanding of the mechanistic associations between the gut microbiota and the brain during PND progression remains very limited. In this review, we begin by providing an overview of the latest progress concerning the gut-brain axis and PND, and then we summarize the influence of perioperative factors on the gut microbiota. Next, we review the literature on the relationship between gut microbiota and PND and discuss how gut microbiota affects cognitive function during the perioperative period. Finally, we explore effective early interventions for PND to provide new ideas for related clinical research.

Changing Pain Management Strategy from Opioid-Centric towards Improve Postoperative Cognitive Dysfunction with Dexmedetomidine

OBJECTIVE

This study was aimed to investigate the effectiveness of dexmedetomidine (DEX) on improving the level of pain and disability to find out the possible correlation between psychological factors with pain management satisfaction and physical function in patients with femoral neck fractures.

METHODS

One hundred twenty-four adult patients with stable femoral neck fractures (type I and II, Garden classification) who underwent internal fixation, were prospectively enrolled including 62 patients in the DEX group and 62 patients in the control group. The magnitude of disability using Harris Hip Score, Postoperative Cognitive Dysfunction (POCD) using Mini-Mental State Examination (MMSE score), Quality of Recovery (QoR-40), pain-related anxiety (PASS-20), pain management and pain catastrophizing scale (PCS) were recorded on the first and second day after surgery.

RESULTS

The DEX group on the first and second days after surgery exhibited higher quality of recovery scores, greater satisfaction with pain management, low disability scores, less catastrophic thinking, lower pain anxiety, greater mini mental state examination scores and less opioid intake and the differences were statistically significant compared with the control group (P<0.001). Emergence agitation and incidence of POCD were significantly less in the DEX group (P<0.001). Decreased disability was associated with less catastrophic thinking and lower pain anxiety, but not associated with more opioid intake (P<0.001). Higher QoR-40 scores had a negative correlation with more catastrophic thinking and more opioid intake (P<0.001). Greater satisfaction with pain management was correlated with less catastrophic thinking and less opioid intake (P<0.001).

CONCLUSION

Using DEX as an adjunct to anesthesia could significantly improve postoperative cognitive dysfunction and the quality of recovery and these improvements were accompanied by decrease in pain, emergence agitation, and opioid consumption by DEX administration. Since pain relief and decreased disability were not associated with prescribing greater amounts of opioid intake in the patients, improving psychological factors, including reducing catastrophic thinking or self-efficacy about pain, could be a more effective strategy to reduce pain and disability, meanwhile reducing opioid prescription in the patients. Our findings showed that DEX administration is safe sedation with anti-inflammatory, analgesic and antiemetic effects and it could help change pain management strategy from opioid-centric towards improved postoperative cognitive dysfunction.

The Influence of Different Dexmedetomidine Doses on Cognitive Function at Early Period of Patients Undergoing Laparoscopic Extensive Total Hysterectomy

Background

This study aims to analyze the influence of different dexmedetomidine doses on cognitive function. It works on early periods of patients undergoing laparoscopic extensive total hysterectomy.

Method

119 patients with gynecological cancer underwent a laparoscopic extensive total hysterectomy. The operation was performed at the Affiliated Women's and Children's Hospital of Xiamen University from January 2019 to June 2020. The score of MoCA and the level of TNF-α, IL-6, S-100β protein, NSE, and GFAP of each group were compared 1 day before and after operation and 3 and 7 days after operation.

Result

In four groups, remifentanil, sufentanil, and propofol were given in the following order: group A > group D > group C > group B. Group A > group D > group C in terms of time spent in the recovery room, extubation, and recovery from anesthesia. The difference between groups B and C was not significant (P > 0.05). Compared with group A, group B scored higher in MoCA at 1 day (T1), 3 days (T2), and 7 days (T3) after operation (P < 0.05). At the same scoring point, the score was group B > group C > group D > group A. The POCD of four groups all occurred at 3 days after surgery. Compared with the T0 point, the level of TNF-α and IL-6 of the four groups at T1 and T2 was significantly increased (P < 0.05). At T3, the level of TNF-α and IL-6 gradually decreased. At various periods, the levels of S-100 protein, NSE, and GFAP in groups B, C, and D were lower than those in group A (P0.05). Group B had a substantially higher rate of bradycardia than the other three groups (P0.05). The incidence of chills, respiratory depression, and restlessness in group A differed significantly from the other three groups (P < 0.05).

Conclusion

Using 0.5 μg/kg dexmedetomidine during the perianaesthesia can effectively reduce anesthetic drugs in patients. They had a laparoscopic extensive complete hysterectomy, which helps to reduce the adverse responses and the occurrence of POCD while also protecting brain function.

The effects of anaesthetics and sedatives on brain inflammation

Microglia are involved in many dynamic processes in the central nervous system (CNS) including the development of inflammatory processes and neuromodulation. Several sedative, analgesic or anaesthetic drugs, such as opioids, ∝2-adrenergic agonists, ketamine, benzodiazepines and propofol can cause both neuroprotective and harmful effects on the brain. The purpose of this review is to present the main findings on the use of these drugs and the mechanisms involved in microglial activation. Alpha 2-adrenergic agonists, propofol and benzodiazepines have several pro- or anti-inflammatory effects on microglia. Long-term use of benzodiazepines and propofol causes neuroapoptotic effects and α2-adrenergic agonists may attenuate these effects. Conversely, morphine and fentanyl may have proinflammatory effects, causing behavioural changes in patients and changes in cell viability in vitro. Conversely, chronic administration of morphine induces CCL5 chemokine expression in microglial cells that promotes their survival.

The Effect of Dexmedetomidine and Esmolol on Early Postoperative Cognitive Dysfunction After Middle Ear Surgery Under Hypotensive Technique: A Comparative, Randomized, Double-blind Study

OBJECTIVES

Postoperative cognitive dysfunction (POCD) is multifactorial, which may be caused by anesthetic and surgical causes or cerebral injury. This study aimed to evaluate the effect of dexmedetomidine as a neuroprotective drug compared to esmolol on the prevalence of POCD in adult patients undergoing middle ear surgeries under hypotensive anesthesia.

METHODS

This study included male and female adult patients, according to American Society of Anesthesiology physical status (ASA) I, the patients who underwent middle ear surgeries under hypotensive anesthesia were randomly assigned to two groups that received esmolol and dexmedetomidine. The demographic data, heart rate, mean arterial blood pressure, duration of the surgery, evaluation of the surgical field, and the Mini-Mental State Examination (MMSE) (preoperatively and at 1, 6 and 24 hours postoperatively) were recorded.

RESULTS

There was a significant difference between the numbers of patients who had POCD in MMSE1: 12 cases in the esmolol group (41.37%) compared to three cases in the dexmedetomidine group (10.34%) (P = 0.016), in MMSE6: 10 cases in the esmolol group (34.48%) compared with two cases in the dexmedetomidine group (6.89%) (P = 0.023) and in MMSE24: seven cases in the esmolol group (24.13%) compared with one case in the dexmedetomidine group (3.44%) (P = 0.022), while the median and range of MMSE score were comparable between the two groups (P > 0.05).

CONCLUSIONS

This study suggests that intraoperative use of dexmedetomidine as an adjuvant to hypotensive anesthesia reduces the incidence of POCD compared to esmolol.

The involvement of NLRP3 inflammasome in the treatment of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, and it is characterised by progressive deterioration in cognitive and memory abilities, which can severely influence the elderly population's daily living abilities. Although researchers have made great efforts in the field of AD, there are still no well-established strategies to prevent and treat this disease. Therefore, better clarification of the molecular mechanisms associated with the onset and progression of AD is critical to provide a theoretical basis for the establishment of novel preventive and therapeutic strategies. Currently, it is generally believed that neuroinflammation plays a key role in the pathogenesis of AD. Inflammasome, a multiprotein complex, is involved in the innate immune system, and it can mediate inflammatory responses and pyroptosis, which lead to neurodegeneration. Among the various types of inflammasomes, the NLRP3 inflammasome is the most characterised in neurodegenerative diseases, especially in AD. The activation of the NLRP3 inflammasome causes the generation of caspase-1-mediated interleukin (IL)-1β and IL-18 in microglia cells, where neuroinflammation is involved in the development and progression of AD. Thus, the NLRP3 inflammasome is likely to be a crucial therapeutic molecular target for AD via regulating neuroinflammation. In this review, we summarise the current knowledge on the role and regulatory mechanisms of the NLRP3 inflammasome in the pathogenic mechanisms of AD. We also focus on a series of potential therapeutic treatments targeting NLRP3 inflammasome for AD. Further clarification of the regulatory mechanisms of the NLRP3 inflammasome in AD may provide more useful clues to develop novel AD treatment strategies.

Effect of dexmedetomidine combined with etomidate on IL-17A and S-100β expression levels in rats with postoperative cognitive dysfunction

The present study aimed to explore the effects of dexmedetomidine combined with etomidate on the expression levels of interleukin (IL)-17A and S-100β in rats with postoperative cognitive dysfunction (POCD). A total of 50 SD rats were randomly allocated into the control group, model group, etomidate group (Eto group), dexmedetomidine group (Dex group) and dexmedetomidine combined with etomidate group (Dex-Eto group). Inhalation anesthesia was used in all five groups. Apart from the control group, partial lobectomy was performed to construct a rat model of cognitive dysfunction. The rats of the model group received no intravenous anesthesia, except general anesthesia with intubation. Morris water maze test was performed before injection (T₀), at the 1st day (T₁), the 3rd day (T₂) and the 5th day (T₃) after operation to assess the memory ability of the rats. At the end of T₃, the expression levels of IL-17A, S-100β, TNF-α, IL-6 and IL-1β in serum were detected by ELISA and the expression of NF-κB p65 by western blot analysis. Compared with the control group, the model group showed an increased escape latency and swimming distance, decreased number of times of crossing the platform and target quadrant residence time, and increased expression levels of IL-17A, S-100β, TNF-α, IL-6, IL-1β and NF-κB p65. Compared with the model group, the escape latency and swimming distance in the Dex, Eto and Dex-Eto groups were reduced, whereas the number of times of crossing the platform and the target quadrant residence time were increased. In addition, the expression levels of IL-17A, S-100β, TNF-α, IL-6, IL-1β and NF-κB p65 were decreased in the Dex, Eto and Dex-Eto groups, compared with the model group. Among the Dex, Eto and Dex-Eto groups, the escape latency and swimming distance in the Dex-Eto group were the shortest, the number of times of crossing the platform and the target quadrant residence time were the highest, and IL-17A, S-100β, TNF-α, IL-6, IL-1β and NF-κB p65 expression levels were the lowest. In conclusion, dexmedetomidine combined with etomidate can effectively improve POCD.

Pharmacological Agents That Prevent Postoperative Cognitive Dysfunction in Patients With General Anesthesia: A Network Meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is associated with prolonged hospital stays, increased mortality, and negative socioeconomic consequences. Dexmedetomidine, ketamine, dexamethasone, and lidocaine have previously been reported to be effective for preventing POCD.

STUDY QUESTION

In this network meta-analysis, we apply direct and indirect comparisons to rank these pharmacological agents in terms of their effect on POCD, through which we seek to provide evidence for future clinical medication.

DATA SOURCES

A comprehensive literature search of PubMed, EMBASE, the Cochrane Library, and Web of Science was conducted to identify randomized controlled trials that examined the effects of dexmedetomidine, ketamine, dexamethasone, or lidocaine on POCD induced by general anesthesia.

STUDY DESIGN

For eligible studies, 2 reviewers independently extracted data and assessed the respective risk of bias. Bayesian network meta-analysis was conducted using R-3.4.1 software. A total of 30 articles were included in this meta-analysis.

RESULTS

Direct comparison showed that dexmedetomidine [odds ratio (OR) = 0.42, 95% confidence interval (CI): 0.32-0.55] may decrease the incidence of POCD for noncardiac surgery; dexmedetomidine (OR = 0.08, 95% CI: 0.01-0.63) and ketamine (OR = 0.09, 95% CI: 0.02-0.32) were found to decrease POCD for cardiac surgery. The R-software ranking result for prevention of POCD was dexmedetomidine, lidocaine, ketamine, placebo, and dexamethasone, respectively, in noncardiac surgery, and dexmedetomidine, ketamine, lidocaine, placebo, and dexamethasone in cardiac surgery.

CONCLUSION

Dexmedetomidine exhibited obvious superiority to other agents for noncardiac surgery; dexmedetomidine and ketamine exhibited a significantly better performance than other agents for cardiac surgery. Dexamethasone did not show better efficacy than the placebo. However, more rigorously designed studies comprising larger sample sizes are needed to confirm our findings.

Overexpression of lncRNA Gm43050 alleviates apoptosis and inflammation response induced by sevoflurane treatment by regulating miR-640/ZFP91

AIMS

The present study investigated the function and mechanism of lncRNA Gm43050 in sevoflurane-induced abnormal cognition.

METHODS

Primary hippocampal neurons were used to establish the model of abnormal cognitive disorder. Overexpression and knockdown experiments were performed to analyze cell death rates, proliferation, apoptosis and the inflammatory response. The dual-luciferase reporter assay was used to analyze the potential binding targets of lncRNA Gm43050. Rescue experiments were used to assess the downstream targets of Gm43050.

RESULTS

We found that lncRNA Gm43050 was in the cytoplasm. Overexpression of lncRNA Gm43050 had no impact on proliferation but significantly reduced the cell death rates and apoptosis. The inflammation markers IL-6, IL-1β, IL-8 and TNF-α were manifestly downregulated in the overexpression group. Opposite effects were detected in the lncRNA Gm43050 knockdown group. Bioinformatics analysis showed that miR-640 may be the potential target of Gm43050. Additionally, we found that ZFP91 was the downstream target of miR-640.

CONCLUSION

We provided comprehensive data of the function and mechanism of lncRNA Gm43050 in abnormal cognition. Our study showed that lncRNA Gm43050 exerted its important role via the regulation of miR-640 and ZFP91.

Dexmedetomidine Pretreatment Improves Lipopolysaccharide-induced Iron Homeostasis Disorder in Aged Mice

BACKGROUND

Iron homeostasis disorder and neuroinflammation are the most commonly known factors that promote the occurrence and development of cognitive impairment in people. Dexmedetomidine has an anti-inflammatory effect, and it reduces the incidence of postoperative cognitive dysfunction. Therefore, the aim of this study is to verify whether dexmedetomidine could improve lipopolysaccharide-induced iron homeostasis disorder in aged mice, and show neuroprotective effect.

METHODS

First part, forty 12 month old male Kunming(KM) mice were divided into group N and group D: Normal saline group (group N), Dexmedetomidine group (group D). Second part, sixty 12-month-old male KM mice were divided into the following three groups: Normal saline group (group N), Lipopolysaccharide group (group LPS) and Dexmedetomidine + Lipopolysaccharide group (group D + LPS). The mice in group D + LPS were given dexmedetomidine, and given LPS intraperitoneally 2 h later. Mice underwent an oriented navigation test and a space exploration test in the Morris Water maze (MWM) test. The expression levels of Interleukin-6 ( IL-6), L-ferritin (FTL) and Transferrin receptor-1 (TfR1) in hippocampus were detected by the Western blot analysis; the hippocampal hepcidin mRNA was detected by Real-time PCR(RT-PCR); the reactive oxygen species (ROS) in the hippocampus was measured using ROS test kit.

RESULTS

Dexmedetomidine improved the cognitive decline induced by LPS. Dexmedetomidine reduced the level of hippocampal IL-6, and it attenuated the increase in their levels caused by LPS. It had no effect on hippocampal hepcidin mRNA, FTL, TfR1 and ROS but it could attenuate the increase caused by LPS.

CONCLUSION

Dexmedetomidine has no effect on iron metabolism pathway, but it can improve the cognitive decline and the iron disorder by reducing neuroinflammation and oxidative stress. The research indicates that dexmedetomidine plays a neuroprotective role.

Influence of postoperative analgesia on systemic inflammatory response and postoperative cognitive dysfunction after femoral fractures surgery: a randomized controlled trial

BACKGROUND AND OBJECTIVES

To investigate the possible effect of postoperatively applied analgesics-epidurally applied levobupivacaine or intravenously applied morphine-on systemic inflammatory response and plasma concentration of interleukin (IL)-6 and to determine whether the intensity of inflammatory response is related to postoperative cognitive dysfunction (POCD).

METHODS

This is a randomized, prospective, controlled study in an academic hospital. Patients were 65 years and older scheduled for femoral fracture fixation from July 2016 to September 2017. Inflammatory response was assessed by leukocytes, neutrophils, C reactive protein (CRP) and fibrinogen levels in four blood samples (before anesthesia, 24 hours, 72 hours and 120 hours postoperatively) and IL-6 concentration from three blood samples (before anesthesia, 24 hours and 72 hours postoperatively). Cognitive function was assessed using the Mini-Mental State Examination preoperatively, from the first to the fifth postoperative day and on the day of discharge.

RESULTS

The study population included 70 patients, 35 in each group. The incidence of POCD was significantly lower in the levobupivacaine group (9%) than in the morphine group (31%) (p=0.03). CRP was significantly lower in the levobupivacaine group 72 hours (p=0.03) and 120 hours (p=0.04) after surgery. IL-6 values were significantly lower in the levobupivacaine group 72 hours after surgery (p=0.02). The only predictor of POCD in all patients was the level of IL-6 72 hours after surgery (p=0.03).

CONCLUSIONS

There is a statistically significant association between use of epidural levobupivacaine and a reduction in some inflammatory markers. Postoperative patient-controlled epidural analgesia reduces the incidence of POCD compared with intravenous morphine analgesia in the studied population.

TRIAL REGISTRATION NUMBER

NCT02848599.

Anesthesiology and cognitive impairment: a narrative review of current clinical literature

Background

The impact of general anesthesia on cognitive impairment is controversial and complex. A large body of evidence supports the association between exposure to surgery under general anesthesia and development of delayed neurocognitive recovery in a subset of patients. Existing literature continues to debate whether these short-term effects on cognition can be attributed to anesthetic agents themselves, or whether other variables are causative of the observed changes in cognition. Furthermore, there is conflicting data on the relationship between anesthesia exposure and the development of long-term neurocognitive disorders, or development of incident dementia in the patient population with normal preoperative cognitive function. Patients with pre-existing cognitive impairment present a unique set of anesthetic considerations, including potential medication interactions, challenges with cooperation during assessment and non-general anesthesia techniques, and the possibility that pre-existing cognitive impairment may impart a susceptibility to further cognitive dysfunction.

Main body

This review highlights landmark and recent studies in the field, and explores potential mechanisms involved in perioperative cognitive disorders (also known as postoperative cognitive dysfunction, POCD). Specifically, we will review clinical and preclinical evidence which implicates alterations to tau protein, inflammation, calcium dysregulation, and mitochondrial dysfunction. As our population ages and the prevalence of Alzheimer’s disease and other forms of dementia continues to increase, we require a greater understanding of potential modifiable factors that impact perioperative cognitive impairment.

Conclusions

Future research should aim to further characterize the associated risk factors and determine whether certain anesthetic approaches or other interventions may lower the potential risk which may be conferred by anesthesia and/or surgery in susceptible individuals.

Anesthetic management of geriatric patients

The number of elderly patients who frequently access health care services is increasing worldwide. While anesthesiologists are developing the expertise to care for these elderly patients, areas of concern remain. We conducted a comprehensive search of major international databases (PubMed, Embase, and Cochrane) and a Korean database (KoreaMed) to review preoperative considerations, intraoperative management, and postoperative problems when anesthetizing elderly patients. Preoperative preparation of elderly patients included functional assessment to identify preexisting cognitive impairment or cardiopulmonary reserve, depression, frailty, nutrition, polypharmacy, and anticoagulation issues. Intraoperative management included anesthetic mode and pharmacology, monitoring, intravenous fluid or transfusion management, lung-protective ventilation, and prevention of hypothermia. Postoperative checklists included perioperative analgesia, postoperative delirium and cognitive dysfunction, and other complications. A higher level of perioperative care was required for older surgical patients, as multiple chronic diseases often makes them prone to developing postoperative complications, including functional decline and loss of independence. Although the guiding evidence remains poor so far, elderly patients have to be provided optimal perioperative care through close interdisciplinary, interprofessional, and cross-sectional collaboration to minimize unwanted postoperative outcomes. Furthermore, along with adequate anesthetic care, well-planned postoperative care should begin immediately after surgery and extend until discharge.

Dexmedetomidine and sufentanil combination versus sufentanil alone for postoperative intravenous patient-controlled analgesia: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Previous studies have demonstrated that dexmedetomidine improves the quality of postoperative analgesia. In the present study, we performed a meta-analysis of randomized controlled trials to quantify the effect of dexmedetomidine as an adjuvant to sufentanil for postoperative patient-controlled analgesia (PCA).

METHODS

PubMed, Embase, the Cochrane Library, and Web of Science were systematically searched for randomized controlled trials in which dexmedetomidine was used as an adjuvant for PCA with sufentanil. In the retrieved studies, we quantitatively analyzed pain intensity, sufentanil consumption, and drug-related side effects.

RESULTS

Nine studies with 907 patients were included in this meta-analysis. Compared with sufentanil alone, dexmedetomidine-sufentanil for postoperative intravenous PCA reduced pain intensity at 24 h (mean difference (MD) = - 0.70points; 95% confidence interval (CI): - 1.01, - 0.39; P < 0.00001) and 48 h postoperatively (MD = -0.61points; 95% CI: - 1.00, - 0.22; P = 0.002). Moreover, dexmedetomidine-sufentanil reduced sufentanil consumption during the first 24 h (MD = -13.77 μg; 95% CI: - 18.56, - 8.97; P < 0.00001) and 48 h postoperatively (MD = -20.81 μg; 95% CI: - 28.20, - 13.42; P < 0.00001). Finally, dexmedetomidine-sufentanil improved patient satisfaction without increasing the incidence of side effects.

CONCLUSIONS

Dexmedetomidine as an adjuvant to sufentanil for postoperative PCA can reduce postoperative pain score and sufentanil consumption.

Effect of dexmedetomidine on postoperative cognitive dysfunction and inflammation in patients after general anaesthesia: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Neuroprotective effects of dexmedetomidine are reported in preclinical and clinical studies but evidence regarding the postoperative neurocognitive function is still unclear. This study performed a meta-analysis on outcomes of studies which examined neurocognitive performance and inflammatory factors to investigate the effects of dexmedetomidine on postoperative cognitive dysfunction (POCD) and inflammation in patients after general anaesthesia.

METHODS

Literatures were searched in several electronic databases and studies were selected by following precise inclusion criteria. We searched PubMed, EMBASE, the Cochrane Library, China Academic Journals full-text database (CNKI), and Google Scholar to find randomized controlled trials (RCTs) of the influence of dexmedetomidine on POCD and inflammation in patients who had undergone general anaesthesia. Two researchers independently screened the literature, extracted data, and evaluated quality of methodology against inclusion and exclusion criteria. Meta-analyses of pooled ORs of POCD incidences and mean differences in neurocognitive assessment scores and inflammation levels were carried out and subgroup analyses were performed. Stata 12.0 was used to conduct our meta-analysis.

RESULTS

Twenty-six RCTs were included. Compared with controls, perioperative dexmedetomidine treatment significantly reduced the incidence of POCD (pooled ORs = 0.59, 95% confidence interval (CI) 0.45-2.95) and improved Mini-Mental State Examination (MMSE) score (standardized mean difference (SMD) = 1.74, 95% CI 0.43-3.05) on the first postoperative day. Furthermore, perioperative dexmedetomidine treatment significantly decreased IL-6 (SMD = -1.31, 95% CI -1.87-0.75, P < .001) and TNF-α (SMD = -2.14, 95% CI -3.14-1.14, P < .001) compared to saline/comparators treatment. In the stratified analysis by surgical type, age, type of control, and study region, the differences were also significant between dexmedetomidine- and saline-treated patients.

CONCLUSION

Perioperative dexmedetomidine treatment is associated with significantly reduced incidence of POCD and inflammation and better neurocognitive function postoperatively in comparison with both saline controls and comparator anaesthetics.

Dexmedetomidine for the prevention of delirium in critically ill patients - A protocol for a systematic review

BACKGROUND

Delirium is a common complication in critically ill patients and carries an increased risk of mortality and morbidity. Dexmedetomidine can potentially prevent delirium by diminishing predisposing factors. The evidence regarding the use of dexmedetomidine in preventing delirium is conflicting. This protocol aims to identify the beneficial and harmful effects of dexmedetomidine in the prevention of delirium.

METHODS

This protocol uses the recommendations of the Cochrane Collaboration, the Preferred Report Items of Systematic Reviews with Meta-Analysis Protocols, and the eight-step assessment procedure suggested by Jakobsen and colleagues. We wish to assess in critically ill patients, if dexmedetomidine versus placebo can reduce the incidence of delirium and improve clinical outcomes. We will include all randomised trials assessing the use of dexmedetomidine in the prevention of delirium. To identify trials, we will search the Cochrane Central Register of Controlled Trials, Medical Literature Analysis and Retrieval System Online, Excerpta Medica database, Latin American and Caribbean Health Sciences Literature, Science Citation Index Expanded on Web of Science, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Chinese Science Journal Database, and BIOSIS. Two authors will screen the literature and extract data. We will use the Cochrane risk of bias tool to evaluate trials. Extracted data will be analysed using Review Manager 5 and Trial Sequential Analysis. We will create a "Summary of Findings"-table in which we will present our primary and secondary outcomes. We will assess the quality of evidence using GRADE.

DISCUSSION

This systematic review can potentially aid clinicians in decision-making and benefit the many critically ill patients at risk of delirium.

Dexmedetomidine for the management of delirium in critically ill patients-A protocol for a systematic review

BACKGROUND

Delirium is a common complication in critically ill patients and carries an increased risk of mortality and morbidity. Dexmedetomidine can potentially treat delirium by diminishing predisposing factors. The evidence regarding the use of dexmedetomidine in the management of delirium is conflicting. This protocol aims to identify the beneficial and harmful effects of dexmedetomidine in the management of delirium.

METHODS

This protocol uses the recommendations of the Cochrane Collaboration, the Preferred Report Items of Systematic reviews with Meta-Analysis Protocols, and the eight-step assessment procedure suggested by Jakobsen and colleagues. We wish to assess in critically ill patients with delirium, if dexmedetomidine vs placebo is effective in managing delirium and improving clinical outcomes. We will include all relevant randomised clinical trials assessing the use of dexmedetomidine in treating delirium. To identify trials, we will search the Cochrane Central Register of Controlled Trials, Medical Literature Analysis and Retrieval System Online, Excerpta Medica database, Latin American and Caribbean Health Sciences Literature, Science Citation Index Expanded on Web of Science, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Chinese Science Journal Database, and BIOSIS. Two authors will screen the literature and extract data. The Cochrane risk of bias tool will be used to evaluate included trials. Extracted data will be analysed using Review Manager 5 and Trial Sequential Analysis. We will create a 'Summary of Findings'-table in which we will present our primary and secondary outcomes. We will assess the quality of evidence using GRADE assessment.

DISCUSSION

This systematic review can potentially aid clinicians in decision making and benefit the many critically ill patients developing delirium.

Effects of acute hypercapnia on cognitive function in patients undergoing bronchoscope intervention

Background

There are multiple studies that have revealed that hypercapnia possessed neuroprotection, the conclusive cognitive impacts of permissive hypercapnia in medicine is still unclear.

Methods

A total of 102 patients registered for this research work had accomplished cognitive tests; with 64 patients possessing moderate hypercapnia all through bronchoscope intervention (BI). Thirty-six patients completed collection of blood specimens. Every patient underwent the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) a day before the surgery (T0), as well as at 7 days (T7). Serum specimens were used to measure levels of S100B, neuron-specific enolase (NSE), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), superoxide dismutase (SOD) prior to the administration of anesthesia (T0), one day (T1) and seven days (T7) after surgery.

Results

In comparison with the preoperative MMSE scores, Group Hypercapnia (Group H) on 7 days after surgery, exhibited a significant increased score (P=0.00). In comparison with the preoperative MoCA scores, Group H on 7 days after surgery exhibited a significant increased score (P=0.00). Meanwhile, the MoCA scores in Group H exhibited considerably higher elevation as compared with that in the Group Control (Group C) (P=0.01). No substantial differences were observed in serum S100B and NSE levels between Group H and Group C (P=0.23, P=0.14). Serum IL-6, TNF-α, SOD and MDA levels shared similarity between two groups.

Conclusions

Mild and moderate hypercapnia augmented cognitive activity with the help of MMSE tests and MoCA tests, whereby the latent reasons were not sure. As suggested by this study, hypercapnia up to 100 mmHg during BI was less likely to affect cognitive function adversely.

Effects of Dexmedetomidine Combined with Sufentanil on Postoperative Delirium in Young Patients After General Anesthesia

Background

This study was designed to evaluate the effects of combined usage of dexmedetomidine (DEX) and sufentanil on young patients with postoperative delirium (POD) after general anesthesia.

Material/Methods

We randomized 100 young patients with POD into 4 groups: Group D, Group S, Group DS1, and Group DS2, with loading and maintenance doses of DEX and/or sufentanil administered according to the experimental protocol. Hemodynamic variables, standard visual analogue scale (VAS) scores, sedation agitation scale (SAS) scores, stress hormones, and inflammatory biomarkers were assessed at 5 time-points: baseline (T₁); 1 h (T₂), 2 h (T₃), 4 h (T₄), and 8 h (T₅) after completion of the loading dose.

Results

At T₃–T₅, hemodynamic indicators in group D were obviously higher than in the other groups (P<0.05). At T₂–T₅, the VAS and SAS scores were noticeably lower than those at T₁ in each group (P<0.05). The VAS and SAS scores were remarkably higher in group D than those in the other groups (P<0.05). Compared with DS1, the incidence of respiratory distress decreased and the incidence of POD increased in group DS2. Compared to T₁, plasma concentrations of epinephrine, norepinephrine, IL-6, and TNF-α all decreased at T₂ and T₅ (P<0.05).

Conclusions

DEX and sufentanil decrease the incidence of POD, ameliorate the abnormities of hemodynamic indicators, and decrease VAS scores, SAS scores, stress hormones, and inflammatory biomarkers, but increase the incidence of respiratory distress. DEX combined with sufentanil may play a synergistic reaction in causing respiratory distress, but remarkably decreases the incidence of POD.

Dexmedetomidine attenuates the toxicity of β‑amyloid on neurons and astrocytes by increasing BDNF production under the regulation of HDAC2 and HDAC5

Cytotoxicity of β-Amyloid (Aβ) is a major contributor to the pathogenesis of Alzheimer's disease. Dexmedetomidine (Dex) has been revealed to have multiple neuroprotective actions as a clinical anesthetic agent. The aim of the present study was to investigate the protection of Dex against Aβ in neurons and astrocytes, and the possible protective mechanisms. Primary neurons and astrocytes were isolated respectively from the hippocampus and cerebral cortex of neonatal Sprague Dawley rats. The neurons and astrocytes were incubated with Aβ in the presence or absence of Dex, which was followed by evaluation of the cell viability and apoptosis. Reverse transcription‑quantitative polymerase chain reaction, western blotting and ELISA assays were performed to assess the levels of specific genes or proteins. The results revealed that Aβ decreased the viabilities of neurons and astrocytes in a dose‑dependent manner, and elevated the rate of apoptosis. However, Dex attenuated the detrimental effects of Aβ. Aβ caused deacetylation of histone H3 by promoting the accumulation of histone deacetylase (HDAC)‑2 and HDAC5 in the cell nucleus, resulting in the reduced production of brain‑derived neurotrophic factor (BDNF). However, Dex reversed the Aβ‑induced deacetylation of histone H3 and thus, increased BDNF production. Using a HDAC inhibitor or recombinant BDNF protein also protected the neurons and astrocytes against Aβ cytotoxicity. These results suggested that the protective effect of Dex against Aβ is particularly relevant to BDNF. Thus, the present study provides a foundation for the further study of Dex protection against Aβ in animal models and pre‑clinical researches.

Surgery, neuroinflammation and cognitive impairment

Trauma experienced during surgery can contribute to the development of a systemic inflammatory response that can cause multi-organ dysfunction or even failure. Post-surgical neuroinflammation is a documented phenomenon that results in synaptic impairment, neuronal dysfunction and death, and impaired neurogenesis. Various pro-inflammatory cytokines, such as TNFα, maintain a state of chronic neuroinflammation, manifesting as post-operative cognitive dysfunction and post-operative delirium. Furthermore, elderly patients with post-operative cognitive dysfunction or delirium are three times more likely to experience permanent cognitive impairment or dementia. We conducted a narrative review, considering evidence extracted from various databases including Pubmed, MEDLINE and EMBASE, as well as journals and book reference lists. We found that further pre-clinical and well-powered clinical studies are required to delineate the precise pathogenesis of post-operative delirium and cognitive dysfunction. Despite the burden of post-operative neurological sequelae, clinical studies investigating therapeutic agents, such as dexmedetomidine, ibuprofen and statins, have yielded conflicting results. In addition, evidence supporting novel therapeutic avenues, such as nicotinic and HMGB-1 targeting and remote ischaemic pre-conditioning, is limited and necessitates further investigation.

Does Dexmedetomidine Ameliorate Postoperative Cognitive Dysfunction? A Brief Review of the Recent Literature

PURPOSE OF REVIEW

Postoperative cognitive dysfunction (POCD) occurs in 20-50% of postsurgical patients with a higher prevalence in elderly patients and patients with vascular disease and heart failure. In addition, POCD has been associated with many negative outcomes, such as increased hospital length of stay, increased rates of institutionalization, and higher patient mortality. This brief review discusses select evidence suggesting an association between neuroinflammation and POCD and whether the use of dexmedetomidine, a short-acting alpha 2 agonist, may ameliorate the incidence of POCD. We review the recent evidence for neuroinflammation in POCD, dexmedetomidine's properties in reducing inflammatory-mediated brain injury, and clinical studies of dexmedetomidine and POCD.

RECENT FINDINGS

There is evidence to support the anti-inflammatory and immunomodulatory effects of dexmedetomidine in animal models. Several clinical investigations have demonstrated favorable outcomes using dexmedetomidine over placebo for the reduction of postoperative delirium. Few studies have used high-quality endpoints for the assessment of POCD and no demonstrable evidence supports the use of dexmedetomidine for the prevention of POCD. While evidence exists for the neural anti-inflammatory properties of dexmedetomidine, human trials have yielded incomplete results concerning its use for the management of POCD. Dexmedetomidine may reduce acute postoperative delirium, but further studies are needed prior to recommending the use of dexmedetomidine for the direct reduction of POCD.

Dexmedetomidine inhibits inflammation in microglia cells under stimulation of LPS and ATP by c-Fos/NLRP3/caspase-1 cascades

NOD-like receptor 3 (NLRP3) plays critical roles in the initiation of inflammasome-mediated inflammation in microglia, thus becomes an important therapeutic target of Alzheimer's disease (AD). Dexmedetomidine (Dex), a new type of clinical anesthetic agent, shows anti-inflammatory properties and inhibits postoperative cognitive dysfunction in AD patients. The present study was aimed to investigate effect of Dex on NLRP3 activity in activated microglia and reveal the underlying mechanisms. The human microglia clone 3 (HMC3) cells were exposed to 100 ng/ml LPS and 5 mM ATP, in the presence and absence of doses of Dex. Data from ELISA and Western blot assays showed that Dex abrogated the promoting effects of LPS/ATP on the release of pro-inflammatory cytokines including IL-1β and IL-18 in the cell medium and the expression of NLRP3 and its downstream target caspase-1 in HMC3 cells. Furthermore, the present study found that exposure of HMC3 cells to LPS/ATP increased nuclear protein levels of transcription factor c-Fos, but treatment with Dex reversed the increase in c-Fos, as indicated by Western blot and immunofluorescence measures. Luciferase reported assay revealed that c-Fos can bind to the promoter region of NLRP3 gene and positively regulate the expression. These results suggest that Dex inhibiting c-Fos nuclear protein levels promoted by LPS/ATP blocks the up-regulation of NLRP3. This suggestion is supported by co-immunoprecipitation and PCR studies, in which Dex decreased the amount of c-Fos that binds to NLRP3 under the stimulation of LPS/ATP. The present study revealed that Dex inhibits inflammation in microglia cells under stimulation of LPS and ATP by c-Fos/NLRP3/caspase-1 cascades, which adds new understanding of the anti-inflammatory mechanism of Dex.