An Update on Postoperative Cognitive Dysfunction

Smad7 in the hippocampus contributes to memory impairment in aged mice after anesthesia and surgery

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common neurological complication following anesthesia and surgery. Increasing evidence has demonstrated that neuroinflammation caused by systemic inflammatory responses during the perioperative period is a key factor in the occurrence of POCD. In addition, SMAD family member 7 (Smad7) has been confirmed to play vital roles in the pathogenesis and treatment of inflammatory diseases, such as inflammatory bowel disease. However, whether Smad7 participates in the regulatory process of neuroinflammation and apoptosis in the development of POCD is still unknown.

METHODS

In this study, a POCD mouse model was constructed by unilateral nephrectomy under anesthesia, and cognitive function was assessed using the fear conditioning test and open field test. The expression of Smad7 at the mRNA and protein levels in the hippocampus 3 days after surgery was examined by qRT-PCR, western blot and immunofluorescence assays. Furthermore, to identify whether the elevation of Smad7 in the hippocampus after unilateral nephrectomy contributes to cognitive impairment, the expression of Smad7 in the hippocampal CA1 region was downregulated by crossing Smad7fl/fl conditional mutant mice and CaMKIIα-Cre line T29-1 transgenic mice or stereotaxic injection of shRNA-Smad7. Inflammation and apoptosis in the hippocampus were assessed by measuring the mRNA levels of typical inflammatory cytokines, including TNF-α, IL-1β, IL-6, CCL2, CXCL1, and CXCL2, and the protein levels of apoptotic proteins, including Bax and Bcl2. In addition, apoptosis in the hippocampus postoperation was investigated by a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining assay. Finally, western blotting was used to explore how Smad7 mediates inflammation and apoptosis postoperation.

RESULTS

The results unequivocally revealed that elevated Smad7 in the hippocampal CA1 region significantly inhibited TGF-β signal transduction by blocking Smad2/3 phosphorylation, which enhanced neuroinflammation and apoptosis in the hippocampus and further led to learning and memory impairment after surgery.

CONCLUSIONS

Our results revealed that Smad7 contributes to cognitive impairment after surgery by enhancing neuroinflammation and apoptosis in the hippocampus and might serve as a promising therapeutic target for the treatment of memory impairment after anesthesia surgery.

The Effect of Low-Dose Esketamine on Postoperative Neurocognitive Dysfunction in Elderly Patients Undergoing General Anesthesia for Gastrointestinal Tumors: A Randomized Controlled Trial

Purpose

This study aims to evaluate the effects of the intraoperative application of low-dose esketamine on postoperative neurocognitive dysfunction (PND) in elderly patients undergoing general anesthesia for gastrointestinal tumors.

Methods

Sixty-eight elderly patients were randomly allocated to two groups: the esketamine group (group Es) (0.25 mg/kg loading, 0.125mg/kg/h infusion) and the control group (group C) (received normal saline). The primary outcome was the incidence of delayed neurocognitive recovery (DNR). The secondary outcomes were intraoperative blood loss, the total amount of fluid given during surgery, propofol and remifentanil consumption, cardiovascular adverse events, use of vasoactive drugs, operating and anesthesia time, the number of cases of sufentanil remedial analgesia, the incidence of postoperative delirium (POD), the intraoperative hemodynamics, bispectral index (BIS) value at 0, 1, 2 h after operation and numeric rating scale (NRS) pain scores within 3 d after surgery.

Results

The incidence of DNR in group Es (16.13%) was lower than in group C (38.71%) (P <0.05). The intraoperative remifentanil dosage and the number of cases of dopamine used in group Es were lower than in group C (P <0.05). Compared with group C, DBP was higher at 3 min after intubation, and MAP was lower at 30 min after extubation in group Es (P<0.05). The incidence of hypotension and tachycardia in group Es was lower than in group C (P <0.05). The NRS pain score at 3 d after surgery in group Es was lower than in group C (P <0.05).

Conclusion

Low-dose esketamine infusion reduced to some extent the incidence of DNR in elderly patients undergoing general anesthesia for gastrointestinal tumors, improved intraoperative hemodynamics and BIS value, decreased the incidence of cardiovascular adverse events and the intraoperative consumption of opioids, and relieved postoperative pain.

Comparative effect of deliberate hypotensive anesthesia using nitroglycerine vs. phentolamine on event related potentials and cognitive functions in patients undergoing septoplasty: a randomized controlled trial

BACKGROUND

Postoperative cognitive dysfunction is a noteworthy complication of deliberate hypotensive anesthesia. The aim of this work was to compare the effect of deliberate hypotensive anesthesia using nitroglycerine versus phentolamine on event-related potentials and cognitive function in patients undergoing septoplasty surgery.

METHODS

This prospective randomized controlled trial was conducted on 80 patients indicated for septoplasty under general anesthesia; 40 patients received intra-operative Nitroglycerine and 40 patients received intra-operative Phentolamine. Cognitive assessment (using Paired Associate Learning test (PALT) and Benton Visual Retention test (BVRT)) and P300 recording were done for all included patients pre-operatively and one week postoperatively.

RESULTS

The scores of PALT and Benton BVRT significantly declined one week following surgery in both Nitroglycerine and Phentolamine groups. There was no statistically significant difference between Nitroglycerine and Phentolamine groups in the postoperative decline in either PALT or BVRT (P-value = 0.342, 0.662 respectively). The values of P300 latency showed a significant delay one week following surgery in both Nitroglycerine and Phentolamine groups (P-value ≤ 0.001, 0.001), but in Nitroglycerine group, the delay is significantly higher than in Phentolamine group (P-value = 0.003). The values of P300 amplitude significantly decreased one week following surgery in both Nitroglycerine and Phentolamine groups (P-value ≤ 0.001, 0.001), but there was no statistically significant difference between Nitroglycerine and Phentolamine groups (P-value = 0.099).

CONCLUSION

Phentolamine is preferred over nitroglycerin in deliberate hypotensive anesthesia because it has less harmful effect on cognitive function than nitroglycerin.

Downregulation of Nrf2 in the Hippocampus Contributes to Postoperative Cognitive Dysfunction in Aged Rats by Sensitizing Oxidative Stress and Neuroinflammation

Postoperative cognitive dysfunction (POCD) is a recognized clinical complication defined by a new cognitive impairment arising after a surgical procedure. Elderly patients are especially vulnerable to cognitive impairment after surgical operations, but the underlying mechanisms remain elusive. Oxidative stress and neuroinflammation in the hippocampus, a brain region involved in memory formation, are considered as major contributors to the development of POCD. Activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of endogenous inducible defense system, plays a crucial role in protecting cells against oxidative stress and inflammation by enhancing transcription of antioxidant and anti-inflammatory target genes. Here, we examined whether aging downregulates Nrf2 in the hippocampus and, if so, whether downregulation of hippocampal Nrf2 contributes to POCD in aging. Young and aged rats underwent abdominal surgery or sham operation. One week later, cognitive function was assessed, and brains were collected for molecular studies. Compared with young sham rats, aged sham rats exhibited a significant reduction in expression of Nrf2 in the hippocampus. Interestingly, the expression of Nrf2 downstream target genes and levels of reactive oxygen species (ROS) and proinflammatory cytokines in the hippocampus as well as cognitive function were comparable between aged sham and young sham rats. After abdominal surgery, young rats showed significant upregulation of Nrf2 and its target genes in the hippocampus. However, aged rats did not show changes in expression of Nrf2 and its target genes but had increased levels of ROS and proinflammatory cytokines in the hippocampus, along with cognitive impairment as indicated by reduced contextual freezing time. Moreover, upregulation of hippocampal Nrf2 in aged rats with intracerebroventricular infusion of a Nrf2 activator reduced levels of ROS and proinflammatory cytokines in the hippocampus, ameliorating cognitive dysfunction after surgery. The results suggest that aging-induced downregulation of Nrf2 in the hippocampus causes the failure to activate Nrf2-regulated antioxidant defense system in response to surgical insult, which contributes to POCD by sensitizing oxidative stress and neuroinflammation. Nrf2 activation in the brain may be a novel strategy to prevent the cognitive decline in elderly patients after surgery.

Dexmedetomidine Mitigates Microglial Activation Associated with Postoperative Cognitive Dysfunction by Modulating the MicroRNA-103a-3p/VAMP1 Axis

Surgery-induced microglial activation is critical in mediating postoperative cognitive dysfunction (POCD) in elderly patients, where the important protective effect of dexmedetomidine has been indicated. However, the mechanisms of action of dexmedetomidine during the neuroinflammatory response that underlies POCD remain largely unknown. We found that lipopolysaccharide (LPS) induced substantial inflammatory responses in primary and BV2 microglial cells. The screening of differentially expressed miRNAs revealed that miR-103a-3p was downregulated in these cell culture models. Overexpression of miR-103a-3p mimics and inhibitors suppressed and enhanced the release of inflammatory factors, respectively. VAMP1 expression was upregulated in LPS-treated primary and BV-2 microglial cells, and it was validated as a downstream target of miR-103-3p. VAMP1-knockdown significantly inhibited the LPS-induced inflammatory response. Dexmedetomidine treatment markedly inhibited LPS-induced inflammation and the expression of VAMP1, and miR-103a-3p expression reversed this inhibition. Moreover, dexmedetomidine mitigated microglial activation and the associated inflammatory response in a rat model of surgical trauma that mimicked POCD. In this model, dexmedetomidine reversed miR-103a-3p and VAMP1 expression; this effect was abolished by miR-103a-3p overexpression. Taken together, the data show that miR-103a-3p/VAMP1 is critical for surgery-induced microglial activation of POCD.

Spine Surgery Under Spinal vs General Anesthesia: Prospective Analysis of Quality of Life, Fatigue, and Cognition

BACKGROUND

There has recently been increasing interest in the use of spinal anesthesia (SA) for spine surgery. The literature that compared spine surgery under SA vs general anesthesia (GA) focused on safety, perioperative outcomes, and costs.

OBJECTIVE

To test if SA is associated with less postoperative fatigue, cognitive dysfunction, and better quality of life in patients undergoing lumbar spine surgery compared with GA.

METHODS

We conducted a prospective nonrandomized study in patients undergoing elective lumbar spine surgery under SA or GA by a single surgeon. Fatigue was assessed with the fatigue visual analog scale scale (0-10) and Chalder Fatigue Scale, quality of life with Medical Outcomes Study 12-item Short Form (SF-12), and differences in cognition with Mini-Mental State Examination. Patients were baselined before surgery and assessed again 1 mo after surgery.

RESULTS

Fifty patients completed the study, 25 underwent surgery under SA and 25 under GA. The groups were homogeneous for baseline clinical characteristics, with no differences in preoperative fatigue, quality of life, and cognition. At 1 mo after surgery, SA compared with GA had better fatigue scores: fatigue visual analog scale (2.9 ± 1.5 vs 5.9 ± 2.3 [P < .0001]) and Chalder Fatigue Scale (11.2 ± 3.1 vs 16.9 ± 3.9 [P < .0001]). One month postoperatively, we observed a significant difference in the SF-12 physical component, with SA having 38.8 ± 8.9 vs 29.4 ± 10.3 (P = .002). We did not observe significant postoperative differences in the SF-12 mental component or Mini-Mental State Examination.

CONCLUSION

Our study demonstrates that SA offers unique patient-centered advantages to GA for elective spine surgery. One month after surgery, patients who received SA had less postoperative fatigue and better quality of life.

An Update on Postoperative Cognitive Dysfunction Following Cardiac Surgery

Postoperative cognitive dysfunction is extremely prevalent following cardiac surgery. The increasing patient age and comorbidity profile increases their susceptibility to cognitive impairment. The underlying pathophysiological mechanisms leading to cognitive impairment are not clearly elucidated. Using the contemporary literature (2015-present), this narrative review has three aims. Firstly, to provide an overview of postoperative cognitive impairment. Secondly, to analyse the predominant pathophysiological mechanisms leading to cognitive dysfunction following cardiac surgery such as inflammation, cerebral hypoperfusion, cerebral microemboli, glycaemic control and anaesthesia induced neurotoxicity. Lastly, to assess the current therapeutic strategies of interest to address these pathophysiological mechanisms, including the administration of dexamethasone, the prevention of prolonged cerebral desaturations and the monitoring of cerebral perfusion using near-infrared spectroscopy, surgical management strategies to reduce the neurological effects of microemboli, intraoperative glycaemic control strategies, the effect of volatile vs. intravenous anaesthesia, and the efficacy of dexmedetomidine.

Changes in the quick mild cognitive impairment test over time: A normative study in an adult sample in Taiwan

BACKGROUND

The Quick Mild Cognitive Impairment (Qmci) test has been suggested to be an easy-to-use and precise screening tool for detecting postoperative cognitive dysfunction (POCD). To provide essential information for future POCD studies in Taiwan, the present study provided data regarding the Taiwan version of the Qmci (Qmci-TW) test conducted in the normative Taiwanese population and changes in them over time.

METHODS

The present study recruited adult native Taiwanese volunteers without known neurologic or psychiatric diseases. All enrolled participants received protocolized serial Qmci-TW test at baseline, 2-day follow-up, and 6-month follow-up.

RESULTS

In total, 30 participants, 15 men and 15 women, were enrolled in this study. The baseline Qmci-TW score ranged from 55 to 80, with a mean of 68.9 and a standard deviation (SD) of 7. At 2-day follow-up, the mean Qmci-TW test score was significantly higher (by 5.3; SD = 7.3) than that at baseline (P = 0.001). At 6-month follow-up, the mean Qmci-TW score was 71.3 (SD = 6.1), with no significant difference compared with that at baseline. The decline in Qmci-TW scores by > 9 points on postoperative day 1 and by > 11 points at 6-month follow-up was the criterion for POCD.

CONCLUSION

The present study provided data regarding the Qmci-TW test conducted in the normative Taiwanese population and its time trajectory during the 6-month follow-up.

Assessment of a digital game as a neuropsychological test for postoperative cognitive dysfunction

OBJECTIVE

Postoperative cognitive dysfunction may result from worsening in a condition of previous impairment. It causes greater difficulty in recovery, longer hospital stays, and consequent delay in returning to work activities. Digital games have a potential neuromodulatory and rehabilitation effect. In this study, a digital game was used as a neuropsychological test to assess postoperative cognitive dysfunction, with preoperative patient performance as control.

METHODS

It was a non-controlled study, with patients selected among candidates for elective non-cardiac surgery, evaluated in the pre- and postoperative periods. The digital game used has six phases developed to evaluate selective attention, alternating attention, visuoperception, inhibitory control, short-term memory, and long-term memory. The digital game takes about 25 minutes. Scores are the sum of correct answers in each cognitive domain. Statistical analysis compared these cognitive functions pre- and post-surgery using a generalized linear mixed model (ANCOVA).

RESULTS

Sixty patients were evaluated, 40% male and 60% female, with a mean age of 52.7 ± 13.5 years. Except for visuoperception, a reduction in post-surgery scores was found in all phases of the digital game.

CONCLUSION

The digital game was able to detect decline in several cognitive functions postoperatively. As its completion is faster than in conventional tests on paper, this digital game may be a potentially recommended tool for assessing patients, especially the elderly and in the early postoperative period.

Restoration of Proresolution Pathway with Exogenous Resolvin D1 Prevents Sevoflurane-Induced Cognitive Decline by Attenuating Neuroinflammation in the Hippocampus in Rats with Type 2 Diabetes Mellitus

Sevoflurane (SEV), a commonly used volatile anesthetic, has been shown to cause cognitive decline in diabetic rats by aggregating neuroinflammation in the hippocampus, but the underlying mechanisms are unknown. Recent evidence suggests that neuroinflammation could be a consequence of failure to resolve inflammation by specialized pro-resolving lipid mediators including resolvin D1 (RvD1). Here we first examined whether type 2 diabetes mellitus (DM) alters RvD1 proresolution pathway. Diabetic Goto-Kakizaki (GK) rats and non-diabetic Wistar rats received control or 2.6% SEV exposure for 4 h. Seven days after exposure, GK control rats, compared with Wistar control rats, had significantly lower RvD1 levels in plasma and CSF and decreased RvD1 receptor FPR2 expression in the hippocampus. SEV increased RvD1 levels in plasma and CSF and FPR2 expression in the hippocampus in Wistar rats but not in GK rats. We next examined whether RvD1 treatment of GK rats can prevent SEV-induced neuroinflammation and cognitive decline. GK rats received control, SEV or SEV and once-daily treatment with exogenous RvD1 (0.2 ug/kg, ip) for 7 days. RvD1 administration markedly increased RvD1 levels in plasma and CSF and FPR2 expression in the hippocampus in GK rats received SEV. Compared with GK control rats, GK rats received SEV exhibited shorter freezing times in trace fear conditioning task, which was accompanied by increased microglia activity and pro-inflammatory cytokine expression in the hippocampus. RvD1 administration attenuated SEV-induced increases in microglia activity and pro-inflammatory cytokine expression in the hippocampus, preventing cognitive decline in GK rats. Notably, neither SEV nor RvD1 altered metabolic parameters in GK rats. The results suggest that RvD1 proresolution pathway is impaired in the brain of diabetic GK rats. which may enhance the susceptibility to SEV, contributing to neuroinflammation and cognitive decline. Restoration of RvD1 proresolution pathway in diabetic GK rats with exogenous RvD1 can prevent SEV-induced cognitive decline by attenuating neuroinflammation in the hippocampus.

Risk factors and predictive value of perioperative neurocognitive disorders in elderly patients with gastrointestinal tumors

BACKGROUND

This study aims to investigate the risk factors of perioperative neurocognitive disorders (PNDs) mainly including postoperative cognitive dysfunction (POCD) in elderly patients with gastrointestinal tumors, and evaluate its predictive value.

METHODS

A total of 222 eligible elderly patients (≥65 years) scheduled for elective gastroenterectomy under general anesthesia were enrolled. The cognitive function assessment was carried out 1 day before surgery and 7 days after surgery. Receiver operating characteristic curve analysis was performed to evaluate the predictive value of risk factors for early POCD. The risk factors for POCD were analyzed using univariate and multivariate logistic regression model.

RESULTS

Of all the 222 enrolled patients, 91 (41.0%) developed early POCD and 40 (18.0%) were identified as major POCD within 7 days after the surgery. Visual analogue score (VAS, 1st day, resting) ≥4 (OR = 7.618[3.231-17.962], P < 0.001) and alcohol exposure (OR = 2.398[1.174-4.900], P = 0.016) were independent risk factors for early POCD. VAS score (1st, resting) ≥4 (OR = 13.823[4.779-39.981], P < 0.001), preoperative white blood cell (WBC) levels ≥10 × 10*9/L (OR = 5.548[1.128-26.221], P = 0.035), blood loss ≥500 ml (OR = 3.317[1.094-10.059], P = 0.034), history of hypertension (OR = 3.046[1.267-7.322], P = 0.013), and neutrophil-lymphocyte ratio (NLR) ≥2 (OR = 3.261[1.020-10.419], P = 0.046) were independent risk factors for major POCD. Receiver operating characteristic curve analysis indicated that VAS score (1st day, resting) was a significant predictor for major POCD with a cut-off value of 2.68 and an area under the curve of 0.860 (95% confidence interval: 0.801-0.920, P < 0.001).

CONCLUSIONS

The risk factors for early POCD after gastroenterectomy included high VAS score (1st day, resting) and alcohol exposure. High VAS score, preoperative WBC levels ≥10 × 10*9/L, blood loss ≥500 ml, NLR ≥2, and history of hypertension were independent risk factors for major POCD. Among them, VAS score was one of the important predictors.

Effects of Apolipoprotein Ε ε4 allele on early postoperative cognitive dysfunction after anesthesia

BACKGROUND

Postoperative cognitive dysfunction (POCD) is one of the main causes of morbidity after noncardiac surgery; however, the pathogenic mechanisms of POCD have remained unclear until now. In this study, we performed a pilot study to investigate the association between apolipoprotein E (ApoE) ε4 and POCD in older patients undergoing intravenous anesthesia (IVA) and inhalation anesthesia (IAA).

METHODS

In total, 180 patients from Shenzhen People's Hospital were recruited and randomly divided into an IVA group and an IAA group. The IVA group and IAA group received propofol and sevoflurane treatment, respectively. Within 7 days after surgery, the mini-mental state examination (MMSE) was used daily to assess the cognitive function of both groups of patients. The genotypes of the ApoE gene were detected using the restriction fragment length polymorphism technique. In addition, the serum levels of (soluble protein-100β) S‑100β and (Interleukin- 6) L‑6 were also analyzed.

RESULTS

Compared to the preoperative and IVA groups, the MMSE score in the IAA group significantly decreased at 3 days after surgery. Furthermore, the IAA group had a higher percentage of patients who scored less than 25 points than the IVA group at 3 days after surgery. The decrease in the MMSE score was closely related to the ApoE ε4 allele in the IAA group, but this correlation was not observed in the IVA group. The levels of S‑100β and IL‑6 were increased sharply in patients with the ε4/ε4 genotype who received IAA compared with IVA at 1 day after surgery.

CONCLUSION

The results of the study indicated that the ApoΕ ε4/ε4 genotype was a risk factor for early POCD in older patients undergoing sevoflurane anesthesia.

Effect of preoperative hospitalisation period on postoperative cognitive dysfunction in patients undergoing hip surgery under regional anaesthesia

AIM OF THE STUDY

The main objective of this prospective and observational study was to investigate the effect of the preoperative hospitalisation period on early postoperative cognitive dysfunction (POCD) development in patients undergoing total hip replacement surgery under regional anaesthesia.

MATERIALS AND METHODS

Between November 2013 and September 2014, 64 patients were enrolled in the study. Mini Mental Test (MMT) scores were obtained on the initial admission day (MMT1), 24 hours prior to the surgery (MMT2) and 24 hours after the surgery (MMT3). The patients were divided into two groups according to the MMT scores: 'no cognitive dysfunction' (group 1) and 'cognitive dysfunction' (group 2). Differences between the groups were evaluated statistically. The statistical significance level was set as P < .05 in a 95% confidence interval.

RESULTS

The POCD incidence rate was calculated as 43.8% in all patients. The preoperative hospitalisation duration was significantly longer in patients with POCD than in patients without POCD (P < .001). The factors that affected POCD development were found to be advanced age (P < .001), high American Society of Anesthesiologists scores (P = .004), the presence of comorbid disease (P = .025), durations of surgery (P = .018) and decreased postoperative haematocrit levels (P = .014).

CONCLUSION

In this study, we observed that patients with early POCD had relatively longer preoperative hospitalisation periods than those in patients without POCD. We consider that prolonged preoperative hospitalisation may contribute to increased POCD incidence rates in patients with risk factors.

Effect of electroacupuncture on postoperative cognitive dysfunction for patients undergoing total knee arthroplasty: A protocol for systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Electroacupuncture is increasingly used in rehabilitation for postoperative cognitive dysfunction (POCD), but relevant evidence remains unclear for patients receiving total knee arthroplasty (TKA).

METHODS

The databases research of PubMed, EMBASE, CINAHL, and China National Knowledge Infrastructure (CNKI) will be conducted from inception to December 31, 2020. The relevant randomized controlled trials (RCTs) from data will be screened one by one. The remaining studies that meet the inclusion criteria will be extracted and analyzed using RevMan V.5.3 software. Paired 2 reviewers will assess quality of the included studies and publication bias by using the Cochrane Collaboration risk of bias tool, and Egger test and Begg test respectively. And grading of recommendations assessment, development and evaluation (GRADE) will be used to estimate the quality of evidence.

RESULTS

In this study, we will analyze the effect of electroacupuncture on Mini-Mental State Examination (MMSE), interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), S100-β protein, and adverse events for patients with TKA.

CONCLUSION

Our findings will provide evidence for the effectiveness of electroacupuncture on the treatment and prevention of POCD for TKA patients.

REGISTRATION NUMBER

Available at: https://osf.io/azyt9 (DOI number: 10.17605/OSF.IO/AZYT9).

Cognitive Dysfunction and Mortality After Carotid Endarterectomy

Background: Carotid endarterectomy (CEA) has been associated with both postoperative cognitive dysfunction (POCD) and improvement (POCI). However, the prognostic significance of postoperative cognitive changes related to CEA is largely unknown. The aim of this study was to examine the associations between postoperative cognitive changes after CEA and long-term survival.

Methods: We studied 43 patients 1 day before CEA as well as 4 days and 3 months after surgery with an extensive neuropsychological test array, and followed them for up to 14 years. POCD and POCI relative to baseline were determined with the reliable change index derived from 17 healthy controls. Associations between POCD/POCI and mortality within the patient group were studied with Cox regression analyses adjusted for confounders.

Results: POCD in any functional domain was evident in 28% of patients 4 days after surgery and in 33% of patients 3 months after surgery. POCI was shown in 23% of patients at 4 days and in 44% of patients at 3 months. POCD at 3 months was associated with higher long-term mortality (hazard ratio 5.0, 95% CI 1.8–13.9, p = 0.002) compared with patients with no cognitive decline.

Conclusions: Our findings suggest that POCD in a stable phase, 3 months after CEA predicts premature death. Evaluation of postoperative cognitive changes is essential, and POCD in a stable phase after CEA should prompt scrutiny of underlying factors and better adherence to therapies to prevent recurrences and to promote early intervention in imminent deterioration.

Hydrogen sulfide attenuates postoperative cognitive dysfunction through promoting the pathway of Warburg effect-synaptic plasticity in hippocampus

Postoperative cognitive dysfunction (POCD) is deemed to a severe surgical complication without effective treatment. Previous work has confirmed the important modulatory role of hydrogen sulfide (H₂S) in cognitive function. This study was proposed to explore whether H₂S relieves POCD and the possible mechanisms. We demonstrated that NaHS (a donor of H₂S) reversed the inhibited endogenous H₂S generation in the hippocampus of postoperative rats. NaHS attenuated the cognitive impairment of postoperative rats in the Y-maze, Novel object recognition, and Morris water maze tests. NaHS enhanced the expressions of synaptic plasticity-related proteins, synapsin-1 and PSD-95, increased the synaptic density, and decreased the destruction of synaptic structures in the hippocampus of postoperative rats. Moreover, NaHS promoted Warburg effect in the hippocampus of postoperative rats, as reflected by increases in the expressions of hexokinase 2, pyruvate kinase M2, lactate dehydrogenase A, and pyruvate dehydrogenase kinase 1, an enhancement in the content of lactate, and a reduction in the expression of pyruvate dehydrogenase. The inhibitor of Warburg effect, 2-Deoxy-D-glucose (2-DG), not only reversed NaHS-enhanced Warburg effect in the hippocampus of postoperative rats, but also significantly abolished NaHS-exerted protective effect on cognitive function. Furthermore, 2-DG reversed NaHS-exerted enhancement in the expressions of synapsin-1 and PSD-95, increase in the synaptic density, and decrease in the destruction of synaptic structures in the hippocampus of postoperative rats. Collectively, these results indicate that H₂S alleviates POCD through enhancing hippocampal Warburg effect, which subsequently improves synaptic plasticity in the hippocampus.

The Effects of Bispectral Index-Guided Anesthesia on Postoperative Delirium in Elderly Patients: A Systematic Review and Meta-Analysis

OBJECTIVE

Postoperative delirium (POD) is a form of delirium that affects patients who have undergone surgical procedures and anesthesia, usually peaking between 1 and 3 days after their operation. The aim of this meta-analysis was to determine whether monitoring of depth of anesthesia may influence the incidence of POD.

METHODS

A systematic literature search was conducted on studies that reported POD in elderly patients (>60 years old) who underwent surgery. This meta-analysis was carried out using random-effects model.

RESULTS

Compared with control group, intraoperative bispectral index (BIS) monitoring reduced POD (odds ratio 1.32, 95% confidence interval 1.11-1.57, P = 0.001, I² = 51%). In the mixed-surgery group, compared with the control group, BIS monitoring decreased the incidence of POD (odds ratio 1.24, 95% confidence interval 1.07-1.44, P = 0.004, I² = 61%). There was also no significant difference in the incidence of POD among patients who underwent cardiac, colon, and orthopedic surgeries.

CONCLUSIONS

BIS monitoring during surgery can reduce the incidence of POD in elderly patients. Whether BIS monitoring may reduce the incidence of POD in a single type of surgery needs further study.

Protective effect of dexmedetomidine infusion combined with epidural blockade on postoperative complications after surgery: A prospective randomized controlled clinical trial

Objectives

This prospective, randomized, controlled study aimed to explore the efficacy of dexmedetomidine combined with epidural blockade on postoperative recovery of elderly patients after radical resection for colorectal cancer.

Methods

Ninety-six elderly patients who underwent radical resection for colorectal cancer were randomly divided into the following four groups: dexmedetomidine, epidural blockade (ropivacaine), combined (dexmedetomidine + epidural blockade), and control (0.9% saline). The Mini-Mental State Examination (MMSE), Visual Analog Scale (VAS), and Ramsay scores at 48 hours, and time to first activity, length of hospital stay, and postoperative complication rates at 3 months were assessed.

Results

Twelve hours after surgery, Ramsay scores were higher in the combined compared with the control and epidural blockade groups. Twenty-four hours after surgery, MMSE scores were higher in the combined compared with the other groups. The combined group showed the lowest VAS scores except at 48 hours. Time to first activity and length of hospital stay were significantly shorter in the combined compared with the other groups. There was no difference in total postoperative complication rates among the groups.

Conclusions

A combination of intraoperative dexmedetomidine infusion and epidural blockade could mitigate pain after surgery, improve cognitive dysfunction in early surgery, and facilitate recovery.

Risk assessment of dementia after hysterectomy: Analysis of 14-year data from the National Health Insurance Research Database in Taiwan

BACKGROUND

Anesthesia and surgery may increase the risk of dementia in the elderly, but the higher prevalence of dementia in women and other evidence suggest that dementia risk increases in younger women undergoing hysterectomy. In this study, we assessed the risk of dementia after hysterectomy.

METHODS

Hysterectomies registered in the National Health Insurance Research Database from 2000 to 2013 were evaluated using a retrospective generational research method. Multivariate Cox regression analysis was used to assess the effect of age at surgery, anesthesia method, and surgery type on the hazard ratio (HR) for the development of dementia.

RESULTS

Among 280 308 patients who underwent hysterectomy, 4753 (1.7%) developed dementia. Age at surgery and anesthesia method were associated with the occurrence of dementia, independent of surgery type. Among patients 30-49 years of age, general anesthesia (GA) was associated with a higher risk of dementia than spinal anesthesia (SA). The HR for GA was 2.678 (95% confidence interval [CI] = 1.269-5.650) and the risk of dementia increased by 7.4% for every 1-year increase in age (HR = 1.074; 95% CI = 1.048-1.101). In patients >50 years of age, the HR for GA was 1.206 (95% CI = 1.057-1.376), and the risk of dementia increased by 13.0% for every 1-year increase in age (HR = 1.130; 95% CI = 1.126-1.134).

CONCLUSION

The risk of dementia in women who underwent hysterectomy was significantly affected by older age at surgery, and the risk might not increase linearly with age, but show instead an S-curve with exponential increase at about 50 years of age. Although less significant, GA was associated with higher risk than SA, and the effect of the anesthesia method was greater in patients <50 years of age. In contrast, the surgical procedure used was not associated to the risk of dementia.

Application of Acupuncture to Attenuate Immune Responses and Oxidative Stress in Postoperative Cognitive Dysfunction: What Do We Know So Far?

Postoperative cognitive dysfunction (POCD) is a common sequela following surgery and hospitalization. The prevention and management of POCD are important during clinical practice. POCD more commonly affects elderly patients who have undergone major surgery and can result in major decline in quality of life for both patients and their families. Acupuncture has been suggested as an effective intervention for many neurological disorders. In recent years, there are increasing interest in the use of acupuncture to prevent and treat POCD. In this review, we summarized the clinical and preclinical evidence of acupuncture on POCD using a narrative approach and discussed the potential mechanisms involved. The experimental details and findings of studies were summarized in tables and analyzed. Most of the clinical studies suggested that acupuncture before surgery could reduce the incidence of POCD and reduce the levels of systematic inflammatory markers. However, their reliability is limited by methodological flaws. Animal studies showed that acupuncture reduced cognitive impairment and the associated pathology after various types of surgery. It is possible that acupuncture modulates inflammation, oxidative stress, synaptic changes, and other cellular events to mitigate POCD. In conclusion, acupuncture is a potential intervention for POCD. More clinical studies with good research design are required to confirm its effectiveness. At the same time, findings from animal studies will help reveal the protective mechanisms, in which systematic inflammation is likely to play a major role.

[Effect of ulinastatin on isoflurane-induced neuronal apoptosis in the hippocampus of rats]

OBJECTIVE

To investigate the effect of ulinastatin pretreatment on isoflurane-induced mitochondria-dependent neuronal apoptosis in the hippocampus of rats.

METHODS

Thirty-six male SD rats were randomly assigned into control group, isoflurane group and ulinastatin group. In the latter two groups, the rats were subjected to acute exposure to 0.75% isoflurane for 6 h and pretreated with 50 000 U/kg of ulinastatin before isoflurane exposure, respectively. After the treatments, apoptosis of the hippocampal neurons was detected using TUNEL assay, and the mitochondrial membrane potential (△ ψm) was measured using JC-1 mitochondrial membrane potential kit; cytochrome C release and caspase-3 activity were examined with Western blotting, and intracellular reactive oxygen species (ROS) was detected using the fluorescent probe H2DCFDA.

RESULTS

Compared with those in the control group, the rats with acute exposure to isoflurane showed markedly increased TUNEL-positive cells in the hippocampus (P &lt; 0.05), which were obviously reduced by ulinastatin pretreatment (P &lt; 0.05). The △ψm of the hippocampal neurons was significantly reduced after isoflurane exposure (P &lt; 0.05), and was partly recovered by ulinastatin pretreatment (P &lt; 0.05). Acute exposure to isoflurane resulted in obviously increased cellular ROS, cytochrome C release and caspase-3 activity in the hippocampal neurons (P &lt; 0.05), and these changes were significantly inhibited by ulinastatin pretreatment (P &lt; 0.05).

CONCLUSIONS

Ulinastatin pretreatment provides neuroprotection against isoflurane-induced apoptosis of the hippocampal neurons in rats possibly by inhibiting mitochondria-dependent apoptosis pathway.

miR-124/VAMP3 is a novel therapeutic target for mitigation of surgical trauma-induced microglial activation

Activation of microglia and the subsequently elevated inflammatory cytokine release in the brain during surgery predispose individuals to cognitive dysfunction, also known as postoperative cognitive dysfunction (POCD). miR-124 is one of the most abundant microRNAs in the brain that regulates microglial function. Elucidating the role of miR-124 in microglial activation in the context of surgery may therefore promote understanding of as well as therapeutic development for post-surgical disorders involving microglial activation. The downstream targets of miR-124 were investigated using bioinformatic screening and dual-luciferase reporter assay validation, and vesicle-associated membrane protein 3 (VAMP3) was identified as a potential target. The kinetics of miR-124/VAMP3 expression was first examined in vitro in microglial cells (primary microglia and BV2 microglial cells) following lipopolysaccharide (LPS) stimulation. LPS induced a time-dependent decrease of miR-124 and upregulated the expression of VAMP3. Manipulating miR-124/VAMP3 expression by using miR-124 mimics or VAMP3-specific siRNA in LPS-stimulated BV2 microglial cells inhibited BV2 microglial activation-associated inflammatory cytokine release. To further examine the role of miR-124/VAMP3 in a surgical setting, we employed a rat surgical trauma model. Significant microglial activation and altered miR-124/VAMP3 expression were observed following surgical trauma. We also altered miR-124/VAMP3 expression in the rat surgical trauma model by administration of exogenous miR-124 and by using electroacupuncture, which is a clinically applicable treatment that modulates microglial function and minimizes postoperative disorders. We determined that electroacupuncture treatment specifically increases the expression of miR-124 in the hypothalamus and hippocampus. Increased miR-124 expression with a concomitant decrease in VAMP3 expression resulted in decreased inflammatory cytokine release related to microglial activation post-surgery. Our study indicates that miR-124/VAMP3 is involved in surgery-induced microglial activation and that targeting miR-124/VAMP3 could be a potential therapeutic strategy for postoperative disorders involving microglial activation.

A new acoustic coupling fluid with ability to reduce ultrasound imaging artefacts in brain tumour surgery-a phase I study

Background

A novel acoustic coupling fluid (ACF), with the potential to reduce surgically induced image artefacts during intraoperative ultrasound imaging in brain tumour surgery, has been evaluated with respect to image quality and safety in a clinical phase 1 study.

Methods

Fifteen patients with glioblastoma (WHO grade IV) were included. All adverse events were registered in a 6-month study period. During acquisition of 3D ultrasound image volumes, three different concentrations of the ACF and Ringer’s solution were filled into the resection cavity. The effect of ACF on the ultrasound images was rated by the operating surgeon, and by five independent neurosurgeons evaluating a pair of blinded images from all patients. Images from all patients were analysed by comparing pixel brightness in a noise-affected region and a reference region.

Results

The operating surgeon deemed the ACF images to have less noise than images obtained with Ringers’s solution. The blinded evaluations by the independent neurosurgeons were significantly in favour of ACF (p < 0.0001). The analyses of pixel intensities showed that the ACF images had lower amount of noise than images obtained with Ringer’s solution. No radiological sign of inflammation nor circulatory changes was found in the early postoperative MR images. Of the nine complications registered as serious events in the study period, none was deemed to be caused by the ACF.

Conclusion

The ultrasound (US) images obtained using ACF have significantly less noise than US images obtained with Ringer’s solution. The rate of adverse events was comparable to what has been reported for similar groups of patients.

Near Infrared Spectroscopy Based Clinical Algorithm Applicability During Spinal Neurosurgery and Postoperative Cognitive Disturbances

Background and Objectives: Postoperative cognitive disturbances (POCD) can significantly alter postoperative recovery. Inadequate intraoperative cerebral oxygen supply is one of the inciting causes of POCD. Near-infrared spectroscopy (NIRS) devices monitor cerebral oxygen saturation continuously and can help to guide intraoperative patient management. The aim of the study was to evaluate the applicability of the NIRS-based clinical algorithm during spinal neurosurgery and to find out whether it can influence postoperative cognitive performance. Materials and Methods: Thirty four patients scheduled for spinal neurosurgery were randomized into a study group (n = 23) and a control group (n = 11). We monitored regional cerebral oxygen saturation (rScO2) throughout surgery, using a NIRS device (INVOS 4100). If rScO2 dropped bilaterally or unilaterally by more than 20% from baseline values, or under an absolute value of 50%, the NIRS-based algorithm was initiated in the study group. In the control group, rScO2 was monitored blindly. To evaluate cognitive function, Montreal-Cognitive Assessment (MoCA) scale was used in both groups before and after the surgery. Results: In the study group, rScO2 dropped below the threshold in three patients and the NIRS-based algorithm was activated. Firstly, we verified correct positioning of the head; secondly, we increased mean systemic arterial pressure in the three patients by injecting repeated intravenous bolus doses of Ephedrine, ultimately resulting in an rScO2 increase above the approved threshold level. None of the three patients showed POCD. In the control group, one patient showed a drop in rScO2 of 34% from baseline and presented with a POCD. RScO2 drop occurred with other stable intraoperative measurements. Conclusions: A significant rScO2 drop may occur during spinal surgery in prone position despite other intraoperative measurements remaining stable, allowing it to stay otherwise unrecognized. Use of the NIRS-based clinical algorithm can help to avoid POCD in patients after spinal surgery.

Measuring and monitoring cognition in the postoperative period

It is common for patients of all ages to experience some degree of cognitive disturbance following surgery. In most cases, impairment appears mild and is restricted to the acute post-operative period, resolving steadily and speedily. In a small number of cases, however, deficits may be more pronounced and/or endure for longer periods, significantly delaying recovery and increasing the risk of serious clinical complications. The ability to accurately measure postoperative cognition, and track recovery of function, is an important clinical task. This review explores practical and methodological issues that may confound this process, examining how best to obtain reliable and meaningful measures of cognition before and after surgery. It considers neuropsychological test selection, administration, analysis and interpretation and offers evidence-based practice points for clinicians and researchers.

The Trendelenburg Position and Cognitive Decline: A Case-Control Interventional Study Involving Healthy Volunteers

Background

Postoperative cognitive decline (POCD) is defined as a new cognitive impairment arising after a surgical intervention. Aspects of cognitive function can be assessed using various validated cognitive function tests including the N-back task, the Stroop task, and the lexical decision-making task (LDT). There is some concern that prolonged Trendelenburg positioning during laparoscopic colorectal surgery may cause POCD.

Objective

The objective of this study was to assess the effect of time spent in the Trendelenburg position on cognitive function.

Methods

Volunteers were placed in the Trendelenburg position for 3 hours and, then, supine for 30 minutes. Validated cognitive function tests including 1-, 2-, and 3-back tasks, Stroop test, and LDT were performed at baseline and every 30 minutes after Trendelenburg positioning. Cognitive decline was defined per the International Study of Postoperative Cognitive Dysfunction trial: a decrease in accuracy from the volunteers’ baseline or an increase in response time from the volunteers’ baseline by >2 control group SDs.

Results

We recruited 15 healthy volunteers (8 males, 7 females) with an average age of 69 years (range 57-81) and average body mass index of 27.7 kg/m² (range 20.9-33). Accuracy remained within 2 SDs at all time points. An increase in response time did occur, and of 15 participants, 3 (20%) showed cognitive decline in the Trendelenburg position after 30 minutes, 4 (27%) after 1 hour, 5 (33%) after 90 minutes, 4 (27%) after 120 and 150 minutes, and 6 (40%) after 180 minutes. On moving to a supine position, 33% (5/15) participants showed cognitive decline.

Conclusions

The results of this study indicate that Trendelenburg positioning leads to cognitive decline. This may have implications for patients undergoing prolonged Trendelenburg positioning during laparoscopic colorectal surgery.

Preoperative Serum 25-Hydroxyvitamin D Level, a Risk Factor for Postoperative Cognitive Dysfunction in Elderly Subjects Undergoing Total Joint Arthroplasty

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a very common postoperative complication occurring mainly after high-risk surgery, especially in the elderly individuals. This study aimed to investigate potential risk factors for POCD in elderly patients after total joint arthroplasty (TJA).

MATERIALS AND METHODS

A total of 257 eligible elderly patients (≥65 years) who were scheduled for elective TJA for osteoarthritis with general anesthesia were enrolled. An experienced psychiatrist was invited to evaluate the cognitive function at baseline (1 day before the surgery) and at day 7 after the surgery. Univariate and multiple logistic regression analyses were performed to screen risk factors associated with POCD. Receiver-operating characteristic curve analysis was performed to assess the predictive value of serum 25-hydroxyvitamin D [25(OH)D] expression for POCD.

RESULTS

Of all the 257 enrolled patients, 55 (21.4%) developed POCD within 7 days after the surgery. Serum 25(OH)D level was the only independent risk factor associated with POCD (odds ratio: 1.77, 95% confidence interval: 1.13-2.78, P = 0.016) by multiple logistic regression analysis. The area under the curve of 25(OH)D for POCD was 0.687, with the cut-off value of 11.2 ng/mL, sensitivity of 41.82% and specificity of 78.71% respectively (95% confidence interval: 0.617-0.757, P < 0.001).

CONCLUSIONS

Our results revealed that preoperative serum 25(OH)D level was an independent risk factor for POCD in elderly subjects after TJA.

Postoperative cognitive dysfunction and short-term neuroprotection from blueberries: a pilot study

BACKGROUND

General anesthesia may be a risk factor for post-operative cognitive impairment, which could be counteracted by neuroprotective compounds. The aims of this study were to determine cognitive functions impaired by general anesthesia and to test blueberry juice as a neuroprotective agent against neuropsychological dysfunctions induced by general anesthesia.

METHODS

Twenty-six patients undergoing elective major surgery were randomized into two groups, receiving either 500 mL/day of blueberry juice within 14 preoperative days (G1) or to a control group (G0). Neuropsychological tests were performed around 20 days before surgery (T0), as well as both three hours (T1) and 24 hours (T2) after surgery. All the scores were statistically analyzed to find significant differences between groups and within the three times.

RESULTS

The control (G0) group showed a significant decrease in the performance in the Prose Memory Test (P<0.001), the Attentional Matrices Test (P<0.01), and the Trail Making Test Part B (P<0.01) after general anesthesia. Significant differences were reported in the Prose Memory test, T0 versus T1 (P<0.01), T0 versus T2 (P<0.001); in the Trail Making Test Part B, T0 versus T2 (P<0.01); and the Attentional Matrices test, and T0 versus T2 (P<0.001). The G1 group did not show any decrease in the performance of the three tests.

CONCLUSIONS

General anesthesia induces a short-term impairment of verbal memory and selective and divided attention. Blueberry compounds may prevent these neuropsychological deficits through a neuroprotective action in patients undergoing general anesthesia.

Peri- and postoperative cognitive and consecutive functional problems of elderly patients

PURPOSE OF REVIEW

From an elderly patient's perspective, acute and chronic cognitive disturbances are among the most harmful complications that can occur following surgery. For elderly patients, these complications often mean the end of an independent life. This article focuses on this serious aspect, which is increasingly prevalent in our aging society. Cognitive disturbances are associated with severe outcome impairments and increased mortality. This article aims to provide a current overview regarding the diagnosis, pathophysiology, prevention, and treatment of this severe social problem.

RECENT FINDINGS

The current knowledge of risk factors, diagnosis, prevention, and treatment of postoperative delirium and postoperative cognitive dysfunction should help to raise awareness and improve the outcome of delirious patients, particularly in the elderly population.

SUMMARY

Especially in elderly patients, postoperative delirium constitutes a common, severe complication. Early diagnosis and supportive treatment are essential to improve outcome. To date, no pharmacological treatment strategy was effective, so that further research about the underlying pathophysiology and the development of treatment strategies are urgently required.

Tools to screen and measure cognitive impairment after surgery and anesthesia

Cognition is essential to all aspects of our everyday life. Although we take our cognitive function for granted, the perioperative period is prone to several aggressions that might impair it. Postoperative cognitive dysfunction, has been the aim of many studies recently, and was shown to be very common with an incidence that can reach 40%, yielding not only impairment in cognition, but also longer hospital stays, higher costs and greater mortality. While several studies have revealed some of the mechanisms contributing to postoperative cognitive dysfunction, the search for the perfect instrument to screen and measure cognitive (dys)function has proven more elusive. The present paper aims to review several cognitive evaluation methods, discussing their advantages and disadvantages as well as their potential clinical applications in evaluating the dynamics of the recovery of cognitive function after anesthesia and surgery. The current availability of easy to use computerized tests might provide the tools necessary to identify patients at risk, and promptly provide them with the adequate course of action.

Indication of Cognitive Change and Associated Risk Factor after Thoracic Surgery in the Elderly: A Pilot Study

Background: This pilot study investigated the effects of partial pulmonary lobectomy lung surgery on cognitive functions of elderly Japanese patients. It is recognized that elderly patients undergoing surgery have increased risk of Postoperative Cognitive Decline (POCD), a condition in which learning, memory, and processing speed is greatly reduced after surgery. Since elderly patients are more likely to exhibit symptoms of POCD, the incidence is increasing as the population receiving surgery is aging.

Methods: Cognitive function was measured for all subjects (n = 12) before and after surgery using three different cognitive tests: Mini-Mental Status Exam-Japanese (MMSE-J), Frontal Assessment Battery (FAB), and a computerized Cogstate Brief Battery (CBB). Changes in these measures indicate changes in cognitive function. In addition, the 12-item General Health Questionnaire (GHQ-12), the Geriatric Depression Scale (GDS), and the 5-item Quality of Life questionnaire (QOL-5) were administered at each time point to measure mental and emotional state. Changes in outcome measures were analyzed via Wilcoxon signed-rank test. Exploratory correlation analysis was conducted using Spearman’s rho.

Results: Data show a decline in detection (DET; p = 0.045) and identification (IDN; p = 0.038). Spearman’s correlation coefficient show a significant correlation between postoperative DET scores and postoperative IDN scores (ρ = 0.78, p = 0.005), a significant correlation between change in IDN and baseline GHQ-12 scores (ρ = -0.595, p = 0.027), and a significant correlation between change in one-back (OBK) scores and duration of anesthesia (ρ = -0.72, p = 0.012).

Discussion: This was the first report to examine cognitive decline after major thoracic surgery in Japanese patients. Previous studies have evidenced that POCD is a common phenomenon after surgery, and that age is a major risk factor. The CCB measured significant change in two cognitive domains: attention and psycomotor function. This study clarified that decline in cognition is detectable in certain measures after thoracic surgery in the elderly Japanese patient population. Additionally, longer anesthetic exposure may negatively impact attention and working memory, and preoperative mental wellbeing is a possible predictor of POCD. These preliminary results have important implications and support the need for future studies.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

[Factors for the development of persistent postoperative cognitive dysfunction in patients undergoing coronary artery bypass surgery under extracorporeal circulation]

AIM

To analyze the factors contributing to the increased risk of persistent postoperative cognitive dysfunction (POCD) in patients undergoing coronary artery bypass surgery (CABS) under extracorporeal circulation (EC).

SUBJECTS AND METHODS

257 male patients aged 45 to 69 years with coronary heart disease (CHD) undergoing elective CABS under EC were examined. In addition to conventional clinical examination, all the patients underwent neuropsychological testing 3-5 days before, 7-14 days and 1 year after CABS. Persistent POCD was diagnosed if there was a 20% decline in cognitive domains at 1-year postoperatively versus preoperatively in 20% of the tests of an entire neuropsychological battery. Binary logistic regression analysis was applied to identify the factors supposedly increasing the risk of persistent POCD.

RESULTS

It was found that high baseline cognitive status, early POCD after CABG under EC, low adherence to the prescribed treatment regimen, as well as progressive carotid artery (CA) stenosis could predict with a high (85%) probability that persistent POCD might develop at 1 year after surgery.

CONCLUSION

The findings are suggestive of the multifactorial origin of persistent POCD, a significant role in the development of which is played by not only the preoperative cognitive status, but also by postoperative factors, such as the degree of adherence to the prescribed treatment regimen, early POCD, and progressive CA stenosis.

Perioperative Gabapentin Does Not Reduce Postoperative Delirium in Older Surgical Patients: A Randomized Clinical Trial

BACKGROUND

Postoperative pain and opioid use are associated with postoperative delirium. We designed a single-center, randomized, placebo-controlled, parallel-arm, double-blinded trial to determine whether perioperative administration of gabapentin reduced postoperative delirium after noncardiac surgery.

METHODS

Patients were randomly assigned to receive placebo (N = 347) or gabapentin 900 mg (N = 350) administered preoperatively and for the first 3 postoperative days. The primary outcome was postoperative delirium as measured by the Confusion Assessment Method. Secondary outcomes were postoperative pain, opioid use, and length of hospital stay.

RESULTS

Data for 697 patients were included, with a mean ± SD age of 72 ± 6 yr. The overall incidence of postoperative delirium in any of the first 3 days was 22.4% (24.0% in the gabapentin and 20.8% in the placebo groups; the difference was 3.20%; 95% CI, 3.22% to 9.72%; P = 0.30). The incidence of delirium did not differ between the two groups when stratified by surgery type, anesthesia type, or preoperative risk status. Gabapentin was shown to be opioid sparing, with lower doses for the intervention group versus the control group. For example, the morphine equivalents for the gabapentin-treated group, median 6.7 mg (25th, 75th quartiles: 1.3, 20.0 mg), versus control group, median 6.7 mg (25th, 75th quartiles: 2.7, 24.8 mg), differed on the first postoperative day (P = 0.04).

CONCLUSIONS

Although postoperative opioid use was reduced, perioperative administration of gabapentin did not result in a reduction of postoperative delirium or hospital length of stay.

Evaluation of Early Postoperative Cognitive Dysfunction Incidence and Involved Neurocognitive Functions in Patients with Cardiac and Noncardiac Surgery Under General Anesthesia

Objective: To analyse postoperative cognitive dysfunction’s (POCD) incidence and cognitive areas involved, in patients with cardiac and general surgery.

Material and Methods: Prospective observational study on 130 patients undergoing general or heart surgery on cardiopulmonary bypass, under general anesthesia. Two groups, 65 members each. Group A had a heart surgery and group B a noncardiac surgery. The same type of anesthetic drugs were used. All patients completed the Montreal Cognitive Assesment (MoCA) questionnaire: preoperative, 24 hours after stopping any medicine acting on central nervous system and 7 days postoperative. We compared the MoCA scores obtained on different cognitive domains in this moments for each group of patients, for neurocognitive functions: visuo-spatial executive, naming, attention, verbal fluency, abstraction, recall, orientation, final score. We compared the scores between the two groups at 24 hours and 7 days postoperatively for the same domains.

Results: POCD was found at 24 hours testing in both groups. At 7 days postoperatively POCD was not found in any of the groups. There was no statistically significant difference in total final score between two groups at 24 hours nor at 7 days postoperative testing. There are significant differences between the two groups, with lower score in cardiac group in 5 of 7 fields at 24 hours testing, with the persistence of difference in 2 of 7 fields at 7 days.

Conclusions: Overall POCD was present at 24 hours but was not found at 7 days testing for none of the groups. POCD is present in some neurocognitive domains and this depends on surgery type.

Postoperative Cognitive Dysfunction in the Elderly: A Review Comparing the Effects of Desflurane and Sevflurane

PURPOSE

The incidence of postoperative cognitive dysfunction (POCD) remains a relatively common complication in the elderly following surgery. Use of anesthesia for surgery might precipitate certain cognitive alterations. The purpose of this review is to address the impact of two volatile anesthetic agents, desflurane and sevoflurane, on POCD.

DESIGN

The focus of this review was on postoperative recovery and complications using two anesthetic agents.

METHODS

Several databases including PubMed and Cochrane were searched from the date of inception. The search words POCD, elderly, general anesthetics, desflurane, and sevoflurane were used and the search was limited to human, randomized clinical trials, and English.

FINDINGS

The findings show no difference in the emergence time between sevoflurane and desflurane and the incidence of POCD.

CONCLUSIONS

No definitive conclusion can be drawn about the type of anesthetic used and its relation to occurrence of POCD. However, the information presented is crucial, which can help to improve anesthetic usage and patient safety.

General anesthesia exposure and risk of dementia: a meta-analysis of epidemiological studies

The association between exposure to general anesthesia and dementia risk has been inconsistently reported across epidemiological studies. To better understand the association, we conducted a meta-analysis of epidemiological studies. PubMed and Embase were searched through April 2017. Random-effects models were used to pool association estimates. We further evaluated potential dose-response relationship. Based on literature search, seven prospective/cohort studies, 11 case-control studies, and a pooled analysis of six case-control studies were identified. Sixteen of these studies were with high quality. After pooling available risk estimates, overall no significant association between exposure to general anesthesia (yes versus no) and dementia risk was detected (odds ratio (OR) = 1.03, 95% confidence interval (CI) 0.90–1.19, p for heterogeneity < 0.001). The null association persisted in the majority of subgroup analyses, although a significant positive association was detected in studies collecting anesthesia exposure using records (OR = 1.22, 95% CI 1.01–1.47, p for heterogeneity < 0.001), a method that is less prone to bias compared with interview or questionnaire using proxy reporters. Based on the dose-response analysis of three studies, a significant nonlinear relationship between times of exposure to general anesthesia and increased risk of dementia was suggested (p < 0.0001). Overall, this meta-analysis suggests that overall the evidence from epidemiological studies supporting a link between general anesthesia exposure and an increased dementia risk is not very strong, while an association was suggested in the studies collecting anesthesia exposure using records and those providing anesthesia exposure frequency data. Further well-designed studies are warranted to better characterize the relationship of interest.

Activation of cannabinoid receptor type 2 attenuates surgery-induced cognitive impairment in mice through anti-inflammatory activity

Background

Neuroinflammation plays a major role in postoperative cognitive dysfunction (POCD). Accumulated evidence indicates that cannabinoid receptor type 2 (CB2R) can mediate anti-inflammatory and immunomodulatory effects in part by controlling microglial activity. However, the impact of CB2R on postoperative cognition has not been investigated. We hypothesized that CB2R is involved in surgery-induced cognitive impairment in adult mice.

Methods

Adult C57BL/6 mice were subjected to intramedullary fixation surgery for tibial fracture under isoflurane anesthesia and CB2R agonist (JWH133) or CB2R antagonist (AM630) treatment. The mice were trained 24 h prior to surgery using a fear conditioning protocol and assessed in a novel context on postoperative days 1, 3, and 7 to evaluate cognitive function. Open-field testing was performed to evaluate the locomotor activity of the mice. The expression levels of IL-1β, TNF-α, MCP-1, and CB2R in the hippocampus and prefrontal cortex were assessed by Western blotting; the expression of microglial marker CD11b in the CA1 area of the hippocampus and medial prefrontal cortex was assessed by immunostaining.

Results

The mice displayed no changes in locomotor activity after surgery and drug treatments. The mice exhibited impaired hippocampal-dependent memory accompanied by an increased expression of proinflammatory factors in the hippocampus and prefrontal cortex 1, 3, and 7 days after surgery, while hippocampal-independent memory remained unaffected at the same time points. JWH133 treatment attenuated surgery-induced memory loss, while AM630 treatment aggravated surgery-induced memory loss, paralleled by a decreased or increased expression of proinflammatory factors in the hippocampus and prefrontal cortex. The expression of CB2R in the hippocampus and prefrontal cortex was upregulated following surgery; however, it was downregulated by postoperative treatment with JWH133. Similarly, the expression of CD11b in the CA1 area of the hippocampus and medial prefrontal cortex was upregulated following surgery and downregulated by postoperative treatment with JWH133.

Conclusions

These findings indicate that CB2R may modulate the neuroinflammatory and cognitive impairment in a mouse model of orthopedic surgery, and the activation of CB2R may effectively ameliorate the hippocampal-dependent memory loss of mice in the early postoperative stage.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-017-0913-7) contains supplementary material, which is available to authorized users.

Role of β2-microglobulin in postoperative cognitive decline

Aim: β2-microglobulin (β2M) was proved to affect hippocampal functions in mice. Materials & methods: Seventy-one patients undergoing aortic valve replacement were analyzed in prospective observational study. Kidney biomarkers and Mini Mental State Examinations (MMSEs) were performed before procedure, at discharge and after 6 months. Results: Patients with β2M increase over the median change (>0.42 mg/l) experienced a significant in-hospital drop in MMSE (p = 0.005). Patients with β2M increase over the median change also failed to improve a delayed-word-recall domain of the test (p = 0.826) while patients with a lower increase improved results in the domain (p = 0.004). After 6 months, MMSE improvement was associated with a significant decrease in β2M (p = 0.042). Conclusion: These are the first in man data demonstrating relation between changes in cognition and β2M. The phenomenon was reversible which indicates its therapeutic potential.