Tools to screen and measure cognitive impairment after surgery and anesthesia

Association between genetic variation rs57095329 of microRNA-146a and development of cognitive impairment after anesthesia: a case-control study in a Chinese Han population

The latest studies have demonstrated that aberrant expression of microRNA-146a is related to cognitive decline. The rs57095329 polymorphism occurring in the miR-146a promoter modulates its expression and causes downstream pathogenicity. A case-control study in a Chinese Han population was established to investigate the genetic association between the miR-146a rs57095329 polymorphism and postoperative cognitive dysfunction (POCD). 242 patients with POCD and another 238 non-POCD cases were enrolled in the case-control study. Serum miR-146a levels were detected by qRT-PCR. miR-146a rs57095329 polymorphism was genotyped using the ABI PRISM SNaPshot method. The genetic association between the rs57095329 polymorphism and POCD was assessed by regression analysis. No significant difference was detected for age, gender and BMI between POCD and non-POCD groups. MiR-146a rs57095329 polymorphism revealed significant generic associations with POCD in both dominant and recessive models, and the AA genotype may increase the risk of developing POCD. qRT-PCR indicated the upregulation of miR-146a level in POCD group. Serum levels of miR-146a and inflammatory factors were higher in rs57095329 AA genotype carriers than in AG/GG genotype carriers. Rs57095329 polymorphism was independently associated with the development of POCD. In conclusion, miR-146a rs57095329 polymorphism was associated with POCD in the Chinese Han population. The rs57095329 AA genotype was the causative genotype for POCD and was related to the upregulation of miR-146a and inflammatory factor levels.

CO2 delivery techniques in mini-sternotomy surgery and neurological events: a multicentric study

BACKGROUND

The impact of air bubbles into the cerebral circulation after open heart surgery has been a topic of discussion since the introduction of the heart-lung machine. The aim of the study was to evaluate whether the use of a dedicated commercial sponge diffuser is better than a custom-made narrow section cannula or the absence of CO2 in preventing neurological events after aortic valve replacement via J mini-sternotomy.

METHODS

Three cohorts of J-shaped mini-sternotomy performed at three different centers were prospectively compared: CO2 supplied via sponge diffuser, CO2 supplied via cannula, and no CO2 supply. Propensity matching was used to obtain comparable groups. The primary endpoints were postoperative stroke, transitory ischemic attack, convulsions, and dizziness. Secondary endpoints were 30-day mortality, duration of mechanical ventilation, and intensive care unit length of stay.

RESULTS

275 patients were enrolled in the study. After propensity matching, the sponge diffuser cohort had a significantly lower duration of mechanical ventilation (P < 0.001) and 30-day mortality (P = 0.05) when compared to the cannula cohort and the no-CO2 cohort, a lower incidence of all neurological events (P = 0.03) and dizziness (P = 0.05) when compare to the no-CO2 cohort, and a lower intensive care unit length of stay when compared to the cannula cohort (P = 0.001).

CONCLUSIONS

The sponge diffuser used to deliver the CO2 into the surgical field during aortic valve replacement via J mini-sternotomy has been demonstrated to guarantee better neurological outcomes compared to a custom-made narrow section cannula or the absence of CO2.

Incidence of Postoperative Cognitive Dysfunction Following Inhalational vs Total Intravenous General Anesthesia: A Systematic Review and Meta-Analysis

Postoperative cognitive dysfunction (POCD) has been increasingly recognized as a contributor to postoperative complications. A consensus-working group recommended that POCD should be distinguished between delayed cognitive recovery, ie, evaluations up to 30 days postoperative, and neurocognitive disorder, ie, assessments performed between 30 days and 12 months after surgery. Additionally, the choice of the anesthetic, either inhalational or total intravenous anesthesia (TIVA) and its effect on the incidence of POCD, has become a focus of research. Our primary objective was to search the literature and conduct a meta-analysis to verify whether the choice of general anesthesia may impact the incidence of POCD in the first 30 days postoperatively. As a secondary objective, a systematic review of the literature was conducted to estimate the effects of the anesthetic on POCD between 30 days and 12 months postoperative. For the primary objective, an initial review of 1913 articles yielded ten studies with a total of 3390 individuals. For the secondary objective, four studies with a total of 480 patients were selected. In the first 30 days postoperative, the odds-ratio for POCD in TIVA group was 0.46 (95% CI = 0.26-0.81; p = 0.01), compared to the inhalational group. TIVA was associated with a lower incidence of POCD in the first 30 days postoperatively. Regarding the secondary objective, due to the small number of selected articles and its high heterogeneity, a metanalysis was not conducted. Given the heterogeneity of criteria for POCD, future prospective studies with more robust designs should be performed to fully address this question.

The effect of intraoperative dexmedetomidine on cognitive dysfunction after surgery: a updated meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is one of the most common. Neuroprotective effects of dexmedetomidine (DEX) are reported in previous studies but evidence regarding the POCD is still unclear. In order to gain latest evidence, the present study analyzes the outcomes of randomized controlled trials (RCTs) which utilized DEX with general anaesthesia perioperatively.

METHOD

Four online databases (PubMed, Embase, the Cochrane Library, and CNKI) were used to find relevant RCTs to conduct systematic analysis. All studies comparing the incidence of POCD or MMSE score between the DEX group and the placebo or comparator group in patients undergoing general anaesthetic surgery were eligible for inclusion. Based on the inclusion and exclusion criteria, the studies were selected. This meta-analysis was performed using odds ratios (ORs) with 95% confidence intervals (CIs) for dichotomous data and standardized mean difference (SMD) and 95% CIs for continuous data as effective measures.

RESULTS

In total of 21 studies were included in this meta-analysis. The results showed that the incidence of POCD in DEX group was significantly lower than the control group on the first (OR = 0.36, 95% CI 0.24-0.54),third (OR = 0.45,95% CI 0.33-0.61) and seventh (OR = 0.40,95% CI 0.26-0.60) postoperative days; the MMSE scores in DEX group were higher than the control group on the first (SMD = 1.24, 95% CI 1.08-1.41), third(SMD = 1.09, 95%CI 0.94-1.24) and seventh (SMD = 3.28, 95% CI 1.51-5.04) postoperative days.

CONCLUSIONS

Intraoperative DEX use can ameliorate the POCD of patients who received surgical operations under general anesthesia, and effectively reduce the incidence of POCD and improve MMSE score.

An Association Between C-Reactive Protein Levels and the Occurrence of Cognitive Dysfunction After Heart Valve Replacement

Background

Postoperative cognitive dysfunction (POCD) is defined as cognitive dysfunction related to inflammation after surgical procedures, which is common following cardiac surgery. Cognitive deficits are thought to result from a systemic inflammatory response. C-reactive protein (CRP) and other proinflammatory cytokines, which are released in response to inflammation, disrupt the blood–brain barrier and neurotransmission, resulting in POCD. This study aimed to determine the correlation between POCD and increased levels of CRP in patients who had undergone heart valve replacement.

Methods

This study comprised 32 patients with normal cognitive function undergoing heart valve replacement. The CRP levels were measured before surgery and on the second postoperative day, and cognitive function was examined via the Indonesian-adapted Montreal Cognitive Assessment (MOCA-INA) on the third postoperative day. Data were analyzed using Spearman correlation test.

Results

Of the 32 patients, 28 (87.5%) experienced POCD. The median level of CRP was 6.6 mg/dL (interquartile range: 4.0, 8.3 g/dL). According to Spearman correlation test, increased levels of CRP were significantly related to POCD following heart valve replacement (p = 0.003, r = 0.501). The receiver operating characteristic curve indicated that the CRP cutoff level was 3.345 mg/dL, and the sensitivity and specificity were 89.3% and 75%, respectively.

Conclusion

High expression level of CRP was correlated with POCD following heart valve replacement.

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.

Consistency and applicability of different brief screen instrument of cognitive function in elderly population

BACKGROUND

Screening for cognitive impairment (CI) is often hampered by lack of consensus as to which screening instrument to use. The aim is to assess the consistence and applicability of different CI screening tools.

METHOD

In a cross-sectional study from October 2017 to September 2018 in 7 communities in Shanghai, China, elder (≧60) residential volunteers with no history of major cardiovascular diseases, cancers and other comorbidities known to affect cognitive functions were recruited. The participants underwent tests with 7 cognitive function screening instruments. Multivariate linear regressions were performed to test correlations between demographic characteristics, including gender, age, education, and marital status, with cognitive test scores. Mini-Mental State Examination (MMSE) score adjusted according to the correlation coefficients was used to detect CI with a cutoff of 24. Other cognitive function scores were compared between participants with and without CI. In addition, Pearson's correlation test was used to detect association between different test scores.

RESULTS

172 participants with relatively low education levels were included. Age and education showed significant association with cognitive test scores. Using adjusted MMSE, 39.6% of participants were identified with CI, while the percentage was 87.2% when adjusted Montreal Cognitive Assessment (MoCA) with cutoff of 26 was used. Analysis of "abnormal" test scores showed that MMSE had the highest percentage of valid data (98.8%). MoCA and Isaacs test of Verbal Fluency (VF) score had correlation with most the other scores, while MMSE only significantly associated with VF and MoCA.

CONCLUSIONS

MMSE may still present the most applicable tools for quick screen of cognitive functions, especially when environmental conditions may interfere with participants' attention.

Apoptosis inhibition is involved in improvement of sevoflurane-induced cognitive impairment following normobaric hyperoxia preconditioning in aged rats

Sevoflurane, a commonly used anesthetic agent has been confirmed to induce cognitive impairment in aged rats. Normobaric hyperoxia preconditioning has been demonstrated to induce neuroprotection in rats. The present study aimed to determine whether normobaric hyperoxia preconditioning could ameliorate cognitive deficit induced by sevoflurane and the possible mechanism by which it may exert its effect. A total of 66, 20-month-old male Sprague-Dawley rats were randomly divided into 3 groups (n=22 each): Rats in the control (C) and sevoflurane anesthesia (S) groups received no normobaric hyperoxia preconditioning before sevoflurane exposure, rats in the normobaric hyperoxia pretreatment (HO) group received normobaric hyperoxia preconditioning before sevoflurane exposure (95% oxygen for 4 continuous h daily for 6 consecutive days). The anesthesia rats (S and HO groups), were exposed to 2.5% sevoflurane for 5 h, while the sham anesthesia rats (C group) were exposed to no sevoflurane. The neurobehavioral assessment was performed using a Morris water maze test, the expressions of the apoptosis proteins were determined using western blot analysis, and the apoptosis rate and cytosolic calcium concentration were measured by flow cytometry. Normobaric hyperoxia preconditioning improved prolonged escape latency and raised the number of platform crossings induced by sevoflurane in the Morris water maze test, increased the level of bcl-2 protein, and decreased the level of bax and active caspase-3 protein, the apoptosis rate and cytosolic calcium concentration in the hippocampus 24 h after sevoflurane exposure. The findings of the present study may imply that normobaric hyperoxia preconditioning attenuates sevoflurane-induced spatial learning and memory impairment, and this effect may be partly related to apoptosis inhibition in the hippocampus. In conclusion, normobaric hyperoxia preconditioning may be a promising strategy against sevoflurane-induced cognitive impairment by inhibiting the hippocampal neuron apoptosis.

Current Perspectives on Postoperative Cognitive Dysfunction in the Ageing Population

Postoperative cognitive dysfunction (POCD) is defined as a prolonged cognitive function impairment that occurs within weeks to months of a surgical procedure. It is especially prevalent in the elderly population, leading to increased morbidity and mortality. As anaesthetic and surgical care continues to improve and become increasingly safer, a significantly greater number of older patients have elective surgical procedures today, yet this comes with an increased POCD risk as they go through the perioperative phases. Although the pathophysiology behind the development of POCD is still under investigation, current causative mechanisms include the mode of anaesthesia administered, anaesthetic used, cerebral hypoperfusion, hyperventilation and neuroinflammation. These findings lend an insight into the importance of being cognisant of the higher likelihood of POCD in at-risk patients, including the elderly, and taking precautions to include preoperative and postoperative cognitive testing, careful monitoring during anaesthesia, blood pressure control and early treatment of postoperative complications as they arise. In this review, we provide an update on the current understanding of the pathophysiology leading to POCD, identifying risk factors, prevention and treatment strategies, with a specific focus on the elderly population.

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.

The influence of anesthetic techniques on postoperative cognitive function in elderly patients undergoing hip fracture surgery: General vs spinal anesthesia

BACKGROUND

Hip fracture is common and morbid in elderly patients. Postoperative cognitive dysfunction (POCD) is also very common in these subjects undergoing surgery with an incidence which exceeds 40% in some reports. To date, the evidence is ambiguous as to whether anesthetic technique may affect the patients' outcome as far as postoperative cognitive function is concerned.

OBJECTIVE

The aim of this study was to compare the effect of general and subarachnoid (spinal) anesthesia on the development of POCD up to 30 days after surgery in elderly patients undergoing hip fracture surgery. Methods Subjects over 65 years with hip fracture undergoing surgery were recruited for this study. They were enrolled and randomized to receive either general anesthesia (GA group) or subarachnoid (spinal) anesthesia (S group). Cognitive function was assessed using a battery of neuropsychological tests undertaken preoperatively and at 30 days postoperatively. The incidence of delirium was examined during the same period and their functional status, in terms of activities of daily living was also recorded.

RESULTS

A total of seventy patients, 33 men and 37 females, mean age of 76 years were analyzed. Thirty-three patients received general anesthesia (GA group) and 37 subarachnoid (spinal) anesthesia (S group). The two groups of patients were similar with respect to baseline characteristics, comorbidities and perioperative data. The results of neuropsychological testing showed that there were no significant differences between the groups in eight out of ten neurocognitive tests at baseline and 30 days after surgery. There was a statistically significant decline of the Instrumental Activities of Daily Living Scale score in S group compared with group GA on the 30th postoperative day (p = 0.043). A significant decline was also present in Color-Word Task test in S group compared with group GA at baseline (p = 0.014) and 30 days postoperatively (p = 0.003). Postoperative delirium was present in four patients (12%) for the GA group, and in 10 patients (27%) for the group receiving subarachnoid anesthesia.

CONCLUSION

We concluded that the choice of anesthesia modality does not appear to influence the emergence of postoperative cognitive dysfunction in elderly patients undergoing hip fracture surgery.