The assessment of postoperative cognitive function

Postoperative cognitive function (POCD) has been subject to extensive research. In the literature, large differences are apparent in methodology such as the test batteries, the interval between sessions, the endpoints to be analysed, statistical methods, and how neuropsychological deficits are defined. Traditionally, intelligence tests or tests developed for clinical neuropsychology have been used. The tests for detecting POCD should be based on well-described sensitivity and suitability in relation to surgical patients. In tests using scores, floor/ceiling effects may compromise the evaluation if the tests are either too easy or to difficult. Uncontrolled testing facilities and change of test personnel may affect the test performance. Practice effects are pronounced in neuropsychological tests but have generally been ignored. The use of a suitable normative population is essential to allow correction for practice effects and variability between sessions. Missing follow-up may severely compromise valid conclusions since subjects unable or unwilling to be examined are particularly prone to suffer from POCD. In the statistical analysis of the test results, the evaluation should be based on differences between pre- and postoperative performance. Parametric statistical tests are not relevant unless the appropriate Gaussian distributions are present, perhaps after transformation of data. The definition of cognitive dysfunction should be restrictive and the criteria should be fulfilled in only a small proportion of volunteers. In the literature, these requirements often have not been fulfilled. This precludes a reasonable estimation of the incidence of POCD and the conclusions of comparative studies should be interpreted with great caution. In this review article, we present a number of recommendations for the design and execution of studies within this area. In addition, the critical reader may use these recommendations in the evaluation of the literature.     

The incidence of cognitive decline after (not) undergoing coronary artery bypass grafting: the impact of a controlled definition

BACKGROUND: After coronary artery bypass grafting (CABG), 20-30% of patients are reported to suffer from cognitive decline. Studies reporting these high incidences, however, have not included an appropriate control group. METHODS: We repeatedly administered a series of neuropsychological tests to 112 healthy middle-aged volunteers not undergoing surgery, and applied two widely used definitions of cognitive decline to their test results. In addition, we re-analysed the neuropsychological test data of 281 CABG patients with a definition of cognitive decline that takes into account the natural variability of test performance that was found in the volunteers. RESULTS: Three months after their first assessment, 14-28% of the volunteers suffered from cognitive decline according to the definitions of cognitive decline after CABG. Using the controlled definition of cognitive decline that takes the natural variability in test performance into account, we found that only 7.7% of the CABG patients suffered from cognitive decline at 3 months after their operation. CONCLUSION: These data suggest that the incidence of cognitive dysfunction after CABG has previously been greatly overestimated.     

Choice reaction time in patients with post-operative cognitive dysfunction

Background: Post‐operative cognitive dysfunction (POCD) is detected by administration of a neuropsychological test battery. Reaction time testing is at present not included as a standard test. Choice reaction time (CRT) data from the first International Study of Post‐operative Cognitive Dysfunction study were collected, but the association between POCD and reaction time has not been presented before. We hypothesized that CRT could be used as a screening tool for POCD. Methods: Patients aged 60 years or older scheduled for major surgery with general anaesthesia were recruited from 13 centres in nine countries. CRT was measured 52 times using the four boxes test. Patients performed the test before surgery (n=1083), at 1 week (n=926) and at 3 months (n=852) post‐operatively. CRT for the individual patient was determined as the median time of correct responses. The usefulness of the CRT as a screening tool for POCD was determined by the receiver–operator characteristic (ROC) curve. Results: Patients with POCD 1 week after surgery had a significantly longer reaction time compared with patients without POCD: 857 (221) vs. 762 (201) ms, respectively (P<0.0001). Also at 3 months, patients with POCD had a significantly longer CRT. ROC curves revealed that a reaction time of 813 ms was the most appropriate cut‐off at 1 week and 762 ms at 3 months but the positive predictive value for POCD was low: 34.4% and 14.7%, respectively. Conclusions: Post‐operative cognitive dysfunction is associated with impaired performance in the CRT test but the test is a poor predictor of POCD.     

心脏手术后的认知功能障碍

大脑功能障碍是指智力下降等不同程度脑功能改变。随着心脏外科的发展，有关中枢神经系统并发症日益受到重视。 1 危险因素 术前已有中风、主动脉近端硬化、贫血与老龄化、高血压和糖尿病等均可使体外循环后中风风险增加。术中发生中风的主要风险因子是体外循环时间和反复地钳夹主动脉。其他如围术期心律失常、低心排综合征等情况也会使体外循环后认知功能障碍增加。     

Postoperative cognitive decline

Memory loss and lack of concentration are symptoms that frequently occur in patients who have undergone a surgical procedure. Although cognitive function can be assessed using neuropsychological tests, reliable diagnosis of postoperative cognitive decline (POCD) appears to be difficult. Therefore, the true incidence of POCD is unknown. Severe POCD, which is apparent even without neuropsychological testing, is reported most frequently after cardiac and hip-replacement surgery. In these cases, POCD probably reflects microembolic brain injury. Apart from the nature of the surgical procedure, advanced age is the most important risk factor for POCD. The anesthetic technique is not a determinant of POCD: the risk of POCD appears to be similar after both general and regional anesthesia. This review article was invited by the Editorial Board members of the Journal of Anesthesia and was peer-reviewed as were the other articles in this journal.     

Postoperative cognitive dysfunction: incidence and prevention

Postoperative cognitive dysfunction (POCD) is a decline in cognitive function for weeks or months after surgery. Due to its subtle nature, neuropsychological testing is necessary for its detection. The interpretation of literature on POCD is difficult because of numerous methodological limitations, particularly the different definitions of POCD and the lack of data from control groups. POCD is common after cardiac surgery, and recent studies have now verified that POCD also exists after major non-cardiac surgery, although at a lower incidence. The risk of POCD increases with age, and the type of surgery is also important because there is a very low incidence associated with minor surgery. Regional anaesthesia does not seem to reduce the incidence of POCD, and cognitive function does not seem to improve after carotid surgery as has previously been suggested.     

术后认知功能障碍的炎症机制

背景 术后认知功能障碍(postoperative cognitive dysfunction,POCD)是老年患者手术后常见的中枢神经系统并发症.目前POCD的发病机制尚不清楚.POCD的发生影响了患者术后恢复,延长了住院时间,增加了术后并发症的发生率和死亡率;对家庭及社会造成严重的经济负担,POCD将成为一个严重的...     

甲基强的松龙对老年患者胸腔镜辅助肺叶切除术后认知功能的影响

目的评价甲基强的松龙对行胸腔镜辅助肺叶切除术老年患者术后认知功能的影响。方法择期行胸腔镜辅助肺叶切除术的老年患者60例,男31例,女29例,年龄65~75岁,BMI18.5~23.9kg/m2,ASAⅠ或Ⅱ级。采用随机数字表法,将患者分为甲基强的松龙组(M组)和对照组(C组),每组30例。M组于单肺通气前静脉滴注甲基强的松龙2mg/kg,C组于同时点静脉滴注等容量生理盐水。于术前1d,术后3和7d采用简易精神状态量表(MMSE)评估患者认知功能,计算患者术后认知功能障碍(POCD)发生率。于术前1d,术后1、3和7d晨8:00空腹抽取外周静脉血记录血清皮质醇浓度和空腹血糖浓度。记录术后7d肺部感染或肺不张等肺部并发症情况。结果与术前1d比较,两组术后3dMMSE评分明显降低(P0.05)。与C组比较,M组术后3dMMSE评分明显升高(P0.05),POCD发生率明显降低(P0.05),血清皮质醇浓度明显降低(P0.05)。两组不同时点空腹血糖浓度差异无统计学意义,术后7d肺部并发症情况差异无统计学意义。结论在行胸腔镜肺叶切除术老年患者中甲基强的松龙降低了POCD的发生率,短暂抑制术后皮质醇水平,不增加患者术后高血糖和肺部并发症的风险。     

丰富环境对新生小鼠暴露于七氟醚所致微清蛋白中间神经元表型缺失及认知功能损伤的影响

目的观察微清蛋白(parvalbumin,PV)在七氟醚麻醉致小鼠认知功能损害中的表达变化,并研究丰富环境是否能改善此种变化。方法 6日龄新生雄性C57BL/6小鼠144只随机均分为四组(n=36):对照+标准环境组(CS组)、对照+丰富环境组(CE组)、七氟醚+标准环境组(SS组)及七氟醚+丰富环境组(SE组)。SS及SE组分别在出生后第6、7、8天每天接受1次2h的3%七氟醚麻醉+30%氧气;CS及CE组在相应日龄吸入30%氧气。从P8到P90,CE及SE组小鼠每天接受2h丰富环境饲养,CS及SS组则在标准环境下饲养。小鼠于P42行旷场实验,于P42-43和P89-90分别行场景条件性恐惧实验。并于P9、P14、P42、P60及P90取小鼠皮层及海马组织,采用Western blot检测小鼠额叶皮层及海马中微清蛋白的表达。结果旷场实验测试中,四组探索路程和中央格停留时间差异无统计学意义。场景性恐惧实验测试中,SS组P43僵直反应时间百分比明显低于CS组(P0.05),但在P90差异无统计学意义;在P9和P14,SS组前额皮层及海马中PV表达明显低于CS组(P0.01),但在P60、P90恢复正常;在P42,SE组前额皮层及海马中PV表达明显高于SS组(P0.05);线性回归分析表明:小鼠前额皮层中PV表达量与环境诱导僵直时间成显著正相关(r=0.670 7,P=0.000 1),小鼠海马中PV表达量与环境诱导僵直时间成显著正相关(r=0.509 6,P=0.001 9)。结论七氟醚暴露(P6-P8)可致小鼠认知功能损伤伴随前额皮层和海马PV表达降低,丰富环境可减轻此种损伤。     

Postoperative cognitive dysfunction after noncardiac surgery: a systematic review

This article describes a systematic review on the research into postoperative cognitive dysfunction (POCD) in noncardiac surgery to ascertain the status of the evidence and to examine the methodologies used in studies. The review demonstrated that in the early weeks after major noncardiac surgery, a significant proportion of people show POCD, with the elderly being more at risk. Minimal evidence was found that patients continue to show POCD up to 6 months and beyond. Studies on regional versus general anesthesia have not found differences in POCD. Many studies were found to be underpowered, and a number of other methodologic difficulties were identified. These include the different types of surgery in studies and variations in the number and range of neuropsychological tests used. A particular issue is the variety of definitions used to classify individuals as having POCD.     

细胞自噬在认知功能障碍机制中的研究进展

认知功能障碍是各种原因导致的认知功能损害,严重影响患者的生活质量。高龄、既往心脑血管疾病、麻醉及手术等均是其危险因素。细胞自噬是维持细胞能量稳态必需的细胞内降解途径,与应激、感染、癌症及神经退行性疾病等密切相关。近年来大量研究表明,细胞自噬在认知功能障碍机制中发挥重要作用。神经元内自噬水平异常会破坏细胞稳态,严重时可影响患者的认知功能。通过调控各种细胞自噬信号通路可明显改善细胞缺氧、促进能量及物质代谢,改善认知功能,以上为临床认知功能障碍的预防和治疗提供了新的思路。     

Off-pump versus on-pump coronary artery bypass surgery and postoperative pulmonary dysfunction

OBJECTIVE: To investigate how off-pump coronary artery bypass grafting (CABG) affects postoperative pulmonary function when compared with on-pump CABG. DESIGN: Prospective clinical study. SETTING: University-affiliated teaching hospital. PARTICIPANTS: Adult patients (n = 39) undergoing elective coronary artery bypass surgery with or without cardiopulmonary bypass. INTERVENTIONS: Two groups of patients were compared: 19 consecutive patients undergoing off-pump CABG surgery and 20 consecutive patients undergoing conventional CABG surgery. MEASUREMENTS AND MAIN RESULTS: Pulmonary function tests (flow volume loops and lung volumes with plethysmography) were done preoperatively and 72 hours postoperatively. Arterial blood gases and PaO2/FIO2 were measured at various stages. Sequential chest x-rays were obtained and evaluated for pleural changes, pulmonary edema, and atelectasis. In both groups, PaO2/FIO2 ratios decreased progressively throughout the perioperative period, with no significant differences between the groups at any stage during the study. There was a significant decline in postoperative pulmonary function tests in both groups, but there was no difference between groups at 72 hours postoperatively. No differences were found in the time to extubation, atelectasis scores, or postoperative complications. CONCLUSIONS: Off-pump CABG does not confer major protection from postoperative pulmonary dysfunction compared with CABG surgery with CPB. Strategies for minimizing pulmonary impairment after CABG surgery should be directed to factors other than the use of CPB.     

Short-term DTI predictors of cognitive dysfunction in mild traumatic brain injury

Primary objective: To explore whether baseline diffusion tensor imaging (DTI) metrics are predictive of cognitive functioning 6 months post-injury in patients with mild traumatic brain injury (MTBI).

Research design: Seventeen patients with MTBI and 29 sex- and age-matched healthy controls were studied.

Methods and procedures: Participants underwent an MRI protocol including DTI, at an average of 4.0 (range: 1-10) days post-injury. Mean diffusivity (MD) and fractional anisotropy (FA) were measured in the following white matter (WM) regions: centra semiovale, the genu and the splenium of the corpus callosum and the posterior limb of the internal capsule. Participants underwent neuropsychological (NP) testing at baseline and at 6-month follow-up. Least squares regression analysis was used to evaluate the association of MD and FA with each NP test score at baseline and follow-up.

Main outcomes and results: Compared to controls, average MD was significantly higher (p = 0.02) and average FA significantly lower (p = 0.0001) in MTBI patients. At the follow-up, there was a trend toward a significant association between baseline MD and response speed (r = -0.53, p = 0.087) and a positive correlation between baseline FA and Prioritization form B (r = 0.72, p = 0.003).

Conclusions: DTI may provide short-term non-invasive predictive markers of cognitive functioning in patients with MTBI.     

Postoperative cognitive dysfunction and mortality following lung transplantation

Preliminary evidence suggests that postoperative cognitive dysfunction (POCD) is common after lung transplantation. The impact of POCD on clinical outcomes has yet to be studied. The association between POCD and longer‐term survival was therefore examined in a pilot study of posttransplantation survivors. Forty‐nine participants from a prior randomized clinical trial underwent a neurocognitive assessment battery pretransplantation and 6 months posttransplantation, including assessments of the domains of Executive Function (Trail Making Test, Stroop, Digit Span), Processing Speed (Ruff 2 and 7 Test, Digit Symbol Substitution Test), and Verbal Memory (Verbal Paired Associates, Logical Memory, Animal Naming, and Controlled Oral Word Association Test). During a 13‐year follow‐up, 33 (67%) participants died. Greater neurocognition was associated with longer survival (hazard ratio [HR] = 0.49 [0.25‐0.96], P = .039), and this association was strongest on tests assessing Processing Speed (HR = 0.58 [0.36‐0.95], P = .03) and Executive Function (HR = 0.52 [0.28‐0.97], P = .040). In addition, unadjusted analyses suggested an association between greater Memory performance and lower risk of CLAD (HR = 0.54 [0.29‐1.00], P = .050). Declines in Executive Function tended to be predictive of worse survival. These preliminary findings suggest that postoperative neurocognition is predictive of subsequent mortality among lung transplant recipients. Further research is needed to confirm these findings in a larger sample and to examine mechanisms responsible for this relationship.