[Effects of cerebral oxygen changes during coronary bypass surgery on postoperative cognitive dysfunction in elderly patients: a pilot study]

Postoperative cognitive dysfunction: Review of pathophysiology, diagnostics and preventive strategies

Postoperative cognitive impairment is a common disorder after major surgery. Advances in medicine and treatment have resulted in an increasingly ageing population undergoing major surgical procedures. Since age is the most important risk factor for postoperative cognitive decline, it is not surprising that impairment of cognitive functions after surgery was recorded in almost a third of elderly patients. Postoperative cognitive dysfunction is part of the spectrum of postoperative cognitive impairment and researchers often confuse it with postoperative delirium and delayed neurocognitive recovery. This is the cause of great differences in the results of research that is focused on the incidence and possible prevention of postoperative cognitive dysfunction. In this review, we focused on current recommendations for a uniform nomenclature of postoperative cognitive impairment and diagnosis of postoperative cognitive dysfunction, the presumed pathophysiology of postoperative cognitive dysfunction and recommendations for its treatment and possible prevention strategies.

Effect of percutaneous cerebral oximetry-guided anaesthetic management on postoperative delirium in older adults undergoing off-pump coronary artery bypass grafting: study protocol for a single-centre prospective randomised controlled trial in a tertiary academic hospital in China

INTRODUCTION

Postoperative delirium is a prominent and clinically important complication in older adults after coronary artery bypass grafting (CABG) surgery, resulting in prolonged hospital stay, long-term cognitive impairment and increased morbidity and mortality. Many studies have shown that cerebral desaturation is associated with increased risk of postoperative delirium during on-pump cardiac surgery. However, few studies have focused on the effect of optimising regional cerebral oxygen saturation (rSO2) on postoperative delirium during off-pump CABG. The purpose of this study is to investigate whether intraoperative anaesthetic management based on percutaneous cerebral oximetry monitoring decreases the incidence of postoperative delirium in older adults undergoing off-pump CABG.

METHODS

This single-centre randomised controlled trial will randomly assign 200 patients to the intervention group or the control group at a ratio of 1:1. The patients in the intervention group will be observed by percutaneous cerebral oximetry monitoring that the desaturation (a drop of more than 20% from baseline value or rSO2 less than 55% for >60 consecutive seconds at either probe) during the procedure triggered the intervention strategies, while the cerebral oximetry data of the control group will be hidden from the clinical team and patients will be anaesthetised by the usual anaesthetic management. The primary outcome will be the incidence of postoperative delirium during the first 7 days after off-pump CABG. Delirium will be comprehensively evaluated by the combination of the Richmond Agitation Sedation Scale and the Confusion Assessment Method for the intensive care unit. The secondary outcomes will include the incidence of postoperative acute kidney injury and myocardial infarction during the hospital stay, as well as the intensive care unit and hospital length of stay.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of the Chinese Academy of Medical Sciences, Fuwai Hospital (No 2022-1824). Written informed consent will be obtained from each patient or their legal representatives before enrolment. The results of this trial will be published in an international peer-reviewed scientific journal.

TRIAL REGISTRATION NUMBER

ChiCTR2300068537.

Effects of regional cerebral oxygen saturation monitoring on postoperative cognitive dysfunction in older patients: a systematic review and meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is common after surgery and anesthesia, particularly in older patients. It has been reported that regional cerebral oxygen saturation (rSO₂) monitoring potentially influences the occurrence of POCD. However, its role in the prevention of POCD remains controversial in older patients. Additionally, the quality of evidence on this topic is still relatively poor.

METHODS

The electronic databases PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched using the indicated keywords from their inception to June 10, 2022. We limited our meta-analysis to randomized controlled trials (RCTs) that assessed the effects of rSO₂ monitoring on POCD in older patients. Methodological quality and risk of bias were assessed. The primary outcome was the incidence of POCD during hospitalization. The secondary outcomes were postoperative complications and the length of hospital stay (LOS). Odds ratios (OR) and 95% confidence intervals (CI) were calculated to determine the incidence of POCD and postoperative complications. The standardized mean difference (SMD) instead of the raw mean difference and 95% CI were calculated for LOS.

RESULTS

Six RCTs, involving 377 older patients, were included in this meta-analysis. The incidence of POCD ranges from 17 to 89%, with an overall prevalence of 47% in our pooled analysis. Our results demonstrated that rSO₂-guided intervention could reduce the incidence of POCD in older patients undergoing non-cardiac surgery (OR, 0.44; 95% CI, 0.25 to 0.79; P = 0.006) rather than cardiac surgery (OR, 0.69; 95% CI, 0.32 to 1.52; P = 0.36). Intraoperative rSO₂ monitoring was also associated with a significantly shorter LOS in older patients undergoing non-cardiac surgery (SMD, -0.93; 95% CI, -1.75 to -0.11; P = 0.03). Neither the incidence of postoperative cardiovascular (OR, 1.12; 95% CI, 0.40 to 3.17; P = 0.83) nor surgical (OR, 0.78; 95% CI, 0.35 to 1.75; P = 0.54) complications were affected by the use of rSO₂ monitoring.

CONCLUSION

The use of rSO₂ monitoring is associated with a lower risk of POCD and a shorter LOS in older patients undergoing non-cardiac surgery. This may have the potential to prevent POCD in high-risk populations. Further large RCTs are still warranted to support these preliminary findings.

Cerebral near-infrared spectroscopy monitoring (NIRS) in children and adults: a systematic review with meta-analysis

BACKGROUND

Cerebral oxygenation monitoring utilising near-infrared spectroscopy (NIRS) is increasingly used to guide interventions in clinical care. The objective of this systematic review with meta-analysis and Trial Sequential Analysis is to evaluate the effects of clinical care with access to cerebral NIRS monitoring in children and adults versus care without.

METHODS

This review conforms to PRISMA guidelines and was registered in PROSPERO (CRD42020202986). Methods are outlined in our protocol (doi: 10.1186/s13643-021-01660-2).

RESULTS

Twenty-five randomised clinical trials were included (2606 participants). All trials were at a high risk of bias. Two trials assessed the effects of NIRS during neonatal intensive care, 13 during cardiac surgery, 9 during non-cardiac surgery and 1 during neurocritical care. Meta-analyses showed no significant difference for all-cause mortality (RR 0.75, 95% CI 0.51-1.10; 1489 participants; I2 = 0; 11 trials; very low certainty of evidence); moderate or severe, persistent cognitive or neurological deficit (RR 0.74, 95% CI 0.42-1.32; 1135 participants; I2 = 39.6; 9 trials; very low certainty of evidence); and serious adverse events (RR 0.82; 95% CI 0.67-1.01; 2132 participants; I2 = 68.4; 17 trials; very low certainty of evidence).

CONCLUSION

The evidence on the effects of clinical care with access to cerebral NIRS monitoring is very uncertain.

IMPACT

The evidence of the effects of cerebral NIRS versus no NIRS monitoring are very uncertain for mortality, neuroprotection, and serious adverse events. Additional trials to obtain sufficient information size, focusing on lowering bias risk, are required. The first attempt to systematically review randomised clinical trials with meta-analysis to evaluate the effects of cerebral NIRS monitoring by pooling data across various clinical settings. Despite pooling data across clinical settings, study interpretation was not substantially impacted by heterogeneity. We have insufficient evidence to support or reject the clinical use of cerebral NIRS monitoring.

Cerebral oximetry and preventing neurological complication post-cardiac surgery: a systematic review

OBJECTIVES

This systematic review aims to provide an up-to-date summary of the current literature examining the relationship between intraoperative regional cerebral oxygen saturation and neurological complications after cardiac surgery.

METHODS

Observational and interventional studies investigating the link between regional cerebral oxygen saturation and postoperative delirium, cognitive dysfunction and stroke were included. After database searching and study screening, study characteristics and major findings were extracted.

RESULTS

Twenty-seven studies were identified. Of the observational studies (n = 17), 8 reported that regional cerebral oxygen desaturations were significantly associated with neurological complications after cardiac surgery. Of the interventional studies (n = 10), 3 provided evidence for monitoring cerebral oximetry during cardiac surgery as a means of reducing incidence of postoperative cognitive dysfunction or stroke. There was significant heterogeneity in the tools and rigor used to diagnose neurological complications.

CONCLUSIONS

Studies to date show an inconsistent relationship between regional cerebral oxygen saturation and neurological outcomes after cardiac surgery, and lack of clear benefit of targeting cerebral oximetry to minimize neurological complications. Standardized assessments, definitions of impairment and desaturation thresholds will help determine the benefits of cerebral oximetry monitoring during cardiac surgery.

Alveolar Recruitment Maneuver Reduces Cerebral Oxygen Saturation and Cerebral Blood Flow Velocity in Patients During Carotid Endarterectomy

BACKGROUND This study aimed to determine the effects of alveolar recruitment maneuver (RM) on cerebral oxygen saturation and cerebral blood velocity in patients undergoing carotid endarterectomy (CEA) before clamping of the carotid artery. MATERIAL AND METHODS In this crossover exploratory study, all patients were randomized to undergo an RM (30 cmH₂O of continuous airway pressure for 30 s) and a "sham" maneuver (SM; 5 cmH₂O for 30 s), followed by an alternative intervention after a 5-min equilibration period. Near-infrared spectroscopy (NIRS) was used to monitor regional cerebral oxygen saturation (rSO₂), and transcranial Doppler ultrasonography (TCD) to evaluate blood velocity of the middle cerebral artery (V-MCA). Changes in rSO₂, V-MCA, mean arterial pressure (MAP), and heart rate (HR) in response to the 2 interventions were compared. RESULTS A total of 59 patients underwent the study procedure. RM reduced rSO₂, V-MCA, MAP, and HR, but these variables slightly changed during SM. A significant drop in rSO₂ was observed immediately after RM compared with the baseline value (68.51±4.4% vs 64.12±5.15%; P<0.001). The decrease in rSO₂ was higher during the RM than during the SM (-6±4% vs 1±2%; P<0.001). Similarly, change in V-MCA was more significant in response to RM than SM (-26±19% vs 19±16%; P<0.001). The V-MCA value changed from 39 cm/s to 29 cm/s after RM. In addition, V-MCA of the ipsilateral to the surgical side decreased more obviously than the contralateral side (-26±19% vs -20±17%; P=0.001). CONCLUSIONS An RM at 30 cmH₂O of continuous airway pressure for 30 s decreased rSO₂ and V-MCA. In addition, MAP and HR were affected.

Diagnostic Criteria of Postoperative Cognitive Dysfunction: A Focused Systematic Review

Postoperative Cognitive Dysfunction (POCD) is characterized by a deterioration in cognitive performance after surgery and is increasingly addressed in research studies. However, a uniform definition of POCD seems to be lacking, which is a major threat to clinical research in this area. We performed a focused systematic review to determine the current degree of heterogeneity in how POCD is defined across studies and to identify those diagnostic criteria that are used most commonly. The search identified 173 records, of which 30 were included. Neurocognitive testing was most commonly performed shortly before surgery and at 7 days postoperatively. A variety of neurocognitive tests were used to test a range of cognitive domains, including complex attention, language, executive functioning, perceptual-motor function, and learning and memory. The tests that were used most commonly were the Mini-Mental State Examination, the digit span test, the trail making test part A, and the digit symbol substitution test, but consensus on which test result would be considered “positive” for POCD was sparse. The results of this systematic review suggest the lack of a consistent approach towards defining POCD. However, commonalities were identified which may serve as a common denominator for deriving consensus-based diagnostic guidelines for POCD.

Risk Factors for Delirium and Cognitive Decline Following Coronary Artery Bypass Grafting Surgery: A Systematic Review and Meta-Analysis

Background

Coronary artery bypass grafting (CABG) is known to improve heart function and quality of life, while rates of surgery‐related mortality are low. However, delirium and cognitive decline are common complications. We sought to identify preoperative, intraoperative, and postoperative risk or protective factors associated with delirium and cognitive decline (across time) in patients undergoing CABG.

Methods and Results

We conducted a systematic search of Medline, PsycINFO, EMBASE, and Cochrane (March 26, 2019) for peer‐reviewed, English publications reporting post‐CABG delirium or cognitive decline data, for at least one risk factor. Random‐effects meta‐analyses estimated pooled odds ratio for categorical data and mean difference or standardized mean difference for continuous data. Ninety‐seven studies, comprising data from 60 479 patients who underwent CABG, were included. Moderate to large and statistically significant risk factors for delirium were as follows: (1) preoperative cognitive impairment, depression, stroke history, and higher European System for Cardiac Operative Risk Evaluation (EuroSCORE) score, (2) intraoperative increase in intubation time, and (3) postoperative presence of arrythmia and increased days in the intensive care unit; higher preoperative cognitive performance was protective for delirium. Moderate to large and statistically significant risk factors for acute cognitive decline were as follows: (1) preoperative depression and older age, (2) intraoperative increase in intubation time, and (3) postoperative presence of delirium and increased days in the intensive care unit. Presence of depression preoperatively was a moderate risk factor for midterm (1–6 months) post‐CABG cognitive decline.

Conclusions

This meta‐analysis identified several key risk factors for delirium and cognitive decline following CABG, most of which are nonmodifiable. Future research should target preoperative risk factors, such as depression or cognitive impairment, which are potentially modifiable.

Registration

URL: https://www.crd.york.ac.uk/prosp​ero/; Unique identifier: CRD42020149276.