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

Anaesthesia-related cognitive dysfunction following cardiothoracic surgery in late middle-age and younger adults: A scoping review

BACKGROUND

The incidence of postoperative cognitive dysfunction (POCD) is notably high after cardiac surgery, ranging from 25% to 30%, and is associated with a lower quality of life, increased patient dependency, and heightened mortality. Anaesthesia during cardiothoracic surgery significantly contributes to the risk of POCD in older adults by adversely affecting the brain, including reductions in blood flow and oxygen levels.

AIM

This review aimed to evaluate factors associated with anaesthesia-related postoperative cognitive dysfunction (POCD) among adults younger than 65 years who underwent cardiothoracic surgeries.

STUDY DESIGN

A systematic keyword search, following the scoping review framework, was performed in the PubMed and CINAHL databases. Original English-language studies that included adults younger than 65 years and addressed cognitive function after surgery along with anaesthesia management were included. Retrospective studies, animal research and in vitro and in vivo studies were excluded.

RESULTS

Twenty-three articles were included (65.2% interventional studies). All studies lacked theoretical or conceptual frameworks. Ketamine's neuroprotective potential is questionable, and intravenous lidocaine may be considered a possible early agent for preventing POCD, but long-term effectiveness is uncertain. Compared to inhalational anaesthesia, total intravenous anaesthesia (TIVA) may be related to a decreased incidence of POCD. Variation in POCD assessment impacted the lack of homogeneity in obtained data. Moreover, the shorter-term timing of POCD evaluation such as in early days after surgery could be greatly influenced by medication and delirium.

CONCLUSION

Although strategies such as TIVA, the use of neuroprotective anaesthetics and comprehensive preoperative assessments are suggested to prevent POCD, this multifactorial phenomenon cannot be explicitly attributed solely to anaesthetics or anaesthesia-related techniques. Use of standardized, reliable and valid tools for POCD assessment is encouraged for cross-study comparison.

RELEVANCE TO CLINICAL PRACTICE

Nurses and certified nurse anaesthetists must be aware of risk factors for postoperative delirium and POCD so they can assess patients before and after surgery. Patients and caregivers need to be educated about cognitive changes after surgery and advised to report them to their health care provider if they occur.

Communication Regarding the Myocardial Ischemia/Reperfusion and Cognitive Impairment: A Narrative Literature Review

Coronary artery disease is a prevalent ischemic disease that results in insufficient blood supply to the heart muscle due to narrowing or occlusion of the coronary arteries. Various reperfusion strategies, including pharmacological thrombolysis and percutaneous coronary intervention, have been developed to enhance blood flow restoration. However, these interventions can lead to myocardial ischemia/reperfusion injury (MI/RI), which can cause unpredictable complications. Recent research has highlighted a compelling association between MI/RI and cognitive function, revealing pathophysiological mechanisms that may explain altered brain cognition. Manifestations in the brain following MI/RI exhibit pathological features resembling those observed in Alzheimer's disease (AD), implying a potential link between MI/RI and the development of AD. The pro-inflammatory state following MI/RI may induce neuroinflammation via systemic inflammation, while impaired cardiac function can result in cerebral under-perfusion. This review delves into the role of extracellular vesicles in transporting deleterious substances from the heart to the brain during conditions of MI/RI, potentially contributing to impaired cognition. Addressing the cognitive consequence of MI/RI, the review also emphasizes potential neuroprotective interventions and pharmacological treatments within the MI/RI model. In conclusion, the review underscores the significant impact of MI/RI on cognitive function, summarizes potential mechanisms of cardio-cerebral communication in the context of MI/RI, and offers ideas and insights for the prevention and treatment of cognitive dysfunction following MI/RI.

Multivariable model of postoperative delirium in cardiac surgery patients: proteomic and demographic contributions

Background

Delirium following cardiac surgery is common, morbid, and costly, but may be prevented with risk stratification and targeted intervention. Preoperative protein signatures may identify patients at increased risk for worse postoperative outcomes, including delirium. In this study, we aimed to identify plasma protein biomarkers and develop a predictive model for postoperative delirium in older patients undergoing cardiac surgery, while also uncovering possible pathophysiological mechanisms.

Methods

SOMAscan analysis of 1,305 proteins in the plasma from 57 older adults undergoing cardiac surgery requiring cardiopulmonary bypass was conducted to define delirium-specific protein signatures at baseline (PREOP) and postoperative day 2 (POD2). Selected proteins were validated in 115 patients using the ELLA multiplex immunoassay platform. Proteins were combined with clinical and demographic variables to build multivariable models that estimate the risk of postoperative delirium and bring light to the underlying pathophysiology.

Results

A total of 115 and 85 proteins from SOMAscan analyses were found altered in delirious patients at PREOP and POD2, respectively (p<0.05). Using four criteria including associations with surgery, delirium, and biological plausibility, 12 biomarker candidates (Tukey's fold change (|tFC|)>1.4, Benjamini-Hochberg (BH)-p<0.01) were selected for ELLA multiplex validation. Eight proteins were significantly altered at PREOP, and seven proteins at POD2 (p<0.05), in patients who developed postoperative delirium compared to non-delirious patients. Statistical analyses of model fit resulted in the selection of a combination of age, sex, and three proteins (angiopoietin-2 (ANGPT2); C-C motif chemokine 5 (CCL5); and metalloproteinase inhibitor 1 (TIMP1); AUC=0.829) as the best performing predictive model for delirium at PREOP. The delirium-associated proteins identified as biomarker candidates are involved with inflammation, glial dysfunction, vascularization, and hemostasis, highlighting the multifactorial pathophysiology of delirium.

Conclusion

Our study proposes a model of postoperative delirium that includes a combination of older age, female sex, and altered levels of three proteins. Our results support the identification of patients at higher risk of developing postoperative delirium after cardiac surgery and provide insights on the underlying pathophysiology. ClinicalTrials.gov ( NCT02546765 ).

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.