Is postoperative cognitive decline after cardiac surgery associated with plasma beta amyloid 1–42 levels?

Background Postoperative cognitive decline following cardiac surgery is one of the frequently reported complications affecting postoperative outcome, characterized by impairment of memory or concentration. The aetiology is considered multifactorial and the research conducted so far has presented contradictory results. The proposed mechanisms to explain the cognitive decline associated with cardiac surgery include the neurotoxic accumulation of β-amyloid (Aβ) proteins similar to Alzheimer's disease. The comparison of coronary artery bypass grafting procedures concerning postoperative cognitive decline and plasmatic Aβ1-42 concentrations has not yet been conducted. Methods The research was designed as a controlled clinical study of patients with coronary artery disease undergoing surgical myocardial revascularization with or without the use of a cardiopulmonary bypass machine. All patients completed a battery of neuropsychological tests and plasmatic Aβ1-42 concentrations were collected. Results The neuropsychological test results postoperatively were significantly worse in the cardiopulmonary bypass group and the patients had larger shifts in the Aβ1-42 preoperative and postoperative values than the group in which off-pump coronary artery bypass was performed. Conclusions The conducted research confirmed the earlier suspected association of plasmatic Aβ1-42 concentration to postoperative cognitive decline and the results further showed that there were less changes and lower concentrations in the off-pump coronary artery bypass group, which correlated to less neurocognitive decline. There is a lot of clinical contribution acquired by this research, not only in everyday decision making and using amyloid proteins as biomarkers, but also in the development and application of non-pharmacological and pharmacological neuroprotective strategies.

A Comprehensive Review of Cerebral Oximetry in Cardiac Surgery

Background: Patients who undergo cardiac surgery are at increased risk of stroke, postoperative cognitive decline, and delirium. These neurocognitive complications have led to increased costs, intensive care unit stays, morbidity, and mortality. As a result, there is a significant push to mitigate any neurological complications in cardiac surgery patients. Near-infrared spectroscopy to measure regional cerebral oxygen saturations has gained consideration due to its non-invasive, user-friendly, and relatively inexpensive nature. Aim of Study: To provide a comprehensive summary of cerebral oximetry in cardiac surgery. The review interrogates multiple systematic reviews assessing different outcomes in cardiac surgery to assess if cerebral oximetry is effective. Further, the review analyzes all available interventions for an acute desaturation to determine the efficacy of individual interventions. Methods: A narrative review of randomized controlled trials, observational studies, and systematic reviews with metanalyses were performed through August 2021. Results: There is significant heterogeneity amongst studies regarding the definition of a clinically significant cerebral desaturation. In addition, the assessment of neurocognitive outcomes has large variability, making metanalysis challenging. To date, cerebral oximetry use during cardiac surgery has not been associated with improvements in neurocognitive outcomes, morbidity, or mortality. The evidence to support particular interventions for an acute desaturation is equivocal. Conclusions: Future research is needed to quantify a clinically significant cerebral desaturation and to determine which interventions for an acute desaturation effectively improve clinical outcomes.

Role of Dexmedetomidine in Early POCD in Patients Undergoing Thoracic Surgery

Importance. Postoperative cognitive dysfunction (POCD) occurs in 6%–53% of elderly patients receiving major surgery and is related to longer hospital stays, increased hospital costs, and 1-year mortality. An increasing number of studies suggest that using dexmedetomidine (Dex) in critical care units is associated with reduced incidence of delirium. However, perioperative use of Dex for the prevention of POCD has not been well studied. Objective. To evaluate whether a low-dose perioperative infusion of Dex reduces early POCD. Design. This study was a double-blind, randomized, placebo-controlled trial that randomly assigned patients to Dex or saline placebo infused during surgery and patient-controlled intravenous analgesia (PCIA) infusion. Patients were assessed for postoperative cognitive decline. Interventions. Dex was infused at a loading dose of 0.5 μg/kg intravenously (15 min after entering the operation room) followed by a continuous infusion at a rate of 0.5 μg/kg/h until one-lung ventilation or artificial pneumothorax ended. Patients in the Dex group received regular PCIA pump with additional dose of Dex (200 μg). Results. In total, 126 patients were randomized, and 102 patients were involved in the result analysis. The incidence of POCD was 36.54% (19/52) in the Dex group and 32.00% (16/50) in the normal saline (NS) group, with no statistic difference. No significant difference was observed between the two groups in terms of Telephone Interview for Cognitive Status-Modified (TICS-m) scores at different times. However, the TICS-m score at 7 days after surgery was significantly lower than that at 30 days in 102 patients ( 32.93 ± 0.42 vs. 33.92 ± 0.47 , P = 0.03 ). The visual analogue scale scores in the Dex group were significantly lower than those in the NS group 1 day postoperation at rest and activity (2.00 [1.00–3.00] vs. 3.00 [2.00–4.00], P < 0.01 ; 4.00 [3.00–5.00] vs. 5.00 [4.00–6.00], P < 0.05 , respectively). Patients receiving Dex or NS had no statistical difference in activities of daily living (ADLs) scores at 7 and 30 days after surgery, but the ADL score at 30 days after surgery showed a significant reduction compared with that at 7 days ( P < 0.01 ). Patients in the Dex group had a shorter hospital length of stay ( 15.26 ± 3.77 vs. 17.69 ± 5.09 , P = 0.02 ) and less expenses ( 52458.71 ± 10649.30 vs. 57269.03 ± 9269.98 , P = 0.04 ) than those in the NS group. Conclusions. Low-dose Dex in the perioperative period did not reduce the incidence of early POCD in thoracic surgery. However, it relieved postoperative pain, decreased the hospitalization expenses, and shortened the length of stay.

Postoperative Management for the Obese Patient

Obesity results in physiologic changes that effect nearly every organ system, including respiratory, cardiovascular, gastrointestinal, endocrine, genitourinary, and neuropsychiatric. These changes are associated with complications in the postoperative period that the anesthesia provider must take into account when planning the anesthetic of the obese patient. Obesity is associated with obstructive sleep apnea, obesity hypoventilation syndrome, and restrictive-type changes in lung volumes that decrease the obese patient’s ability to compensate for the changes that take place with anesthesia. The anesthetic provider should conduct a thorough preoperative evaluation, ensure complete reversal of neuromuscular blockade prior to extubation to prevent obstruction, ensure adequate pain control without compromising respiratory function, and consider use of Continuous positive airway pressure (CPAP) machines for patients on home CPAP. Obesity is also associated with an increased risk of perioperative arrhythmias, thrombotic events, impaired wound healing, decreased kidney function, and postoperative cognitive decline. Anesthetic providers should make every effort to take steps in order to prevent these complications and be knowledgeable about their management should they occur. This review contains 3 figures, 2 tables, 37 references

Postoperative Management for the Obese Patient

Obesity results in physiologic changes that effect nearly every organ system, including respiratory, cardiovascular, gastrointestinal, endocrine, genitourinary, and neuropsychiatric. These changes are associated with complications in the postoperative period that the anesthesia provider must take into account when planning the anesthetic of the obese patient. Obesity is associated with obstructive sleep apnea, obesity hypoventilation syndrome, and restrictive-type changes in lung volumes that decrease the obese patient’s ability to compensate for the changes that take place with anesthesia. The anesthetic provider should conduct a thorough preoperative evaluation, ensure complete reversal of neuromuscular blockade prior to extubation to prevent obstruction, ensure adequate pain control without compromising respiratory function, and consider use of Continuous positive airway pressure (CPAP) machines for patients on home CPAP. Obesity is also associated with an increased risk of perioperative arrhythmias, thrombotic events, impaired wound healing, decreased kidney function, and postoperative cognitive decline. Anesthetic providers should make every effort to take steps in order to prevent these complications and be knowledgeable about their management should they occur. This review contains 3 figures, 2 tables, 37 references

High-Mobility Group Box-1 and Its Potential Role in Perioperative Neurocognitive Disorders

: Aseptic surgical trauma provokes the release of HMGB1, which engages the innate immune response after binding to pattern-recognition receptors on circulating bone marrow-derived monocytes (BM-DM). The initial systemic inflammation, together with HMGB1, disrupts the blood–brain barrier allowing penetration of CCR2-expressing BM-DMs into the hippocampus, attracted by the chemokine MCP-1 that is upregulated by HMGB1. Within the brain parenchyma quiescent microglia are activated and, together with the translocated BM-DMs, release proinflammatory cytokines that disrupt synaptic plasticity and hence memory formation and retention, resulting in postoperative cognitive decline (PCD). Neutralizing antibodies to HMGB1 prevents the inflammatory response to trauma and PCD.

Develop a Clinical Prediction Model for Postoperative Cognitive Dysfunction after Major Noncardiac Surgery in Elderly Patients: A Protocol for a Prospective Observational Study

Perioperative neurocognitive disorders (PNDs) refer to cognitive decline identified in the preoperative or postoperative period. It has been reported that the incidence of postoperative neurocognitive impairment after noncardiac surgery in patients older than 65 at 1 week was 25.8∼41.4%, and at 3 months 9.9∼12.7%. PNDs will last months or even develop to permanent dementia, leading to prolonged hospital stays, reduced quality of life, and increased mortality within 1 year. Despite the high incidence and poor prognosis of PNDs in the aged population, no effective clinical prediction model has been established to predict postoperative cognitive decline preoperatively. To develop a clinical prediction model for postoperative neurocognitive dysfunction, a prospective observational study (Clinical trial registration number: ChiCTR2000036304) will be performed in the Shanghai General Hospital during January 2021 to October 2022. A sample size of 675 patients aged &#x3e;65 years old, male or female, and scheduled for elective major noncardiac surgery will be recruited. A battery of neuropsychological tests will be used to test the cognitive function of patients at 1 week, 1 month, and 3 months postoperatively. We will evaluate the associations of PNDs with a bunch of candidate predictors including general characteristics of patients, blood biomarkers, indices associated with anesthesia and surgery, retinal nerve-fiber layer thickness, and frailty index to develop the clinical prediction model by using multiple logistic regression analysis and least absolute shrinkage and the selection operator (LASSO) method. The <i>k</i>-fold cross-validation method will be utilized to validate the clinical prediction model. In conclusion, this study was aimed to develop a clinical prediction model for postoperative cognitive dysfunction of old patients. It is anticipated that the knowledge gained from this study will facilitate clinical decision-making for anesthetists and surgeons managing the aged patients undergoing noncardiac surgery.