Contemporary Neuroprotection Strategies during Cardiac Surgery: State of the Art Review

Neuroprotective Strategies in Coronary Artery Disease Interventions

Neuroprotective strategies in coronary artery interventions are essential due to the rising number of high-risk patients undergoing procedures like coronary artery bypass grafting (CABG), totally endoscopic coronary artery bypass (TECAB), and hybrid revascularization. In this review article, we summarize the neurological complications associated with coronary artery disease intervention and the risk mitigation strategies. CABG carries significant risks, including ischemic stroke, encephalopathy, seizures, and peripheral nerve injuries. Risk factors include advanced age, hypertension, diabetes, and atherosclerosis. Off-pump CABG minimizes stroke risk by avoiding aortic manipulation and CPB. TECAB and hybrid revascularization have fewer reported neurological complications but still pose risks of stroke and cranial nerve injuries. Pharmacological neuroprotection includes agents such as barbiturates, volatile anesthetics, lidocaine, NMDA receptor antagonists, magnesium, nimodipine, corticosteroids, and aprotinin. Deep hypothermic circulatory arrest (DHCA) is reserved for complex aortic cases requiring a bloodless surgical field. Intraoperative strategies involve cerebral perfusion monitoring, embolic protection devices, and therapeutic hypothermia. Preoperative optimization targets risk factors, arrhythmia prevention, and antiplatelet therapy management. Postoperatively, timely antiplatelet administration, glucose control, hemodynamic stabilization, and cognitive monitoring are critical. Comprehensive neuroprotective approaches, spanning pre- to postoperative phases, aim to reduce neurological complications and enhance outcomes in coronary interventions.

Effects of Midazolam and Dexmedetomidine on Cognitive Dysfunction Following Open-Heart Surgery: A Comprehensive Review

PURPOSE

Patients undergoing open-heart surgery often face significant challenges in postoperative cognitive dysfunction (POCD). There has been growing interest in understanding how anesthesia medications, such as dexmedetomidine (DEX) and midazolam, impact cognitive function in these patients.

METHOD

This comprehensive review aims to detail the effect of DEX and midazolam on cognitive outcomes following open-heart surgery.

FINDINGS

Midazolam, a highly selective and commonly used benzodiazepine for preoperative anxiolytics and sedation has been associated with POCD. However, evidence regarding its impact on cognitive function is vague; some studies suggest a potential link between midazolam administration and cognitive impairment, while others report no effect or even an improvement in cognitive abilities. DEX is a potential neuroprotective agent in cardiac surgery. The effects of DEX on cognitive function, including a reduction in POCD incidence and severity, have been reported in several studies. It modulates the inflammatory responses, attenuates oxidative stress, and preserves cerebral perfusion. Although DEX and midazolam show promising results, their effects on cognitive function following open-heart surgery are yet to be elucidated.

CONCLUSION

Various factors, including patient characteristics, perioperative management, and surgical procedures, may influence these outcomes, highlighting the need for further research to better understand the roles of these agents in cognitive function following open-heart surgery.

A Comprehensive Review on the Role of Melatonin's Anesthetic Applications in Pediatric Care

Anesthesia is critical to pediatric care, ensuring the safety and comfort of children undergoing medical procedures. With a growing interest in alternative anesthetic agents, melatonin has emerged as a promising candidate due to its sedative, analgesic, anti-inflammatory, and neuroprotective properties. This comprehensive review explores the potential applications of melatonin in pediatric anesthesia. We delve into the pharmacological characteristics of melatonin, its anesthetic properties, and its clinical applications in pediatric care, including preoperative sedation, adjunct to general anesthesia, postoperative pain management, and prevention of emergence delirium. Additionally, we discuss the safety profile of melatonin, potential adverse effects, and comparative analysis with traditional anesthetics. Finally, we highlight future research directions to provide insights into melatonin's role in pediatric anesthesia and its implications for clinical practice.

Potential mechanisms of multimodal prehabilitation effects on surgical complications: a narrative review

Continuous advances in prehabilitation research over the past several decades have clarified its role in improving preoperative risk factors, yet the evidence demonstrating reduced surgical complications remains uncertain. Describing the potential mechanisms underlying prehabilitation and surgical complications represents an important opportunity to establish biological plausibility, develop targeted therapies, generate hypotheses for future research, and contribute to the rationale for implementation into the standard of care. In this narrative review, we discuss and synthesize the current evidence base for the biological plausibility of multimodal prehabilitation to reduce surgical complications. The goal of this review is to improve prehabilitation interventions and measurement by outlining biologically plausible mechanisms of benefit and generating hypotheses for future research. This is accomplished by synthesizing the available evidence for the mechanistic benefit of exercise, nutrition, and psychological interventions for reducing the incidence and severity of surgical complications reported by the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). This review was conducted and reported in accordance with a quality assessment scale for narrative reviews. Findings indicate that prehabilitation has biological plausibility to reduce all complications outlined by NSQIP. Mechanisms for prehabilitation to reduce surgical complications include anti-inflammation, enhanced innate immunity, and attenuation of sympathovagal imbalance. Mechanisms vary depending on the intervention protocol and baseline characteristics of the sample. This review highlights the need for more research in this space while proposing potential mechanisms to be included in future investigations.

Cerebrovascular events after cardiovascular surgery: diagnosis, management and prevention strategies

Introduction

Cerebrovascular events after cardiac surgery are among the most serious complications, related to a greater risk of patient mortality. This problem can occur following the formation of gas emboli during open heart surgery.

Aim

To address all the mechanisms that can lead to embolic events after cardiovascular surgery, how to manage them and how to possibly prevent them.

Material and methods

A search of the PubMed database was conducted. We reviewed the clinical literature and examined all aspects to identify the root causes that can lead to the formation of emboli.

Results

Among the studies reviewed, it was found that the main causes include manipulation of the aorta, inadequate deaeration after cardiac surgery, and blood-component contact of extracorporeal circulation. It has been reported that gas emboli can lead to deleterious damage such as damage to the cerebral vascular endothelium, disruption of the blood-brain barrier, complement activation, leukocyte aggregation, increased platelet adhesion, and fibrin deposition in the microvascular system.

Conclusions

Stroke after cardiovascular surgery is one of the most important complications, with a great impact on operative mortality and patient survival. Efforts have been made over time to understand all the pathophysiological mechanisms related to this complication, with the aim of reducing its incidence. One of the goals should be to improve both the surgical technique and the perfusion modality and minimize the formation of air bubbles or to facilitate their elimination during the cardiopulmonary bypass procedure.

Cerebral Perfusion and Neuromonitoring during Complex Aortic Arch Surgery: A Narrative Review

Complex ascending and aortic arch surgery requires the implementation of different cerebral protection strategies to avoid or limit the probability of intraoperative brain damage during circulatory arrest. The etiology of the damage is multifactorial, involving cerebral embolism, hypoperfusion, hypoxia and inflammatory response. These protective strategies include the use of deep or moderate hypothermia to reduce the cerebral oxygen consumption, allowing the toleration of a variable period of absence of cerebral blood flow, and the use of different cerebral perfusion techniques, both anterograde and retrograde, on top of hypothermia, to avoid any period of intraoperative brain ischemia. In this narrative review, the pathophysiology of cerebral damage during aortic surgery is described. The different options for brain protection, including hypothermia, anterograde or retrograde cerebral perfusion, are also analyzed, with a critical review of the advantages and limitations under a technical point of view. Finally, the current systems of intraoperative brain monitoring are also discussed.

Simple open-heart surgery protocol for sickle-cell disease patients: a retrospective cohort study comparing patients undergoing mitral valve surgery

OBJECTIVES

Sickle-cell disease (SCD) patients are considered to be at high risk from open-heart surgery. This study assessed the role of a simple sickling-prevention protocol.

METHODS

Perioperative non-specific and SCD-specific morbidity and 30-day mortality are investigated in a retrospective cohort study on patients undergoing isolated mitral valve surgery. Patients with and without SCD were compared. In the SCD cohort, a bundle of interventions was applied to limit the risk of sickling: 'on-demand' transfusions to keep haemoglobin levels of around 7-8 g/dl, cardiopulmonary bypass (CPB) with higher blood flow and perfusion temperature, close monitoring of acid-base balance and oxygenation.

RESULTS

Twenty patients with and 40 patients without SCD were included. At baseline, only preoperative haemoglobin levels differed between cohorts (8.1 vs 11.8 g/dl, P < 0.001). Solely SCD patients received preoperative transfusions (45.0%). Intraoperative transfusions were significantly larger in SCD patients during CPB (priming: 300 vs 200 ml; entire length: 600 vs 300 ml and 20 vs 10 ml/kg). SCD patients had higher perfusion temperatures during CPB (34.7 vs 33.0°C, P = 0.01) with consequently higher pharyngeal temperature, both during cooling (34.1 vs 32.3°C, P = 0.02) and rewarming (36.5 vs 36.2°C, P = 0.02). No mortality occurred, and non-SCD-specific complications were comparable between groups, but one SCD patient suffered from perioperative cerebrovascular accident with seizures, and another had evident haemolysis.

CONCLUSIONS

SCD patients may undergo open-heart surgery for mitral valve procedures with an acceptable risk profile. Simple but thoughtful perioperative management, embracing 'on-demand' transfusions and less-aggressive CPB cooling is feasible and probably efficacious.