Ortoleva, Jamel P.

Abstract: Extracorporeal membrane oxygenation (ECMO) is increasingly used to support patients with severe cardiac or respiratory failure. Neurological complications occur across ECMO configurations and represent a major contributor to mortality and long-term disability. Major neurological complications include ischemic and hemorrhagic stroke, hypoxic ischemic brain injury, seizures, delirium, spinal cord and peripheral nervous system injury, and brain death. The mechanisms underlying neurological injury during ECMO are multifactorial and are influenced by ECMO configuration, reflecting differences in cerebral perfusion, gas exchange, anticoagulation exposure, and precannulation physiologic insults. This review synthesizes neurological complications associated with ECMO, neurological monitoring, and outcomes.

Cardiogenic shock in adults continues to carry a high mortality despite advances in cardiac care, interventions and critical care. A major advancement in cardiogenic shock care came with the advent of temporary mechanical circulatory support including the intra-aortic balloon pump, ventricular assist devices, and venoarterial extracorporeal membrane oxygenation (VA ECMO). VA ECMO is a type of temporary mechanical circulatory support used in selected patients with cardiogenic shock that have failed to be adequately supported by less invasive approaches including vasoactive medications, volume optimization, and other temporary mechanical circulatory support. VA ECMO is resource intensive support strategy that requires expertise and cooperation from multiple specialties. Complications during VA ECMO support are common and include bleeding, acute kidney injury, stroke, mechanical complications during cannulation, hemolysis, and limb ischemia. VA ECMO circuits drain blood from the venous system, oxygenate and remove carbon dioxide, and return it to the arterial system, providing biventricular support. VA ECMO may be deployed peripherally (through femoral or internal jugular veins and returning blood to axillary or femoral arteries), or centrally from the right atrium to the aorta. Vascular access used for peripheral VA ECMO is large and includes arterial cannulas (usually 15 to 19 French), venous cannulas (usually 21 to 25 French), and a distal perfusion catheter (5 to 8 French). VA ECMO causes significant physiologic changes including reduced pulmonary blood flow, an inflammatory response, increases in left ventricular afterload, dual circulation when initiated through most peripheral sites, and coagulopathy. Management considerations for patients supported by VA ECMO are complex for multiple reasons including the differing approaches to the underlying cause of cardiogenic shock (for example, ischemic vs. non ischemic etiologies), patient comorbidities, whether the goal is recovery, heart transplant, or dischargeable ventricular assist device. Weaning from VA ECMO is a complex process with multiple possible approaches, and decannulation is most commonly accomplished through surgical or percutaneous approaches. There is a paucity of literature on VA ECMO and most guidance is based on retrospective data and expert opinion. What follows is an overview of VA ECMO for cardiogenic shock.

OBJECTIVES: Vasoplegia is a common complication of cardiac surgery that uses cardiopulmonary bypass and contributes to morbidity and mortality, yet a consensus definition does not exist. The objective of this study was to evaluate the diagnostic criteria and definitions used to characterize vasoplegia and how different criteria influence incidence estimates. DATA SOURCES: Ovid Embase, Ovid MEDLINE, Scopus, Web of Science Core Collection, ClinicalTrials.gov, Ovid Cochrane Central Register of Controlled Trials, and the World Health Organization’s International Clinical Trials Registry Platform clinical trials registry. STUDY SELECTION: Randomized clinical trials and observational studies reporting on vasoplegia in adults undergoing any type of cardiac surgery that used cardiopulmonary bypass. DATA EXTRACTION: Proportional meta-analysis using a random-effects model and the inverse variance method was used to calculate the pooled incidence of vasoplegia and its clinical outcomes. DATA SYNTHESIS: A total of 68 studies encompassing 56,580 patients were identified, from which 63 unique vasoplegia definitions were used. Blood pressure ( n = 57 studies, 84%) and cardiac output ( n = 50 studies, 74%) were among the most common criteria used in vasoplegia definitions; however, there was a vast variety of threshold values applied within these criteria and all other criteria comprising the definitions. The pooled incidence of vasoplegia was 21% (95% CI, 17–25%), acute kidney injury was 32% (95% CI, 21–45%), and mortality was 12% (95% CI, 9–16%). Subgroup analysis revealed that transplantation and left ventricular assist device implantation surgeries, and those with baseline left ventricular ejection fraction less than 40% had a significantly greater incidence of vasoplegia. CONCLUSIONS: The published literature varies greatly in the criteria used to define vasoplegia associated with on-pump cardiac surgery. Generation and adoption of a unified definition for vasoplegia must be an international priority.

Empirical evidence suggests direct thrombin inhibitors (DTIs) produce more favorable hemostatic outcomes than heparin in patients supported by extracorporeal membrane oxygenation (ECMO), yet the exact mechanisms responsible are unknown. We systematically searched databases and registers for studies comparing DTIs to heparin in humans receiving ECMO. A total of 28 studies were identified, most of which (n = 25) used bivalirudin, while the rest (n = 3) used argatroban. In random-effects meta-analysis, DTIs achieved the therapeutic anticoagulation range faster (mean difference = −6.96 hours, 95% confidence interval [CI] = −11.98 to −1.95, p = 0.006) and maintained the therapeutic range for a greater proportion of time (mean difference = 18.6%, 95% CI = 8.78–28.42, p < 0.001) than heparin. Subgroup analysis revealed these effects were similarly significant in adult patients and when bivalirudin was the DTI; however, they were not significant in pediatric patients or when argatroban was the DTI. Sensitivity analysis confirmed robustness of the primary findings in only low-risk of bias studies and in only studies published as full papers. In summary, DTIs—specifically bivalirudin—were associated with faster time to therapeutic anticoagulation and maintained the goal range for a greater percentage of time than heparin during ECMO support.