Cardiovascular Subphenotypes in Acute Respiratory Distress Syndrome

New Right Ventricular Dysfunction in Pediatric Acute Respiratory Distress Syndrome on Venovenous Extracorporeal Membrane Oxygenation

The development of new right ventricular (RV) dysfunction after cannulation to venovenous (VV) extracorporeal membrane oxygenation (ECMO) and its association with worse outcomes is increasingly recognized in adult patients, however, no studies have evaluated this phenomenon in pediatric patients. We report results of a single-center retrospective cohort study at a large academic children's hospital. New RV systolic dysfunction was present in 48% (12/25) of pediatric patients on VV ECMO for acute respiratory distress syndrome (ARDS). There was no statistically significant difference in survival, duration of mechanical ventilation, or hospital length of stay between those with and without RV dysfunction. Over half (5/9, 56%) of survivors with RV dysfunction on ECMO had RV dilation or RV hypertrophy on post-ECMO echocardiograms, and in two patients the RV dysfunction persisted for months following decannulation. Cardiac catheterization and autopsy reports suggested that echocardiographic assessment of RV systolic function alone may not be sufficient to diagnose clinically relevant RV injury. This is the first study to report the prevalence of RV dysfunction on VV ECMO for pediatric ARDS. Future multicenter collaboration is needed to create a clinically relevant definition of pediatric "RV injury" and to further evaluate risk factors and outcomes of RV dysfunction.

Heart-lung crosstalk in acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) is initiated by a primary insult that triggers a cascade of pathological events, including damage to lung epithelial and endothelial cells, extracellular matrix disruption, activation of immune cells, and the release of pro-inflammatory mediators. These events lead to increased alveolar-capillary barrier permeability, resulting in interstitial/alveolar edema, collapse, and subsequent hypoxia and hypercapnia. ARDS not only affects the lungs but also significantly impacts the cardiovascular system. We conducted a comprehensive literature review on heart-lung crosstalk in ARDS, focusing on the pathophysiology, effects of mechanical ventilation, hypoxemia, and hypercapnia on cardiac function, as well as ARDS secondary to cardiac arrest and cardiac surgery. Mechanical ventilation, essential for ARDS management, can increase intrathoracic pressure, decrease venous return and right ventricle preload. Moreover, acidemia and elevations in transpulmonary pressures with mechanical ventilation both increase pulmonary vascular resistance and right ventricle afterload. Cardiac dysfunction can exacerbate pulmonary edema and impair gas exchange, creating a vicious cycle, which hinders both heart and lung therapy. In conclusion, understanding the heart-lung crosstalk in ARDS is important to optimize therapeutic strategies. Future research should focus on elucidating the precise mechanisms underlying this interplay and developing targeted interventions that address both organs simultaneously.

Predictors and outcomes associated with right ventricular function in patients with acute respiratory distress syndrome treated with Veno-venous extracorporeal membrane oxygenation

INTRODUCTION

Right ventricular dysfunction is associated with mortality in patients with acute respiratory distress syndrome (ARDS) but information in veno-venous extracorporeal membrane oxygenation (ECMO) settings is limited. Study objectives were to examine factors associated with right ventricular (RV) systolic dysfunction (RVSD) and RV dilation in ECMO patients with ARDS, to compare outcomes in those with and without RVSD and RV dilation defined by qualitative and quantitative parameters, and to describe RVSD evolution during ECMO.

METHODS

Retrospective observational study of adult ARDS patients supported with ECMO at a tertiary care hospital.

RESULTS

Of a total of 62 patients, 56% had RVSD and 61% had RV dilation by qualitative assessment. Male gender, COVID-19, hypercarbia, and pneumothorax were associated with RVSD and RV dilation. In-hospital mortality was significantly higher in patients with RV dilation vs. no dilation (42% vs. 17%, p = .05) but comparisons for patients with and without RVSD (37% vs. 26%, respectively) did not reach statistical significance. Findings were similar when RV size and function were quantified by right to left ventricle end-diastolic area ratio and fractional area change (39% vs. 21% and 36% vs. 20% respectively; p = NS). Of 39 patients with multiple echocardiograms, 9 of 18 with initially normal RV function developed RVSD while RV function normalized in 10 of 21 patients who began ECMO with RVSD.

CONCLUSIONS

Study results suggest an association of RV dilation and RVSD with worse outcomes and a dynamic nature of RV function necessitating close monitoring during the ECMO course.

Surviving Sepsis Campaign Research Priorities 2023

OBJECTIVES

To identify research priorities in the management, epidemiology, outcome, and pathophysiology of sepsis and septic shock.

DESIGN

Shortly after publication of the most recent Surviving Sepsis Campaign Guidelines, the Surviving Sepsis Research Committee, a multiprofessional group of 16 international experts representing the European Society of Intensive Care Medicine and the Society of Critical Care Medicine, convened virtually and iteratively developed the article and recommendations, which represents an update from the 2018 Surviving Sepsis Campaign Research Priorities.

METHODS

Each task force member submitted five research questions on any sepsis-related subject. Committee members then independently ranked their top three priorities from the list generated. The highest rated clinical and basic science questions were developed into the current article.

RESULTS

A total of 81 questions were submitted. After merging similar questions, there were 34 clinical and ten basic science research questions submitted for voting. The five top clinical priorities were as follows: 1) what is the best strategy for screening and identification of patients with sepsis, and can predictive modeling assist in real-time recognition of sepsis? 2) what causes organ injury and dysfunction in sepsis, how should it be defined, and how can it be detected? 3) how should fluid resuscitation be individualized initially and beyond? 4) what is the best vasopressor approach for treating the different phases of septic shock? and 5) can a personalized/precision medicine approach identify optimal therapies to improve patient outcomes? The five top basic science priorities were as follows: 1) How can we improve animal models so that they more closely resemble sepsis in humans? 2) What outcome variables maximize correlations between human sepsis and animal models and are therefore most appropriate to use in both? 3) How does sepsis affect the brain, and how do sepsis-induced brain alterations contribute to organ dysfunction? How does sepsis affect interactions between neural, endocrine, and immune systems? 4) How does the microbiome affect sepsis pathobiology? 5) How do genetics and epigenetics influence the development of sepsis, the course of sepsis and the response to treatments for sepsis?

CONCLUSIONS

Knowledge advances in multiple clinical domains have been incorporated in progressive iterations of the Surviving Sepsis Campaign guidelines, allowing for evidence-based recommendations for short- and long-term management of sepsis. However, the strength of existing evidence is modest with significant knowledge gaps and mortality from sepsis remains high. The priorities identified represent a roadmap for research in sepsis and septic shock.

Redefining ARDS: a paradigm shift

Although the defining elements of "acute respiratory distress syndrome" (ARDS) have been known for over a century, the syndrome was first described in 1967. Since then, despite several revisions of its conceptual definition, it remains a matter of debate whether ARDS is a discrete nosological entity. After almost 60 years, it is appropriate to examine how critical care has modeled this fascinating syndrome and affected patient's outcome. Given that the diagnostic criteria of ARDS (e.g., increased pulmonary vascular permeability and diffuse alveolar damage) are difficult to ascertain in clinical practice, we believe that a step forward would be to standardize the assessment of pulmonary and extrapulmonary involvement in ARDS to ensure that each patient can receive the most appropriate and effective treatment. The selection of treatments based on arbitrary ranges of PaO2/FiO2 lacks sufficient sensitivity to individualize patient care.

Acute Respiratory Distress Syndrome in Patients with Cardiovascular Disease

Heart and lung interaction within the thoracic cavity is well known during inhalation and exhalation, both spontaneously and during mechanical ventilation. Disease and dysfunction of one organ affect the function of the other. A review of the cause-and-effect relationship between cardiovascular disease and acute respiratory distress syndrome (ARDS) is of significance, as the disease burden of both conditions has both a national and global impact on health care. This literature review examines the relationship between cardiovascular disease and ARDS over the past 25 years.

Cardiovascular Subphenotypes in ARDS: Diagnostic and Therapeutic Implications and Overlap with Other ARDS Subphenotypes

Acute respiratory distress syndrome (ARDS) is a highly heterogeneous clinical condition. Shock is a poor prognostic sign in ARDS, and heterogeneity in its pathophysiology may be a barrier to its effective treatment. Although right ventricular dysfunction is commonly implicated, there is no consensus definition for its diagnosis, and left ventricular function is neglected. There is a need to identify the homogenous subgroups within ARDS, that have a similar pathobiology, which can then be treated with targeted therapies. Haemodynamic clustering analyses in patients with ARDS have identified two subphenotypes of increasingly severe right ventricular injury, and a further subphenotype of hyperdynamic left ventricular function. In this review, we discuss how phenotyping the cardiovascular system in ARDS may align with haemodynamic pathophysiology, can aid in optimally defining right ventricular dysfunction and can identify tailored therapeutic targets for shock in ARDS. Additionally, clustering analyses of inflammatory, clinical and radiographic data describe other subphenotypes in ARDS. We detail the potential overlap between these and the cardiovascular phenotypes.