Right Ventricular Function in Acute Respiratory Distress Syndrome: Impact on Outcome, Respiratory Strategy and Use of Veno-Venous Extracorporeal Membrane Oxygenation

Acute respiratory distress syndrome (ARDS) is characterized by protein-rich alveolar edema, reduced lung compliance and severe hypoxemia. Despite some evidence of improvements in mortality over recent decades, ARDS remains a major public health problem with 30% 28-day mortality in recent cohorts. Pulmonary vascular dysfunction is one of the pivot points of the pathophysiology of ARDS, resulting in a certain degree of pulmonary hypertension, higher levels of which are associated with morbidity and mortality. Pulmonary hypertension develops as a result of endothelial dysfunction, pulmonary vascular occlusion, increased vascular tone, extrinsic vessel occlusion, and vascular remodeling. This increase in right ventricular (RV) afterload causes uncoupling between the pulmonary circulation and RV function. Without any contractile reserve, the right ventricle has no adaptive reserve mechanism other than dilatation, which is responsible for left ventricular compression, leading to circulatory failure and worsening of oxygen delivery. This state, also called severe acute cor pulmonale (ACP), is responsible for excess mortality. Strategies designed to protect the pulmonary circulation and the right ventricle in ARDS should be the cornerstones of the care and support of patients with the severest disease, in order to improve prognosis, pending stronger evidence. Acute cor pulmonale is associated with higher driving pressure (≥18 cmH2O), hypercapnia (PaCO2 ≥ 48 mmHg), and hypoxemia (PaO2/FiO2 < 150 mmHg). RV protection should focus on these three preventable factors identified in the last decade. Prone positioning, the setting of positive end-expiratory pressure, and inhaled nitric oxide (INO) can also unload the right ventricle, restore better coupling between the right ventricle and the pulmonary circulation, and correct circulatory failure. When all these strategies are insufficient, extracorporeal membrane oxygenation (ECMO), which improves decarboxylation and oxygenation and enables ultra-protective ventilation by decreasing driving pressure, should be discussed in seeking better control of RV afterload. This review reports the pathophysiology of pulmonary hypertension in ARDS, describes right heart function, and proposes an RV protective approach, ranging from ventilatory settings and prone positioning to INO and selection of patients potentially eligible for veno-venous extracorporeal membrane oxygenation (VV ECMO).

Echocardiographic markers of mortality at 60 days in patients with COVID-19 in the intensive care unit

Introduction Coronavirus disease (COVID)-19 predominantly produces its effects through lung damage, but an important component of multi-organ dysfunction is cardiac involvement. We have few reports that inform about the behavior of echocardiographic images of patients with the most severe forms of the disease. Purpose The present work aims to identify prognostic markers for 60-day mortality in patients hospitalized in intensive care based on echocardiographic findings. Methodology A single-center retrospective cohort was conducted. Hospitalized patients were included in one of the nine intensive care units for COVID-19 confirmed by RT-PCR from May to October 2020. Patients with previous conditions that determined a limitation of the therapeutic effort, those who died before 24 hours and pregnant women were excluded. Portable echocardiograms were performed by two expert cardiologists following the recommendations for isolation and personal protection. The time to death was evaluated as outcome. A Cox proportional hazards model was constructed, HR and 95% confidence intervals with their p values. The study was approved by the institutional ethics committee. Results Of 326 patients included, 153 patients had an echocardiogram. The mean age was 60.7 years, 47 (30.7%) were female and 67 (44.7%) had positive troponin. 91 patients (59.5%) not survive, the mean long of stay was 8.4 (SD: 4.2) days. 111 (72.5%) had shock, 128 (83.7%) severe ARDS (PaO2 / FiO2 <100 mmHg), 142 (92.8%) required invasive ventilatory support, and 86 (56.2%) acute kidney injury. 27 (17.6%) patients had acute pulmonary embolism, 16 (10.4%) acute myocardial infarction and 9 (5.9%) myocarditis. The mean right ventricular ejection fraction was 37%, TAPSE was decreased in 16 cases (10.4%). 41 cases (26.8%) had right diastolic dysfunction. 34/48 (71%) cases had pulmonary hypertension. The average LVEF was 59.3% and 74 (48.4%) had some left ventricular diastolic dysfunction. 12 (7.8%) had left ventricular segmental wall motion abnormality and 16 (10.4%) had pericardial effusion. Univariate analysis identified TAPSE, PSAP, acute cor pulmonale and right ventricular dilatation as variables related to the outcome of mortality. The multivariate Cox model (Table 2) documented that acute cor pulmonale with a HR of 12.8 (95% CI 3.51 - 46.63, p<0.001) and right ventricular dilation with a HR of 4, 87 (95% CI 1.36–17.46, P 0.016) were associated with mortality. Conclusions In patients hospitalized in the intensive care unit for COVID-19, acute cor pulmonale and right ventricular dilatation behaved as independent predictors of in-hospital death. FUNDunding Acknowledgement Type of funding sources: None. Table 1. Baselines characteristics Table 2. Multivariate analisys

Approach to Echocardiography in ARDS Patients in the Prone Position: A Systematic Review

Echocardiography is commonly utilized in patients with acute respiratory distress syndrome (ARDS) for assessment of cardiac function, volume status, and the potential development of acute cor pulmonale. In severe ARDS, prone positioning is frequently used, which imposes technical challenges during transthoracic echocardiography (TTE) image acquisition. Moreover, prone positioning can affect cardiopulmonary function in ways that are reflected on the echocardiographic findings in this position. Historically, a transesophageal approach was recommended when a patient is prone, with few studies reporting utility of TTE in this setting. However, recent publications have begun to address this knowledge gap. This review explores recent literature addressing the use of TTE in prone patients with ARDS, with a special focus on the cardiopulmonary effects of proning and potential solutions to the technical difficulties that arise in this position.