Pulmonary vascular dysfunction in refractory acute respiratory distress syndrome before veno-venous extracorporeal membrane oxygenation

Association of pulmonary arterial pressure with volume status in patients with acute respiratory distress syndrome receiving extracorporeal membrane oxygenation

Background

Data on pulmonary hemodynamic parameters in patients with acute respiratory distress syndrome (ARDS) receiving extracorporeal membrane oxygenation (ECMO) are scarce.

Methods

The associations between pulmonary artery catheter parameters for the first 7 days of ECMO, fluid balance, and hospital mortality were investigated in adult patients (aged ≥19 years) who received venovenous ECMO for refractory ARDS between 2015 and 2017.

Results

Twenty patients were finally included in the analysis (median age, 56.0 years; interquartile range, 45.5-68.0; female, n=10). A total of 140 values were collected for each parameter (i.e., 7 days×20 patients). Net fluid balance was weakly but significantly correlated with systolic and diastolic pulmonary arterial pressures (PAPs; r=0.233 and P<0.001; r=0.376 and P<0.001, respectively). Among the mechanical ventilation parameters, above positive end-expiratory pressure was correlated with systolic PAP (r=0.191 and P=0.025), and static compliance was negatively correlated with diastolic PAP (r=-0.169 and P=0.048). Non-survivors had significantly higher systolic PAPs than in survivors. However, in multivariate analysis, there was no significant association between mean systolic PAP and hospital mortality (odds ratio, 1.500; 95% confidence interval, 0.937-2.404; P=0.091).

Conclusion

Systolic PAP was weakly but significantly correlated with net fluid balance during the early ECMO period in patients with refractory ARDS receiving ECMO.

Combined lung and cardiac ultrasound in COVID-related acute respiratory distress syndrome

BACKGROUND

Lung ultrasound (LU) is a useful tool for monitoring lung involvement in novel coronavirus (COVID) disease, while information on echocardiographic findings in COVID disease is to date scarce and heterogeneous. We hypothesized that lung and cardiac ultrasound examinations, serially and simultaneously performed, could monitor disease severity in COVID-related ARDS.

METHODS

We enrolled 47 consecutive patients with COVID-related ARDS (1st March-31st May 2020). Lung and cardiac ultrasounds were performed on admission, at discharged and when clinically needed.

RESULTS

Most patients were mechanically ventilated (75%) and veno-venous extracorporeal membrane oxygenation was needed in ten patients (21.2%). The in-ICU mortality rate was 27%%. On admission, not survivors showed a higher LUS score (p = 0.006) and a higher incidence of consolidations (p = 0.003), lower values of LVEF (p = 0.027) and a higher RV/LV ratio (0.008). At discharge, a significant reduction in the incidence of subpleural consolidations (p < 0.001) and, thus, in LUS score (p < 0.001) and an increase in patter A findings (p < 0.001) together with reduced systolic pulmonary arterial pressures were detectable. In not survivors at final examination, an increased in LUS score (p < 0.001), and in RV/LV ratio (p < 0.001) associated with a reduction in TAPSE (p = 0.013) were observed. A significant correlation was observed between LUS and systolic pulmonary arterial pressure (p = 0.04). LUS and RV/LV resulted independent predictors of in-ICU death.

CONCLUSIONS

In COVID-related ARDS, the combined lung and cardiac ultrasound proved to be an useful clinical tool in monitoring disease progression and in identifying parameters (LU score and RV/LV ratio) able to risk stratifying these patients.

Assessment of Right Ventricular Function With CT and Echocardiography in Patients With Severe Acute Respiratory Distress Syndrome on Extracorporeal Membrane Oxygenation

Supplemental Digital Content is available in the text.

Changes in right ventricular size and function are frequently observed in patients with severe acute respiratory distress syndrome. The majority of patients who receive venovenous extracorporeal membrane oxygenation undergo chest CT and transthoracic echocardiography. The aims of this study were to compare the use of CT and transthoracic echocardiography to evaluate the right ventricular function and to determine the prevalence of acute cor pulmonale in this patient population.

Cardiac Involvment in COVID-19-Related Acute Respiratory Distress Syndrome

The cardiac involvement in Coronavirus disease (COVID-19) is still under evaluation, especially in severe COVID-19-related Acute Respiratory Distress Syndrome (ARDS). The cardiac involvement was assessed by serial troponin levels and echocardiograms in 28 consecutive patients with COVID-19 ARDS consecutively admitted to our Intensive Care Unit from March 1 to March 31. Twenty-eight COVID-19 patients (aged 61.7 ± 10 years, males 79%). The majority was mechanically ventilated (86%) and 4 patients (14%) required veno-venous extracorporeal membrane oxygenation. As of March 31, the Intensive Care Unit mortality rate was 7%, whereas 7 patients were discharged (25%) with a length of stay of 8.2 ±5 days. At echocardiographic assessment on admission, acute core pulmonale was detected in 2 patients who required extracorporeal membrane oxygenation support. Increased systolic arterial pressure was detected in all patients. Increased Troponin T levels were detectable in 11 patients (39%) on admission. At linear regression analysis, troponin T showed a direct relationship with C-reactive Protein (R square: 0.082, F: 5.95, p = 0.017). In conclusions, in COVID-19-related ARDS, increased in Tn levels was common but not associated with alterations in wall motion kinesis, thus suggesting that troponin T elevation is likely to be multifactorial, mainly linked to disease severely (as inferred by the relation between Tn and C-reactive Protein). The increase in systolic pulmonary arterial pressures observed in all patients may be related to hypoxic vasoconstriction. Further studies are needed to confirm our findings in larger cohorts.

Right Ventricular Hypertrophy in Refractory Acute Respiratory Distress Syndrome Treated With Venovenous Extracorporeal Membrane Oxygenation Support

OBJECTIVE

In severe acute respiratory distress syndrome (ARDS) treated with extracorporeal membrane oxygenation (ECMO), right ventricular (RV failure) and dilation have been investigated with the use of echocardiography, whereas RV hypertrophy has not been addressed in the literature. The present study assessed the incidence of RV hypertrophy using echocardiography before ECMO treatment and at intensive care unit (ICU) discharge in severe ARDS patients.

DESIGN

Observational, retrospective, single-center study.

SETTING

A single ECMO center.

PARTICIPANTS

The study comprised 46 consecutive patients with severe ARDS.

INTERVENTION

Echocardiographic evaluation and ECMO support.

MEASUREMENTS AND MAIN RESULTS

A dual-lumen cannula was implanted in most patients (38/46 [82.6%]). Before the start of ECMO, RV hypertrophy was present in 28 patients (60.8%) with no significant differences in baseline characteristics between the 2 subgroups. The ICU mortality rate was 30.4% (14/46), with no difference between patients with RV hypertrophy and those without. At ICU discharge, all patients showed RV hypertrophy.

CONCLUSIONS

In severe ARDS treated with ECMO support, RV hypertrophy is a common finding and patients with normal RV wall thickness developed RV hypertrophy after ECMO support. The latter finding may suggest that during ECMO support, the right ventricle still may be subjected to increased afterload. However, additional research should be performed to elucidate the spectrum of mechanism(s) involved in the genesis of RV hypertrophy.

The use of echocardiographic indices in defining and assessing right ventricular systolic function in critical care research

PURPOSE

Many echocardiographic indices (or methods) for assessing right ventricular (RV) function are available, but each has its strengths and limitations. In some cases, there might be discordance between the indices. We conducted a systematic review to audit the echocardiographic RV assessments in critical care research to see if a consistent pattern existed. We specifically looked into the kind and number of RV indices used, and how RV dysfunction was defined in each study.

METHODS

Studies conducted in critical care settings and reported echocardiographic RV function indices from 1997 to 2017 were searched systematically from three databases. Non-adult studies, case reports, reviews and secondary studies were excluded. These studies' characteristics and RV indices reported were summarized.

RESULTS

Out of 495 non-duplicated publications found, 81 studies were included in our systematic review. There has been an increasing trend of studying RV function by echocardiography since 2001, and most were conducted in ICU. Thirty-one studies use a single index, mostly TAPSE, to define RV dysfunction; 33 used composite indices and the combinations varied between studies. Seventeen studies did not define RV dysfunction. For those using composite indices, many did not explain their choices.

CONCLUSIONS

TAPSE seemed to be the most popular index in the last 2-3 years. Many studies used combinations of indices but, apart from cor pulmonale, we could not find a consistent pattern of RV assessment and definition of RV dysfunction amongst these studies.

A novel risk score for severe ARDS patients undergoing ECMO after retrieval from peripheral hospitals

BACKGROUND

Extracorporeal Membrane Oxygenation in severe ARDS unresponsive to conventional protective ventilation is associated with elevated costs, resource and complications, and appropriate risk stratification of candidate patients could be useful to recognize those more likely to benefit from ECMO. We aimed to derive a new outcome prediction score for patients retrieved by our ECMO team from peripheral centers, including systematic echocardiographic evaluation before ECMO start.

METHODS

Sixty-nine consecutive patients with refractory ARDS requiring ECMO transferred from peripheral centers to our ICU (a tertiary ECMO referral center), from 1 October 2009 to 31 December 2015, were assessed.

RESULTS

All patients were transported on ECMO (distance, median 77, range 4-456 km) The mortality rate was 41% (28/69). Our new risk score included age ≥ 42 years, BMI < 31 kg/m² , RV dilatation, and pH < 7.35. The proposed cut off (Youden's index method) of nine had a sensitivity of 96% and a specificity of 30% (AUC-ROC: 0.85, 95% CI: 0.76-0.94, P < 0.001). When assessing the discriminatory ability of our risk score in the population of local patients, survivors had a mean value of 15.4 ± 8.6, whereas non-survivors showed a mean value of 20.1 ± 7.4 (P < 0.001).

CONCLUSIONS

Our new risk score shows good discriminatory ability both in patients retrieved from peripheral centers and in those implanted at our center. This score includes variables easily available at bedside, and, for the first time, a pathophysiologic element, RV dilatation.

Incidence Proportion of Acute Cor Pulmonale in Patients with Acute Respiratory Distress Syndrome Subjected to Lung Protective Ventilation: A Systematic Review and Meta-analysis

INTRODUCTION

Reported incidence of acute cor pulmonale (ACP) in patients with acute respiratory distress syndrome (ARDS) varies from 10% to 84%, despite being subjected to lung protective ventilation according to the current guidelines. The objective of this review is to find pooled cumulative incidence of ACP in patients with ARDS undergoing lung protective ventilation.

MATERIALS AND METHODS

We searched MEDLINE, EMBASE, Cochrane Library, KoreaMed, LILACS, and WHO Clinical Trial Registry. Cross-sectional or cohort studies were included if they reported or provided data that could be used to calculate the incidence proportion of ACP. Inverse variance heterogeneity (IVhet) and random effect model were used for the main outcome and measures.

RESULTS

We included 16 studies encompassing 1661 patients. The cumulative incidence of ACP using IVhet analysis was 23% (95% confidence interval [CI] = 18%-28%) over 3 days of lung protective ventilation. Random effect analysis of 7 studies (1250 patients) revealed pooled odd ratio of mortality of 1.16 (95% CI = 0.80-1.67, P = 0.44) due to ACP.

CONCLUSION

Patients with ARDS have a 23% risk of developing ACP with lung protective ventilation. Findings of this review indicate the need of updating existing guidelines for ventilating ARDS patients to incorporate right ventricle protective strategy.

The Right Ventricle in ARDS

ARDS is associated with poor clinical outcomes, with a pooled mortality rate of approximately 40% despite best standards of care. Current therapeutic strategies are based on improving oxygenation and pulmonary compliance while minimizing ventilator-induced lung injury. It has been demonstrated that relative hypoxemia can be well tolerated, and improvements in oxygenation do not necessarily translate into survival benefit. Cardiac failure, in particular right ventricular dysfunction (RVD), is commonly encountered in moderate to severe ARDS and is reported to be one of the major determinants of mortality. The prevalence rate of echocardiographically evident RVD in ARDS varies across studies, ranging from 22% to 50%. Although there is no definitive causal relationship between RVD and mortality, severe RVD is associated with increased mortality. Factors that can adversely affect RV function include hypoxic pulmonary vasoconstriction, hypercapnia, and invasive ventilation with high driving pressure. It might be expected that early diagnosis of RVD would be of benefit; however, echocardiographic markers (qualitative and quantitative) used to prospectively evaluate the right ventricle in ARDS have not been tested in adequately powered studies. In this review, we examine the prognostic implications and pathophysiology of RVD in ARDS and discuss available diagnostic modalities and treatment options. We aim to identify gaps in knowledge and directions for future research that could potentially improve clinical outcomes in this patient population.