The Right Ventricle in ARDS

Immune mediators in heart-lung communication

It is often the case that serious, end-stage manifestations of disease result from secondary complications in organs distinct from the initial site of injury or infection. This is particularly true of diseases of the heart-lung axis, given the tight anatomical connections of the two organs within a common cavity in which they collectively orchestrate the two major, intertwined circulatory pathways. Immune cells and the soluble mediators they secrete serve as effective, and targetable, messengers of signals between different regions of the body but can also contribute to the spread of pathology. In this review, we discuss the immunological basis of interorgan communication between the heart and lung in various common diseases, and in the context of organ crosstalk more generally. Gaining a greater understanding of how the heart and lung communicate in health and disease, and viewing disease progression generally from a more holistic, whole-body viewpoint have the potential to inform new diagnostic approaches and strategies for better prevention and treatment of comorbidities.

Do we have our FACTTs straight about cor pulmonale in acute respiratory distress syndrome?

AIMS

The incidence of cor pulmonale in acute respiratory distress syndrome is roughly 20-25% and is associated with nearly 50% increase in mortality risk. Our primary aim was to quantify the association of traditional cor pulmonale risk factors {pH, PaO2:FiO2 ratio, PaCO2, and driving pressure [plateau pressure minus the positive end-expiratory pressure (PEEP)]} and PEEP with the mentioned cor pulmonale parameters.

METHODS AND RESULTS

Using data from the FACTT trial, we examined four cor pulmonale parameters. In addition to pulmonary arterial compliance (Cpa) and pulmonary vascular resistance index (PVRi), we assessed pulmonary artery pulsatility index (PAPi) and effective arterial elastance (Ea) of the pulmonary circulation. Median [interquartile range (IQR)] Cpa on study day 1 was 4.28 mL/mmHg (3.14, 6.08). Increasing pH and P:F were associated with an increase in Cpa. Median (IQR) Ea on Day 1 was 0.48 mmHg/mL (0.36, 0.66). Increase of pH, PaCO2, and P:F were associated with a decrease in Ea, while an increase in PEEP was associated with an increase in Ea. Median (IQR) PAPi on Day 1 was 1.58 (1.13, 2.38). Increase in pH was associated with an increase in PAPi, while increase in PEEP was associated with a decrease in PAPi. Median (IQR) PVRi on Day 1 was 3.86 WU*m2 (2.45, 4.79). Increases in PaCO2 and P:F were associated with a decrease in PVRi, while increasing driving pressure and PEEP were associated with an increase in PVRi.

CONCLUSION

While the FACTT data demonstrate neither a clear nor a consistent relationship between right ventricular-pulmonary arterial function and traditional risk factors, this does not indicate their unimportance.

Echocardiographic Findings in Critically Ill COVID-19 Patients Treated With and Without Extracorporeal Membrane Oxygenation

OBJECTIVES

To describe echocardiographic findings among mechanically ventilated patients with COVID-19 acute respiratory distress syndrome, comparing those with and without venovenous extracorporeal membrane oxygenation (VV ECMO) support.

DESIGN

Single-center, retrospective cohort study.

SETTING

Intensive care unit (ICU) of a quaternary academic center.

PARTICIPANTS

Patients with COVID-19 admitted between March 2020 and June 2021 receiving mechanical ventilation, with an echocardiogram within 72 hours of admission.

INTERVENTIONS

Admission and follow-up echocardiograms during ICU stay.

MEASUREMENTS

Patient characteristics and echocardiographic findings were analyzed. Mortality odds ratio (OR) for right ventricular (RV) systolic dysfunction and acute cor pulmonale (ACP) was calculated.

MAIN RESULTS

Among 242 patients, 145 (60%) received VV ECMO. Median (IQR) PaO2/FiO2 was 76 (65-95) and 98 (85-140) in ECMO and non-ECMO patients, respectively (p ≤ 0.001). Initial echocardiograms showed no significant differences in left ventricular systolic dysfunction (10% v 15 %, p = 0.31) and RV systolic dysfunction (38% v. 27%, p = 0.27) between ECMO and non-ECMO patients. ACP was more frequent in the ECMO group at baseline (41% v. 26 %, p = 0.02). During the ICU stay, patients on ECMO exhibited a higher prevalence of RV systolic dysfunction (55% v 34%, p = 0.001) and ACP (51% v 26%, p = 0.002). RV systolic dysfunction (OR 1.99; 95% CI 1.09-3.63) and ACP (OR 2.95; 95% CI 1.55-5.62) on the follow-up echocardiograms were associated with higher odds of ICU mortality.

CONCLUSIONS

The prevalence of echocardiographic abnormalities, in particular RV dysfunction, was frequent among patients with COVID-19 receiving VV ECMO support and was associated with worse clinical outcomes.

Outcomes of Adult Patients With COVID-19 Transitioning From Venovenous to Venoarterial or Hybrid Extracorporeal Membrane Oxygenation in the Extracorporeal Life Support Organization Registry

This retrospective analysis of the Extracorporeal Life Support Organization (ELSO) registry evaluates the outcomes and identifies risk factors associated with conversion from initial venovenous extracorporeal membrane oxygenation (ECMO) support to venoarterial or hybrid ECMO in patients with coronavirus disease 2019 (COVID-19). We collected deidentified data on all adult patients (≥18 years old) diagnosed with COVID who received venovenous extracorporeal membrane oxygenation between March 2020 and November 2022. Patients initially placed on an ECMO configuration other than venovenous (VV) ECMO were excluded from the analysis. Our analysis included data from 12,850 patients, of which 393 (3.1%) transitioned from VV ECMO to an alternative mode. The primary outcome measure was in-hospital mortality, and the conversion group exhibited a higher in-hospital mortality rate. We also examined baseline variables, including demographic information, biochemical labs, and inotrope requirements. Univariate analysis revealed that pre-ECMO arrest, the need for renal replacement therapy, and the use of inotropic agents, particularly milrinone, were strongly associated with the risk of conversion. Notably, even after implementing a 3:1 propensity score matching, the impact of conversion on both mortality and complications remained substantial. Our study underscores an elevated risk of mortality for COVID-19 patients initially treated with VV ECMO who subsequently require conversion to VA-ECMO or hybrid ECMO.

Assessing Right Ventricle Over Time in Patients on Veno-Venous Extracorporeal Membrane Oxygenation: Insights From Serial Echocardiography

Extracorporeal membrane oxygenation (ECMO) is often used in acute respiratory distress syndrome (ARDS) with refractory hypoxemia. There is limited literature highlighting the development of right ventricular (RV) failure while on ECMO. We conducted a retrospective multicenter observational study including 70 patients who were placed on veno-venous (VV)-ECMO for respiratory failure at Mayo Clinic, Jacksonville, and Mayo Clinic, Rochester, between January 2018 and June 2022 and had at least two post-ECMO transthoracic echoes. The primary outcomes were the incidence and progression of RV dysfunction and dilatation. The secondary outcome was in-patient mortality. Among 70 patients in our cohort, 60.6% had a normal RV function at the time of ECMO placement, whereas only 42% had a normal RV function at the second post-ECMO echo. On multinomial regression, a moderate decrease in RV function was associated with ECMO flow (odds ratio [OR] = 2.32, p = 0.001) and ECMO duration (OR = 1.01, p = 0.01). A moderately dilated RV size was also associated with ECMO flow (OR = 2.62, p < 0.001) and ECMO duration (OR = 1.02, p = 0.02). An increasing degree of RV dysfunction was associated with worse outcomes. Our study showed that the increasing duration and flow of VV-ECMO correlated with progressive RV dilatation and dysfunction, which were associated with poor survival.

Enhancing lung transplantation with ECMO: a comprehensive review of mechanisms, outcomes, and future considerations

BACKGROUND

Lung transplantation (LTx) is a critical intervention for patients with end-stage lung disease. However, challenges such as donor organ scarcity and post-transplant complications significantly affect its success. Recent advancements in Extracorporeal Membrane Oxygenation (ECMO) have shown promise in improving the outcomes and expanding eligibility for LTx.

METHODS

A comprehensive literature review was conducted, focusing on studies that explore the use of ECMO in lung transplantation. A thorough search of relevant studies on ECMO and LTx was conducted using multiple scholarly databases and relevant keywords, resulting in 73 studies that met the inclusion criteria. Sources included peer-reviewed journals and clinical trial results, with emphasis on articles captured recent advancements in ECMO technology and techniques.

RESULTS

ECMO has been crucial in supporting patients before, during, and after LTx. It serves as a bridge to transplantation by maintaining pulmonary and circulatory stability in critically ill patients awaiting donor organs. ECMO also aids in the evaluation of marginal donor lungs and supports patients through acute post-transplant complications. Recent technological advancements have improved the safety and efficacy of ECMO, further solidifying its role in LTx.

CONCLUSION

In conclusion, this review underscores ECMO's critical role in enhancing outcomes across all stages of lung transplantation. Its various configurations and strategies have shown promise in stabilizing critically ill patients and improving transplant success rates. Looking ahead, it's important to gather more information about the long-term outcomes and potential complications associated with ECMO use. More research and data collection will help us understand the benefits and risks better, leading to improved decision-making and patient care in this field.

Right Heart Recovery Post Lung Transplant With COVID-19-Related Acute Respiratory Distress Syndrome

Background: Right heart remodeling is noted in patients with severe COVID-19-associated acute respiratory distress syndrome (ARDS). There is limited information regarding right heart recovery following lung transplantation in this cohort. Methods: Retrospective review of institutional transplant database from June 2020 to June 2022 was performed at Northwestern University in Chicago, Illinois. Demographic, laboratory, histopathologic, lung transplant outcomes, and pre- and postoperative echocardiographic data were recorded and analyzed. Results: Of the 42 patients who underwent lung transplantation for COVID-19-related ARDS, 6 patients were excluded due to having either a single-lung transplant (n = 2), lobar transplant (n = 1), or dual-organ transplant (n = 1) or for missing postoperative TTE data (n = 2) and 36 were included in the study; there were no 90-day deaths, and the 1-year survival rate was 88.8%. Intraoperative hemodynamics data showed a mean pulmonary artery pressure of 49 ± 23 mm Hg. Preoperative echocardiography was evaluated at a median of 15.5 (10-34.3) (IQR) days preoperatively and 140 (108-201) days (IQR) postoperatively. RV size grade improved from an average of 1.7 ± 0.85 to 1.3 ± 0.6 (p < 0.05), while RV function improved from an average of 2.2 ± 1.2 to 1 ± 1 (p < 0.05). There was a reduction in RVSP from 46.5 ± 18 mmHg to 30.1 ± 7.8 mmHg (p < 0.05) and RV free wall strain showed improvement from -13.9 ± 6.1% to -18.5 ± 5.4% (p < 0.05). Conclusions: The results showed that the RV size and systolic function demonstrate improvement with normalization in a relatively short period following lung transplantation for patients with COVID-19-associated ARDS.

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.

The association of radiologic right heart strain indices with the severity of pulmonary parenchymal involvement and prognosis in patients with COVID-19

Introduction

It has been demonstrated that an increase in the diameter of the right ventricle or pulmonary artery in COVID-19 patients could be associated with the severity of lung involvement and may lead to unfavorable outcomes, particularly in the presence of pulmonary vascular diseases. This study investigated the relationship between these right heart strain features, the extent of lung involvement, and their prognostic values in patients without vascular comorbidities.

Methods

This study selected 154 consecutive patients with positive chest computed tomography (CT) findings and no evidence of concurrent pulmonary disease. Clinical characteristics and adverse outcomes in in-hospital settings were collected retrospectively. Diameters of cardiac ventricles and arteries, along with lung opacification scores, were obtained using CT pulmonary angiography (CTPA) findings, and the association of these variables was evaluated.

Results

An increase in pulmonary artery (PA) to ascending aorta (AO) diameter ratio and lung parenchymal damage were significantly and positively correlated (P=0.017), but increased right ventricle (RV) to left ventricle (LV) diameter ratio showed no association with the extent of chest opacification (P=0.098). Evaluating the prognostic ability of both ratios using logistic regression and receiver operating characteristic (ROC) analysis proved no significant class separation in regards to predicting adverse outcomes (PA/AO: OR:1.081, P Value:0.638, RV/LV: OR:1.098, P Value:0.344).

Conclusion

In COVID-19 patients without vascular comorbidities, a higher PA/AO diameter ratio was significantly associated with increased lung involvement severity on CT imaging but not with adverse in-hospital outcomes. Conversely, an increased RV/LV ratio on CTPA did not correlate significantly with adverse outcomes or the severity of parenchymal lung damage.

The long non-coding RNA mir155hg promotes NLRP3-inflammasome activation and oxidative stress response in acute lung injury by targeting miR-450b-5p to regulate HIF-1α

BACKGROUND

Acute lung injury (ALI) can cause multiple organ dysfunction and a high mortality rate. Inflammatory responses, oxidative stress, and immune damage contribute to their pathogenic mechanisms. We studied the role of the newly discovered lncRNA, Lncmir155hg, in ALI.

METHODS

The levels of Lncmir155hg and miR-450b-5p from mice with ALI were detected via polymerase chain reaction analysis (qRT-PCR) and Fluorescence in situ hybridization (FISH). Pathological changes of lung were detected by HE (hematoxylin and eosin) staining, and HIF-1α, NOD-like receptor 3 (NLRP3) and caspase-1 protein changes were detected by immunohistochemistry. MLE-12 cells proliferation was detected by Cell-Counting Kit 8 analysis, and reactive oxygen species (ROS) was detected via flow cytometry. NLRP3, apoptosis-associated speck-like protein (ASC), and caspase-1 were measured via western blotting, and enzyme-linked immunosorbent assays detected the expression of Inflammatory factors. Lncmir155hg, miR-450b-5p, miR-450b-5p, and HIF-1α targets were predicted using LncTar and miRWalk and confirmed in dual-luciferase reporter assays.

RESULTS

In mice with ALI and MLE-12 cells induced by lipopolysaccharide (LPS), Lncmir155hg was high-expressed and miR-450b-5p was low-expressed. sh-Lncmir155hg reduced the damage of lung tissue, the production of inflammatory cytokines and oxidative stress reaction induced by LPS，miR-450b-5p reverses the effect of Lncmir155hg in mice. sh-Lncmir155hg decreased the protein levels of HIF-1α, NLRP3 and caspase-1 in LPS-induced lung tissues. sh-Lncmir155hg + miR-450b-5p inhibitor transfection reversed the effect of sh-Lncmir155hg on the expression of HIF-1α, NLRP3 and caspase-1. Lncmir155hg knockdown induced proliferation and inhibited NLRP3-inflammasome activation and oxidative stress in MLE-12 cells of ALI. miR-450b-5p was identified to have binding with Lncmir155hg, and inhibition of miR-450b-5p eliminated the effect of si-Lncmir155hg in MLE-12 cells of ALI. More importantly, miR-450b-5p was directly combined with HIF-1α, miR-450b-5p mimic promoted proliferation and inhibited activation of inflammasome associated proteins and reaction of oxidative stress, and HIF-1α overexpression abolished these effects.

CONCLUSION

Lncmir155hg aggravated ALI via the miR-450b-5p/HIF-1α axis.

Correlation between worsening pneumonitis and right ventricular systolic function in critically ill patients with COVID-19

BACKGROUND

The pneumonitis associated with coronavirus disease 2019 (COVID-19) infection impacts the right ventricle (RV). However, the association between the disease severity and right ventricular systolic function needs elucidation.

METHOD

We conducted a retrospective study of 108 patients admitted to critical care with COVID-19 pneumonitis to examine the association between tricuspid annular plane systolic excursion (TAPSE) by transthoracic echocardiography as a surrogate for RV systolic function with PaO2/FiO2 ratio as a marker of disease severity and other respiratory parameters.

RESULTS

The median age was 59 years [51, 66], 33 (31%) were female, and 63 (58%) were mechanically ventilated. Echocardiography was performed at a median of 3 days [2, 12] following admission to critical care. The PaO2/FiO2 and TAPSE medians were 20.5 [14.4, 32.0] and 21 mm [18, 24]. There was a statistically significant, albeit weak, association between the increase in TAPSE and the worsening of the PaO2/FiO2 ratio (r2 = 0.041, p = 0.04). This association was more pronounced in the mechanically ventilated (r2 = 0.09, p = 0.02). TAPSE did not correlate significantly with FiO2, PaO2, PaCO2, pH, respiratory rate, or mechanical ventilation. Patients with a TAPSE ≥ 17 mm had a considerably worse PaO2/FiO2 ratio than a TAPSE < 17 mm (18.6 vs. 32.1, p = 0.005). The PaO2/FiO2 ratio predicted TAPSE (OR = 0.94, p = 0.004) with good area under the curve (0.72, p = 0.006). Moreover, a PaO2/FiO2 ratio < 26.7 (moderate pneumonitis) predicted TAPSE > 17 mm with reasonable sensitivity (67%) and specificity (68%).

CONCLUSION

In patients admitted to critical care with COVID-19 pneumonitis, TAPSE increased as the disease severity worsened early in the course of the disease, especially in the mechanically ventilated. A TAPSE within the normal range is not necessarily reassuring in early COVID-19 pneumonitis.

Outcome of Veno-Pulmonary Extracorporeal Life Support in Lung Transplantation Using ProtekDuo Cannula: A Systematic Review and Description of Configurations

Background: Refractory end-stage pulmonary failure may benefit from extracorporeal life support (ECLS) as a bridge to lung transplantation. Veno-venous (VV) extracorporeal membrane oxygenation (ECMO) has been recommended for patients who have failed conventional medical therapy and mechanical ventilation. Veno-arterial (VA) ECMO may be used in patients with acute right ventricular (RV) failure, haemodynamic instability, or refractory respiratory failure. Peripheral percutaneous approaches, either dual-site single-lumen cannulation for veno-pulmonary (VP) ECMO or single-site dual-lumen (dl)VP ECMO, using the ProtekDuo right ventricular assist device (RVAD) cannula, has made this configuration a desirable option as a bridge to transplantation. These configurations support the right ventricle, prevent recirculation by placing the tricuspid and pulmonary valve between the drainage and return cannulas, provide the direct introduction of oxygenated blood into the pulmonary artery, and have been shown to decrease the incidence of acute kidney injury (AKI), requiring continuous renal replacement therapy (CRRT) in certain disease states. This promotes haemodynamic stability, potential sedation-weaning trials, extubation, mobilisation, and pre-transplant rehabilitation. Methods: A web-based literature search in PubMed and EMBASE was undertaken based on a combination of keywords. The PICOS and PRISMA approaches were used. Results: Four case series were identified out of 323 articles, with a total of 34 patients placed on VP ECMO as a bridge to lung transplantation. All relevant data are reviewed and integrated into the Discussion. Conclusions: Despite the limited available evidence, the use of ProtekDuo has become very promising for the management of end-stage lung disease as a bridge to lung transplantation.

Iron Metabolism in the Recovery Phase of Critical Illness with a Focus on Sepsis

Iron is an essential nutrient for humans and microbes, such as bacteria. Iron deficiency commonly occurs in critically ill patients, but supplementary iron therapy is not considered during the acute phase of critical illness since it increases iron availability for invading microbes and oxidative stress. However, persistent iron deficiency in the recovery phase is harmful and has potential adverse outcomes such as cognitive dysfunction, fatigue, and cardiopulmonary dysfunction. Therefore, it is important to treat iron deficiency quickly and efficiently. This article reviews current knowledge about iron-related biomarkers in critical illness with a focus on patients with sepsis, and provides possible criteria to guide decision-making for iron supplementation in the recovery phase of those patients.

Technique for Weaning From Peripheral Venopulmonary Extracorporeal Membrane Oxygenation in Combined Cardiopulmonary Failure

Venopulmonary (VP) extracorporeal membrane oxygenation (ECMO) is a mode capable of supporting both pulmonary and right ventricular (RV) functions. Weaning patients from VP ECMO requires careful assessment of both RV and respiratory system recovery, which may occur at different rates. The weaning strategy described herein begins with weaning of respiratory ECMO support, followed by discontinuation of RV support. We also discuss situations in which the standard weaning strategy may require modification.

Guide to Lung-Protective Ventilation in Cardiac Patients

The incidence of acute respiratory insufficiency has continued to increase among patients admitted to modern-day cardiovascular intensive care units. Positive pressure ventilation (PPV) remains the mainstay of treatment for these patients. Alterations in intrathoracic pressure during PPV has distinct effects on both the right and left ventricles, affecting cardiovascular performance. Lung-protective ventilation (LPV) minimizes the risk of further lung injury through ventilator-induced lung injury and, hence, an understanding of LPV and its cardiopulmonary interactions is beneficial for cardiologists.

Worse survival in patients with right ventricular dysfunction and COVID-19-associated acute respiratory distress requiring extracorporeal membrane oxygenation: A multicenter study from the ORACLE Group

OBJECTIVE

We sought to determine the impact of right ventricular dysfunction on the outcomes of mechanically ventilated patients with COVID-19 requiring veno-venous extracorporeal membrane oxygenation.

METHODS

Six academic centers conducted a retrospective analysis of mechanically ventilated patients with COVID-19 stratified by support with veno-venous extracorporeal membrane oxygenation during the first wave of the pandemic (March to August 2020). Echocardiograms performed for clinical indications were reviewed for right and left ventricular function. Baseline characteristics, hospitalization characteristics, and survival were compared.

RESULTS

The cohort included 424 mechanically ventilated patients with COVID-19, 126 of whom were cannulated for veno-venous extracorporeal membrane oxygenation. Right ventricular dysfunction was observed in 38.1% of patients who received extracorporeal membrane oxygenation and 27.4% of patients who did not receive extracorporeal membrane oxygenation with an echocardiogram. Biventricular dysfunction was observed in 5.5% of patients who received extracorporeal membrane oxygenation. Baseline patient characteristics were similar in both the extracorporeal membrane oxygenation and non-extracorporeal membrane oxygenation cohorts stratified by the presence of right ventricular dysfunction. In the extracorporeal membrane oxygenation cohort, right ventricular dysfunction was associated with increased inotrope use (66.7% vs 24.4%, P < .001), bleeding complications (77.1% vs 53.8%, P = .015), and worse survival independent of left ventricular dysfunction (39.6% vs 64.1%, P = .012). There was no significant difference in days ventilated before extracorporeal membrane oxygenation, length of hospital stay, hours on extracorporeal membrane oxygenation, duration of mechanical ventilation, vasopressor use, inhaled pulmonary vasodilator use, infectious complications, clotting complications, or stroke. The cohort without extracorporeal membrane oxygenation cohort demonstrated no statistically significant differences in in-hospital outcomes.

CONCLUSIONS

The presence of right ventricular dysfunction in patients with COVID-19-related acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation was associated with increased in-hospital mortality. Additional studies are required to determine if mitigating right ventricular dysfunction in patients requiring veno-venous extracorporeal membrane oxygenation improves mortality.

Automated Segmentation and Quantification of the Right Ventricle in 2-D Echocardiography

OBJECTIVE

The right ventricle receives less attention than its left counterpart in echocardiography research, practice and development of automated solutions. In the work described here, we sought to determine that the deep learning methods for automated segmentation of the left ventricle in 2-D echocardiograms are also valid for the right ventricle. Additionally, here we describe and explore a keypoint detection approach to segmentation that guards against erratic behavior often displayed by segmentation models.

METHODS

We used a data set of echo images focused on the right ventricle from 250 participants to train and evaluate several deep learning models for segmentation and keypoint detection. We propose a compact architecture (U-Net KP) employing the latter approach. The architecture is designed to balance high speed with accuracy and robustness.

RESULTS

All featured models achieved segmentation accuracy close to the inter-observer variability. When computing the metrics of right ventricular systolic function from contour predictions of U-Net KP, we obtained the bias and 95% limits of agreement of 0.8 ± 10.8% for the right ventricular fractional area change measurements, -0.04 ± 0.54 cm for the tricuspid annular plane systolic excursion measurements and 0.2 ± 6.6% for the right ventricular free wall strain measurements. These results were also comparable to the semi-automatically derived inter-observer discrepancies of 0.4 ± 11.8%, -0.37 ± 0.58 cm and -1.0 ± 7.7% for the aforementioned metrics, respectively.

CONCLUSION

Given the appropriate data, automated segmentation and quantification of the right ventricle in 2-D echocardiography are feasible with existing methods. However, keypoint detection architectures may offer higher robustness and information density for the same computational cost.

A novel speckle-tracking echocardiography parameter assessing left ventricular afterload

BACKGROUND

Left ventricular stroke work index (LVSWI) and afterload-related cardiac performance (ACP) consider left ventricular (LV) afterload and could be better prognosticators in septic cardiomyopathy. However, their invasive nature prevents their routine clinical applications. This study aimed to investigate (1) whether a proposed speckle-tracking echocardiography parameter, Pressure-Strain Product (PSP), can non-invasively predict catheter-based LVSWI, ACP and serum lactate in an ovine model of septic cardiomyopathy; and (2) whether PSP can distinguish the sub-phenotypes of acute respiratory distress syndrome (ARDS) with or without sepsis-like conditions.

METHODS

Sixteen sheep with ARDS were randomly assigned to either (1) sepsis-like (n = 8) or (2) non-sepsis-like (n = 8) group. Each ARDS and sepsis-like condition was induced by intravenous infusion of oleic acid and lipopolysaccharide, respectively. Pulmonary artery catheter-based LVSWI (the product of stroke work index, mean arterial pressure and .0136), ACP (the percentage of cardiac output measured to cardiac output predicted as normal) and serum lactate were measured simultaneously with transthoracic echocardiography. Two PSP indices were calculated by multiplying the mean arterial blood pressure and either global circumferential strain (PSPcirc) or radial strain (PSPrad).

RESULTS

PSPcirc showed a significant correlation with LVSWI (r2  = .66, p < .001) and ACP (r2  = .82, p < .001) in the sepsis-like group. Although PSP could not distinguish subphenotypes, PSPcirc predicted LVSWI (AUC .86) and ACP (AUC .88), and PSPrad predicted serum lactate (AUC .75) better than LV ejection fraction, global circumferential and radial strain.

CONCLUSIONS

A novel PSP has the potential to non-invasively predict catheter-based LVSWI and ACP, and was associated with serum lactate in septic cardiomyopathy.

Medical and Mechanical Circulatory Support of the Failing Right Ventricle

PURPOSE OF REVIEW

To describe medical therapies and mechanical circulatory support devices used in the treatment of acute right ventricular failure.

RECENT FINDINGS

Experts have proposed several algorithms providing a stepwise approach to medical optimization of acute right ventricular failure including tailored volume administration, ideal vasopressor selection to support coronary perfusion, inotropes to restore contractility, and pulmonary vasodilators to improve afterload. Studies have investigated various percutaneous and surgically implanted right ventricular assist devices in several clinical settings. The initial management of acute right ventricular failure is often guided by invasive hemodynamic data tracking parameters of circulatory function with the use of pharmacologic therapies. Percutaneous microaxial and centrifugal extracorporeal pumps bypass the failing RV and support circulatory function in severe cases of right ventricular failure.

The Effect of Lower Tidal Volume Ventilation Facilitated by Extracorporeal Carbon Dioxide Removal Compared With Conventional Lung Protective Ventilation on Cardiac Function

OBJECTIVES

Lower tidal volume ventilation (targeting 3 mL/kg predicted body weight, PBW) facilitated by extracorporeal carbon dioxide removal (ECCO2R) has been investigated as a potential therapy for acute hypoxemic respiratory failure (AHRF) in the pRotective vEntilation with veno-venouS lung assisT in respiratory failure (REST) trial. We investigated the effect of this strategy on cardiac function, and in particular the right ventricle.

DESIGN

Substudy of the REST trial.

SETTING

Nine U.K. ICUs.

PATIENTS

Patients with AHRF (Pao2/Fio2 < 150 mm Hg [20 kPa]).

INTERVENTION

Transthoracic echocardiography and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements were collected at baseline and postrandomization in patients randomized to ECCO2R or usual care.

MEASUREMENTS

The primary outcome measures were a difference in tricuspid annular plane systolic excursion (TAPSE) on postrandomization echocardiogram and difference in NT-proBNP postrandomization.

RESULTS

There were 21 patients included in the echocardiography cohort (ECCO2R, n = 13; usual care, n = 8). Patient characteristics were similar in both groups at baseline. Median (interquartile range) tidal volumes were lower in the ECCO2R group compared with the usual care group postrandomization; 3.6 (3.1-4.2) mL/kg PBW versus 5.2 (4.9-5.7) mL/kg PBW, respectively (p = 0.01). There was no difference in the primary outcome measure of mean (sd) TAPSE in the ECCO2R and usual care groups postrandomization; 21.3 (5.4) mm versus 20.1 (3.2) mm, respectively (p = 0.60). There were 75 patients included in the NT-proBNP cohort (ECCO2R, n = 36; usual care, n = 39). Patient characteristics were similar in both groups at baseline. Median (interquartile range [IQR]) tidal volumes were lower in the ECCO2R group than the usual care group postrandomization; 3.8 (3.3-4.2) mL/kg PBW versus 6.7 (5.8-8.1) mL/kg PBW, respectively (p < 0.0001). There was no difference in median (IQR) NT-proBNP postrandomization; 1121 (241-5370) pg/mL versus 1393 (723-4332) pg/mL in the ECCO2R and usual care groups, respectively (p = 0.30).

CONCLUSIONS

In patients with AHRF, a reduction in tidal volume facilitated by ECCO2R, did not modify cardiac function.

Dead-Space Ventilation Indices and Mortality in Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

OBJECTIVES

Acute respiratory distress syndrome (ARDS) is associated with high ventilation-perfusion heterogeneity and dead-space ventilation. However, whether the degree of dead-space ventilation is associated with outcomes is uncertain. In this systematic review and meta-analysis, we evaluated the ability of dead-space ventilation measures to predict mortality in patients with ARDS.

DATA SOURCES

MEDLINE, CENTRAL, and Google Scholar from inception to November 2022.

STUDY SELECTION

Studies including adults with ARDS reporting a dead-space ventilation index and mortality.

DATA EXTRACTION

Two reviewers independently identified eligible studies and extracted data. We calculated pooled effect estimates using a random effects model for both adjusted and unadjusted results. The quality and strength of evidence were assessed using the Quality in Prognostic Studies and Grading of Recommendations, Assessment, Development, and Evaluation, respectively.

DATA SYNTHESIS

We included 28 studies in our review, 21 of which were included in our meta-analysis. All studies had a low risk of bias. A high pulmonary dead-space fraction was associated with increased mortality (odds ratio [OR], 3.52; 95% CI, 2.22-5.58; p < 0.001; I2 = 84%). After adjusting for other confounding variables, every 0.05 increase in pulmonary-dead space fraction was associated with an increased odds of death (OR, 1.23; 95% CI, 1.13-1.34; p < 0.001; I2 = 57%). A high ventilatory ratio was also associated with increased mortality (OR, 1.55; 95% CI, 1.33-1.80; p < 0.001; I2 = 48%). This association was independent of common confounding variables (OR, 1.33; 95% CI, 1.12-1.58; p = 0.001; I2 = 66%).

CONCLUSIONS

Dead-space ventilation indices were independently associated with mortality in adults with ARDS. These indices could be incorporated into clinical trials and used to identify patients who could benefit from early institution of adjunctive therapies. The cut-offs identified in this study should be prospectively validated.

Right Ventricular Dysfunction Patterns among Patients with COVID-19 in the Intensive Care Unit: A Retrospective Cohort Analysis

Rationale: Right ventricular (RV) dysfunction is common among patients hospitalized with coronavirus disease (COVID-19); however, its epidemiology may depend on the echocardiographic parameters used to define it. Objectives: To evaluate the prevalence of abnormalities in three common echocardiographic parameters of RV function among patients with COVID-19 admitted to the intensive care unit (ICU), as well as the effect of RV dilatation on differential parameter abnormality and the association of RV dysfunction with 60-day mortality. Methods: We conducted a retrospective cohort study of ICU patients with COVID-19 between March 4, 2020, and March 4, 2021, who received a transthoracic echocardiogram within 48 hours before to at most 7 days after ICU admission. RV dysfunction and dilatation, respectively, were defined by guideline thresholds for tricuspid annular plane systolic excursion (TAPSE), RV fractional area change, RV free wall longitudinal strain (RVFWS), and RV basal dimension or RV end-diastolic area. Association of RV dysfunction with 60-day mortality was assessed through logistic regression adjusting for age, prior history of congestive heart failure, invasive ventilation at the time of transthoracic echocardiogram, and Acute Physiology and Chronic Health Evaluation II score. Results: A total of 116 patients were included, of whom 69% had RV dysfunction by one or more parameters, and 36.3% of these had RV dilatation. The three most common patterns of RV dysfunction were the presence of three abnormalities, the combination of abnormal RVFWS and TAPSE, and isolated TAPSE abnormality. Patients with RV dilatation had worse RV fractional area change (24% vs. 36%; P = 0.001), worse RVFWS (16.3% vs. 19.1%; P = 0.005), higher RV systolic pressure (45 mm Hg vs. 31 mm Hg; P = 0.001) but similar TAPSE (13 mm vs. 13 mm; P = 0.30) compared with those with normal RV size. After multivariable adjustment, 60-day mortality was significantly associated with RV dysfunction (odds ratio, 2.91; 95% confidence interval, 1.01-9.44), as was the presence of at least two parameter abnormalities. Conclusions: ICU patients with COVID-19 had significant heterogeneity in RV function abnormalities present with different patterns associated with RV dilatation. RV dysfunction by any parameter was associated with increased mortality. Therefore, a multiparameter evaluation may be critical in recognizing RV dysfunction in COVID-19.

High driving pressure ventilation induces pulmonary hypertension in a rabbit model of acute lung injury

BACKGROUND

Mechanical ventilation may cause pulmonary hypertension in patients with acute lung injury (ALI), but the underlying mechanism remains elucidated.

METHODS

ALI was induced in rabbits by a two-hit injury, i.e., hydrochloric acid aspiration followed by mechanical ventilation for 1 h. Rabbits were then ventilated with driving pressure of 10, 15, 20, or 25 cmH2O for 7 h. Clinicopathological parameters were measured at baseline and different timepoints of ventilation. RNA sequencing was conducted to identify the differentially expressed genes in high driving pressure ventilated lung tissue.

RESULTS

The two-hit injury induced ALI in rabbits was evidenced by dramatically decreased PaO2/FiO2 in the ALI group compared with that in the control group (144.5 ± 23.8 mmHg vs. 391.6 ± 26.6 mmHg, P < 0.001). High driving pressure ventilation (20 and 25 cmH2O) significantly elevated the parameters of acute pulmonary hypertension at different timepoints compared with low driving pressure (10 and 15 cmH2O), along with significant increases in lung wet/dry ratios, total protein contents in bronchoalveolar lavage fluid, and lung injury scores. The high driving pressure groups showed more pronounced histopathological abnormalities in the lung compared with the low driving pressure groups, accompanied by significant increases in the cross-sectional areas of myocytes, right ventricular weight/body weight value, and Fulton's index. Furthermore, the expression of the genes related to ferroptosis induction was generally upregulated in high driving pressure groups compared with those in low driving pressure groups.

CONCLUSIONS

A rabbit model of ventilation-induced pulmonary hypertension in ALI was successfully established. Our results open a new research direction investigating the exact role of ferroptosis in ventilation-induced pulmonary hypertension in ALI.

Interactions between extracorporeal support and the cardiopulmonary system

This review describes the intricate physiological interactions involved in the application of extracorporeal therapy, with specific focus on cardiopulmonary relationships. Extracorporeal therapy significantly influences cardiovascular and pulmonary physiology, highlighting the necessity for clinicians to understand these interactions for improved patient care. Veno-arterial extracorporeal membrane oxygenation (veno-arterial ECMO) unloads the right ventricle and increases left ventricular (LV) afterload, potentially exacerbating LV failure and pulmonary edema. Veno-venous (VV) ECMO presents different challenges, where optimal device and ventilator settings remain unknown. Influences on right heart function and native gas exchange as well as end-expiratory lung volumes are important concepts that should be incorporated into daily practice. Future studies should not be limited to large clinical trials focused on mortality but rather address physiological questions to advance the understanding of extracorporeal therapies. This includes exploring optimal device and ventilator settings in VV ECMO, standardizing cardiopulmonary function monitoring strategies, and developing better strategies for device management throughout their use. In this regard, small human or animal studies and computational physiological modeling may contribute valuable insights into optimizing the management of extracorporeal therapies.

Mitochondria of lung venular capillaries mediate lung-liver cross talk in pneumonia

Failure of the lung's endothelial barrier underlies lung injury, which causes the high mortality acute respiratory distress syndrome (ARDS). Multiple organ failure predisposes to the mortality, but mechanisms are poorly understood. Here, we show that mitochondrial uncoupling protein 2 (UCP2), a component of the mitochondrial inner membrane, plays a role in the barrier failure. Subsequent lung-liver cross talk mediated by neutrophil activation causes liver congestion. We intranasally instilled lipopolysaccharide (LPS). Then, we viewed the lung endothelium by real-time confocal imaging of the isolated, blood-perfused mouse lung. LPS caused alveolar-capillary transfer of reactive oxygen species and mitochondrial depolarization in lung venular capillaries. The mitochondrial depolarization was inhibited by transfection of alveolar Catalase and vascular knockdown of UCP2. LPS instillation caused lung injury as indicated by increases in bronchoalveolar lavage (BAL) protein content and extravascular lung water. LPS or Pseudomonas aeruginosa instillation also caused liver congestion, quantified by liver hemoglobin and plasma aspartate aminotransferase (AST) increases. Genetic inhibition of vascular UCP2 prevented both lung injury and liver congestion. Antibody-mediated neutrophil depletion blocked the liver responses, but not lung injury. Knockdown of lung vascular UCP2 mitigated P. aeruginosa-induced mortality. Together, these data suggest a mechanism in which bacterial pneumonia induces oxidative signaling to lung venular capillaries, known sites of inflammatory signaling in the lung microvasculature, depolarizing venular mitochondria. Successive activation of neutrophils induces liver congestion. We conclude that oxidant-induced UCP2 expression in lung venular capillaries causes a mechanistic sequence leading to liver congestion and mortality. Lung vascular UCP2 may present a therapeutic target in ARDS.NEW & NOTEWORTHY We report that mitochondrial injury in lung venular capillaries underlies barrier failure in pneumonia, and venular capillary uncoupling protein 2 (UCP2) causes neutrophil-mediated liver congestion. Using in situ imaging, we found that epithelial-endothelial transfer of H2O2 activates UCP2, depolarizing mitochondria in venular capillaries. The conceptual advance from our findings is that mitochondrial depolarization in lung capillaries mediates liver cross talk through circulating neutrophils. Pharmacologic blockade of UCP2 could be a therapeutic strategy for lung injury.

Role of cardiac and lung ultrasound in the COVID-19 era

INTRODUCTION

The primary diagnostic method of Coronavirus disease 2019 is reverse transcription polymerase chain reaction of the nucleic acid of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal swabs. There is growing evidence regarding the 2019 coronavirus disease imaging results on chest X-rays and computed tomography but the accessibility to standard diagnostic methods may be limited during the pandemic.

EVIDENCE ACQUISITION

Databases used for the search were MEDLINE (PubMed), Scopus Search, and Cochrane Library. The research took into consideration studies published in English until March 2022 and was conducted using the following research query: ((((sars cov [MeSH Terms])) OR (COVID-19)) OR (Sars-Cov2)) OR (Coronavirus)) AND (((((2d echocardiography [MeSH Terms]) OR (doppler ultrasound imaging [MeSH Terms]))) OR (echography [MeSH Terms])) OR (LUS)) OR ("LUNG ULTRASOUND")).

EVIDENCE SYNTHESIS

Pulmonary and cardiac ultrasound are cost-effective, widely available, and provide information that can influence management.

CONCLUSIONS

Point-of-care ultrasonography is a method that can provide relevant clinical and therapeutic information in patients with COVID-19 where other diagnostic methods may not be easily accessible.

Role of cardiopulmonary interactions in development of ventilator-induced lung injury-Experimental evidence and clinical Implications

Ventilator-induced lung injury (VILI) impacts outcomes in ARDS and optimization of ventilatory strategies improves survival. Decades of research has identified various mechanisms of VILI, largely focusing on airspace forces of plateau pressure, tidal volume and driving pressure. Experimental evidence indicates the role of adverse cardiopulmonary interaction during mechanical ventilation, contributing to VILI genesis mostly by modulating pulmonary vascular dynamics. Under passive mechanical ventilation, high transpulmonary pressure increases afterload on right heart while high pleural pressure reduces the RV preload. Together, they can result in swings of pulmonary vascular flow and pressure. Altered vascular flow and pressure result in increased vascular shearing and wall tension, in turn causing direct microvascular injury accompanied with permeability to water, proteins and cells. Moreover, abrupt decreases in airway pressure, may result in sudden overperfusion of the lung and result in similar microvascular injury, especially when the endothelium is stretched or primed at high positive end-expiratory pressure. Microvascular injury is universal in VILI models and presumed in the diagnosis of ARDS; preventing such microvascular injury can reduce VILI and impact outcomes in ARDS. Consequently, developing cardiovascular targets to reduce macro and microvascular stressors in the pulmonary circulation can potentially reduce VILI. This paper reviews the role of cardiopulmonary interaction in VILI genesis.

Extracorporeal Membrane Oxygenation to Support COVID-19 Patients: A Propensity-Matched Cohort Study

Background

In patients with severe respiratory failure from COVID-19, extracorporeal membrane oxygenation (ECMO) treatment can facilitate lung-protective ventilation and may improve outcome and survival if conventional therapy fails to assure adequate oxygenation and ventilation. We aimed to perform a confirmatory propensity-matched cohort study comparing the impact of ECMO and maximum invasive mechanical ventilation alone (MVA) on mortality and complications in severe COVID-19 pneumonia.

Materials and Methods

All 295 consecutive adult patients with confirmed COVID-19 pneumonia admitted to the intensive care unit (ICU) from March 13^th, 2020, to July 31^st, 2021 were included. At admission, all patients were classified into 3 categories: (1) full code including the initiation of ECMO therapy (AAA code), (2) full code excluding ECMO (AA code), and (3) do-not-intubate (A code). For the 271 non-ECMO patients, match eligibility was determined for all patients with the AAA code treated with MVA. Propensity score matching was performed using a logistic regression model including the following variables: gender, P/F ratio, SOFA score at admission, and date of ICU admission. The primary endpoint was ICU mortality.

Results

A total of 24 ECMO patients were propensity matched to an equal number of MVA patients. ICU mortality was significantly higher in the ECMO arm (45.8%) compared with the MVA cohort (16.67%) (OR 4.23 (1.11, 16.17); p=0.02). Three-month mortality was 50% with ECMO compared to 16.67% after MVA (OR 5.91 (1.55, 22.58); p < 0.01). Applied peak inspiratory pressures (33.42 ± 8.52 vs. 24.74 ± 4.86 mmHg; p < 0.01) and maximal PEEP levels (14.47 ± 3.22 vs. 13.52 ± 3.86 mmHg; p=0.01) were higher with MVA. ICU length of stay (LOS) and hospital LOS were comparable in both groups.

Conclusion

ECMO therapy may be associated with an up to a three-fold increase in ICU mortality and 3-month mortality compared to MVA despite the facilitation of lung-protective ventilation settings in mechanically ventilated COVID-19 patients. We cannot confirm the positive results of the first propensity-matched cohort study on this topic. This trial is registered with NCT05158816.

Optimal positive end-expiratory pressure reduces right ventricular dysfunction in COVID-19 patients on venovenous extracorporeal membrane oxygenation: A retrospective single-center study

While mechanical ventilation practices on venovenous extracorporeal membrane oxygenation (VV ECMO) are variable, most institutions utilize a lung rest strategy utilizing relatively low positive end-expiratory pressure (PEEP). The effect of PEEP titration using esophageal manometry during VV ECMO on pulmonary and cardiac function is unknown. This was a retrospective study of 69 patients initiated on VV ECMO between March 2020 through November 2021. Patients underwent standard PEEP (typically 10 cm H₂O) or optimal PEEP (PEEP titrated to an end-expiratory transpulmonary pressure 0-3 cm H₂O) throughout the ECMO run. The optimal PEEP strategy had higher levels of applied PEEP (17.9 vs. 10.8 cm H₂O on day 2 of ECMO), decreased incidence of hemodynamically significant RV dysfunction (4.55% vs. 44.0%, p = 0.0001), and higher survival to decannulation (72.7% vs. 44.0%, p = 0.022). Survival to discharge did not reach statistical significance (27% vs. 11%, p = 0.211). In univariate logistic regression analysis, optimal PEEP was associated with less hemodynamically significant RV dysfunction with an odds ratio (OR) of 0.06 (95% confidence interval [CI] = 0.01-0.27, p = 0.0008) and increased survival to decannulation with an OR of 3.39 (95% CI 1.23-9.79), p = 0.02), though other confounding factors may have contributed.

Acute Respiratory Distress Syndrome, Mechanical Ventilation, and Inhalation Injury in Burn Patients

Respiratory failure occurs with some frequency in seriously burned patients, driven by a combination of inflammatory and infection factors. Inhalation injury contributes to respiratory failure in some burn patients via direct mucosal injury and indirect inflammation. In burn patients, respiratory failure leading to acute respiratory distress syndrome, with or without inhalation injury, is effectively managed using principles evolved for non-burn critically ill patients.

Management of Acute Right Ventricular Failure

PURPOSE OF REVIEW

Acute right ventricular failure (RVF) is a frequent condition associated with high morbidity and mortality. This review aims to provide a current overview of the pathophysiology, presentation, and comprehensive management of acute RVF.

RECENT FINDINGS

Acute RVF is a common disease with a pathophysiology that is not completely understood. There is renewed interest in the right ventricle (RV). Some advances have been principally made in chronic right ventricular failure (e.g., pulmonary hypertension). Due to a lack of precise definition and diagnostic tools, acute RVF is poorly studied. Few advances have been made in this field. Acute RVF is a complex, frequent, and life-threatening condition with several etiologies. Transthoracic echocardiography (TTE) is the key diagnostic tool in search of the etiology. Management includes transfer to an expert center and admission to the intensive care unit (ICU) in most severe cases, etiological treatment, and general measures for RVF.

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.

CORONA (COre ultRasOund of covid in iNtensive care and Acute medicine) study: National service evaluation of lung and heart ultrasound in intensive care patients with suspected or proven COVID-19

BACKGROUND

Combined Lung Ultrasound (LUS) and Focused UltraSound for Intensive Care heart (FUSIC Heart - formerly Focused Intensive Care Echocardiography, FICE) can aid diagnosis, risk stratification and management in COVID-19. However, data on its application and results are limited to small studies in varying countries and hospitals. This United Kingdom (UK) national service evaluation study assessed how combined LUS and FUSIC Heart were used in COVID-19 Intensive Care Unit (ICU) patients during the first wave of the pandemic.

METHOD

Twelve trusts across the UK registered for this prospective study. LUS and FUSIC Heart data were obtained, using a standardised data set including scoring of abnormalities, between 1st February 2020 to 30th July 2020. The scans were performed by intensivists with FUSIC Lung and Heart competency as a minimum standard. Data was anonymised locally prior to transfer to a central database.

RESULTS

372 studies were performed on 265 patients. There was a small but significant relationship between LUS score >8 and 30-day mortality (OR 1.8). Progression of score was associated with an increase in 30-day mortality (OR 1.2). 30-day mortality was increased in patients with right ventricular (RV) dysfunction (49.4% vs 29.2%). Severity of LUS score correlated with RV dysfunction (p < 0.05). Change in management occurred in 65% of patients following a combined scan.

CONCLUSIONS

In COVID-19 patients, there is an association between lung ultrasound score severity, RV dysfunction and mortality identifiable by combined LUS and FUSIC Heart. The use of 12-point LUS scanning resulted in similar risk score to 6-point imaging in the majority of cases. Our findings suggest that serial combined LUS and FUSIC Heart on COVID-19 ICU patients may aid in clinical decision making and prognostication.

Isolated diastolic dysfunction is associated with increased mortality in critically ill patients

PURPOSE

Left ventricular (LV) diastolic dysfunction is important in critically ill patients, but prevalence and impact on mortality is not well studied. We classified intensive care patients with normal left ventricular function according to current diastolic guidelines and explored associations with mortality.

MATERIAL AND METHODS

Echocardiography was performed within 24 h of intensive care admission. Patients with reduced LV ejection fraction, regional wall motion abnormality, or a history of cardiac disease were excluded. Patients were classified according to the 2016 EACVI guidelines, Recommendations for the Evaluation of LV Diastolic Function by Echocardiography.

RESULTS

Out of 218 patients, 162 (74%) had normal diastolic function, 21 (10%) had diastolic dysfunction, and 35 (17%) had indeterminate diastolic function. Diastolic dysfunction were more common in female patients, older patients and associated with sepsis, respiratory and cardiovascular comorbidity as well as higher SAPS Score. In a risk-adjusted logistic regression model, patients with indeterminate diastolic dysfunction (OR 4.3 [1.6-11.4], p = 0.004) or diastolic dysfunction (OR 5.1 [1.6-16.5], p = 0.006) had an increased risk of death at 90 days compared to patients with normal diastolic function.

CONCLUSION

Isolated diastolic dysfunction, assessed by a multi-parameter approach, is common in critically ill patients and is associated with mortality.

TRIAL REGISTRATION

Secondary analysis of data from a single-center prospective observational study focused on systolic dysfunction in intensive care unit patients (Clinical Trials ID: NCT03787810.

Right Ventricular Limitation: A Tale of Two Elastances

Right ventricular (RV) dysfunction is a commonly considered cause of low cardiac output in critically ill patients. Its management can be difficult and requires an understanding of how the RV limits cardiac output. We explain that RV stroke output is caught between the passive elastance of the RV walls during diastolic filling and the active elastance produced by the RV in systole. These two elastances limit RV filling and stroke volume and consequently limit left ventricular stroke volume. We emphasize the use of the term "RV limitation" and argue that limitation of RV filling is the primary pathophysiological process by which the RV causes hemodynamic instability. Importantly, RV limitation can be present even when RV function is normal. We use the term "RV dysfunction" to indicate that RV end-systolic elastance is depressed or diastolic elastance is increased. When RV dysfunction is present, RV limitation occurs at lowerpulmonary valve opening pressures and lower stroke volume, but stroke volume and cardiac output still can be maintained until RV filling is limited. We use the term "RV failure" to indicate the condition in which RV output is insufficient for tissue needs. We discuss the physiological underpinnings of these terms and implications for clinical management.

Right ventricle-specific therapies in acute respiratory distress syndrome: a scoping review

OBJECTIVE

To summarize knowledge and identify gaps in evidence regarding treatment of right ventricular dysfunction (RVD) in acute respiratory distress syndrome (ARDS).

DATA SOURCES

We conducted a comprehensive search of MEDLINE, Embase, CINAHL, Web of Science, and the Cochrane Central Register of Controlled Trials.

STUDY SELECTION

Studies were included if they reported effects of treatments on right ventricular function, whether or not the intent was to modify right ventricular function.

DATA EXTRACTION

Data extraction was performed independently and in duplicate by two authors. Data items included the study design, patient population, type of intervention, comparison group, and RV-specific outcomes.

DATA SYNTHESIS

Of 1,430 studies screened, 51 studies reporting on 1,526 patients were included. By frequency, the included studies examined the following interventions: ventilator settings (29.4%), inhaled medications (33.3%), extracorporeal life support (13.7%), intravenous or oral medications (13.7%), and prone positioning (9.8%). The majority of the studies were non-randomized experimental studies (53%), with the next most common being case reports (16%). Only 5.9% of studies were RCTs. In total, 27% of studies were conducted with the goal of modifying RV function.

CONCLUSIONS

Given the prevalence of RVD in ARDS and its association with mortality, the dearth of research on this topic is concerning. This review highlights the need for prospective trials aimed at treating RV dysfunction in ARDS.

Pressure-based beat-to-beat right ventricular ejection fraction and Tau from continuous measured ventricular pressures in COVID-19 ARDS patients

We evaluated pressure-based right ventricular ejection fraction (RVEF) and diastolic isovolumetric relaxation time constant (Tau) from continuously (up to 30 days) invasive measured right ventricular pressures in mechanically ventilated patients with severe COVID-19 acute respiratory distress syndrome (ARDS). We retrospectively calculated beat-to-beat ejection fraction from right ventricular pressures and dp/dt maximum and minimum in 39 patients treated between October 1st, 2020 and June 30th, 2021. After performing a stepwise logistic regression with survival as a dependent variable, we divided the patients into survivors and nonsurvivors based on their 60-day mortality. Independent outcome variables were the values of RVEF and Tau over time after insertion of the right ventricular probe along with right ventricular systolic and diastolic pressures (RVSP) and the estimated pulmonary artery diastolic pressure (ePAD). RVEF increased significantly over time in the survivors (estimate: 0.354; 95% confidence interval, CI: 0.18-0.53; p < 0.001) but remained unchanged in the nonsurvivors. Tau increased significantly in the nonsurvivors (estimate: 0.001; 95% CI: 0.0004-0.0018; p < 0.002) but not in the survivors. On the last measurement day, RVSP and ePAD were significantly lower while RVEF was significantly higher in the survivors compared to the nonsurvivors. In COVID-19 ARDS patient's, calculation of beat-to-beat RVEF and Tau from continuously invasive measured right ventricular pressures seems to unravel contrary trends in RVEF with an increase in the surviving and a decrease in the nonsurviving patients. Tau remained unchanged in the surviving but increased in the nonsurviving patients over time.

Usefulness and limitations of the acute respiratory distress syndrome definitions in non-intubated patients. A narrative review

According to the Berlin Definition of acute respiratory distress syndrome (ARDS), a positive end-expiratory pressure (PEEP) of at least 5 cmH₂O is required to diagnose and grade ARDS. While the Berlin consensus statement specifically acknowledges the role of non-invasive ventilation (NIV) in mild ARDS, this stratification has traditionally presumed a mechanically ventilated patient in the context of moderate to severe ARDS. This may not accurately reflect today's reality of clinical respiratory care. NIV and high-flow nasal cannula oxygen therapy (HFNO) have been used for managing of severe forms of acute hypoxemic respiratory failure with growing frequency, including in patients showing pathophysiological signs of ARDS. This became especially relevant during the COVID-19 pandemic. The levels of PEEP achieved with HFNO have been particularly controversial, and the exact FiO₂ it achieves is subject to variability. Pinpointing the presence of ARDS in patients receiving HNFO and the severity in those receiving NIV therefore remains methodically problematic. This narrative review highlights the evolution of the ARDS definition in the context of non-invasive ventilatory support and provides an overview of the parallel development of definitions and ventilatory management of ARDS. It summarizes the methodology applied in clinical trials to classify ARDS in non-intubated patients and the respective consequences on treatment. As ARDS severity has significant therapeutic and prognostic consequences, and earlier treatment in non-intubated patients may be beneficial, closing this knowledge gap may ultimately be a relevant step to improve comparability in clinical trial design and outcomes.

Right Ventricular Injury Increases Mortality in Patients With Acute Respiratory Distress Syndrome on Veno-Venous Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis

Right ventricular injury (RVI) in the context of acute respiratory distress syndrome (ARDS) is well recognized as an important determinant risk factor of mortality. Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is part of the algorithm for the management of patients with severe ARDS and severely impaired gas exchange. Although VV-ECMO may theoretically protect the RV it is uncertain to what degree RVI persists despite VV-ECMO support, and whether it continues to influence mortality after ECMO initiation. The aim of this systematic review and meta-analysis was to investigate the impact of RVI on mortality in this context, testing the hypothesis that RVI worsens mortality in this cohort. We performed a systematic search that identified seven studies commenting on RVI and mortality in patients with ARDS receiving VV-ECMO. The presence of RVI was associated with greater mortality overall (odds ratios [OR]: 2.72; 95% confidence intervals [CI]: 1.52-4.85; p < 0.00) and across three subgroups (RV dilatational measures: OR: 3.51; 95% CI: 1.51-8.14; p < 0.01, RV functional measures: OR: 1.84; 95% CI: 0.99-3.42; p = 0.05, RV measurements post-ECMO initiation: OR: 1.94; 95% CI: 1.01-3.72; p < 0.05). Prospective studies are needed to investigate the causal relationship between RVI and mortality in this patient group and the best management strategies to reduce mortality.

The Future of Cardiothoracic Surgical Critical Care Medicine as a Medical Science: A Call to Action

Cardiothoracic surgical critical care medicine (CT-CCM) is a medical discipline centered on the perioperative care of diverse groups of patients. With an aging demographic and an increase in burden of chronic diseases the utilization of cardiothoracic surgical critical care units is likely to escalate in the coming decades. Given these projections, it is important to assess the state of cardiothoracic surgical intensive care, to develop goals and objectives for the future, and to identify knowledge gaps in need of scientific inquiry. This two-part review concentrates on CT-CCM as its own subspeciality of critical care and cardiothoracic surgery and provides aspirational goals for its practitioners and scientists. In part one, a list of guiding principles and a call-to-action agenda geared towards growth and promotion of CT-CCM are offered. In part two, an evaluation of selected scientific data is performed, identifying gaps in CT-CCM knowledge, and recommending direction to future scientific endeavors.

Percutaneous Pulmonary Artery Cannulation to Treat Acute Secondary Right Heart Failure While on Veno-venous Extracorporeal Membrane Oxygenation

Right heart failure (RHF) is a common, yet difficult to manage, complication of severe acute respiratory distress syndrome requiring extracorporeal membrane oxygenation (ECMO) that is associated with increased mortality. Reports of the use of percutaneous mechanical circulatory support devices for concurrent right heart and respiratory failure are limited. This series describes the percutaneous cannulation of the pulmonary artery for conversion from veno-venous to veno-pulmonary artery return ECMO in 21 patients who developed secondary RHF. All patients cannulated between May 2019 and September 2021 were included. Either a 19 or 21 French venous cannula was placed percutaneously into the pulmonary artery via the internal jugular or subclavian vein, providing a total of 821 days of support (median 23 [4-71] days per patient) with flows up to 6 L/min. Five patients underwent cannulation at the bedside, with the remainder performed in the cardiac catheterization laboratory. Pulmonary artery cannulation occurred after 12 [8.5-23.5] days of ECMO support. Vasoactive infusion requirements decreased significantly within 24 hours of pulmonary artery cannula placement (p = 0.0004). Nonetheless, 75% of these patients expired after a median of 12 [4-63] days of support, with three patients found to have had significant pericardial effusions peri-arrest. This cannulation technique may be an effective alternative to veno-arterial ECMO cannulation or the placement of a dual-lumen cannula for the treatment of RHF.

Cardiac function in critically ill patients with severe COVID: A prospective cross-sectional study in mechanically ventilated patients

PURPOSE

To evaluate cardiac function in mechanically ventilated patients with COVID-19.

MATERIALS AND METHODS

Prospective, cross-sectional multicenter study in four university-affiliated hospitals in Chile. All consecutive patients with COVID-19 ARDS requiring mechanical ventilation admitted between April and July 2020 were included. We performed systematic transthoracic echocardiography assessing right and left ventricular function within 24 h of intubation.

RESULTS

140 patients aged 57 ± 11, 29% female were included. Cardiac output was 5.1 L/min [IQR 4.5-6.2] and 86% of the patients required norepinephrine. ICU mortality was 29% (40 patients). Fifty-four patients (39%) exhibited right ventricle dilation out of whom 20 patients (14%) exhibited acute cor pulmonale (ACP). Eight out of the twenty patients with ACP exhibited pulmonary embolism (40%). Thirteen patients (9%) exhibited left ventricular systolic dysfunction (ejection fraction <45%). In the multivariate analysis acute cor pulmonale and PaO₂/FiO₂ ratio were independent predictors of ICU mortality.

CONCLUSIONS

Right ventricular dilation is highly prevalent in mechanically ventilated patients with COVID-19 ARDS. Acute cor pulmonale was associated with reduced pulmonary function and, in only 40% of patients, with co-existing pulmonary embolism. Acute cor pulmonale is an independent risk factor for ICU mortality.

Modelling patient specific cardiopulmonary interactions

Mechanical ventilation is well known for having detrimental effects on the cardiovascular system, particularly when using high positive end-expiratory pressure. High positive end-expiratory pressure levels cause a decrease in stroke volume, which, under normal conditions, usually bring about a decrease in stressed blood volume. Stressed blood volume, defined as the total pressure generating volume of the cardiovascular system, has been shown to be a potential index of fluid responsiveness, making it a potentially important diagnostic tool. Generally, respiratory and haemodynamic care are provided independently of one another. However, that positive end-expiratory pressure alters both stroke volume and stressed blood volume suggests both the pulmonary and cardiovascular state should be conjointly optimised and used to guide positive end-expiratory pressure. However, the complex and patient-specific nature of cardiopulmonary interactions which occur during mechanical ventilation presents a challenge for accurate modelling of respiratory and cardiovascular interactions required to better optimise care. Previous models attempting to incorporate cardiopulmonary interactions have suffered from poor reliability at higher PEEP levels, largely due to an exaggerated effect of intrathoracic pressure on the cardiovascular system. A new parameter, alpha, is added to a previously validated cardiopulmonary model, to modulate the percentage of intrathoracic pressure applied to the vena cava and left ventricle. The new parameter aims to increase reliability under high PEEP conditions as well as provide a patient specific solution to modelling cardiopulmonary interactions. The results from the identified optimal alpha are compared to the original model to investigate how this new parameter may be used to create a more patient-specific cardiopulmonary model, which would be better suited for guidance of care in the ICU.

Chest dual-energy CT to assess the effects of steroids on lung function in severe COVID-19 patients

BACKGROUND

Steroids have been shown to reduce inflammation, hypoxic pulmonary vasoconstriction (HPV) and lung edema. Based on evidence from clinical trials, steroids are widely used in severe COVID-19. However, the effects of steroids on pulmonary gas volume and blood volume in this group of patients are unexplored.

OBJECTIVE

Profiting by dual-energy computed tomography (DECT), we investigated the relationship between the use of steroids in COVID-19 and distribution of blood volume as an index of impaired HPV. We also investigated whether the use of steroids influences lung weight, as index of lung edema, and how it affects gas distribution.

METHODS

Severe COVID-19 patients included in a single-center prospective observational study at the intensive care unit at Uppsala University Hospital who had undergone DECT were enrolled in the current study. Patients' cohort was divided into two groups depending on the administration of steroids. From each patient's DECT, 20 gas volume maps and the corresponding 20 blood volume maps, evenly distributed along the cranial-caudal axis, were analyzed. As a proxy for HPV, pulmonary blood volume distribution was analyzed in both the whole lung and the hypoinflated areas. Total lung weight, index of lung edema, was estimated.

RESULTS

Sixty patients were analyzed, whereof 43 received steroids. Patients not exposed to steroids showed a more extensive non-perfused area (19% vs 13%, p < 0.01) and less homogeneous pulmonary blood volume of hypoinflated areas (kurtosis: 1.91 vs 2.69, p < 0.01), suggesting a preserved HPV compared to patients treated with steroids. Moreover, patients exposed to steroids showed a significantly lower lung weight (953 gr vs 1140 gr, p = 0.01). A reduction in alveolar-arterial difference of oxygen followed the treatment with steroids (322 ± 106 mmHg at admission vs 267 ± 99 mmHg at DECT, p = 0.04).

CONCLUSIONS

The use of steroids might cause impaired HPV and might reduce lung edema in severe COVID-19. This is consistent with previous findings in other diseases. Moreover, a reduced lung weight, as index of decreased lung edema, and a more homogeneous distribution of gas within the lung were shown in patients treated with steroids.

TRIAL REGISTRATION

Clinical Trials ID: NCT04316884, Registered March 13, 2020.

Development and validation of a clinical risk model to predict the hospital mortality in ventilated patients with acute respiratory distress syndrome: a population-based study

Background

Large variability in mortality exists in patients of acute respiratory distress syndrome (ARDS), especially those with invasive ventilation. The aim of this study was to develop a model to predict risk of in-hospital death in ventilated ARDS patients.

Methods

Ventilated patients with ARDS from two public databases (MIMIC-III and eICU-CRD) were randomly divided as training cohort and internal validation cohort. Least absolute shrinkage and selection operator (LASSO) and then Logistic regression was used to construct a predictive model with demographic, clinical, laboratory, comorbidities and ventilation variables ascertained at first 24 h of ICU admission and invasive ventilation. Our model was externally validated using data from another database (MIMIC-IV).

Results

A total of 1075 adult patients from MIMIC-III and eICU were randomly divided into training cohort (70%, n = 752) and internal validation cohort (30%, n = 323). 521 patients were included from MIMIC-IV. From 176 potential predictors, 9 independent predictive factors were included in the final model. Five variables were ascertained within the first 24 h of ICU admission, including age (OR, 1.02; 95% CI: 1.01–1.03), mean of respiratory rate (OR, 1.04; 95% CI: 1.01–1.08), the maximum of INR (OR, 1.14; 95% CI: 1.03–1.31) and alveolo-arterial oxygen difference (OR, 1.002; 95% CI: 1.001–1.003) and the minimum of RDW (OR, 1.17; 95% CI: 1.09–1.27). And four variables were collected within the first 24 h of invasive ventilation: mean of temperature (OR, 0.70; 95% CI: 0.57–0.86), the maximum of lactate (OR, 1.15; 95% CI: 1.09–1.22), the minimum of blood urea nitrogen (OR, 1.02; 95% CI: 1.01–1.03) and white blood cell counts (OR, 1.03; 95% CI: 1.01–1.06). Our model achieved good discrimination (AUC: 0.77, 95% CI: 0.73–0.80) in training cohort but the performance declined in internal (AUC: 0.75, 95% CI: 0.69–0.80) and external validation cohort (0.70, 95% CI: 0.65–0.74) and showed modest calibration.

Conclusions

A risk score based on routinely collected variables at the start of admission to ICU and invasive ventilation can predict mortality of ventilated ARDS patients, with a moderate performance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02057-0.

Right ventricular dysfunction in patients with COVID-19 pneumonitis whose lungs are mechanically ventilated: a multicentre prospective cohort study

Cardiovascular complications due to COVID-19, such as right ventricular dysfunction, are common. The combination of acute respiratory distress syndrome, invasive mechanical ventilation, thromboembolic disease and direct myocardial injury creates conditions where right ventricular dysfunction is likely to occur. We undertook a prospective, multicentre cohort study in 10 Scottish intensive care units of patients with COVID-19 pneumonitis whose lungs were mechanically ventilated. Right ventricular dysfunction was defined as the presence of severe right ventricular dilation and interventricular septal flattening. To explore the role of myocardial injury, high-sensitivity troponin and N-terminal pro B-type natriuretic peptide plasma levels were measured in all patients. We recruited 121 patients and 118 (98%) underwent imaging. It was possible to determine the primary outcome in 112 (91%). Severe right ventricular dilation was present in 31 (28%), with interventricular septal flattening present in nine (8%). Right ventricular dysfunction (the combination of these two parameters) was present in seven (6%, 95%CI 3-13%). Thirty-day mortality was 86% in those with right ventricular dysfunction as compared with 45% in those without (p = 0.051). Patients with right ventricular dysfunction were more likely to have: pulmonary thromboembolism (p < 0.001); higher plateau airway pressure (p = 0.048); lower dynamic compliance (p = 0.031); higher plasma N-terminal pro B-type natriuretic peptide levels (p = 0.006); and raised plasma troponin levels (p = 0.048). Our results demonstrate a prevalence of right ventricular dysfunction of 6%, which was associated with increased mortality (86%). Associations were also observed between right ventricular dysfunction and aetiological domains of: acute respiratory distress syndrome; ventilation; thromboembolic disease; and direct myocardial injury, implying a complex multifactorial pathophysiology.

Association of Right Ventricular Dilation and Dysfunction on Echocardiogram with In-Hospital Mortality Among Patients Hospitalized with COVID-19 Compared with Other Acute Respiratory Illness

BACKGROUND

Although right ventricular (RV) dysfunction is associated with mortality in acute COVID-19, the role of RV dilation is uncertain. The prognostic significance of RV dilation and dysfunction among hospitalized patients with acute COVID-19 compared to other respiratory illnesses.

METHODS

We conducted a retrospective cohort study to examine 225 consecutive adults admitted for acute COVID-19 and 6,150 control adults admitted for influenza, pneumonia or ARDS who had a clinical echocardiogram performed. We used logistic regression models to assess associations between RV parameters and in-hospital mortality adjusted for confounders.

RESULTS

Among those with COVID-19, 48/225 (21.3%) died during the index hospitalization compared to 727/6150 (11.8%) with other respiratory illness (p=0.001). Independent of COVID-19, mild and moderate to severe RV dilation were associated with 1.4 and 2.0 times higher risk of inpatient mortality, respectively (95%CI 1.17 to 1.69; p=0.0003; 95%CI 1.62 to 2.47; p<0.0001, respectively). Similarly, mild and moderate RV dysfunction were associated with 1.4 and 1.7 times higher risk of inpatient mortality (95%CI 1.10 to 1.77; p=0.007; 95%CI 1.17 to 2.42; p=0.005, respectively). Relative to normal RV size and non-COVID-19 acute respiratory illness, mild and moderate RV dilation were associated with 1.4 times and 2.0 times higher risk among those without COVID-19 and 1.9 times higher and 3.0 times higher risk among those with COVID-19, with similar findings for RV dysfunction. Having both RV dilation and dysfunction or RV dilation alone were associated with 1.7 times higher risk while RV dysfunction alone was associated with 1.4 times higher risk compared to normal RV size and function.

CONCLUSIONS

RV dilation and dysfunction are associated with increased risk of inpatient mortality among those with COVID-19 and other respiratory illnesses. Abnormal RV findings may identify those at higher risk of short-term mortality from acute respiratory illness including COVID-19 beyond other risk markers.

Echocardiography in Prone Positioned Critically Ill Patients: A Wealth of Information from a Single View

In critically ill patients, standard transthoracic echocardiography (TTE) generally does not facilitate good image quality during mechanical ventilation. We propose a prone-TTE in prone positioned patients, which allows clinicians to obtain a complete apical four-chamber (A-4-C) view. A basic cardiac assessment can be performed in order to evaluate right ventricle function and left ventricle performance, even measuring objective parameters, i.e., tricuspid annular plane systolic excursion (TAPSE); pulmonary artery systolic pressure (PAP), from the tricuspid regurgitation peak Doppler velocity; RV end-diastolic diameter and its ratio to left ventricular end-diastolic diameter; the S’ wave peak velocity with tissue Doppler imaging; the ejection fraction (EF); the mitral annular plane systolic excursion (MAPSE); diastolic function evaluation by the mitral valve; and annular Doppler velocities. Furthermore, by tilting the probe, we can obtain the apical-five-chamber (A-5-C) view, which facilitates the analysis of blood flow at the level of the output tract of the left ventricle (LVOT) and then the estimation of stroke volume. Useful applications of this technique are hemodynamic assessment, titration of fluids, vasoactive drugs therapy, and evaluation of the impact of prone positioning on right ventricle performance and right pulmonary resistances. We believe that considerable information can be drawn from a single view and hope this may be helpful to emergency and critical care clinicians whenever invasive hemodynamic monitoring tools are not available or are simply inconvenient due to clinical reasons.

Right Ventricular Dysfunction is Associated with Increased Mortality in Patients Requiring Venovenous Extracorporeal Membrane Oxygenation for Coronavirus Disease 2019

Respiratory failure caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is associated with mortality. Patients unresponsive to conventional therapy may benefit from temporary venovenous extracorporeal membrane oxygenation (VV-ECMO). We investigated clinical and echocardiographic characteristics, particularly, right ventricular dysfunction, with survival in patients with respiratory failure caused by SARS-CoV-2. We performed a single-center retrospective cohort study of patients requiring VV-ECMO for respiratory failure from COVID-19 infection between January 2020 and December 2020. Demographics, comorbidities, laboratory parameters, and echocardiographic features of left and right ventricular (LV/RV) function were compared between patients who survived and those who could not be weaned from VV-ECMO. In addition, we evaluated outcomes in a separate population managed with venoarterial extracorporeal membrane oxygenation (VA-ECMO). In total, 10/17 patients failed to wean from VV-ECMO and died in the hospital on average 41.5 ± 10.9 days post admission. Seven were decannulated (41%) and survived to hospital discharge. There were no significant differences in demographics, comorbidities, and laboratory parameters between groups. Moderate to severe RV dysfunction was significantly more in those who died (8/10, 80%) compared to survivors (0/7, 0%) (p = 0.002). Patients supported with VA-ECMO had superior survival with 5/9 patients (56%) decannulated and discharged. Moderate to severe RV dysfunction is associated with increased mortality in patients with respiratory failure requiring VV-ECMO for COVID-19.