Extracorporeal Membrane Oxygenation during Respiratory Pandemics: Past, Present, and Future

Ethical Considerations for Mechanical Support

Extracorporeal life support (ECLS) has the ability to support patients with severe forms of cardiac and respiratory failure. Rapid expansion of ECLS, its resource-intensive and invasive nature, and the high acuity illness of supported patients have raised important questions. Specific issues include identification of patients most likely to benefit, the appropriate duration of support amid uncertain prognosis, and what to do when patients become dependent on ECLS but no longer have hope for recovery or transplantation. Careful deliberation of ethical principles and potential dilemmas should be made when considering the use of ECLS in advanced cardiopulmonary failure.

A compact machine perfusion device for whole blood perfusion in isolated rat liver

We established a compact machine perfusion system for whole blood perfusion of rat liver by making use of oxygenation filters as an artificial lung. Livers removed from rats were divided into Krebs-Henseleit (control), 50% blood (hemoglobin: 7 g/dL), and whole blood (hemoglobin: 14 g/dL) groups, then perfused (total perfusate volume: 25 ml) with a small oxygenation filter at 37 °C for 120 min. Blood or perfusate was collected over time, and blood gas and blood cell were measured. In addition, bile volume and portal venous pressure measurements were taken. In all groups, the partial pressure of oxygen was controlled to approximately 400 mmHg. Flow rates were maintained at approximately about 20-30 ml/min according to liver size. Portal venous pressure was normal in the 50% blood and whole blood groups, while lower than the reference value in the Krebs-Henseleit group. Twice as much bile was produced in the 50% blood and whole blood groups relative with the Krebs-Henseleit group. We observed no differences in hemoglobin and red blood cell levels. Lactate levels were normal in the 50% blood and whole blood groups, but were elevated in the Krebs-Henseleit group. Our compact perfusion system using oxygenation filters was able to maintain rat liver function by perfusing a small amount of extracorporeal blood. This system is simple and stable, and may contribute to the future development of machine perfusion systems.

Experience with ECMO therapy for acute respiratory distress syndrome treatment throughout the COVID-19 pandemic

OBJECTIVE

To analyze our experience with extracorporeal membrane oxygenation (ECMO) therapy for acute respiratory distress syndrome (ARDS) treatment during the COVID-19 pandemic.

DESIGN

Retrospective, observational, single center study.

SETTING

Third-level hospital in Spain.

PATIENTS

Adult patients with COVID-19 ARDS treated with an ECMO system in our center between March 2020 and March 2023.

INTERVENTIONS

Retrospective collection of variables during hospital admission and follow-up.

MAIN VARIABLES OF INTEREST

Demographic variables, clinical history, variables related to ECMO therapy, COVID-19 wave number, in-hospital mortality, adverse events, ICU and hospital length of stay, and functional status at follow-up were collected.

RESULTS

Eighty-one patients were included. Of these, 61 patients (75%) died during hospitalization. Patients who died were older and had more comorbidities. During the second, third, and sixth waves, mortality was higher. In the multivariate analysis, the only independent predictor of mortality was age (OR 1.24 95% CI (1.027-1.5, P = 0.025). After discharge, 40% of patients had difficulties returning to normal life due to respiratory failure requiring oxygen and arthropathies.

CONCLUSION

In-hospital mortality increased during the pandemic. Older age was the only independent predictor of mortality. After discharge, no deaths were recorded during the first 18 months of follow-up, although 40% of surviving patients had respiratory and motor sequelae making it difficult for them to return to a normal life.

In-hospital outcomes and 6-month follow-up results of patients supported with extracorporeal membrane oxygenation for COVID-19 from the second wave to the end of the pandemic (EuroECMO-COVID): a prospective, international, multicentre, observational study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) for COVID-19 was thoroughly assessed during the first pandemic wave, but data on subsequent waves are limited. We aimed to investigate in-hospital and 6-month survival of patients with COVID-19 supported with ECMO from the second pandemic wave (Sept 15, 2020) until the end of the pandemic (March 21, 2023, announced by WHO).

METHODS

EuroECMO-COVID is a prospective, observational study including adults (aged ≥16 years) requiring ECMO respiratory support for COVID-19 from 98 centres in 21 countries. We compared patient characteristics and outcomes between in-hospital survivors and non-survivors. Mixed-effects multivariable logistic regressions were used to investigate factors linked to in-hospital mortality. 6-month survival and overall patient status were determined via patient contact or chart review. This study is registered with ClinicalTrials.gov, NCT04366921, and is complete.

FINDINGS

We included 3860 patients (2687 [69·7%] were male and 1169 [30·3%] were female; median age 51 years [SD 11]) from 98 centres in 21 countries. In-hospital mortality was 55·9% (n=2158), with 81·2% (n=1752) deaths occurring during ECMO support. More non-survivors had diabetes, hypertension, cardiovascular disease, and renal failure, and required more pre-ECMO inotropes and vasopressors compared with survivors. Median support duration was 18 days (IQR 10-31) for both groups. Factors linked to in-hospital mortality included older age, pre-ECMO renal failure, pre-ECMO vasopressors use, longer time from intubation to ECMO initiation, and complications, including neurological events, sepsis, bowel ischaemia, renal failure, and bleeding. Of the 1702 (44·1%) in-hospital survivors, 99·7% (n=1697) were alive at 6 months follow-up. Many patients at 6 months follow-up had dyspnoea (501 [32·0%] of 1568 patients), cardiac (122 [7·8%] of 1568 patients), or neurocognitive (168 [10·7%] of 1567 patients) symptoms.

INTERPRETATION

Our data for patients undergoing ECMO support for respiratory distress from the second COVID-19 wave onwards confirmed most findings from the first wave regarding patient characteristics and factors correlated to in-hospital mortality. Nevertheless, in-hospital mortality was higher than during the initial pandemic wave while 6-month post-discharge survival remained favourable (99·7%). Persisting post-discharge symptoms confirmed the need for post-ECMO patient follow-up programmes.

FUNDING

None.

Broadening indications: A descriptive and comparative in-depth analysis of venovenous extracorporeal membrane oxygenation outcomes in trauma and nontrauma patients

BACKGROUND

Venovenous extracorporeal membrane oxygenation (VV ECMO) has been used for medical etiologies of acute respiratory distress syndrome refractory to conventional management. More recently, VV ECMO has been used to stabilize trauma patients with acute lung injury. We hypothesize that patients with traumatic injuries requiring VV ECMO have similar survival outcomes and describe the characteristics between the two populations.

METHODS

This single-center, retrospective cohort study included all trauma and nontrauma patients in an 8-year period who were placed on VV ECMO. Cannulation decisions were made via multidisciplinary discussions between two intensivists and a trauma surgeon. Data were analyzed with descriptive statistics and regression analysis. After testing for normality, significance was defined as a p < 0.05.

RESULTS

A total of 516 patients were identified (438 nontrauma and 78 trauma VV ECMO patients). The trauma patient, defined as undergoing cannulation during initial trauma admission, had a median age of 29 years with 81% of patients being male, while the nontrauma patient had a median age of 41 years with 64% being males. Trauma VV ECMO patients had shorter ECMO courses (216 hours vs. 372 hours, p < 0.001), earlier cannulation (8 hours vs. 120 hours, p < 0.001), higher lactic acid levels precannulation (4.2 mmol/L vs. 2.3 mmol/L, p < 0.001), higher Sequential Organ Failure Assessment scores (13 vs. 11, p = 0.001), and higher Simplified Acute Physiology Scores II (63 vs. 48, p < 0.001). There was no difference in bleeding complications. Survival to discharge rates were similar between trauma and nontrauma VV ECMO groups (69% vs. 71%, p = 0.81).

CONCLUSION

This study demonstrates that trauma VV ECMO patients have higher markers of severe illness/injury when compared with their nontrauma VV ECMO counterparts yet have similar survival rates and shorter ECMO runs. Venovenous extracorporeal membrane oxygenation in trauma patients is a useful treatment modality for refractory hypoxemia, respiratory acidosis, and stabilization because of acute lung and thoracic injury.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level IV.

Analysis of diagnostic criteria for ECMO-associated pneumonia

Ventilator-associated pneumonia (VAP) is a well-established cause of morbidity in critically ill patients. Current VAP criteria exclude patients on extracorporeal membrane oxygenation (ECMO). This retrospective analysis tests the validity of VAP in this population, as well as a new proposed diagnostic criterion for ECMO-associated pneumonia.

Extracorporeal Support for Acute Respiratory Distress Syndrome

Extracorporeal life support (ECLS) has a long history in the management of the acute respiratory distress syndrome (ARDS). The objectives of this review are to summarize the rationale and evidence for ECLS in ARDS including its role in reducing ventilator-induced lung injury (VILI), suggest best practice management strategies during ECLS, and identify areas that require additional research to better inform patient care.

Clinician Prediction of Survival vs Calculated Prediction Scores in Patients Requiring Extracorporeal Membrane Oxygenation

BACKGROUND

Determining appropriate extracorporeal membrane oxygenation (ECMO) candidacy ensures appropriate utilization of this costly resource. The current ECMO survival prediction scores do not consider clinician assessment of patient viability. This study compared clinician prediction of survival to hospital discharge versus prediction scores.

OBJECTIVES

The aim of this study was to compare clinician prediction of patients' survival to hospital discharge versus prognostic prediction scores (Respiratory ECMO Survival Prediction [RESP] or Survival After Veno-Arterial ECMO [SAVE] score) to actual survival.

METHODS

This was an observational descriptive study from January 2020 to November 2021 conducted with interviews of nurses, perfusionists, and physicians who were involved during the initiation of ECMO within the first 24 hours of cannulation. Data were retrieved from the medical record to determine prediction scores and survival outcomes at hospital discharge. Accuracy of clinician prediction of survival was compared to the RESP or SAVE prediction scores and actual survival to hospital discharge.

RESULTS

Accurate prediction of survival to hospital discharge for veno-venous ECMO by nurses was 47%, 64% by perfusionists, 45% by physicians, and 45% by the RESP score. Accurate predictions of patients on veno-arterial ECMO were correct in 54% of nurses, 77% of physicians, and 14% by the SAVE score. Physicians were more accurate than the SAVE score, P = .021, and perfusionists were significantly more accurate than the RESP score, P = .044. There was no relationship between ECMO specialists' years of experience and accuracy of predications.

CONCLUSION

Extracorporeal membrane oxygenation clinicians may have better predictions of survival to hospital discharge than the prediction scores. Further research is needed to develop accurate prediction tools to help determine ECMO eligibility.

Long Term Veno-Pulmonary Arterial Extracorporeal Membrane Oxygenation as Bridge to Lung Transplantation and Its Challenges: A Case Report

We present a case of a patient with acute respiratory distress syndrome due to severe acute respiratory syndrome coronavirus 2 infection who underwent an extracorporeal membrane oxygenation (ECMO) run of 8 months with various configuration changes, including off-label use of cannulas. The patient eventually underwent successful double lung transplantation after a follow-up of 17 months, demonstrating the successful application of a hybrid approach and careful monitoring in the face of supply shortages during the pandemic. This case highlights the challenges faced by ECMO and transplantation centers during the pandemic and the importance of careful communication and planning to optimize patient outcomes.

Radiation Exposure in Extracorporeal Life Support

Extracorporeal membrane oxygenation (ECMO) exposes patients to multiple radiologic studies. We hypothesized ECMO patients endure radiation exposure in excess of the International Commission of Radiological Protection (ICRP) recommendations of cumulative effective dose (CED, >20 mSv and 5-year cumulative limit of CED >100 mSv). We conducted a retrospective observational study in an academic medical center between January 2016 and December 2018 involving adult admissions (N = 306) on ECMO. Ionizing radiation was calculated from reference values to determine CED. Approximately 9.4% (N = 29) patients accrued CED >50 mSv and 4.5% (N = 14) accrued CED >100 mSv during ECMO. Over the entire hospitalization, 28% (N = 85) accrued >50 mSv and 14.7% (N = 45) accrued CED >100 mSv. Median CED during ECMO was 2.3 mSv (IQR, -0.82 to 8.1 mSv), and the entire hospitalization was 17.4 mSv (IQR, -4.5 to 56.6 mSv). Thirteen percent of the median CED accrued during hospitalization could be attributed to ECMO. Longer hospitalization was associated with a higher CED (50 days [IQR, -25 to 76 days] in CED >50 vs. 19 days [IQR, -10 to 32 days] in CED <50). Computer tomography (CT) scans and interventional radiology (IR) procedures contributed to 43.8% and 44.86%, respectively, of CED accrued on ECMO and 52.2% and 37.1% of CED accumulated during the whole hospitalization. Guidelines aimed at mitigating radiation exposure are urgently needed.

Extracorporeal Membrane Oxygenation (ECMO): A Lifeline for Pregnant and Postpartum Women

Extracorporeal membrane oxygenation (ECMO) is a life-saving technology that temporarily supports the heart and lungs in critical care situations. This review article examines the role of ECMO as a lifeline for pregnant and postpartum women facing severe maternal and fetal conditions. The review begins with an overview of the physiology and pathophysiology of ECMO, including its procedure and how it supports cardiopulmonary function. Unique considerations specific to pregnant and postpartum women, such as physiological changes during pregnancy, risks and complications associated with ECMO, and the need to balance maternal and fetal considerations, are discussed. The indications for ECMO in this population are explored, including common maternal indications such as cardiogenic shock, acute respiratory distress syndrome (ARDS), pulmonary embolism, and eclampsia, as well as fetal indications such as fetal distress, hypoxic-ischemic encephalopathy (HIE), and twin-to-twin transfusion syndrome (TTTS). The challenges and considerations in ECMO for pregnant and postpartum women, including ethical considerations and the decision-making process, are highlighted. The review further explores the multidisciplinary care and collaborative approach required, emphasizing the importance of a specialized ECMO team and collaboration between obstetricians, neonatologists, cardiologists, and other specialists. Additionally, patient selection, pre-ECMO assessment, and planning strategies are discussed. The review evaluates existing literature and studies on ECMO in pregnant and postpartum women, analyzing survival rates and maternal and fetal outcomes and comparing different ECMO modalities and strategies. Future directions and research opportunities are presented, including emerging technologies, areas for further research and clinical trials, and improved patient selection and management strategies. The conclusion emphasizes the importance of ECMO as a lifeline for pregnant and postpartum women and the potential impact on maternal and fetal health. The review highlights the need for ongoing research and advancements in ECMO to optimize outcomes and improve care for this unique and vulnerable patient population.

Outcome of Emergency Pulmonary Lobectomy under ECMO Support in Patients with COVID-19

BACKGROUND

 Not much is known about the results of nonelective anatomical lung resections in coronavirus disease 2019 (COVID-19) patients put on extracorporeal membrane oxygenation (ECMO). The aim of this study was to analyze the outcome of lobectomy under ECMO support in patients with acute respiratory failure due to severe COVID-19.

METHODS

 All COVID-19 patients undergoing anatomical lung resection with ECMO support at a German university hospital were included into a prospective database. Study period was April 1, 2020, to April 30, 2021 (first, second, and third waves in Germany).

RESULTS

 A total of nine patients (median age 61 years, interquartile range 10 years) were included. There was virtually no preexisting comorbidity (median Charlson score of comorbidity 0.2). The mean interval between first positive COVID-19 test and surgery was 21.9 days. Clinical symptoms at the time of surgery were sepsis (nine of nine), respiratory failure (nine of nine), acute renal failure (five of nine), pleural empyema (five of nine), lung artery embolism (four of nine), and pneumothorax (two of nine). Mean intensive care unit (ICU) and ECMO days before surgery were 15.4 and 6, respectively. Indications for surgery were bacterial superinfection with lung abscess formation and progressive septic shock (seven of nine) and abscess formation with massive pulmonary hemorrhage into the abscess cavity (two of nine). All patients were under venovenous ECMO with femoral-jugular configuration. Operative procedures were lobectomy (eight) and pneumonectomy (one). Weaning from ECMO was successful in four of nine. In-hospital mortality was five of nine. Mean total ECMO days were 10.3 ± 6.2 and mean total ICU days were 27.7 ± 9.9. Mean length of stay was 28.7 ± 8.8 days.

CONCLUSION

 Emergency surgery under ECMO support seems to open up a perspective for surgical source control in COVID-19 patients with bacterial superinfection and localized pulmonary abscess.

1-Year Outcomes of Lung Transplantation for Coronavirus Disease 2019-Associated End-Stage Lung Disease in the United States

BACKGROUND

Lung transplantation can provide quality of life and survival benefits for patients with coronavirus disease 2019 (COVID-19)-associated end-stage lung disease. Characteristics and outcomes of these lung transplant recipients are limited to mostly single-center experiences or provide a short-term follow-up.

METHODS

Characteristics of deceased donors and adult lung transplant recipients for COVID-19-associated end-stage lung disease between August-2020 and June-2022 were analyzed using deidentified United Network for Organ Sharing database. Post-transplant patient survival of COVID-19 recipients was analyzed and compared with non-COVID-19 recipients. Secondary outcomes were length of hospitalization, post-transplant complications, and rates of organ rejection.

RESULTS

During the study period, 400 lung transplants for COVID-associated end-stage lung disease comprised 8.7% of all lung transplants performed in United States. In the COVID-19 group, Hispanic males received lung transplants at significantly higher rates. The COVID-19 group was younger and had greater need for intensive care unit stay, mechanical ventilation, hemodialysis, extracorporeal membrane oxygenation support, and receipt of antibiotics pre-lung transplant. They had higher lung allocation score, with a shorter wait-list time and received more double lung transplants compared with non-COVID-19 recipients. Post-transplant, the COVID-19 cohort had longer hospital stays, with similar 1-year patient survival (COVID, 86.6% vs non-COVID, 86.3%). Post-transplant, COVID-19-associated deaths were 9.2% of all deaths among lung transplant recipients.

CONCLUSIONS

Lung transplantation offers a effective option for carefully selected patients with end-stage lung disease from prior COVID-19, with short-term and long-term outcomes similar to those for lung transplant recipients of non-COVID-19 etiology.

Timing of Lung Transplant Referral in Patients with Severe COVID-19 Lung Injury Supported by ECMO

Severe respiratory failure caused by COVID-19 often requires mechanical ventilation, including extracorporeal membrane oxygenation (ECMO). In rare cases, lung transplantation (LTx) may be considered as a last resort. However, uncertainties remain about patient selection and optimal timing for referral and listing. This retrospective study analyzed patients with severe COVID-19 who were supported by veno-venous ECMO and listed for LTx between July 2020 and June 2022. Out of the 20 patients in the study population, four who underwent LTx were excluded. The clinical characteristics of the remaining 16 patients were compared, including nine who recovered and seven who died while awaiting LTx. The median duration from hospitalization to listing was 85.5 days, and the median duration on the waitlist was 25.5 days. Younger age was significantly associated with a higher likelihood of recovery without LTx after a median of 59 days on ECMO, compared to those who died at a median of 99 days. In patients with severe COVID-19-induced lung damage supported by ECMO, referral to LTx should be delayed for 8-10 weeks after ECMO initiation, particularly for younger patients who have a higher probability of spontaneous recovery and may not require LTx.

Extracorporeal Membrane Oxygenation Then and Now; Broadening Indications and Availability

Extracorporeal membrane oxygenation (ECMO) is a life support technology provided to children to support respiratory failure, cardiac failure, or cardiopulmonary resuscitation after failure of conventional management. Over the decades, ECMO has expanded in use, advanced in technology, shifted from experimental to a standard of care, and evidence supporting its use has increased. The expanded ECMO indications and medical complexity of children have also necessitated focused studies in the ethical domain such as decisional authority, resource allocation, and equitable access.

Extracorporeal membrane oxygenation in adults receiving haematopoietic cell transplantation: an international expert statement

Combined advances in haematopoietic cell transplantation (HCT) and intensive care management have improved the survival of patients with haematological malignancies admitted to the intensive care unit. In cases of refractory respiratory failure or refractory cardiac failure, these advances have led to a renewed interest in advanced life support therapies, such as extracorporeal membrane oxygenation (ECMO), previously considered inappropriate for these patients due to their poor prognosis. Given the scarcity of evidence-based guidelines on the use of ECMO in patients receiving HCT and the need to provide equitable and sustainable access to ECMO, the European Society of Intensive Care Medicine, the Extracorporeal Life Support Organization, and the International ECMO Network aimed to develop an expert consensus statement on the use of ECMO in adult patients receiving HCT. A steering committee with expertise in ECMO and HCT searched the literature for relevant articles on ECMO, HCT, and immune effector cell therapy, and developed opinion statements through discussions following a Quaker-based consensus approach. An international panel of experts was convened to vote on these expert opinion statements following the Research and Development/University of California, Los Angeles Appropriateness Method. The Appraisal of Guidelines for Research and Evaluation statement was followed to prepare this Position Paper. 36 statements were drafted by the steering committee, 33 of which reached strong agreement after the first voting round. The remaining three statements were discussed by all members of the steering committee and expert panel, and rephrased before an additional round of voting. At the conclusion of the process, 33 statements received strong agreement and three weak agreement. This Position Paper could help to guide intensivists and haematologists during the difficult decision-making process regarding ECMO candidacy in adult patients receiving HCT. The statements could also serve as a basis for future research focused on ECMO selection criteria and bedside management.

Prognostic factors associated with mortality among patients receiving venovenous extracorporeal membrane oxygenation for COVID-19: a systematic review and meta-analysis

BACKGROUND

Venovenous extracorporeal membrane oxygenation (ECMO) can be considered for patients with COVID-19-associated acute respiratory distress syndrome (ARDS) who continue to deteriorate despite evidence-based therapies and lung-protective ventilation. The Extracorporeal Life Support Organization has emphasised the importance of patient selection; however, to better inform these decisions, a comprehensive and evidence-based understanding of the risk factors associated with poor outcomes is necessary. We aimed to summarise the association between pre-cannulation prognostic factors and risk of mortality in adult patients requiring venovenous ECMO for the treatment of COVID-19.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE and Embase from Dec 1, 2019, to April 14, 2022, for randomised controlled trials and observational studies involving adult patients who required ECMO for COVID-19-associated ARDS and for whom pre-cannulation prognostic factors associated with in-hospital mortality were evaluated. We conducted separate meta-analyses of unadjusted and adjusted odds ratios (uORs), adjusted hazard ratios (aHRs), and mean differences, and excluded studies if these data could not be extracted. We assessed the risk of bias using the Quality in Prognosis Studies tool and certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation approach. Our protocol was registered with the Open Science Framework registry, osf.io/6gcy2.

FINDINGS

Our search identified 2888 studies, of which 42 observational cohort studies involving 17 449 patients were included. Factors that had moderate or high certainty of association with increased mortality included patient factors, such as older age (adjusted hazard ratio [aHR] 2·27 [95% CI 1·63-3·16]), male sex (unadjusted odds ratio [uOR] 1·34 [1·20-1·49]), and chronic lung disease (aHR 1·55 [1·20-2·00]); pre-cannulation disease factors, such as longer duration of symptoms (mean difference 1·51 days [95% CI 0·36-2·65]), longer duration of invasive mechanical ventilation (uOR 1·94 [1·40-2·67]), higher partial pressure of arterial carbon dioxide (mean difference 4·04 mm Hg [1·64-6·44]), and higher driving pressure (aHR 2·36 [1·40-3·97]); and centre factors, such as less previous experience with ECMO (aOR 2·27 [1·28-4·05].

INTERPRETATION

The prognostic factors identified highlight the importance of patient selection, the effect of injurious lung ventilation, and the potential opportunity for greater centralisation and collaboration in the use of ECMO for the treatment of COVID-19-associated ARDS. These factors should be carefully considered as part of a risk stratification framework when evaluating a patient for potential treatment with venovenous ECMO.

FUNDING

None.

Same but Different-ECMO in COVID-19 and ARDS of Other Etiologies. Comparison of Survival Outcomes and Management in Different ARDS Groups

Background: COVID-19 has led to increased numbers of patients in need of venovenous extracorporeal membrane oxygenation (ECMO) support, but knowledge on management in comparison to acute respiratory distress syndrome (ARDS) of other etiologies is still lacking. We analyzed venovenous ECMO management and survival outcomes in patients with COVID-19 in comparison to influenza ARDS and pulmonary ARDS of other origin. Results: Retrospective analysis of prospective venovenous ECMO registry-based data collection was performed. One hundred consecutive venovenous ECMO patients with severe ARDS were included (41 COVID-19, 24 influenza A, 35 ARDS of other etiologies). Patients with COVID-19 had higher BMI (body mass index), lower SOFA (Sequential Organ Failure Assessment) and APACHE II (Acute Physiology and Chronic Health Evaluation II) scores, lower C-reactive protein and procalcitonin levels and less vasoactive support at ECMO initiation. Significantly more patients were mechanically ventilated for more than 7 days prior to ECMO initiation in the COVID-19 group, however they were ventilated with lower tidal volumes and more often received additional rescue therapies prior to and on ECMO. COVID-19 patients had significantly more barotrauma and thrombotic events on ECMO. There were no differences in weaning of ECMO, however duration of ECMO runs and ICU length of stay was significantly longer in the COVID-19 group. The leading cause of death in the COVID-19 group was irreversible respiratory failure, while uncontrolled sepsis and multiorgan failure were leading causes in the other 2 groups. All patients who survived ICU treatment were discharged out of hospital, and there were no differences in survival among groups at 180 days. Conclusions: Survival outcomes of venovenous ECMO patients do not differ between COVID-19 and ARDS of other pulmonary etiologies. ARDS guidelines were in greater proportion adhered to in COVID-19 patients, with, however, longer time to ECMO initiation. COVID-19 ARDS seems specific as a more single-organ disease with longer ECMO duration and irreversible respiratory failure as a main cause of ICU mortality.

Extracorporeal membrane oxygenation for COVID-19-related acute respiratory distress syndrome: a narrative review

A growing body of evidence supports the use of extracorporeal membrane oxygenation (ECMO) for severe acute respiratory distress syndrome (ARDS) refractory to maximal medical therapy. ARDS may develop in a proportion of patients hospitalized for coronavirus disease 2019 (COVID-19) and ECMO may be used to manage patients refractory to maximal medical therapy to mitigate the risk of ventilator-induced lung injury and provide lung rest while awaiting recovery. The mortality of COVID-19-related ARDS was variously reassessed during the pandemic. Veno-venous (VV) ECMO was the default choice to manage refractory respiratory failure; however, with concomitant severe right ventricular dysfunction, venoarterial (VA) ECMO or mechanical right ventricular assist devices with extracorporeal gas exchange (Oxy-RVAD) were also considered. ECMO has also been used to manage special populations such as pregnant women, pediatric patients affected by severe forms of COVID-19, and, in cases with persistent and seemingly irreversible respiratory failure, as a bridge to successful lung transplantation. In this narrative review, we outline and summarize the most recent evidence that has emerged on ECMO use in different patient populations with COVID-19-related ARDS.

Discontinuation of ECMO-a review with a note on Indian scenario

Extracorporeal membrane oxygenation (ECMO) has strikingly progressed over the last 20 years in the management of adult and pediatric severe respiratory and cardiac dysfunctions refractory to conventional management. In this review, we will discuss the weaning strategies of veno-venous and veno-arterial ECMO including the bridge to recovery and bridge to transplant along with post-ECMO care. We will also discuss the futility and the management of bridge to nowhere from Indian perspectives.

Comparative outcomes of extracorporeal membrane oxygenation for COVID-19 delivered in experienced European centres during successive SARS-CoV-2 variant outbreaks (ECMO-SURGES): an international, multicentre, retrospective cohort study

BACKGROUND

To inform future research and practice, we aimed to investigate the outcomes of patients who received extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) due to different variants of SARS-CoV-2.

METHODS

This retrospective study included consecutive adult patients with laboratory-confirmed SARS-CoV-2 infection who received ECMO for ARDS in 21 experienced ECMO centres in eight European countries (Austria, Belgium, England, France, Germany, Italy, Portugal, and Spain) between Jan 1, 2020, and Sept 30, 2021. We collected data on patient characteristics, clinical status, and management before and after the initiation of ECMO. Participants were grouped according to SARS-CoV-2 variant (wild type, alpha, delta, or other) and period of the pandemic (first [Jan 1-June 30] and second [July 1-Dec 31] semesters of 2020, and first [Jan 1-June 30] and second [July 1-Sept 30] semesters of 2021). Descriptive statistics and Kaplan-Meier survival curves were used to analyse evolving characteristics, management, and patient outcomes over the first 2 years of the pandemic, and independent risk factors of mortality were determined using multivariable Cox regression models. The primary outcome was mortality 90 days after the initiation of ECMO, with follow-up to Dec 30, 2021.

FINDINGS

ECMO was initiated in 1345 patients. Patient characteristics and management were similar for the groups of patients infected with different variants, except that those with the delta variant had a younger median age and less hypertension and diabetes. 90-day mortality was 42% (569 of 1345 patients died) overall, and 43% (297/686) in patients infected with wild-type SARS-CoV-2, 39% (152/391) in those with the alpha variant, 40% (78/195) in those with the delta variant, and 58% (42/73) in patients infected with other variants (mainly beta and gamma). Mortality was 10% higher (50%) in the second semester of 2020, when the wild-type variant was still prevailing, than in other semesters (40%). Independent predictors of mortality were age, immunocompromised status, a longer time from intensive care unit admission to intubation, need for renal replacement therapy, and higher Sequential Organ Failure Assessment haemodynamic component score, partial pressure of arterial carbon dioxide, and lactate concentration before ECMO. After adjusting for these variables, mortality was significantly higher with the delta variant than with the other variants, the wild-type strain being the reference.

INTERPRETATION

Although crude mortality did not differ between variants, adjusted risk of death was highest for patients treated with ECMO infected with the delta variant of SARS-CoV-2. The higher virulence and poorer outcomes associated with the delta strain might relate to higher viral load and increased inflammatory response syndrome in infected patients, reinforcing the need for a higher rate of vaccination in the population and updated selection criteria for ECMO, should a new and highly virulent strain of SARS-CoV-2 emerge in the future. Mortality was noticeably lower than in other large, multicentre series of patients who received ECMO for COVID-19, highlighting the need to concentrate resources at experienced centres.

FUNDING

None.

Introduction to the Special Issue-Cardiothoracic Surgical Critical Care: A Future of Distinction

Critical care after cardiothoracic surgery is an inseparable component of any successful surgical program addressing intrathoracic pathologies, including heart failure treatment with mechanical circulatory support, and respiratory failure requiring extracorporeal membrane oxygenation (ECMO) therapy [...].

The Use of ECMO for COVID-19: Lessons Learned

The coronavirus disease 2019 (COVID-19) pandemic has seen an increase in global cases of severe acute respiratory distress syndrome (ARDS), with a concomitant increased demand for extracorporeal membrane oxygenation (ECMO). Outcomes of patients with severe ARDS due to COVID-19 infection receiving ECMO support are evolving. The need for surge capacity, practical and ethical limitations on implementing ECMO, and the prolonged duration of ECMO support in patients with COVID-19-related ARDS has revealed limitations in organization and resource utilization. Coordination of efforts at multiple levels, from research to implementation, resulted in numerous innovations in the delivery of ECMO.

Respiratory indications for ECMO: focus on COVID-19

Extracorporeal membrane oxygenation (ECMO) is increasingly being used for patients with severe respiratory failure and has received particular attention during the coronavirus disease 2019 (COVID-19) pandemic. Evidence from two key randomized controlled trials, a subsequent post hoc Bayesian analysis, and meta-analyses support the interpretation of a benefit of ECMO in combination with ultra-lung-protective ventilation for select patients with very severe forms of acute respiratory distress syndrome (ARDS). During the pandemic, new evidence has emerged helping to better define the role of ECMO for patients with COVID-19. Results from large cohorts suggest outcomes during the first wave of the pandemic were similar to those in non-COVID-19 cohorts. As the pandemic continued, mortality of patients supported with ECMO has increased. However, the precise reasons for this observation are unclear. Known risk factors for mortality in COVID-19 and non-COVID-19 patients are higher patient age, concomitant extra-pulmonary organ failures or malignancies, prolonged mechanical ventilation before ECMO, less experienced treatment teams and lower ECMO caseloads in the treating center. ECMO is a high resource-dependent support option; therefore, it should be used judiciously, and its availability may need to be constrained when resources are scarce. More evidence from high-quality research is required to better define the role and limitations of ECMO in patients with severe COVID-19.

Ethical Considerations in Ever-Expanding Utilization of ECLS: A Research Agenda

Technological advancements and rapid expansion in the clinical use of extracorporeal life support (ECLS) across all age ranges in the last decade, including during the COVID-19 pandemic, has led to important ethical considerations. As a costly and resource intensive therapy, ECLS is used emergently under high stakes circumstances where there is often prognostic uncertainty and risk for serious complications. To develop a research agenda to further characterize and address these ethical dilemmas, a working group of specialists in ECLS, critical care, cardiothoracic surgery, palliative care, and bioethics convened at a single pediatric academic institution over the course of 18 months. Using an iterative consensus process, research questions were selected based on: (1) frequency, (2) uniqueness to ECLS, (3) urgency, (4) feasibility to study, and (5) potential to improve patient care. Questions were categorized into broad domains of societal decision-making, bedside decision-making, patient and family communication, medical team dynamics, and research design and implementation. A deeper exploration of these ethical dilemmas through formalized research and deliberation may improve equitable access and quality of ECLS-related medical care.