Mechanical Ventilation Management during Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome. An International Multicenter Prospective Cohort

Management of severe acute respiratory distress syndrome: a primer

This narrative review explores the physiology and evidence-based management of patients with severe acute respiratory distress syndrome (ARDS) and refractory hypoxemia, with a focus on mechanical ventilation, adjunctive therapies, and veno-venous extracorporeal membrane oxygenation (V-V ECMO). Severe ARDS cases increased dramatically worldwide during the Covid-19 pandemic and carry a high mortality. The mainstay of treatment to improve survival and ventilator-free days is proning, conservative fluid management, and lung protective ventilation. Ventilator settings should be individualized when possible to improve patient-ventilator synchrony and reduce ventilator-induced lung injury (VILI). Positive end-expiratory pressure can be individualized by titrating to best respiratory system compliance, or by using advanced methods, such as electrical impedance tomography or esophageal manometry. Adjustments to mitigate high driving pressure and mechanical power, two possible drivers of VILI, may be further beneficial. In patients with refractory hypoxemia, salvage modes of ventilation such as high frequency oscillatory ventilation and airway pressure release ventilation are additional options that may be appropriate in select patients. Adjunctive therapies also may be applied judiciously, such as recruitment maneuvers, inhaled pulmonary vasodilators, neuromuscular blockers, or glucocorticoids, and may improve oxygenation, but do not clearly reduce mortality. In select, refractory cases, the addition of V-V ECMO improves gas exchange and modestly improves survival by allowing for lung rest. In addition to VILI, patients with severe ARDS are at risk for complications including acute cor pulmonale, physical debility, and neurocognitive deficits. Even among the most severe cases, ARDS is a heterogeneous disease, and future studies are needed to identify ARDS subgroups to individualize therapies and advance care.

Mechanical ventilation in patients with acute respiratory distress syndrome: current status and future perspectives

INTRODUCTION

Although there has been extensive research on mechanical ventilation for acute respiratory distress syndrome (ARDS), treatment remains mainly supportive. Recent studies and new ventilatory modes have been proposed to manage patients with ARDS; however, the clinical impact of these strategies remains uncertain and not clearly supported by guidelines. The aim of this narrative review is to provide an overview and update on ventilatory management for patients with ARDS.

AREAS COVERED

This article reviews the literature regarding mechanical ventilation in ARDS. A comprehensive overview of the principal settings for the ventilator parameters involved is provided as well as a report on the differences between controlled and assisted ventilation. Additionally, new modes of assisted ventilation are presented and discussed. The evidence concerning rescue strategies, including recruitment maneuvers and extracorporeal membrane oxygenation support, is analyzed. PubMed, EBSCO, and the Cochrane Library were searched up until June 2023, for relevant literature.

EXPERT OPINION

Available evidence for mechanical ventilation in cases of ARDS suggests the use of a personalized mechanical ventilation strategy. Although promising, new modes of assisted mechanical ventilation are still under investigation and guidelines do not recommend rescue strategies as the standard of care. Further research on this topic is required.

Prognostic value of respiratory compliance course on mortality in COVID-19 patients with vv-ECMO

BACKGROUND

COVID-19-associated acute respiratory distress syndrome (ARDS) supported by veno-venous extra-corporal membrane oxygenation (vv-ECMO) results in a high in-hospital mortality rate of more than 35%. However, after cannulation, no prognostic factor has been described to guide the management of these patients. The objective was to assess the association between static respiratory compliance over the first 10 days post-vv-ECMO implantation on 180-day mortality.

RESULTS

In this multicentric retrospective study in three ECMO referral centers, all patients with COVID-19-associated ARDS supported by vv-ECMO were included from 03/01/2020 to 12/31/2021. Patients were ventilated with ultra-protective settings targeting a driving pressure lower than 15 cmH₂O. 122 patients were included. Median age was 59 IQR (52-64), 83 (68%) were male, with a median body mass index of 33 (28-37) kg/m². Delay between first symptoms to vv-ECMO implantation was 16 (10-21) days. Six-month death was 48%. Over the first ten days, compliance increased in 180 day survivors [from 18 (12-25) to 20 (15-27) mL/cmH₂O] compared to non-survivors [from 12 (9-20) to 10 (8-14) mL/cmH₂O, p interaction < 0.0001]. A time varying multivariable Cox model found age, history of chronic lung disease, compliance from day one to day ten and sweep gas flow from day one to day ten as independent factors associated with 180-day mortality.

CONCLUSIONS

In COVID-19-associated ARDS, static respiratory compliance course over the first ten days post-vv-ECMO implantation is associated with 180-day mortality. This new information may provide crucial information on the patient's prognosis for intensivists.

Response to Prone Position in COVID-19 and Non-COVID-19 Patients with Severe ARDS Supported by vvECMO

BACKGROUND

For moderate to severe acute respiratory distress syndrome (ARDS), lung-protective ventilation combined with prolonged and repeated prone position (PP) is recommended. For the most severe patients for whom this strategy failed, venovenous extracorporeal membrane oxygenation (vv-ECMO) allows a reduction in ventilation-induced lung injury and improves survival. Some aggregated data have suggested a benefit regarding survival in pursuing PP during vv-ECMO. The combination of PP and vv-ECMO has been also documented in COVID-19 studies, although there is scarce evidence concerning respiratory mechanics and gas exchange response. The main objective was to compare the physiological response of the first PP during vv-ECMO in two cohorts of patients (COVID-19-related ARDS and non-COVID-19 ARDS) regarding respiratory system compliance (C_RS) and oxygenation changes.

METHODS

This was a single-center, retrospective, and ambispective cohort study in the ECMO center of Marseille, France. ECMO was indicated according to the EOLIA trial criteria.

RESULTS

A total of 85 patients were included, 60 in the non-COVID-19 ARDS group and 25 in the COVID-19-related ARDS group. Lung injuries of the COVID-19 cohort exhibited significantly higher severity with a lower C_RS at baseline. Concerning the main objective, the first PP during vv-ECMO was not associated with a change in C_RS or other variation in respiratory mechanic variables in both cohorts. By contrast, oxygenation was improved only in the non-COVID-19 ARDS group after a return to the supine position. Mean arterial pressure was higher during PP as compared with a return to the supine position in the COVID-19 group.

CONCLUSION

We found distinct physiological responses to the first PP in vv-ECMO-supported ARDS patients according to the COVID-19 etiology. This could be due to higher severity at baseline or specificity of the disease. Further investigations are warranted.

Lung ultrasound to evaluate pulmonary changes in patients with cardiogenic shock undergoing extracorporeal membrane oxygenation: a retrospective study

PURPOSE

The aim of the study was to evaluate the value of lung ultrasound (LUS) in patients with cardiogenic shock treated by venoarterial extracorporeal membrane oxygenation (VA-ECMO).

METHODS

A retrospective study was conducted in Xuzhou Central Hospital from September 2015 to April 2022. Patients with cardiogenic shock who received VA-ECMO treatment were enrolled in this study. The LUS score was obtained at the different time points of ECMO.

RESULTS

Twenty-two patients were divided into a survival group (n = 16) and a nonsurvival group (n = 6). The intensive care unit (ICU) mortality was 27.3% (6/22). The LUS scores in the nonsurvival group were significantly higher than those in the survival group after 72 h (P < 0.05). There was a significant negative correlation between LUS scores and PaO₂/FiO₂ and LUS scores and pulmonary dynamic compliance(Cdyn) after 72 h of ECMO treatment (P < 0.001). ROC curve analysis showed that the area under the ROC curve (AUC) of T₇₂-LUS was 0.964 (95% CI 0.887 ~ 1.000, P < 0.01).

CONCLUSION

LUS is a promising tool for evaluating pulmonary changes in patients with cardiogenic shock undergoing VA-ECMO.

TRIAL REGISTRATION

The study had been registered in the Chinese Clinical Trial Registry(NO.ChiCTR2200062130 and 24/07/2022).

Randomized controlled trial of ultra-protective vs. protective ventilation strategy in veno-arterial extracorporeal membrane oxygenation patients with refractory cardiogenic shock: a study protocol for the ultra-ECMO trial

Background

A protective or ultra-protective tidal volume strategy is widely applied to patients with acute respiratory distress syndrome (ARDS). The use of very low tidal volume has the potential to further redece ventilation-induced lung injury (VILI) comparde with a "normal" lung protective management. Plus, cardiogenic pulmonary edema (CPE) caused by hydrostatic mechanisms in patients with cardiogenic shock has similar respiratory mechanics to those found in patients with ARDS. And no consensus exists on mechanical ventilation parameter settings in patients with VA-ECMO. The study aimed to investigate the impact of an ultra-protective tidal volume strategy on the 28-day ventilator-free day (VFD) number in VA-ECMO-supported patients with refractory cardiogenic shock, including cardiac arrest.

Methods

The Ultra-ECMO trial is a randomized controlled, open-label, single-center prospective superiority trial. At the onset of ECMO initiation, we will divide patients randomly into an intervention group and a control group in a 1:1 ratio. The control group will adopt protective ventilation settings [initial tidal volume: 6 ml/kg of predicted body weight (PBW)] for ventilation, and the intervention group will adopt ultra-protective ventilation settings (initial tidal volume: 4 ml/kg of PBW) for ventilation. The procedure is expected to last 72 h, after which the ventilator settings will be at the intensivists' discretion. The primary outcome is the VFD number at 28 days after inclusion. The secondary outcomes will include respiratory mechanics; analgesic/sedation dosage; lung ultrasound score; interleukin-6, interleukin-8, and monocyte chemotactic protein-1 levels in broncho-alveolar lavage fluid at the moment of enrollment (T0), 24, 48, and 72 h (T1, T2, and T3, respectively) after ECMO initiation; total time (in days) required for ECMO weaning; length of stay in the intensive care unit; total cost of hospitalization; amounts of resuscitative fluids; and in-hospital mortality.

Discussion

VA-ECMO-treated patients without ARDS possess abnormal lung function. CPE, thoracic compliance reduction, and poor pulmonary blood perfusion are frequently present, and these patients can more easily progress to ARDS. It seems that targeting the protective tidal volume can lower adverse outcome incidence rates, even in patients without ARDS. This trial seeks to answer the question of whether adopting an ultra-protective tidal volume strategy can lead to superior primary and secondary outcomes compared to adopting a protective tidal volume strategy in patients treated by VA-ECMO. The Ultra-ECMO trial will provide an innovative mechanical ventilation strategy for VA-ECMO-supported patients for improving treatment outcomes at biological and potentially clinical levels.

Clinical Trial Registration

ChiCTR2200067118.

Setting and Monitoring of Mechanical Ventilation During Venovenous ECMO

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2023. Other selected articles can be found online at  https://www.biomedcentral.com/collections/annualupdate2023 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from  https://link.springer.com/bookseries/8901 .

Mechanical power of ventilation and driving pressure: two undervalued parameters for pre extracorporeal membrane oxygenation ventilation and during daily management?

The current ARDS guidelines highly recommend lung protective ventilation which include plateau pressure (P_plat < 30 cm H₂O), positive end expiratory pressure (PEEP > 5 cm H₂O) and tidal volume (V_t of 6 ml/kg) of predicted body weight. In contrast, the ELSO guidelines suggest the evaluation of an indication of veno-venous extracorporeal membrane oxygenation (ECMO) due to hypoxemic or hypercapnic respiratory failure or as bridge to lung transplantation. Finally, these recommendations remain a wide range of scope of interpretation. However, particularly patients with moderate-severe to severe ARDS might benefit from strict adherence to lung protective ventilation strategies. Subsequently, we discuss whether extended physiological ventilation parameter analysis might be relevant for indication of ECMO support and can be implemented during the daily routine evaluation of ARDS patients. Particularly, this viewpoint focus on driving pressure and mechanical power.

Extracorporeal Membrane Oxygenation During Pregnancy

In the last 2 decades, the use of venovenous (VV) and venoarterial (VA) extracorporeal membrane oxygenation (ECMO) during pregnancy and the postpartum period has increased, mirroring the increased utilization in nonpregnant individuals worldwide. VV ECMO provides respiratory support for patients with acute respiratory distress syndrome (ARDS) who fail conventional mechanical ventilation. With the COVID-19 pandemic, the use of VV ECMO has increased dramatically and data during pregnancy and the postpartum period are overall reassuring. In contrast, VA ECMO provides both respiratory and cardiovascular support. Data on the use of VA ECMO during pregnancy are extremely limited.

Extracorporeal Membrane Oxygenation in Pediatric Acute Respiratory Distress Syndrome: From the Second Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

To systematically review and assimilate literature on children receiving extracorporeal membrane oxygenation (ECMO) support in pediatric acute respiratory distress syndrome (PARDS) with the goal of developing an update to the Pediatric Acute Lung Injury Consensus Conference recommendations and statements about clinical practice and research.

DATA SOURCES

Electronic searches of MEDLINE (Ovid), Embase (Elsevier), and CINAHL Complete (EBSCOhost).

STUDY SELECTION

The search used a medical subject heading terms and text words to capture studies of ECMO in PARDS or acute respiratory failure. Studies using animal models and case reports were excluded from our review.

DATA EXTRACTION

Title/abstract review, full-text review, and data extraction using a standardized data collection form.

DATA SYNTHESIS

The Grading of Recommendations Assessment, Development, and Evaluation approach was used to identify and summarize evidence and develop recommendations. There were 18 studies identified for full-text extraction. When pediatric data was lacking, adult and neonatal data from randomized clinical trials and observational studies were considered. Six clinical recommendations were generated related to ECMO indications, initiation, and management in PARDS. There were three good practice statements generated related to ECMO indications, initiation, and follow-up in PARDS. Two policy statements were generated involving the impact of ECMO team organization and training in PARDS. Last, there was one research statement.

CONCLUSIONS

Based on a systematic literature review, we propose clinical management, good practice and policy statements within the domains of ECMO indications, initiation, team organization, team training, management, and follow-up as they relate to PARDS.

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.

Extracorporeal Membrane Oxygenation in Acute Respiratory Failure

Venovenous (VV) extracorporeal membrane oxygenation (ECMO) is a form of mechanical life support that provides full respiratory bypass in patients with severe respiratory failure as a bridge to recovery or lung transplantation. The use of ECMO for respiratory failure and capable centers offering ECMO has expanded over the years, increasing its availability. As VV-ECMO provides an artificial mechanism for oxygenation and decarboxylation of native blood, it allows for an environment in which safer mechanical ventilatory care may be provided, allowing for treatment and resolution of underlying respiratory pathologies. Landmark clinical trials have provided a framework for better understanding patient selection criteria, resource utilization, and outcomes associated with ECMO when applied in settings of refractory respiratory failure. Maintaining close vigilance and management of complications during ECMO as well as identifying strategies post-ECMO (e.g., recovery, transplantation, etc.), are critical to successful ECMO support. In this review, we examine considerations for candidate selection for VV-ECMO, review the evidence of utilizing VV-ECMO in respiratory failure, and provide practical considerations for managing respiratory ECMO patients, including complication identification and management, as well as assessing for the ability to separate from ECMO support and the procedures for decannulation.

Early and Dose-Dependent Xenogeneic Mesenchymal Stem Cell Therapy Improved Outcomes in Acute Respiratory Distress Syndrome Rodent Through Ameliorating Inflammation, Oxidative Stress, and Immune Reaction

This study tested whether human umbilical cord-derived mesenchymal stem cells (HUCDMSCs) treatment effectively protected the rat lung against acute respiratory distress syndrome (ARDS) injury, and benefits of early and dose-dependent treatment. Rat pulmonary epithelial cell line L2 (PECL2) were categorized into G1 (PECL2), G2 (PECL2 + healthy rat lung-derived extraction/50 mg/ml co-cultured for 24 h), G3 (PECL2 + ARDS rat lung-derived extraction/50 mg/ml co-cultured for 24 h), and G4 (condition as G3 + HUCDMSCs/1 × 105/co-cultured for 24 h). The result showed that the protein expressions of inflammatory (HMGB-1/TLR-2/TLR-4/MAL/TRAM/MyD88/TRIF/TRAF6/IkB/NF-κB/IL-1β/TNF-α), oxidative-stress/mitochondrial-damaged (NOX-1/NOX-2/ASK1/p-MKK4/p-MKK7/JNKs/JUN/cytosolic-cytochrome-C/cyclophilin-D/DRP1), and cell-apoptotic/fibrotic (cleaved-caspase 3/cleaved-PARP/TGF-β/p-Smad3) biomarkers were significantly increased in G3 than in G1/G2 and were significantly reversed in G4 (all P < 0.001), but they were similar between G1/G2. Adult male rats (n = 42) were equally categorized into group 1 (normal control), group 2 (ARDS only), group 3 [ARDS + HUCDMSCs/1.2 × 106 cells intravenous administration at 3 h after 48 h ARDS induction (i.e., early treatment)], group 4 [ARDS + HUCDMSCs/1.2 × 106 cells intravenous administration at 24 h after 48 h ARDS induction (late treatment)], and group 5 [ARDS + HUCDMSCs/1.2 × 106 cells intravenous administration at 3 h/24 h after-48 h ARDS induction (dose-dependent treatment)]. By day 5 after ARDS induction, the SaO2%/immune regulatory T cells were highest in group 1, lowest in group 2, significantly lower in group 4 than in groups 3/5, and significantly lower in group 3 than in group 5, whereas the circulatory/bronchioalveolar lavage fluid inflammatory cells (CD11b-c+/LyG6+/MPO+)/circulatory immune cells (CD3-C4+/CD3-CD8+)/lung-leakage-albumin level/lung injury score/lung protein expressions of inflammatory (HMGB-1/TLR-2/TLR-4/MAL/TRAM/MyD88/TRIF/TRAF6/IκB-β/p-NF-κB/IL-1β/TNF-α)/fibrotic (p-SMad3/TGF-β), apoptosis (mitochondrial-Bax/cleaved-caspase-3)/oxidative-cell-stress (NOX-1/NOX-2/ASK1/p-MKK4/p-MKK7/p-JNKs/p-cJUN)/mitochondrial damaged (cyclophilin-D/DRP1/cytosolic-cytochrome-C) biomarkers displayed an opposite pattern of SaO2% among the groups (all P < 0.0001). Early administration was superior to and two-dose counterpart was even more superior to late HUCDMSCs treatment for protecting the lung against ARDS injury.

Extracorporeal Membrane Oxygenation for Refractory Asthma Exacerbations With Respiratory Failure

BACKGROUND

Asthma exacerbations with respiratory failure (AERF) are associated with hospital mortality of 7% to 15%. Extracorporeal membrane oxygenation (ECMO) has been used as a salvage therapy for refractory AERF, but controlled studies showing its association with mortality have not been performed.

RESEARCH QUESTION

Is treatment with ECMO associated with lower mortality in refractory AERF compared with standard care?

STUDY DESIGN AND METHODS

This is a retrospective, epidemiologic, observational cohort study using a national, administrative data set from 2010 to 2020 that includes 25% of US hospitalizations. People were included if they were admitted to an ECMO-capable hospital with an asthma exacerbation, and were treated with short-acting bronchodilators, systemic corticosteroids, and invasive ventilation. People were excluded for age < 18 years, no ICU stay, nonasthma chronic lung disease, COVID-19, or multiple admissions. The main exposure was ECMO vs No ECMO. The primary outcome was hospital mortality. Key secondary outcomes were ICU length of stay (LOS), hospital LOS, time receiving invasive ventilation, and total hospital costs.

RESULTS

The study analyzed 13,714 patients with AERF, including 127 with ECMO and 13,587 with No ECMO. ECMO was associated with reduced mortality in the covariate-adjusted (OR, 0.33; 95% CI, 0.17-0.64; P = .001), propensity score-adjusted (OR, 0.36; 95% CI, 0.16-0.81; P = .01), and propensity score-matched models (OR, 0.48; 95% CI, 0.24-0.98; P = .04) vs No ECMO. Sensitivity analyses showed that mortality reduction related to ECMO ranged from OR 0.34 to 0.61. ECMO was also associated with increased hospital costs in all three models (P < .0001 for all) vs No ECMO, but not with decreased ICU LOS, hospital LOS, or time receiving invasive ventilation.

INTERPRETATION

ECMO was associated with lower mortality and higher hospital costs, suggesting that it may be an important salvage therapy for refractory AERF following confirmatory clinical trials.

Impact of Prone Position in COVID-19 Patients on Extracorporeal Membrane Oxygenation

OBJECTIVES

Prone positioning and venovenous extracorporeal membrane oxygenation (ECMO) are both useful interventions in acute respiratory distress syndrome (ARDS). Combining the two therapies is feasible and safe, but the effectiveness is not known. Our objective was to evaluate the potential survival benefit of prone positioning in venovenous ECMO patients cannulated for COVID-19-related ARDS.

DESIGN

Retrospective analysis of a multicenter cohort.

PATIENTS

Patients on venovenous ECMO who tested positive for severe acute respiratory syndrome coronavirus 2 by reverse transcriptase polymerase chain reaction or with a diagnosis on chest CT were eligible.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients on venovenous ECMO for respiratory failure in whom prone position status while on ECMO and in-hospital mortality were known were included. Of 647 patients in 41 centers, 517 were included. Median age was 55 (47-61), 78% were male and 95% were proned before cannulation. After cannulation, 364 patients (70%) were proned and 153 (30%) remained in the supine position for the whole ECMO run. There were 194 (53%) and 92 (60%) deaths in the prone and the supine groups, respectively. Prone position on ECMO was independently associated with lower in-hospital mortality (odds ratio = 0.49 [0.29-0.84]; p = 0.010). In 153 propensity score-matched pairs, mortality rate was 49.7% in the prone position group versus 60.1% in the supine position group (p = 0.085). Considering only patients alive at decannulation, propensity-matched proned patients had a significantly lower mortality rate (22.4% vs 37.8%; p = 0.029) than nonproned patients.

CONCLUSIONS

Prone position may be beneficial in patients supported by venovenous ECMO for COVID-19-related ARDS but more data are needed to draw definitive conclusions.

Impact of Prone Position in COVID-19 Patients on Extracorporeal Membrane Oxygenation

OBJECTIVES

Prone positioning and venovenous extracorporeal membrane oxygenation (ECMO) are both useful interventions in acute respiratory distress syndrome (ARDS). Combining the two therapies is feasible and safe, but the effectiveness is not known. Our objective was to evaluate the potential survival benefit of prone positioning in venovenous ECMO patients cannulated for COVID-19-related ARDS.

DESIGN

Retrospective analysis of a multicenter cohort.

PATIENTS

Patients on venovenous ECMO who tested positive for severe acute respiratory syndrome coronavirus 2 by reverse transcriptase polymerase chain reaction or with a diagnosis on chest CT were eligible.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients on venovenous ECMO for respiratory failure in whom prone position status while on ECMO and in-hospital mortality were known were included. Of 647 patients in 41 centers, 517 were included. Median age was 55 (47-61), 78% were male and 95% were proned before cannulation. After cannulation, 364 patients (70%) were proned and 153 (30%) remained in the supine position for the whole ECMO run. There were 194 (53%) and 92 (60%) deaths in the prone and the supine groups, respectively. Prone position on ECMO was independently associated with lower in-hospital mortality (odds ratio = 0.49 [0.29-0.84]; p = 0.010). In 153 propensity score-matched pairs, mortality rate was 49.7% in the prone position group versus 60.1% in the supine position group (p = 0.085). Considering only patients alive at decannulation, propensity-matched proned patients had a significantly lower mortality rate (22.4% vs 37.8%; p = 0.029) than nonproned patients.

CONCLUSIONS

Prone position may be beneficial in patients supported by venovenous ECMO for COVID-19-related ARDS but more data are needed to draw definitive conclusions.

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.

A Dedicated Expert ECMO-Team and Strict Patient Selection Improve Survival of Patients with Severe SARS-CoV-2 ARDS Supported by VV-ECMO

The SARS-CoV-2 pandemic has overwhelmed health care systems worldwide since its first wave. Intensive care units have been under a significant amount of pressure as patients with the most severe form of the disease presented with acute respiratory distress syndrome (ARDS). A proportion of them experienced refractory acute respiratory failure and had to be supported with veno-venous extracorporeal membrane oxygenation (VV-ECMO). The present retrospective study reports the experiences of our ECMO center in the management of COVID-19 patients with refractory ARDS. Patient characteristics and outcomes are presented through the different waves of the pandemic. A cohort study was conducted on patients with refractory ARDS due to COVID-19 infection who were admitted to the intensive care unit (ICU) at the Geneva University Hospital and supported with VV-ECMO between 14 March 2020 and January 2022. The VV-ECMO implementation criteria were defined according to an institutional algorithm validated by the local crisis unit of the hospital and the Swiss Society of Intensive Care Medicine. Among the 500 ARDS patients admitted to our ICU, 41 patients with a median age of 57 (52−63) years, a body mass index (BMI) of 28 (26−32) kg/m2, and a SAPS II score of 57 (47−67), and 27 (66%) of whom were men required VV-ECMO. None of the patients were vaccinated. The time of ventilation, including noninvasive ventilation (NIV) and mechanical ventilation (MV), and the time of MV before ECMO were 7 (4−11) days and 4 (1−7) days, respectively. The time under ECMO was 20 (10−27) days. The ICU and hospital lengths of stay were 36 (21−45) days and 45 (33−69) days, respectively. The survival rate for patients on ECMO was 59%. Comparative analysis between survivors and non-survivors highlighted that survivors had a significantly shorter ventilation duration before ECMO (NIV + MV: 5.5 (1.3−9) vs. 9 (6.5−13.5) days, p = 0.0026 and MV alone: 1.6 (0.4−5.5) vs. 5.8 (5−8) days, p < 0.0001). The management of patients on ECMO by an experienced ECMO team dedicated to this activity was associated with improved survival (78% vs. 28%, p = 0.0012). Between the first wave and the following waves, patients presented with a higher incidence of ventilator-associated pneumonia (100% vs. 82%, p = 0.0325) but had better survival rates (74% vs. 35%, p = 0.024). The present study suggests that both the prompt insertion of VV-ECMO to control refractory hypoxemia and the involvement of an ECMO team improve the survival of COVID-19 patients.

Ultra-lung-protective ventilation and biotrauma in severe ARDS patients on veno-venous extracorporeal membrane oxygenation: a randomized controlled study

BACKGROUND

Ultra-lung-protective ventilation may be useful during veno-venous extracorporeal membrane oxygenation (vv-ECMO) for severe acute respiratory distress syndrome (ARDS) to minimize ventilator-induced lung injury and to facilitate lung recovery. The objective was to compare pulmonary and systemic biotrauma evaluated by numerous biomarkers of inflammation, epithelial, endothelial injuries, and lung repair according to two ventilator strategies on vv-ECMO.

METHODS

This is a prospective randomized controlled study. Patients were randomized to receive during 48 h either ultra-lung-protective ventilation combining very low tidal volume (1-2 mL/kg of predicted body weight), low respiratory rate (5-10 cycles per minute), positive expiratory transpulmonary pressure, and 16 h of prone position or lung-protective-ventilation which followed the ECMO arm of the EOLIA trial (control group).

RESULTS

The primary outcome was the alveolar concentrations of interleukin-1-beta, interleukin-6, interleukin-8, surfactant protein D, and blood concentrations of serum advanced glycation end products and angiopoietin-2 48 h after randomization. Enrollment was stopped for futility after the inclusion of 39 patients. Tidal volume, respiratory rate, minute ventilation, plateau pressure, and mechanical power were significantly lower in the ultra-lung-protective group. None of the concentrations of the pre-specified biomarkers differed between the two groups 48 h after randomization. However, a trend to higher 60-day mortality was observed in the ultra-lung-protective group compared to the control group (45 vs 17%, p = 0.06).

CONCLUSIONS

Despite a significant reduction in the mechanical power, ultra-lung-protective ventilation during 48 h did not reduce biotrauma in patients with vv-ECMO-supported ARDS. The impact of this ventilation strategy on clinical outcomes warrants further investigation. Trial registration Clinical trial registered with www.

CLINICALTRIALS

gov ( NCT03918603 ). Registered 17 April 2019.

Early decrease of ventilatory ratio after prone position ventilation may predict successful weaning in patients with acute respiratory distress syndrome: A retrospective cohort study

Background

Previous studies usually identified patients who benefit the most from prone positioning by oxygenation improvement. However, inconsistent results have been reported. Physiologically, pulmonary dead space fraction may be more appropriate in evaluating the prone response. As an easily calculated bedside index, ventilatory ratio (VR) correlates well with pulmonary dead space fraction. Hence, we investigated whether the change in VR after prone positioning is associated with weaning outcomes at day 28 and to identify patients who will benefit the most from prone positioning.

Materials and methods

This retrospective cohort study was performed in a group of mechanically ventilated, non-COVID ARDS patients who received prone positioning in the ICU at Zhongda hospital, Southeast University. The primary outcome was the rate of successful weaning patients at day 28. Arterial blood gas results and corresponding ventilatory parameters on five different time points around the first prone positioning were collected, retrospectively. VR responders were identified by Youden's index. Competing-risk regression models were used to identify the association between the VR change and liberation from mechanical ventilation at day 28.

Results

One hundred and three ARDS patients receiving prone positioning were included, of whom 53 (51%) successfully weaned from the ventilator at day 28. VR responders were defined as patients showing a decrease in VR of greater than or equal to 0.037 from the baseline to within 4 h after prone. VR responders have significant longer ventilator-free days, higher successful weaning rates and lower mortality compared with non-responders at day 28. And a significant between-group difference exists in the respiratory mechanics improvement after prone (P < 0.05). A linear relationship was also found between VR change and compliance of the respiratory system (Crs) change after prone (r = 0.32, P = 0.025). In the multivariable competing-risk analysis, VR change (sHR 0.57; 95% CI, 0.35-0.92) was independently associated with liberation from mechanical ventilation at day 28.

Conclusion

Ventilatory ratio decreased more significantly within 4 h after prone positioning in patients with successful weaning at day 28. VR change was independently associated with liberation from mechanical ventilation at day 28.

Association of Ventilator Settings With Mortality in Pediatric Patients Treated With Extracorporeal Life Support for Respiratory Failure

Extracorporeal life support (ECLS) is a treatment for acute respiratory failure that can provide extracorporeal gas exchange, allowing lung rest. However, while most patients remain mechanically ventilated during ECLS, there is a paucity of evidence to guide the choice of ventilator settings. We studied the associations between ventilator settings 24 hours after ECLS initiation and mortality in pediatric patients using a retrospective analysis of data from the Extracorporeal Life Support Organization Registry. 3497 patients, 29 days to 18 years of age, treated with ECLS for respiratory failure between 2015 and 2021, were included for analysis. 93.3% of patients on ECLS were ventilated with conventional mechanical ventilation. Common settings included positive end-expiratory pressure (PEEP) of 10 cm H 2 O (45.7%), delta pressure (ΔP) of 10 cm H 2 O (28.3%), rate of 10-14 breaths per minute (55.9%), and fraction of inspired oxygen (FiO 2 ) of 0.31-0.4 (30.3%). In a multivariate model, PEEP >10 cm H 2 O ( versus PEEP < 8 cm H 2 O, odds ratio [OR]: 1.53, 95% CI: 1.20-1.96) and FiO 2 ≥0.45 ( versus FiO 2 < 0.4; 0.45 ≤ FiO 2 < 0.6, OR: 1.31, 95% CI: 1.03-1.67 and FiO 2 ≥ 0.6, OR: 2.30; 95% CI: 1.81-2.93) were associated with higher odds of mortality. In a secondary analysis of survivors, PEEP 8-10 cm H 2 O was associated with shorter ECLS run times ( versus PEEP < 8 cm H 2 O, coefficient: -1.64, 95% CI: -3.17 to -0.11), as was ΔP >16 cm H 2 O ( versus ΔP < 10 cm H 2 O, coefficient: -2.72, 95% CI: -4.30 to -1.15). Our results identified several categories of ventilator settings as associated with mortality or ECLS run-time. Further studies are necessary to understand whether these results represent a causal relationship.

Effect of Hypoxemia on Outcome in Respiratory Failure Supported With Extracorporeal Membrane Oxygenation: A Cardinality Matched Cohort Study

Venovenous extracorporeal membrane oxygenation (ECMO) is recommended in adult patients with refractory acute respiratory failure (ARF), but there is limited evidence for its use in patients with less severe hypoxemia. Prior research has suggested a lower PaO 2 /FiO 2 at cannulation is associated with higher short-term mortality, but it is unclear whether this is due to less severe illness or a potential benefit of earlier ECMO support. In this exploratory cardinality-matched observational cohort study, we matched 668 patients who received venovenous ECMO as part of a national severe respiratory failure service into cohorts of "less severe" and "very severe" hypoxemia based on the median PaO 2 /FiO 2 at ECMO institution of 68 mmHg. Before matching, ICU mortality was 19% in the 'less severe' hypoxemia group and 28% in the "very severe" hypoxemia group (RR for mortality = 0.69, 95% CI 0.54-0.88). After matching on key prognostic variables including underlying diagnosis, this difference remained statistically present but smaller: (23% vs. 30%, RR = 0.76, 95% CI 0.59-0.99). This may suggest the observed survival benefit of venovenous ECMO is not solely due to reduced disease severity. Further research is warranted to examine the potential role of ECMO in ARF patients with less severe hypoxemia.

Complications Associated With Venovenous Extracorporeal Membrane Oxygenation-What Can Go Wrong?

OBJECTIVES

Despite increasing use and promising outcomes, venovenous extracorporeal membrane oxygenation (V-V ECMO) introduces the risk of a number of complications across the spectrum of ECMO care. This narrative review describes the variety of short- and long-term complications that can occur during treatment with ECMO and how patient selection and management decisions may influence the risk of these complications.

DATA SOURCES

English language articles were identified in PubMed using phrases related to V-V ECMO, acute respiratory distress syndrome, severe respiratory failure, and complications.

STUDY SELECTION

Original research, review articles, commentaries, and published guidelines from the Extracorporeal Life support Organization were considered.

DATA EXTRACTION

Data from relevant literature were identified, reviewed, and integrated into a concise narrative review.

DATA SYNTHESIS

Selecting patients for V-V ECMO exposes the patient to a number of complications. Adequate knowledge of these risks is needed to weigh them against the anticipated benefit of treatment. Timing of ECMO initiation and transfer to centers capable of providing ECMO affect patient outcomes. Choosing a configuration that insufficiently addresses the patient's physiologic deficit leads to consequences of inadequate physiologic support. Suboptimal mechanical ventilator management during ECMO may lead to worsening lung injury, delayed lung recovery, or ventilator-associated pneumonia. Premature decannulation from ECMO as lungs recover can lead to clinical worsening, and delayed decannulation can prolong exposure to complications unnecessarily. Short-term complications include bleeding, thrombosis, and hemolysis, renal and neurologic injury, concomitant infections, and technical and mechanical problems. Long-term complications reflect the physical, functional, and neurologic sequelae of critical illness. ECMO can introduce ethical and emotional challenges, particularly when bridging strategies fail.

CONCLUSIONS

V-V ECMO is associated with a number of complications. ECMO selection, timing of initiation, and management decisions impact the presence and severity of these potential harms.

Impact of ventilator settings during venovenous extracorporeal membrane oxygenation on clinical outcomes in influenza-associated acute respiratory distress syndrome: a multicenter retrospective cohort study

Background

Patients with influenza-associated acute respiratory distress syndrome (ARDS) requiring venovenous extracorporeal membrane oxygenation (vv-ECMO) support have a high mortality rate. Ventilator settings have been known to have a substantial impact on outcomes. However, the optimal settings of mechanical ventilation during vv-ECMO are still unknown.

Methods

This multicenter retrospective cohort study was conducted in the intensive care units (ICUs) of three tertiary referral hospitals in Taiwan between July 2009 and December 2019. It aims to describe the effect of ventilator settings during vv-ECMO on patient outcomes.

Results

A total of 93 patients with influenza receiving ECMO were screened. Patients were excluded if they: were receiving venoarterial ECMO, died within three days of vv-ECMO initiation, or were transferred to the tertiary referral hospital >24 hours after vv-ECMO initiation. A total of 62 patients were included in the study, and 24 (39%) died within six months. During the first three days of ECMO, there were no differences in tidal volume (5.1 vs. 5.2 mL/kg, p = 0.833), dynamic driving pressure (15 vs. 14 cmH2O, p = 0.146), and mechanical power (11.3 vs. 11.8 J/min, p = 0.352) between survivors and non-survivors. However, respiratory rates were significantly higher in non-survivors compared with survivors (15 vs. 12 breaths/min, p = 0.013). After adjustment for important confounders, a higher mean respiratory rate of >12 breaths/min was still associated with higher mortality (adjusted hazard ratio = 3.31, 95% confidence interval = 1.10-9.97, p = 0.034).

Conclusions

In patients with influenza-associated ARDS receiving vv-ECMO support, we found that a higher respiratory rate was associated with higher mortality. Respiratory rate might be a modifiable factor to improve outcomes in this patient population.

Extracorporeal Life Support for Status Asthmaticus: Early Outcomes in Teens and Young Adults

Extracorporeal life support (ECLS) may be life saving for patients with status asthmaticus (SA), a difficult-to-treat, severe subset of asthma. Contemporary ECLS outcomes for SA in teens and young adults are not well described. The Extracorporeal Life Support Organization (ELSO) Registry was reviewed (2009-2019) for patients (15-35 years) with a primary diagnosis of SA. In-hospital mortality and complications were described. Multivariable logistic regression was used to identify independent risk factors for hospital mortality. Overall, 137 patients, (26 teens and 111 young adults; median age 25 years) were included. Extracorporeal life support utilization for SA sharply increased in 2010, coinciding with increased ECLS utilization overall. Median ECLS duration and length of stay were 97 hours and 11 days, respectively. In-hospital mortality and major complication rates were 10% and 11%, respectively. Nonsurvivors were more likely to have experienced ECLS complications, compared to survivors (86% vs. 42%, p = 0.003). Independent risk factors for in-hospital mortality included pre-ECLS arrest and any renal and/or neurologic complication. Prospective studies designed to evaluate complications and subsequent failure to rescue may help optimize quality improvement efforts.

The impact of reduction in intensity of mechanical ventilation upon venovenous ECMO initiation on radiographically assessed lung edema scores: A retrospective observational study

Background

Patients with severe acute respiratory distress syndrome (ARDS) typically receive ultra-protective ventilation after extracorporeal membrane oxygenation (ECMO) is initiated. While the benefit of ECMO appears to derive from supporting “lung rest”, reductions in the intensity of mechanical ventilation, principally tidal volume limitation, may manifest radiologically. This study evaluated the relative changes in radiographic assessment of lung edema (RALE) score upon venovenous ECMO initiation in patients with severe ARDS.

Methods

Digital chest x-rays (CXR) performed at baseline immediately before initiation of ECMO, and at intervals post (median 1.1, 2.1, and 9.6 days) were reviewed in 39 Adult ARDS patients. One hundred fifty-six digital images were scored by two independent, blinded radiologists according to the RALE (Radiographic Assessment of Lung Edema) scoring criteria. Ventilatory data, ECMO parameters and fluid balance were recorded at corresponding time points. Multivariable analysis was performed analyzing the change in RALE score over time relative to baseline.

Results

The RALE score demonstrated excellent inter-rater agreement in this novel application in an ECMO cohort. Mean RALE scores increased from 28 (22–37) at baseline to 35 (26–42) (p < 0.001) on D1 of ECMO; increasing RALE was associated with higher baseline APACHE III scores [ß value +0.19 (0.08, 0.30) p = 0.001], and greater reductions in tidal volume [ß value −2.08 (−3.07, −1.10) p < 0.001] after ECMO initiation. Duration of mechanical ventilation, and ECMO support did not differ between survivors and non-survivors.

Conclusions

The magnitude of reductions in delivered tidal volumes correlated with increasing RALE scores (radiographic worsening) in ARDS patients receiving ECMO. Implications for patient centered outcomes remain unclear. There is a need to define appropriate ventilator settings on venovenous ECMO, counterbalancing the risks vs. benefits of optimal “lung rest” against potential atelectrauma.

Mesenchymal stromal cells alleviate acute respiratory distress syndrome through the cholinergic anti-inflammatory pathway

Mesenchymal stromal cells (MSCs) have been considered a promising alternative for treatment of acute respiratory distress syndrome (ARDS). However, there is significant heterogeneity in their therapeutic efficacy, largely owing to the incomplete understanding of the mechanisms underlying the therapeutic activities of MSCs. Here, we hypothesize that the cholinergic anti-inflammatory pathway (CAP), which is recognized as a neuroimmunological pathway, may be involved in the therapeutic mechanisms by which MSCs mitigate ARDS. Using lipopolysaccharide (LPS) and bacterial lung inflammation models, we found that inflammatory cell infiltration and Evans blue leakage were reduced and that the expression levels of choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) in lung tissue were significantly increased 6 hours after MSC infusion. When the vagus nerve was blocked or α7 nicotinic acetylcholine (ACh) receptor (α7nAChR)-knockout mice were used, the therapeutic effects of MSCs were significantly reduced, suggesting that the CAP may play an important role in the effects of MSCs in ARDS treatment. Our results further showed that MSC-derived prostaglandin E2 (PGE2) likely promoted ACh synthesis and release. Additionally, based on the efficacy of nAChR and α7nAChR agonists, we found that lobeline, the nicotinic cholinergic receptor excitation stimulant, may attenuate pulmonary inflammation and alleviate respiratory symptoms of ARDS patients in a clinical study (ChiCTR2100047403). In summary, we reveal a previously unrecognized MSC-mediated mechanism of CAP activation as the means by which MSCs alleviate ARDS-like syndrome, providing insight into the clinical translation of MSCs or CAP-related strategies for the treatment of patients with ARDS.

Veno-venous Extracorporeal Membrane Oxygenation for pregnant women with Acute Respiratory Distress Syndrome: a narrative review

Acute respiratory distress syndrome remains an uncommon condition during pregnancy. In patients with severe acute respiratory distress syndrome, when oxygenation or ventilation cannot be supported sufficiently using best practice conventional mechanical ventilation and additional therapies, veno-venous extracorporeal membrane oxygenation may be considered. In the past two decades, there has been increasing adoption of this technique to support adult patients with refractory acute respiratory distress syndrome. However, its use for the management of pregnant women is rare and remains a challenge. This narrative review addresses acute respiratory distress syndrome and its management during pregnancy, and then focuses on indications, contraindications, challenges, potential complications, and outcomes of the use of veno-venous extracorporeal membrane oxygenation for acute respiratory distress syndrome in the pregnant patient.

Effect of prone positioning on gas exchange according to lung morphology in patients with acute respiratory distress syndrome

BACKGROUND

There are limited data on the clinical effects of prone positioning according to lung morphology. We aimed to determine whether the gas exchange response to prone positioning differs according to lung morphology.

METHODS

This retrospective study included adult patients with moderate-to-severe acute respiratory distress syndrome (ARDS). The lung morphology of ARDS was assessed by chest computed tomography scan and classified as "diffuse" or "focal." The primary outcome was change in partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) ratio after the first prone positioning session: first, using the entire cohort, and second, using subgroups of patients with diffuse ARDS matched 2 to 1 with patients with focal ARDS at baseline.

RESULTS

Ninety-five patients were included (focal ARDS group, 23; diffuse ARDS group, 72). Before prone positioning, the focal ARDS group showed worse oxygenation than the diffuse ARDS group (median PaO2/FiO2 ratio, 79.9 mm Hg [interquartile range (IQR)], 67.7-112.6 vs. 104.0 mm Hg [IQR, 77.6-135.7]; P=0.042). During prone positioning, the focal ARDS group showed a greater improvement in the PaO2/FiO2 ratio than the diffuse ARDS group (median, 55.8 mm Hg [IQR, 11.1-109.2] vs. 42.8 mm Hg [IQR, 11.6-83.2]); however, the difference was not significant (P=0.705). Among the PaO2/FiO2-matched cohort, there was no significant difference in change in PaO2/FiO2 ratio after prone positioning between the groups (P=0.904).

CONCLUSIONS

In patients with moderate-to-severe ARDS, changes in PaO2/FiO2 ratio after prone positioning did not differ according to lung morphology. Therefore, prone positioning can be considered as soon as indicated, regardless of ARDS lung morphology.

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome Associated with COVID-19: An Emulated Target Trial Analysis

Rationale: Whether patients with coronavirus disease (COVID-19) may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. Objectives: To estimate the effect of ECMO on 90-day mortality versus IMV only. Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO versus no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 < 80 or PaCO2 ⩾ 60 mm Hg). We controlled for confounding using a multivariable Cox model on the basis of predefined variables. Measurements and Main Results: A total of 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability on Day 7 from the onset of eligibility criteria (87% vs. 83%; risk difference, 4%; 95% confidence interval, 0-9%), which decreased during follow-up (survival on Day 90: 63% vs. 65%; risk difference, -2%; 95% confidence interval, -10 to 5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand and when initiated within the first 4 days of IMV and in patients who are profoundly hypoxemic. Conclusions: In an emulated trial on the basis of a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and regions with ECMO capacities specifically organized to handle high demand.

Impact of Time-Varying Intensity of Mechanical Ventilation on 28-Day Mortality Depends on Fluid Balance in Patients With Acute Respiratory Distress Syndrome: A Retrospective Cohort Study

Background

Recent studies have mainly focused on the association between baseline intensity of mechanical ventilation (driving pressure or mechanical power) and mortality in acute respiratory distress syndrome (ARDS). It is unclear whether the association between the time-varying intensity of mechanical ventilation and mortality is significant and varies according to the fluid balance trajectories.

Methods

We conducted a secondary analysis based on the NHLBI ARDS Network’s Fluid and Catheter Treatment Trial (FACTT). The primary outcome was 28-day mortality. The group-based trajectory modeling (GBTM) was employed to identify phenotypes based on fluid balance trajectories. Bayesian joint models were used to account for informative censoring due to death during follow-up.

Results

A total of 1,000 patients with ARDS were included in the analysis. Our study identified two phenotypes of ARDS, and compared patients with Early Negative Fluid Balance (Early NFB) and patients with Persistent-Positive Fluid Balance (Persistent-PFB) accompanied by higher tidal volume, higher static driving pressure, higher mechanical power, and lower PaO₂/FiO₂, over time during mechanical ventilation. The 28-day mortality was 14.8% in Early NFB and 49.6% in Persistent-PFB (p < 0.001). In the Bayesian joint models, the hazard ratio (HR) of 28-day death for time-varying static driving pressure [HR 1.03 (95% CI 1.01–1.05; p < 0.001)] and mechanical power [HR 1.01 (95% CI 1.002–1.02; p = 0.01)] was significant in patients with Early NFB, but not in patients with Persistent-PFB.

Conclusion

Time-varying intensity of mechanical ventilation was associated with a 28-day mortality of ARDS in a patient with Early NFB but not in patients with Persistent-PFB.

Invasive mechanical ventilation in patients with acute respiratory distress syndrome receiving extracorporeal support: a narrative review of strategies to mitigate lung injury

Veno-venous extracorporeal membrane oxygenation is indicated in patients with acute respiratory distress syndrome and severely impaired gas exchange despite evidence-based lung protective ventilation, prone positioning and other parts of the standard algorithm for treating such patients. Extracorporeal support can facilitate ultra-lung-protective ventilation, meaning even lower volumes and pressures than standard lung-protective ventilation, by directly removing carbon dioxide in patients needing injurious ventilator settings to maintain sufficient gas exchange. Injurious ventilation results in ventilator-induced lung injury, which is one of the main determinants of mortality in acute respiratory distress syndrome. Marked reductions in the intensity of ventilation to the lowest tolerable levels under extracorporeal support may be achieved and could thereby potentially mitigate ventilator-induced lung injury and theoretically patient self-inflicted lung injury in spontaneously breathing patients with high respiratory drive. However, the benefits of this strategy may be counterbalanced by the use of continuous deep sedation and even neuromuscular blocking drugs, which may impair physical rehabilitation and impact long-term outcomes. There are currently a lack of large-scale prospective data to inform optimal invasive ventilation practices and how to best apply a holistic approach to patients receiving veno-venous extracorporeal membrane oxygenation, while minimising ventilator-induced and patient self-inflicted lung injury. We aimed to review the literature relating to invasive ventilation strategies in patients with acute respiratory distress syndrome receiving extracorporeal support and discuss personalised ventilation approaches and the potential role of adjunctive therapies in facilitating lung protection.

Lung-Dependent Areas Collapse, Monitored by Electrical Impedance Tomography, May Predict the Oxygenation Response to Prone Ventilation in COVID-19 Acute Respiratory Distress Syndrome

OBJECTIVES

ICUs have had to deal with a large number of patients with acute respiratory distress syndrome COVID-19, a significant number of whom received prone ventilation, which is a substantial consumer of care time. The selection of patients that we have to ventilate in prone position seems interesting. We evaluate the correlation between the percentage of collapsed dependent lung areas in the supine position, monitoring by electrical impedance tomography and the oxygenation response (change in Pao2/Fio2 ratio) to prone position.

DESIGN

An observational prospective study.

SETTING

From October 21, 2020, to 30 March 30, 2021. At the Sainte Anne military teaching Hospital and the Timone University Hospital.

PATIENTS

Fifty consecutive patients admitted in our ICUs, with COVID-19 acute respiratory distress syndrome and required mechanical, were included. Twenty-four (48%) received prone ventilation. Fifty-eight prone sessions were investigated.

INTERVENTIONS

An electrical impedance tomography recording was made in supine position, daily and repeated just before and just after the prone session. The daily dependent area collapse was calculated in relation to the previous electrical impedance tomography recording. Prone ventilation response was defined as a Pao2/Fio2 ratio improvement greater than 20%.

MEASUREMENT AND MAIN RESULTS

The main outcome was the correlation between dependent area collapse and the oxygenation response to prone ventilation. Dependent area collapse was correlated with oxygenation response to prone ventilation (R2 = 0.49) and had a satisfactory prediction accuracy of prone response with an area under the curve of 0.94 (95% CI, 0.87-1.00; p < 0.001). Best Youden index was obtained for a dependent area collapse greater than 13.5 %. Sensitivity of 92% (95% CI, 78-97), a specificity of 91% (95% CI, 72-97), a positive predictive value of 94% (95% CI, 88-100), a negative predictive value of 87% (95% CI, 78-96), and a diagnostic accuracy of 91% (95% CI, 84-98).

CONCLUSIONS

Dependent lung areas collapse (> 13.5%), monitored by electrical impedance tomography, has an excellent positive predictive value (94%) of improved oxygenation during prone ventilation.

Monitoring during extracorporeal membrane oxygenation

PURPOSE OF REVIEW

Extracorporeal membrane oxygenation (ECMO) offers advanced mechanical support to patients with severe acute respiratory and/or cardiac failure. Ensuring an adequate therapeutic approach as well as prevention of ECMO-associated complications, by means of timely liberation, forms an essential part of standard ECMO care and is only achievable through continuous monitoring and evaluation. This review focus on the cardiorespiratory monitoring tools that can be used to assess and titrate adequacy of ECMO therapy; as well as methods to assess readiness to wean and/or discontinue ECMO support.

RECENT FINDINGS

Surrogates of tissue perfusion and near infrared spectroscopy are not standards of care but may provide useful information in select patients. Echocardiography allows to determine cannulas position, evaluate cardiac structures, and function, and diagnose complications. Respiratory monitoring is mandatory to achieve lung protective ventilation and identify early lung recovery, surrogate measurements of respiratory effort and ECMO derived parameters are invaluable in optimally managing ECMO patients.

SUMMARY

Novel applications of existing monitoring modalities alongside evolving technological advances enable the advanced monitoring required for safe delivery of ECMO. Liberation trials are necessary to minimize time sensitive ECMO related complications; however, these have yet to be standardized.

Mechanical Ventilation during ECMO: Lessons from Clinical Trials and Future Prospects

Acute Respiratory Distress Syndrome (ARDS) accounts for 10% of ICU admissions and affects 3 million patients each year. Despite decades of research, it is still associated with one of the highest mortality rates in the critically ill. Advances in supportive care, innovations in technologies and insights from recent clinical trials have contributed to improved outcomes and a renewed interest in the scope and use of Extracorporeal life support (ECLS) as a treatment for severe ARDS, including high flow veno-venous Extracorporeal Membrane Oxygenation (VV-ECMO) and low flow Extracorporeal Carbon Dioxide Removal (ECCO2R). The rationale being that extracorporeal gas exchange allows the use of lung protective ventilator settings, thereby minimizing ventilator-induced lung injury (VILI). Ventilation strategies are adapted to the patient's condition during the different stages of ECMO support. Several areas in the management of mechanical ventilation in patients on ECMO, such as the best ventilator mode, extubation-decannulation sequence and tracheostomy timing, are tailored to the patients' recovery. Reduction in sedation allowing mobilization, nutrition and early rehabilitation are subsequent therapeutic goals after lung rest has been achieved.

Electrical Impedance Tomography in Acute Respiratory Distress Syndrome Management

OBJECTIVE

To describe, through a narrative review, the physiologic principles underlying electrical impedance tomography, and its potential applications in managing acute respiratory distress syndrome (ARDS). To address the current evidence supporting its use in different clinical scenarios along the ARDS management continuum.

DATA SOURCES

We performed an online search in Pubmed to review articles. We searched MEDLINE, Cochrane Central Register, and clinicaltrials.gov for controlled trials databases.

STUDY SELECTION

Selected publications included case series, pilot-physiologic studies, observational cohorts, and randomized controlled trials. To describe the rationale underlying physiologic principles, we included experimental studies.

DATA EXTRACTION

Data from relevant publications were reviewed, analyzed, and its content summarized.

DATA SYNTHESIS

Electrical impedance tomography is an imaging technique that has aided in understanding the mechanisms underlying multiple interventions used in ARDS management. It has the potential to monitor and predict the response to prone positioning, aid in the dosage of flow rate in high-flow nasal cannula, and guide the titration of positive-end expiratory pressure during invasive mechanical ventilation. The latter has been demonstrated to improve physiologic and mechanical parameters correlating with lung recruitment. Similarly, its use in detecting pneumothorax and harmful patient-ventilator interactions such as pendelluft has been proven effective. Nonetheless, its impact on clinically meaningful outcomes remains to be determined.

CONCLUSIONS

Electrical impedance tomography is a potential tool for the individualized management of ARDS throughout its different stages. Clinical trials should aim to determine whether a specific approach can improve clinical outcomes in ARDS management.

Vasoactive Inotropic Score as a Prognostic Factor during (Cardio-) Respiratory ECMO

The vasoactive inotropic score (VIS) is calculated as a weighted sum of all administered vasopressor and inotropic medications and quantifies the amount of pharmacological cardiovascular support in patients with the most severe combined cardiopulmonary failure supported with extracorporeal membrane oxygenation (ECMO). This study evaluated (1) whether VIS prior to the initiation of ECMO is an independent predictor of survival in these patients and (2) whether VIS might guide the selection of the appropriate extracorporeal cannulation modality (Veno-Venous ‘V-V’ or Veno-VenoArterial ‘V-VA’). In this study, 39 V-VA and 182 V-V ECMO runs were retrospectively analyzed. VIS immediately prior to ECMO initiation (pre-ECMO) was 40 (10/113) in all patients, 30 (10/80) in patients with V-V ECMO and 207 (60/328) in patients with V-VA ECMO. Pre-ECMO VIS was an independent predictor of survival in univariate (AUC = 0.68, p = 0.001) and multi-variable analyses (p = 0.02). Pre-ECMO VIS was clearly associated with mortality (p = 0.001) in V-V ECMO group; however, V-VA ECMO disrupted this association (p = 0.18). Therefore, in conjunction with echocardiography, VIS might assist in selecting the appropriate ECMO cannulation strategy as patients with a pre-ECMO VIS ≥ 61.4 had significantly lower odds of survival compared to those with lower VIS.

Impact of the inspiratory oxygen fraction on the cardiac output during jugulo-femoral venoarterial extracorporeal membrane oxygenation in the rat

Background

Venoarterial extracorporeal membrane oxygenation (V-A ECMO) with femoral access has gained wide acceptance in the treatment of critically ill patients. Since the patient´s cardiac output (CO) can compete with the retrograde aortic ECMO-flow, the aim of this study was to examine the impact of the inspiratory oxygen fraction on the cardiac function during V-A ECMO therapy.

Methods

Eighteen male Lewis rats (350–400 g) received V-A ECMO therapy. The inspiratory oxygen fraction on the ventilator was randomly set to 0.5 (group A), 0.21 (group B), or 0 in order to simulate apnea (group C), respectively. Each group consisted of six animals. Arterial blood pressure, central venous saturation (ScvO2), CO, stroke volume, left ventricular ejection fraction (LVEF), end diastolic volume, and pressure were measured. Cardiac injury was determined by analyzing the amount of lactate dehydrogenase (LDH).

Results

During anoxic ventilation the systolic, mean and diastolic arterial pressure, CO, stroke volume, LVEF and ScvO2 were significantly impaired compared to group A and B. The course of LDH values revealed no significant differences between the groups.

Conclusion

Anoxic ventilation during V-A ECMO with femoral cannulation leads to cardiogenic shock in rats. Therefore, awake V-A ECMO patients might be at risk for hypoxia-induced complications.

2021 Acute Respiratory Distress Syndrome Update, With Coronavirus Disease 2019 Focus

Acute respiratory distress syndrome (ARDS) is a heterogeneous lung disease responsible for significant morbidity and mortality among critically ill patients, including those infected with severe acute respiratory syndrome coronavirus 2, the virus responsible for coronavirus disease 2019. Despite recent advances in pathophysiology, diagnostics, and therapeutics, ARDS is dangerously underdiagnosed, and supportive lung protective ventilation and prone positioning remain the mainstay interventions. Rescue therapies, including neuromuscular blockade and venovenous extracorporeal membrane oxygenation, remain a key component of clinical practice, although benefits are unclear. Even though coronavirus disease 2019 ARDS has some distinguishing features from traditional ARDS, including delayed onset, hyperinflammatory response, and pulmonary microthrombi, it clinically is similar to traditional ARDS and should be treated with established supportive therapies.

Mathematical modelling of oxygenation under veno-venous ECMO configuration using either a femoral or a bicaval drainage

BACKGROUND

The bicaval drainage under veno-venous extracorporeal membrane oxygenation (VV ECMO) was compared in present experimental study to the inferior caval drainage in terms of systemic oxygenation.

METHOD

Two mathematical models were built to simulate the inferior vena cava-to-right atrium (IVC → RA) route and the bicaval drainage-to-right atrium return (IVC + SVC → RA) route using the following parameters: cardiac output (Q_C), IVC flow/Q_C ratio, venous oxygen saturation, extracorporeal pump flow (Q_EC), and pulmonary shunt (PULM-Shunt) to obtain pulmonary artery oxygen saturation (S_PAO₂) and systemic blood oxygen saturation (SaO₂).

RESULTS

With the IVC → RA route, S_PAO₂ and SaO₂ increased linearly with Q_EC/Q_C until the threshold of the IVC flow/Q_C ratio, beyond which the increase in S_PAO₂ reached a plateau. With the IVC + SVC → RA route, S_PAO₂ and SaO₂ increased linearly with Q_EC/Q_C until 100% with Q_EC/Q_C = 1. The difference in required Q_EC/Q_C between the two routes was all the higher as SaO₂ target or PULM-Shunt were high, and occurred all the earlier as PULM-Shunt were high. The required Q_EC between the two routes could differ from 1.0 L/min (Q_C = 5 L/min) to 1.5 L/min (Q_C = 8 L/min) for SaO₂ target = 90%. Corresponding differences of Q_EC for SaO₂ target = 94% were 4.7 L/min and 7.9 L/min, respectively.

CONCLUSION

Bicaval drainage under ECMO via the IVC + SVC → RA route gave a superior systemic oxygenation performance when both Q_EC/Q_C and pulmonary shunt were high. The VV-V ECMO configuration (IVC + SVC → RA route) might be an attractive rescue strategy in case of refractory hypoxaemia under VV ECMO.

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

Background

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

Methods

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

Results

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

Conclusion

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

Ultraprotective versus apneic ventilation in acute respiratory distress syndrome patients with extracorporeal membrane oxygenation: a physiological study

Background

Even an ultraprotective ventilation strategy in severe acute respiratory distress syndrome (ARDS) patients treated with extracorporeal membrane oxygenation (ECMO) might induce ventilator-induced lung injury and apneic ventilation with the sole application of positive end-expiratory pressure may, therefore, be an alternative ventilation strategy. We, therefore, compared the effects of ultraprotective ventilation with apneic ventilation on oxygenation, oxygen delivery, respiratory system mechanics, hemodynamics, strain, air distribution and recruitment of the lung parenchyma in ARDS patients with ECMO.

Methods

In a prospective, monocentric physiological study, 24 patients with severe ARDS managed with ECMO were ventilated using ultraprotective ventilation (tidal volume 3 ml/kg of predicted body weight) with a fraction of inspired oxygen (FiO₂) of 21%, 50% and 90%. Patients were then treated with apneic ventilation with analogous FiO₂. The primary endpoint was the effect of the ventilation strategy on oxygenation and oxygen delivery. The secondary endpoints were mechanical power, stress, regional air distribution, lung recruitment and the resulting strain, evaluated by chest computed tomography, associated with the application of PEEP (apneic ventilation) and/or low V_T (ultraprotective ventilation).

Results

Protective ventilation, compared to apneic ventilation, improved oxygenation (arterial partial pressure of oxygen, p < 0.001 with FiO₂ of 50% and 90%) and reduced cardiac output. Both ventilation strategies preserved oxygen delivery independent of the FiO₂. Protective ventilation increased driving pressure, stress, strain, mechanical power, as well as induced additional recruitment in the non-dependent lung compared to apneic ventilation.

Conclusions

In patients with severe ARDS managed with ECMO, ultraprotective ventilation compared to apneic ventilation improved oxygenation, but increased stress, strain, and mechanical power. Apneic ventilation might be considered as one of the options in the initial phase of ECMO treatment in severe ARDS patients to facilitate lung rest and prevent ventilator-induced lung injury.

Trial registration: German Clinical Trials Register (DRKS00013967). Registered 02/09/2018. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00013967.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-022-00604-9.

Resuscitation Using ECPR During In-Hospital Cardiac Arrest (RESCUE-IHCA) Mortality Prediction Score and External Validation

OBJECTIVES

The aim of this study was to develop and validate a score to accurately predict the probability of death for adult extracorporeal cardiopulmonary resuscitation (ECPR).

BACKGROUND

ECPR is being increasingly used to treat refractory in-hospital cardiac arrest (IHCA), but survival varies from 20% to 40%.

METHODS

Adult patients with extracorporeal membrane oxygenation for IHCA (ECPR) were identified from the American Heart Association GWTG-R (Get With the Guidelines-Resuscitation) registry. A multivariate survival prediction model and score were developed to predict hospital death. Findings were externally validated in a separate cohort of patients from the Extracorporeal Life Support Organization registry who underwent ECPR for IHCA.

RESULTS

A total of 1,075 patients treated with ECPR were included. Twenty-eight percent survived to discharge in both the derivation and validation cohorts. A total of 6 variables were associated with in-hospital death: age, time of day, initial rhythm, history of renal insufficiency, patient type (cardiac vs noncardiac and medical vs surgical), and duration of the cardiac arrest event, which were combined into the RESCUE-IHCA (Resuscitation Using ECPR During IHCA) score. The model had good discrimination (area under the curve: 0.719; 95% CI: 0.680-0.757) and acceptable calibration (Hosmer and Lemeshow goodness of fit P = 0.079). Discrimination was fair in the external validation cohort (area under the curve: 0.676; 95% CI: 0.606-0.746) with good calibration (P = 0.66), demonstrating the model's ability to predict in-hospital death across a wide range of probabilities.

CONCLUSIONS

The RESCUE-IHCA score can be used by clinicians in real time to predict in-hospital death among patients with IHCA who are treated with ECPR.

Extracorporeal membrane oxygenation for COVID-19 and influenza H1N1 associated acute respiratory distress syndrome: a multicenter retrospective cohort study

Background

Extracorporeal membrane oxygenation (ECMO) has become an established rescue therapy for severe acute respiratory distress syndrome (ARDS) in several etiologies including influenza A H1N1 pneumonia. The benefit of receiving ECMO in coronavirus disease 2019 (COVID-19) is still uncertain. The aim of this analysis was to compare the outcome of patients who received veno-venous ECMO for COVID-19 and Influenza A H1N1 associated ARDS.

Methods

This was a multicenter retrospective cohort study including adults with ARDS, receiving ECMO for COVID-19 and influenza A H1N1 pneumonia between 2009 and 2021 in seven Italian ICU. The primary outcome was any-cause mortality at 60 days after ECMO initiation. We used a multivariable Cox model to estimate the difference in mortality accounting for patients’ characteristics and treatment factors before ECMO was started. Secondary outcomes were mortality at 90 days, ICU and hospital length of stay and ECMO associated complications.

Results

Data from 308 patients with COVID-19 (N = 146) and H1N1 (N = 162) associated ARDS who had received ECMO support were included. The estimated cumulative mortality at 60 days after initiating ECMO was higher in COVID-19 (46%) than H1N1 (27%) patients (hazard ratio 1.76, 95% CI 1.17–2.46). When adjusting for confounders, specifically age and hospital length of stay before ECMO support, the hazard ratio decreased to 1.39, 95% CI 0.78–2.47. ICU and hospital length of stay, duration of ECMO and invasive mechanical ventilation and ECMO-associated hemorrhagic complications were higher in COVID-19 than H1N1 patients.

Conclusion

In patients with ARDS who received ECMO, the observed unadjusted 60-day mortality was higher in cases of COVID-19 than H1N1 pneumonia. This difference in mortality was not significant after multivariable adjustment; older age and longer hospital length of stay before ECMO emerged as important covariates that could explain the observed difference.

Trial registration number: NCT05080933, retrospectively registered.

CEPP: Canadian Extracorporeal Life Support (ECLS) Protocol Project

Background

Extracorporeal life support (ECLS) is associated with high morbidity and mortality. Complications and mortality are higher at lower-volume centres. Most Canadian ECLS institutions are low-volume centres. Protocols offer one way to share best practices among institutions to improve outcomes. Whether Canadian centres have ECLS protocols, and whether these protocols are comprehensive and homogenous across centres, is unknown.

Methods

Purposeful sampling with mixed methods was used. A Delphi panel defined key elements relevant to the ECLS process. Documentation used in the delivery of ECLS services was requested from programs. Institutional protocols were assessed using deductive coding to determine the presence of key elements.

Results

A total of 37 key elements spanning 5 domains (referral, initiation, maintenance, termination, and administration) were identified. Documentation from 13 institutions across 10 provinces was obtained. Institutions with heart or lung transplantation programs had more-complete documentation than did non-transplantation programs. Only 5 key elements were present in at least 50% of protocols (anticoagulation strategy, ventilation strategy, defined referral process, selection criteria, weaning process), and variation was seen in how institutions approached each of these elements.

Conclusions

The completeness of ECLS protocols varies across Canada. Programs describe variable approaches to key elements. This variability might represent a lack of evidence or consensus in these areas and creates the opportunity for collaboration among institutions to share protocols and best practice. The key-element framework provides a common language that programs can use to develop ECLS programs, initiate quality-improvement projects, and identify research agendas.

Oxigenación con membrana extracorpórea en el paciente COVID-19: resultados del Registro Español ECMO-COVID de la Sociedad Española de Cirugía Cardiovascular y Endovascular (SECCE)

Introducción y objetivos

La oxigenación con membrana extracorpórea (ECMO) ha resultado ser una opción terapéutica en los pacientes con insuficiencia respiratoria o cardiaca severa por COVID-19. Las indicaciones y manejo de estos pacientes están aún por determinar. Nuestro objetivo es evaluar los resultados de la terapia ECMO en pacientes con COVID-19 incluidos en un registro prospectivo e intentar optimizar los resultados.

Métodos

En marzo de 2020 se inició un registro multicéntrico anónimo prospectivo de pacientes con COVID-19 tratados mediante ECMO veno-arterial (V-A) o veno-venosa (V-V). Se registraron las variables clínicas, analíticas y respiratorias preimplante, datos de implante y evolución de la terapia. El evento primario fue la mortalidad hospitalaria de cualquier causa y los eventos secundarios fueron la recuperación funcional y el evento combinado de recuperación funcional y mortalidad de cualquier causa a partir de los 3 meses de seguimiento tras el alta.

Resultados

Se analizó a un total de 365 pacientes procedentes de 25 hospitales, 347 V-V y 18 V-A (edad media de 52,7 y 49,4 años, respectivamente). Los pacientes con ECMO V-V fueron más obesos, presentaban menos fracaso orgánico diferente al pulmonar y precisaron menos terapia inotrópica previa al implante. El 33,3% y el 34,9% de los pacientes con ECMO V-A y V-V, respectivamente, fueron dados de alta del hospital (p = NS) y la mortalidad fue similar, del 56,2% y 50,9% de los casos respectivamente, la inmensa mayoría durante la ECMO y sobre todo por fracaso multiorgánico. El 14,0% (51 pacientes) permanecían ingresados. El seguimiento medio fue de 196 ± 101,7 días. En el análisis multivariante, resultaron protectores de evento primario en pacientes con ECMO V-V el peso corporal (OR 0,967; IC 95%: 0,95-0,99; p = 0,004) y la procedencia del propio hospital (OR 0,48; IC 95%: 0,27-0,88; p = 0,018), mientras que la edad (OR 1,063; IC 95%: 1,005-1,12; p = 0,032), la hipertensión arterial (3,593; IC 95%: 1,06-12,19; p = 0,04) y las complicaciones en ECMO globales (2,44; IC 95%: 0,27-0,88; p = 0,019), digestivas (OR 4,23, IC 95%: 1,27-14,07; p = 0,019) y neurológicas (OR 4,66; IC 95%: 1,39-15,62; p = 0,013) fueron predictores independientes de mortalidad. El único predictor independiente de aparición de los eventos secundarios resultó el momento de seguimiento del paciente.

Conclusiones

La terapia con ECMO permite supervivencias hospitalarias hasta del 50% en pacientes con COVID-19 grave. La edad, la hipertensión arterial y las complicaciones en ECMO son los predictores de mortalidad hospitalaria en pacientes con ECMO V-V. Un mayor peso corporal y la procedencia del propio hospital son factores protectores. La recuperación funcional solo se ve influida por el tiempo de seguimiento transcurrido tras el alta. La estandarización de los criterios de implante y manejo del paciente con COVID grave mejoraría los resultados y la futura investigación clínica.