Mortality Risk Assessment in COVID-19 Venovenous Extracorporeal Membrane Oxygenation

Triage of V-V ECMO referrals for COVID-19 respiratory failure

BACKGROUND

As the pandemic progressed, the use of extracorporeal membrane oxygenation (ECMO) for COVID-19-related acute respiratory distress syndrome increased, and patient triage and transfer to ECMO centers became important to optimize patient outcomes. Our objectives are to identify predictors of patient transfer for veno-venous extracorporeal membrane oxygenation (V-V ECMO) evaluation as well as to describe the outcomes of accepted patients.

METHODS

This is a single-center, retrospective analysis of V-V ECMO transfer requests for adult patients with known or suspected COVID-19 and respiratory failure from March 2020 until March 2021. Data were collected prospectively during the triage process for transfer requests as part of clinical patient care at our institution.

RESULTS

Of 341 referred patients, 112 (33%) were accepted for transfer to our facility, whereas 229 (67%) patients were declined for transfer. The Classification and Regression Tree analysis showed that patients' high pressure during airway pressure release ventilation (APRV) and age were the variables most significantly associated with the decision to accept or decline patients for transfer.

CONCLUSIONS

Our triage process enabled one-third of referred patients to be transferred for evaluation, with nearly 70% of those patients ultimately receiving ECMO support. High ventilator settings on APRV and young age were associated with acceptance for transfer. Accepted patients also had a higher incidence of adjunctive therapies (proning and paralysis) prior to transfer request, less cardiac or renal dysfunction, and a shorter duration of mechanical ventilation. Further research is warranted to investigate the outcomes of nontransferred patients.

Impact of extracorporeal membrane oxygenation treatments on acquired von Willebrand syndrome in patients with out-of-hospital cardiac arrest: a retrospective observational study

BACKGROUND

Von Willebrand factor (vWF) plays a crucial role in hemostasis, acting as a key factor for platelet adhesion/aggregation and as a transport protein for coagulation factor VIII. vWF is secreted as a giant multimer, and it undergoes shear stress-dependent cleavage by a specific metalloproteinase in plasma. Among vWF multimers, high-molecular-weight (large) multimers are essential for hemostasis. Acquired von Willebrand syndrome, linked to various conditions, is a hemostatic disorder due to reduced vWF activity. Extracorporeal membrane oxygenation (ECMO), utilized recently for out-of-hospital cardiac arrest patients, generates high shear stress inside the pump. This stress may induce a conformational change in vWF, enhancing cleavage by a specific metalloproteinase and thereby reducing vWF activity. However, no study has investigated the effects of ECMO on vWF-related factors in patients receiving or not receiving ECMO. This study aimed to elucidate the relationship between ECMO treatment and acquired von Willebrand syndrome-related factors in patients with out-of-hospital cardiac arrest.

METHODS

This study included patients with cardiogenic out-of-hospital cardiac arrest admitted to our hospital. The patients were categorized into two groups (ECMO and non-ECMO) based on the presence or absence of ECMO treatment. Plasma samples were collected from patients admitted to the emergency department (days 0-4). The vWF antigen (vWF: Ag), vWF ristocetin cofactor activity (vWF: RCo), and factor VIII activity were measured. Additionally, a large multimer of vWF was evaluated through vWF multimer analysis, utilizing western blotting to probe vWF under non-reducing conditions.

RESULTS

The ECMO and non-ECMO groups included 10 and 22 patients, respectively. The median ECMO treatment in the ECMO group was 64.6 h. No differences in vWF: Ag or factor VIII activity were observed between the two groups during the observation period. However, the ECMO group exhibited a decrease in large vWF multimers and vWF: RCo during ECMO. Strong correlations were observed between vWF: RCo and vWF: Ag in both groups, although the relationships were significantly different between the two groups.

CONCLUSIONS

ECMO treatment in patients with out-of-hospital cardiac arrest resulted in the loss of large vWF multimers and decreased vWF activity. Hence, decreased vWF activity should be considered as a cause of bleeding during ECMO management.

Feasibility and outcomes with subclavian vein access for crescent jugular dual lumen catheter for venovenous extracorporeal membrane oxygenation in COVID-19 related acute respiratory distress syndrome

INTRODUCTION

Femoral-femoral Veno-Venous ExtraCorporeal Life Support (V-V ECLS) has been associated with higher infections rates, vascular site bleeding complications, and restricted patient mobility. Jugular or bicaval dual lumen V-V ECLS conceptually overcomes some of these adverse factors, but experience has shown that jugular vein cannulation still limits mobility and has increased bleeding complications. Technique and outcomes of subclavian vein single-cannulation with Crescent jugular dual-lumen V-V ECLS is described.

METHOD

five patients with COVID-19 related acute respiratory distress syndrome (ARDS) underwent right subclavian vein V-V ECLS placement with the Crescent 32 French jugular dual-lumen V-V ECLS catheter. A standardized percutaneous technique was developed that allowed efficient insertion without need for any specialized imaging (i.e. transesophageal echocardiogram) and outcomes assessed.

RESULTS

Mean age of the five patients was 41.2 years, all obese with an average basal mass index of 45.2 kg/m2 and mean days to decannulation of 24.2 days. Outcomes discovered included; improved patient mobility allowing physical rehabilitation, no vascular access site related complications requiring surgery or endovascular intervention, and none had evidence of superior vena cava syndrome. One patient had subclavian/axillary vein thrombosis with resolution after 3 months of direct-acting oral anticoagulants, and one patient had blood cultures positive at day 37, nearing decannulation.

CONCLUSION

Subclavian vein access for crescent jugular dual lumen V-V ECLS catheter appears to be safe and feasible with added benefits of decreased bleeding and increased mobility over jugular or femoral-femoral access site for long term V-V ECLS support in COVID-19 related ARDS patients.

Outcomes of COVID-19 patients undergoing extracorporeal membrane oxygenation: A systematic review and meta-Analysis

BACKGROUND

The Coronavirus Disease 2019 (COVID-19) pandemic has been ongoing for over 3 years, during which numerous clinical and experimental studies have been conducted. The objective of this systematic review and meta-analysis was to assess the survival probability and complications of COVID-19 patients receiving extracorporeal membrane oxygenation (ECMO).

METHODS

We searched the databases by using Population-Intervention-Comparison-Outcome-Study Design (PICOS). We conducted a search of the PubMed, Web of Science, and EMBASE databases to retrieve studies published until December 10, 2022. A random-effects meta-analysis, subgroup analysis, and assessed the studies using the Newcastle-Ottawa Scale score. The results were presented as pooled morbidity with 95% confidence intervals.

RESULTS

The study was conducted on 19 studies that enrolled a total of 1494 patients, and the results showed a pooled survival probability of 66.0%. The pooled morbidity for intracranial hemorrhage was 8.7%, intracranial thrombosis 7.0%, pneumothorax 9.0%, pulmonary embolism 11.0%, pulmonary hemorrhage 9.0%, heart failure 14.0%, liver failure 13.0%, renal injury 44.0%, gastrointestinal hemorrhage 6.0%, gastrointestinal ischemia 6.0% and venous thrombosis 31.0%.

CONCLUSION

This systematic review and meta-analysis of observational studies focused on the survival probability and complications of COVID-19 patients undergoing ECMO, which are significant in evaluating the use of ECMO in COVID-19 patients and provide a basis for further research.

TRIAL REGISTRATION

Our study was registered on PROSPERO with registration number CRD42022382555.

Supervised machine learning model to predict mortality in patients undergoing venovenous extracorporeal membrane oxygenation from a nationwide multicentre registry

BACKGROUND

Existing models have performed poorly when predicting mortality for patients undergoing venovenous extracorporeal membrane oxygenation (VV-ECMO). This study aimed to develop and validate a machine learning (ML)-based prediction model to predict 90-day mortality in patients undergoing VV-ECMO.

METHODS

This study included 368 patients with acute respiratory failure undergoing VV-ECMO from 16 tertiary hospitals across South Korea between 2012 and 2015. The primary outcome was the 90-day mortality after ECMO initiation. The inputs included all available features (n=51) and those from the electronic health record (EHR) systems without preprocessing (n=40). The discriminatory strengths of ML models were evaluated in both internal and external validation sets. The models were compared with conventional models, such as respiratory ECMO survival prediction (RESP) and predicting death for severe acute respiratory distress syndrome on VV-ECMO (PRESERVE).

RESULTS

Extreme gradient boosting (XGB) (areas under the receiver operating characteristic curve, AUROC 0.82, 95% CI (0.73 to 0.89)) and light gradient boosting (AUROC 0.81 (95% CI 0.71 to 0.88)) models achieved the highest performance using EHR's and all other available features. The developed models had higher AUROCs (95% CI 0.76 to 0.82) than those of RESP (AUROC 0.66 (95% CI 0.56 to 0.76)) and PRESERVE (AUROC 0.71 (95% CI 0.61 to 0.81)). Additionally, we achieved an AUROC (0.75) for 90-day mortality in external validation in the case of the XGB model, which was higher than that of RESP (0.70) and PRESERVE (0.67) in the same validation dataset.

CONCLUSIONS

ML prediction models outperformed previous mortality risk models. This model may be used to identify patients who are unlikely to benefit from VV-ECMO therapy during patient selection.

Decreased PRESET-Score corresponds with improved survival in COVID-19 veno-venous extracorporeal membrane oxygenation

INTRODUCTION

The PREdiction of Survival on ECMO Therapy Score (PRESET-Score) predicts mortality while on veno-venous extracorporeal membrane oxygenation (VV ECMO) for acute respiratory distress syndrome. The aim of our study was to assess the association between PRESET-Score and survival in a large COVID-19 VV ECMO cohort.

METHODS

This was a single-center retrospective study of COVID-19 VV ECMO patients from 15 March 2020, to 30 November 2021. Univariable and Multivariable analyses were performed to assess patient survival and score differences.

RESULTS

A total of 105 patients were included in our analysis with a mean PRESET-Score of 6.74. Overall survival was 65.71%. The mean PRESET-Score was significantly lower in the survivor group (6.03 vs 8.11, p < 0.001). Patients with a PRESET-Score less than or equal to six had improved survival compared to those with a PRESET-Score greater than or equal to 8 (97.7% vs. 32.5%, p < 0.001). In a multivariable logistic regression, a lower PRESET-Score was also predictive of survival (OR 2.84, 95% CI 1.75, 4.63, p < 0.001).

CONCLUSION

We demonstrate that lower PRESET scores are associated with improved survival. The utilization of this validated, quantifiable, and objective scoring system to help identify COVID-19 patients with the greatest potential to benefit from VV-ECMO appears feasible. The incorporation of the PRESET-Score into institutional ECMO candidacy guidelines can help insure and improve access of this limited healthcare resource to all critically ill patients.

Comparison of Sedation and Analgesia Requirements in Patients With SARS-CoV-2 Versus Non-SARS-CoV-2 Acute Respiratory Distress Syndrome on Veno-Venous ECMO

BACKGROUND

Increased analgosedation requirements have been described in patients with acute respiratory distress syndrome (ARDS) on extracorporeal membrane oxygenation (ECMO) support due to unique pharmacokinetic challenges. There is a paucity of data comparing sedation requirements in patients on ECMO for ARDS secondary to SARS-CoV-2 versus other etiologies of respiratory failure.

OBJECTIVE

To compare sedation and analgesia requirements in adult patients with SARS-CoV-2 versus non-SARS-CoV-2 ARDS requiring veno-venous (VV) ECMO support.

METHODS

We performed a retrospective cohort study of adult patients receiving sedation and analgesia on VV-ECMO support. Patients were excluded if cannulated at an outside hospital for greater than 24 hours, expired within 48 hours of ECMO cannulation, or received neuromuscular blocking agents for greater than 7 consecutive days following ECMO cannulation.

RESULTS

We evaluated 108 patients on VV-ECMO support, including 44 with non-SARS-CoV-2 ARDS and 64 with SARS-CoV-2 ARDS. The median daily dexmedetomidine requirements were significantly higher in the SARS-CoV-2 cohort (16.7 vs 13.4 mcg/kg/day, P = 0.03), while the median propofol daily requirements were significantly higher in the non-SARS-CoV-2 cohort (40.3 vs 53.5 mg/kg/day, P < 0.01). There was no difference in daily requirements of opioids, benzodiazepines, and ketamine between groups. Use of adjunct agents to facilitate weaning was significantly higher in the SARS-CoV-2 cohort (78.1% vs 43.2%, P < 0.01).

CONCLUSION AND RELEVANCE

Patients with ARDS on VV-ECMO support require multiple analgosedative agents with concomitant use of nonparenteral adjunct agents. Further studies are needed to evaluate optimal analgosedation strategies in patients on ECMO support.

Venovenous extracorporeal membrane oxygenation for coronavirus disease 2019 patients: A systematic review and meta-analysis

OBJECTIVE

Although the application of venovenous extracorporeal membrane oxygenation (VV-ECMO) in coronavirus disease 2019 (COVID-19) patients with acute respiratory distress syndrome (ARDS) is accumulating, the feasibility and safety of this therapy remain controversial. We aimed to evaluate the effect of VV-ECMO in the treatment of these patients.

METHODS

A comprehensive literature search was performed using PubMed, Embase, the Cochrane Library, and International Clinical Trials Registry Platform databases through November 2021. According to the inclusion and exclusion criteria, the included studies were screened, and meta-analysis was performed by R software (version 4.0.2).

RESULTS

Forty-two studies including 2037 COVID-19 patients supported with VV-ECMO due to ARDS were identified. The pooled analysis revealed that 30-, 60-, and 90-day mortality among patients were respectively 46% (95% CI 37%-57%, I2 = 66%), 46% (95% CI 30%-70%, I2 = 93%), and 49% (95% CI 43%-58%, I2 = 52%), and the pooled incidence rate of in-hospital mortality, major bleeding, hemorrhagic stroke, thrombosis, pulmonary embolism, deep venous thrombosis, and renal replacement therapy were respectively 35%, 39%, 11%, 40%, 15%, 21%, and 44%.

CONCLUSION

Although COVID-19 patients may have a higher risk of bleeding, hemorrhagic stroke, and acute kidney injury during ECMO therapy, the survival rate was more than half of the cases. Our data may support the application of VV-ECMO in COVID-19 patients.

Venovenous extracorporeal membrane oxygenation in COVID-19-related acute respiratory distress syndrome : What's the catch?

COVID-19 is still around, and in the most severe cases can rapidly progress to acute respiratory distress syndrome. When mechanical ventilation fails to improve oxygenation, we desperately shift our management to venovenous extracorporeal membrane oxygenation (vv-ECMO). In this opinion article, we discuss which patients are the most suitable to select for this technique, reiterate previous observations in acute respiratory distress syndrome, and the options for the patients judged not fitting for ECMO.

Evaluation of the discrimination and calibration of predictive scores of mortality in ECMO for patients with COVID-19

BACKGROUND

The criteria for the selection of COVID-19 patients that could benefit most from ECMO organ support are yet to be defined. In this study, we evaluated the predictive performance of ECMO mortality predictive models in patients with COVID-19. We also performed a cost-benefit analysis depending on the mortality predicted probability. We conducted a retrospective cohort study in COVID-19 patients who received ECMO at two tertiary care hospitals between March 2020 to July 2021.

MATERIALS AND METHODS

We evaluated the discrimination (C-statistic), calibration (Cox calibration), and accuracy of the prediction of death due to severe ARDS in V-V ECMO score (PRESERVE), the Respiratory Extracorporeal Membrane Oxygenation Survival Score (RESP) score, and the PREdiction of Survival on ECMO Therapy-Score (PRESET) score. In addition, we compared the RESP score with Plateau pressure instead of Peak pressure.

RESULTS

We included a total of 36 patients, 29 (80%) of them male and with a median (IQR) APACHE of 10 (8-15). The PRESET score had the highest discrimination (AUROCs 0.81 [95%CI 0.67-0.94]) and calibration (calibration-in-the-large 0.5 [95%CI -1.4 to 0.3]; calibration slope 2.2 [95%CI 0.7/3.7]). The RESP score with Plateau pressure had higher discrimination than the conventional RESP score. The cost per QALY in the USA, adjusted to life expectancy, was higher than USD 100 000 in patients older than 45 years with a PRESET > 10.

CONCLUSION

The PRESET score had the highest predictive performance and could help in the selection of patients that benefit most from this resource-demanding and highly invasive organ support.

Significance of heparin induced thrombocytopenia (HIT) in COVID-19: a systematic review and meta-analysis

Heparin-induced thrombocytopenia (HIT) occurs in approximately 3% of patients receiving heparinoids. About 30-75% of patients with type 2 of HIT develop thrombosis as a result of platelet activation. The most important clinical symptom is thrombocytopenia. Patients with severe COVID-19 are among those receiving heparinoids. This meta-analysis performed to picture the current knowledge and results of published studies in this field. Three search engines were searched and 575 papers were found. After evaluation, 37 articles were finally selected of which 13 studies were quantitatively analyzed. The pooled frequency rate of suspected cases with HIT in 13 studies with 11,241 patients was 1.7%. The frequency of HIT was 8.2% in the extracorporeal membrane oxygenation subgroup with 268 patients and 0.8% in the hospitalization subgroup with 10,887 patients. The coincidence of these two conditions may increase the risk of thrombosis. Of the 37 patients with COVID-19 and confirmed HIT, 30 patients (81%) were treated in the intensive care unit or had severe COVID-19. The most commonly used anticoagulants were UFH in 22 cases (59.4%). The median platelet count before treatment was 237 (176-290) x 10³/µl and the median nadir platelet count was 52 (31-90.5) x 10³/µl.

Multi-horizon predictive models for guiding extracorporeal resource allocation in critically ill COVID-19 patients

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) resource allocation tools are currently lacking. We developed machine learning (ML) models for predicting COVID-19 patients at risk of receiving ECMO to guide patient triage and resource allocation.

MATERIAL AND METHODS

We included COVID-19 patients admitted to intensive care units for >24 h from March 2020 to October 2021, divided into training and testing development and testing-only holdout cohorts. We developed ECMO deployment timely prediction model ForecastECMO using Gradient Boosting Tree (GBT), with pre-ECMO prediction horizons from 0 to 48 h, compared to PaO2/FiO2 ratio, Sequential Organ Failure Assessment score, PREdiction of Survival on ECMO Therapy score, logistic regression, and 30 pre-selected clinical variables GBT Clinical GBT models, with area under the receiver operator curve (AUROC) and precision recall curve (AUPRC) metrics.

RESULTS

ECMO prevalence was 2.89% and 1.73% in development and holdout cohorts. ForecastECMO had the best performance in both cohorts. At the 18-h prediction horizon, a potentially clinically actionable pre-ECMO window, ForecastECMO, had the highest AUROC (0.94 and 0.95) and AUPRC (0.54 and 0.37) in development and holdout cohorts in identifying ECMO patients without data 18 h prior to ECMO.

DISCUSSION AND CONCLUSIONS

We developed a multi-horizon model, ForecastECMO, with high performance in identifying patients receiving ECMO at various prediction horizons. This model has potential to be used as early alert tool to guide ECMO resource allocation for COVID-19 patients. Future prospective multicenter validation would provide evidence for generalizability and real-world application of such models to improve patient outcomes.

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.

Early Guided Palliative Care Communication for Patients With COVID-19 Receiving ECMO

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) combined with COVID-19 presents challenges (eg, isolation, anticipatory grief) for patients and families.

OBJECTIVE

To (1) describe characteristics and outcomes of patients with COVID-19 receiving ECMO, (2) develop a practice improvement strategy to implement early, semistructured palliative care communication in ECMO acknowledgment meetings with patients' families, and (3) examine family members' experiences as recorded in clinicians' notes during these meetings.

METHODS

Descriptive observation of guided, in-depth meetings with families of patients with COVID-19 receiving ECMO, as gathered from the electronic medical record of a large urban academic medical center. Most meetings were held within 3 days of initiation of ECMO.

RESULTS

Forty-three patients received ECMO between March and October 2020. The mean patient age was 44 years; 63% of patients were Hispanic/Latino, 19% were Black, and 7% were White. Documentation of the ECMO acknowledgment meeting was completed for 60% of patients. Fifty-six percent of patients survived to hospital discharge. Family discussions revealed 7 common themes: hope, reliance on faith, multiple family members with COVID-19, helping children adjust to a new normal, visitation restrictions, gratitude for clinicians and care, and end-of-life discussions.

CONCLUSION

Early and ongoing provision of palliative care is feasible and useful for highlighting a range of experiences related to COVID-19. Palliative care is also useful for educating patients and families on the benefits and limitations of ECMO therapy.

Time From Infiltrate on Chest Radiograph to Venovenous Extracorporeal Membrane Oxygenation in COVID-19 Affects Mortality

Venovenous extracorporeal membrane oxygenation (VV ECMO) has been used to treat severe coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome; however, patient selection criteria have evolved throughout the pandemic. In this study, we sought to determine the association of patient mortality with time from positive COVID-19 test and infiltrate on chest radiograph (x-ray) to VV ECMO cannulation. We hypothesized that an increasing duration between a positive COVID-19 test or infiltrates on chest x-ray and cannulation would be associated with increased mortality. This is a single-center retrospective chart review of COVID-19 VV ECMO patients from March 1, 2020 to July 28, 2021. Unadjusted and adjusted multivariate analyses were performed to assess for mortality differences. A total of 93 patients were included in our study. Increased time, in days, from infiltrate on chest x-ray to cannulation was associated with increased mortality in both unadjusted (5-9, P = 0.002) and adjusted regression analyses (odds ratio [OR]: 1.49, 95% CI: 1.22-1.81, P < 0.01). Time from positive test to cannulation was not found to be significant between survivors and nonsurvivors (7.5-11, P = 0.06). Time from infiltrate on chest x-ray to cannulation for VV ECMO should be considered when assessing patient candidacy. Further larger cohort and prospective studies are required.

Evolving outcomes of extracorporeal membrane oxygenation during the first 2 years of the COVID-19 pandemic: a systematic review and meta-analysis

Background

Extracorporeal membrane oxygenation (ECMO) has been used extensively for coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS). Reports early in the pandemic suggested that mortality in patients with COVID-19 receiving ECMO was comparable to non-COVID-19-related ARDS. However, subsequent reports suggested that mortality appeared to be increasing over time. Therefore, we conducted an updated systematic review and meta-analysis, to characterise changes in mortality over time and elucidate risk factors for poor outcomes.

Methods

We conducted a meta-analysis (CRD42021271202), searching MEDLINE, Embase, Cochrane, and Scopus databases, from 1 December 2019 to 26 January 2022, for studies reporting on mortality among adults with COVID-19 receiving ECMO. We also captured hospital and intensive care unit lengths of stay, duration of mechanical ventilation and ECMO, as well as complications of ECMO. We conducted random-effects meta-analyses, assessed risk of bias of included studies using the Joanna Briggs Institute checklist and evaluated certainty of pooled estimates using GRADE methodology.

Results

Of 4522 citations, we included 52 studies comprising 18,211 patients in the meta-analysis. The pooled mortality rate among patients with COVID-19 requiring ECMO was 48.8% (95% confidence interval 44.8–52.9%, high certainty). Mortality was higher among studies which enrolled patients later in the pandemic as opposed to earlier (1st half 2020: 41.2%, 2nd half 2020: 46.4%, 1st half 2021: 62.0%, 2nd half 2021: 46.5%, interaction p value = 0.0014). Predictors of increased mortality included age, the time of final patient enrolment from 1 January 2020, and the proportion of patients receiving corticosteroids, and reduced duration of ECMO run.

Conclusions

The mortality rate for patients receiving ECMO for COVID-19-related ARDS has increased as the pandemic has progressed. The reasons for this are likely multifactorial; however, as outcomes for these patients evolve, the decision to initiate ECMO should include the best contextual estimate of mortality at the time of ECMO initiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04011-2.

The Year in Extracorporeal Membrane Oxygenation: Selected Highlights From 2021

This review summarizes the extracorporeal membrane oxygenation (ECMO) or extracorporeal life support literature published in 2021. This Selected Highlights article is not intended to be an exhaustive review of the literature, but rather a summarizing of key themes that developed in the ECMO literature during 2021. The primary topics presented include the following: ECMO for coronavirus disease 2019, extracorporeal cardiopulmonary resuscitation, periprocedural cardiopulmonary support with ECMO, and anticoagulation for ECMO.

Coagulation abnormalities in patients with COVID-19 on venovenous ECLS increased risk for technical complications and support times but had no impact on survival

BACKGROUND

Patients with severe coronavirus disease-19 (COVID-19)-associated acute respiratory distress on venovenous extracorporeal lung support (V-V ECLS) showed high incidence of vascular as well as ECLS-related thrombotic complications. The latter may influence the outcome of the patients.

METHODS

This is a retrospective monocentric study on prospectively collected data of technical complications including 69 adult COVID-19 patients on V-V ECLS (ECLS Registry, March 2020 until April 2021) without and with system exchanges. Alterations in ECLS-specific data, hemolysis, coagulation and hemostasis parameters were analyzed.

RESULTS

Every second COVID-19 patient on V-V ECLS developed technical complications. Optimized ECLS management at our ECLS center reduced cases of acute clot formation (pump head thrombosis, acute oxygenator thrombosis) (17%), and allowed early identification of progressive clotting processes (worsened gas transfer, coagulation disorder) (14%, 54%) with a significant overhang of hyperfibrinolysis (37%). Although COVID-19 disease and technical complications caused prolonged length of stay at the intensive care unit and ECLS support times, the proportion of successful weaning and survival rates were comparable with patients without system exchange.

CONCLUSION

The survival of ECLS patients with COVID-19 was independent of the requirement for system exchange due to technical-induced coagulation disorders. Close monitoring for circuit clotting is mandatory in COVID-19 patients and is one prerequisite for successful organ support in these difficult patients.

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.

Contraindications to the Initiation of Veno-Venous ECMO for Severe Acute Respiratory Failure in Adults: A Systematic Review and Practical Approach Based on the Current Literature

(1) Background: Extracorporeal membrane oxygenation (ECMO) is increasingly used for acute respiratory failure with few absolute but many relative contraindications. The provider in charge often has a difficult time weighing indications and contraindications to anticipate if the patient will benefit from this treatment, a decision that often decides life and death for the patient. To assist in this process in coming to a good evidence-based decision, we reviewed the available literature. (2) Methods: We performed a systematic review through a literature search of the MEDLINE database of former and current absolute and relative contraindications to the initiation of ECMO treatment. (3) Results: The following relative and absolute contraindications were identified in the literature: absolute-refusal of the use of extracorporeal techniques by the patient, advanced stage of cancer, fatal intracerebral hemorrhage/cerebral herniation/intractable intracranial hypertension, irreversible destruction of the lung parenchyma without the possibility of transplantation, and contraindications to lung transplantation; relative-advanced age, immunosuppressed patients/pharmacological immunosuppression, injurious ventilator settings > 7 days, right-heart failure, hematologic malignancies, especially bone marrow transplantation and graft-versus-host disease, SAPS II score ≥ 60 points, SOFA score > 12 points, PRESERVE score ≥ 5 points, RESP score ≤ -2 points, PRESET score ≥ 6 points, and "do not attempt resuscitation" order (DN(A)R status). (4) Conclusions: We provide a simple-to-follow algorithm that incorporates absolute and relative contraindications to the initiation of ECMO treatment. This algorithm attempts to weigh pros and cons regarding the benefit for an individual patient and hopefully assists caregivers to make better, informed decisions.

Prediction models for diagnosis and prognosis of covid-19: systematic review and critical appraisal

OBJECTIVE

To review and appraise the validity and usefulness of published and preprint reports of prediction models for diagnosing coronavirus disease 2019 (covid-19) in patients with suspected infection, for prognosis of patients with covid-19, and for detecting people in the general population at increased risk of covid-19 infection or being admitted to hospital with the disease.

DESIGN

Living systematic review and critical appraisal by the COVID-PRECISE (Precise Risk Estimation to optimise covid-19 Care for Infected or Suspected patients in diverse sEttings) group.

DATA SOURCES

PubMed and Embase through Ovid, up to 1 July 2020, supplemented with arXiv, medRxiv, and bioRxiv up to 5 May 2020.

STUDY SELECTION

Studies that developed or validated a multivariable covid-19 related prediction model.

DATA EXTRACTION

At least two authors independently extracted data using the CHARMS (critical appraisal and data extraction for systematic reviews of prediction modelling studies) checklist; risk of bias was assessed using PROBAST (prediction model risk of bias assessment tool).

RESULTS

37 421 titles were screened, and 169 studies describing 232 prediction models were included. The review identified seven models for identifying people at risk in the general population; 118 diagnostic models for detecting covid-19 (75 were based on medical imaging, 10 to diagnose disease severity); and 107 prognostic models for predicting mortality risk, progression to severe disease, intensive care unit admission, ventilation, intubation, or length of hospital stay. The most frequent types of predictors included in the covid-19 prediction models are vital signs, age, comorbidities, and image features. Flu-like symptoms are frequently predictive in diagnostic models, while sex, C reactive protein, and lymphocyte counts are frequent prognostic factors. Reported C index estimates from the strongest form of validation available per model ranged from 0.71 to 0.99 in prediction models for the general population, from 0.65 to more than 0.99 in diagnostic models, and from 0.54 to 0.99 in prognostic models. All models were rated at high or unclear risk of bias, mostly because of non-representative selection of control patients, exclusion of patients who had not experienced the event of interest by the end of the study, high risk of model overfitting, and unclear reporting. Many models did not include a description of the target population (n=27, 12%) or care setting (n=75, 32%), and only 11 (5%) were externally validated by a calibration plot. The Jehi diagnostic model and the 4C mortality score were identified as promising models.

CONCLUSION

Prediction models for covid-19 are quickly entering the academic literature to support medical decision making at a time when they are urgently needed. This review indicates that almost all pubished prediction models are poorly reported, and at high risk of bias such that their reported predictive performance is probably optimistic. However, we have identified two (one diagnostic and one prognostic) promising models that should soon be validated in multiple cohorts, preferably through collaborative efforts and data sharing to also allow an investigation of the stability and heterogeneity in their performance across populations and settings. Details on all reviewed models are publicly available at https://www.covprecise.org/. Methodological guidance as provided in this paper should be followed because unreliable predictions could cause more harm than benefit in guiding clinical decisions. Finally, prediction model authors should adhere to the TRIPOD (transparent reporting of a multivariable prediction model for individual prognosis or diagnosis) reporting guideline.

SYSTEMATIC REVIEW REGISTRATION

Protocol https://osf.io/ehc47/, registration https://osf.io/wy245.

READERS' NOTE

This article is a living systematic review that will be updated to reflect emerging evidence. Updates may occur for up to two years from the date of original publication. This version is update 3 of the original article published on 7 April 2020 (BMJ 2020;369:m1328). Previous updates can be found as data supplements (https://www.bmj.com/content/369/bmj.m1328/related#datasupp). When citing this paper please consider adding the update number and date of access for clarity.