The ELIEO trial will test whether starting veno-venous extracorporeal membrane oxygenation (vvECMO) early in severe acute respiratory distress syndrome (ARDS) improves survival compared with a strategy that reserves ECMO for rescue. The investigators plan to randomize 508 adults across experienced ECMO centers and measure all-cause mortality at 90 days. This publication is a study protocol, not a report of treatment results. Recruitment began in March 2025; the authors reported nine participants enrolled as of May 2026.
Why ECMO timing matters
For patients with severe ARDS, lung-protective ventilation, prone positioning, and other supportive measures are central to care. vvECMO can support gas exchange when conventional treatment cannot maintain adequate oxygenation or carbon dioxide clearance, but the decision to initiate extracorporeal support exposes patients to cannulation, bleeding, thrombosis, and resource burdens. A clinically important unresolved question is whether waiting until conventional treatment fails forfeits an opportunity to reduce ventilator-associated injury—or whether earlier extracorporeal support would expose some patients to unnecessary risk.
The authors place ELIEO in the context of prior ECMO research, including CESAR and EOLIA, and observational studies linking longer ventilation before ECMO with worse outcomes. These data are relevant but cannot independently establish that earlier ECMO causes better survival. ELIEO is designed to test the strategy prospectively.
Study design: 508 adults and two treatment strategies
ELIEO is described as an open-label, prospective, randomized, multicenter trial with center-stratified allocation. The planned population comprises adults with severe ARDS who meet defined oxygenation or ventilation criteria. Participating hospitals must be experienced in ARDS management and ECMO support. Both groups receive standard ARDS care, including lung-protective ventilation and adjunctive therapies.
Early vvECMO arm: ECMO is to begin within 24 hours after arrival at the ECMO center ICU or after eligibility is established. Conventional/rescue arm: optimized ARDS care continues, with vvECMO reserved for predefined deterioration or failure of conventional management. Importantly, the comparison is between treatment strategies; it is not a guarantee that every patient in the conventional arm will ultimately receive ECMO.
Who is eligible?
The protocol targets severe ARDS, with a PaO2/FiO2 ratio of 100 mm Hg or lower plus additional criteria related to persistent hypoxemia or hypercapnic acidosis despite optimized ventilation. The detailed entry criteria include a short interval since ARDS onset and no more than seven days of mechanical ventilation. Exclusions include age under 18 years, pregnancy, cardiac failure requiring VA ECMO, and chronic respiratory insufficiency treated with oxygen.
These restrictions matter for interpreting future results. Even if the study ultimately identifies a benefit, that benefit cannot automatically be extended to all respiratory-failure patients, those with longer ventilation exposure, or patients requiring circulatory rather than isolated respiratory support.
How the rescue strategy is defined
In the conventional arm, ECMO is permitted when lung-protective ventilation cannot be delivered or when severe, persistent gas-exchange failure occurs despite corrective measures. The protocol specifies, among other criteria, a PaO2/FiO2 ratio below 60 mm Hg or progressive acidosis with pH below 7.2 for six hours, or arterial oxygen saturation below 80% for more than six hours despite indicated adjunctive interventions. These are trial-specific rescue criteria, not universal bedside instructions for every ECMO program.
Crossovers are expected by design: patients randomized to conventional care may receive rescue ECMO if they deteriorate. The primary intention-to-treat analysis will therefore evaluate the effect of assigning patients to an early-versus-conventional strategy, rather than a pure comparison of patients who actually received ECMO at different times.
Primary and secondary outcomes
The primary outcome is 90-day all-cause mortality. The statistical plan specifies a two-sided log-rank test with an O’Brien–Fleming group-sequential design. The planned enrollment is 508 patients, and the authors describe an interim analysis after 94 events.
Secondary outcomes include 28-day mortality, Sequential Organ Failure Assessment (SOFA) scores, duration of ventilation, ICU length of stay, ventilator-associated pneumonia, bleeding and thrombotic complications, delirium, ICU-acquired weakness, discharge destination, and functional recovery. The study also plans to record coagulation, inflammation, ventilatory, and hemodynamic parameters over time. A 90-day follow-up includes functional assessments such as the Barthel Index.
What the protocol can—and cannot—tell us
The paper supplies a prespecified clinical question, eligibility rules, intervention pathways, outcomes, and statistical methods. Those features make it a useful record against which the eventual trial report can be compared. They do not demonstrate a survival benefit, a reduction in ventilator-induced lung injury, or improved functional outcomes today. No comparative clinical outcome results are presented.
As of May 2026, the manuscript reported only nine patients enrolled, despite a target of 508. The authors expected completion of recruitment in 2028 and preparation of a final report in 2029. Recruitment pace, adherence, center-to-center variation, and crossover will be important when judging the eventual evidence.
Important methodological and reporting considerations
The open-label design is understandable for an intervention such as ECMO, but it can influence cointerventions, thresholds for escalation, and some secondary outcomes. Standardization of ventilation and adjunctive care across experienced centers should help, although differences in patient selection and center practices may remain. The investigators plan an intention-to-treat primary analysis, with additional per-protocol and adjusted analyses.
The published protocol also contains an inconsistency worth clarifying: its abstract says an interim analysis is planned after enrollment of the 94th patient, whereas the statistical-analysis and safety-monitoring sections specify 94 events. These are not equivalent milestones. The statistical section’s event-based description should not be silently substituted for the conflicting abstract statement.
Another practical consideration is sponsorship. The paper reports support from Maquet Cardiopulmonary GmbH, part of Getinge, and identifies the sponsor as responsible for trial conduct and the final publication decision. That relationship should be considered when reviewing the completed trial alongside its prespecified protocol and registration.
Implications for perfusionists and ECMO teams
ELIEO asks a question with direct implications for ECMO referral pathways, circuit readiness, staffing, anticoagulation management, and intensive-care resource planning. If early initiation ultimately improves meaningful outcomes, programs may need to reassess the timing of consultation and transfer. If no benefit emerges, the findings may support avoiding unnecessary exposure to extracorporeal support in patients who can recover with optimized conventional therapy.
For now, the appropriate conclusion is limited: the trial is underway, and the optimal initiation strategy remains under investigation. Perfusionists should not interpret this protocol as evidence that routine early vvECMO is superior to rescue ECMO. Decisions for individual patients continue to require multidisciplinary assessment and current clinical guidance.
Editorial appraisal: This is a prospectively registered randomized-trial protocol with a clinically meaningful primary endpoint and clear comparison groups. Its evidence value is chiefly methodological until outcomes are reported. The open-label design, slow early enrollment, possible crossover, and the inconsistent interim-analysis description are limitations to watch.
Keywords: ELIEO, ECMO timing, early vvECMO, rescue ECMO, severe ARDS, respiratory failure, mechanical ventilation, EOLIA, ECMO clinical trial, 90-day mortality.
Source: Bernard A, Haeberle H, Mirakaj V, Zago M, Koeppen M, Fodi C-K, Martus P, Rosenberger P. Early vs Late Initiation of Extracorporeal Membrane Oxygenation: Protocol for a Prospective, Randomized, Multicenter Study. JMIR Research Protocols. 2026;15:e86652. Original publication. DOI: 10.2196/86652. Trial registration: NCT04208126. Published under CC BY 4.0; © the original authors. This is an independent iPerfusion educational appraisal, not the trial investigators’ report.
