Extracorporeal membrane oxygenation (EMCO) is an important adjunct therapy for those with severe acute respiratory distress syndrome or respiratory failure.1 Additionally, it has become an increasingly important method to bridge patients to lung transplant.2–4 However, discrepancies remain regarding which patients are appropriate for bridging and their respective outcomes.5–8 Although older age has been used as a relative contraindication to initiate ECMO, this practice varies across centers.9,10 Current evidence is limited regarding the outcomes of those bridged to transplant using ECMO in the elderly population.

In this article, Zhou et al.11 retrospectively investigate the outcomes of ECMO as a bridging strategy in patients greater than or equal to 65 years of age. Since 2008, there has been an increase in bridge to transplantation (BTT) using ECMO compared to mechanical ventilation alone. Additionally, there has been a sharper increase since 2018. Despite the growing use of ECMO, elderly bridged patients only accounted for 159 patients during the study period. In both the adjusted and unadjusted analysis, patients older than 65 BTT by ECMO had worse survival compared to those that were not (1 year survival: no-BTT 85.9%, Mechanical Ventilation (MV)-only BTT 82.1%, ECMO BTT 68.4%, Hazard Ratio (HR) 2.62 [no-BTT versus ECMO BTT], p = 0.001) (3 year survival no-BTT 66.2%, MV-only BTT 60.8%, ECMO BTT 50.9%, HR 1.91 [no-BTT versus ECMO BTT] p < 0.001), HR 1.58 (MV-only BTT versus ECMO BTTp = 0.005). Furthermore, patients bridged with ECMO were more likely to have a longer hospital length of stay, be intubated at 72 hours, and require dialysis posttransplantation. Interestingly, the conditional survival (survival after the first year of transplant) did show no difference in the short-term outcomes between the study groups.

As the authors noted, the study does have multiple limitations. First, the comparison between MV and EMCO should be interpreted cautiously, given the limited data on the initiation and length of mechanical ventilation pretransplant. Second, the low number of patients older than 65 and bridged using ECMO limited the generalizability of the study. Third, the study takes place over a relatively long era, and it is conceivable that, as ECMO outcomes have generally improved, outcomes in BTT patients have improved. Finally, the retrospective nature of the study certainly introduces bias into the study groups that cannot be completely adjusted for.

We believe the central question created by this study is not whether elderly patients should be bridged, but which ones. Options to treat older patients with end-stage lung disease are limited. Despite multiple reports showing worse outcomes of ECMO and lung transplant in the elderly population, the outcomes are similar in carefully selected individuals.12–19 Thus, many physicians would consider veno-venous ECMO use or lung transplant to be reasonable in select older patients. Despite the improvement in bridging strategies over the years, there is still insufficient data to strategize patient selection.20,21 In addition, the benefit of ambulating patients on ECMO or physical therapy remains unanswered in this patient population.20,22,23 The conditional survival reported in the study suggests that patient selection can impact outcomes in patients who are older. Therefore, narrowing down on patient selection and further improvement in bridging strategies could lead to comparable outcomes long term.

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