Veno-venous extracorporeal membrane oxygenation for the acute respiratory distress syndrome: a bridge too far?

Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO) provides a bridge to recovery in patients with acute respiratory failure due to the acute respiratory distress syndrome (ARDS). Survival in ARDS has improved over 15 years, and VV-ECMO may rescue even the most severe of these patients. Predictors of survival on ICU are based upon the principles of reversibility of the inciting aetiology, and premorbid 'reserve' - an imprecise term encompassing comorbidities and frailty. ECMO can support failing organs for prolonged periods, thus sometimes masking trajectories of decline, or unmasking irretrievable intrinsic conditions at a later time point in the critical illness. Clinicians are confronted with new on-treatment dilemmas: how long should we continue this high level of care? Will the patient's limited respiratory reserve manage off ECMO? Or are we hastening their demise? How long is it justifiable to keep someone on ECMO, if the predicted survival off is ultimately poor, but they are in a stable state whilst supported? The palliative withdrawal from ECMO is unchartered territory that requires further study. We describe two representative cases and discuss the wide ethical issues surrounding the initiation and withdrawal of ECMO.