Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is generally used as a salvage therapy for patients with severe respiratory failure despite well-conducted therapeutic optimization, including prone position [1]. In some patients, VV-ECMO fails to restore arterial oxygenation saturation (SaO2) to acceptable targets [2]. Thus, we propose a simple clinical algorithm to correct SaO2 based on physiological knowledge of the multiple mechanisms involved in this specific clinical setting (Fig. 1).