Introduction. Patients with extracorporeal life support (ECLS) may be at risk of inadequate tissue perfusion and oxygenation that leads to multiple-organ dysfunction. Near-infrared spectroscopy has emerged in recent years as a non-invasive tool for monitoring peripheral oxygenation (StO2) in various tissues, including muscle. Using a dynamic vascular occlusive test (VOT), StO2 abnormalities were identified during septic shock and severe trauma, suggesting microvascular dysfunction [1-3]. We wondered whether StO2 abnormalities could exist during the early phase of ECLS.