Objective: Pump-driven extracorporeal gas exchange systems have been advocated in patients suffering from severe acute respiratory distress syndrome who are at risk for life-threatening hypoxemia and/or hypercapnia. This requires extended technical and staff support. Design: We report retrospectively our experience with a new pumpless extracorporeal interventional lung assist (iLA) establishing an arteriovenous shunt as the driving pressure. Setting: University hospital. Patients., Ninety patients with acute respiratory distress syndrome. Interventions. Interventional lung assist was inserted in 90 patients with acute respiratory distress syndrome. Measurements and Main Results: Oxygenation improvement, carbon dioxide elimination, hemodynamic variables, and the amount of vasopressor substitution were reported before, 2 hrs after, and 24 hrs after implementation of the system. Interventional lung assist led to an acute and moderate increase in arterial oxygenation (PaO2/FiO(2) ratio 2 hrs after initiation of iLA [median and interquartile range], 82 mm Hg [64-103]) compared with pre-iLA (58 mm Hg [47-78], p <.05). Oxygenation continued to improve for 24 hrs after implementation (101 mm Hg [74-142], p <.05). Hypercapnia was promptly and markedly reversed by iLA within 2 hrs (PaCO2, 36 mm Hg [30-44]) in comparison with before (60 mm Hg (48-80], p <.05], which allowed a less aggressive ventilation. For hemodynamic stability, all patients received continuous norepinephrine infusion. The incidence of complications was 24.4%, mostly due to ischemia in a lower limb. Thirty-seven of 90 patients survived, creating a lower mortality rate than expected from the Sequential Organ Failure Assessment score. Conclusions. Interventional lung assist might provide a sufficient rescue measure with easy handling properties and low cost in patients with severe acute respiratory distress syndrome and persistent hypoxia/hypercapnia.