The Effect of Catheter Size on the Efficacy of Ultralow-flow Extracorporeal Carbon Dioxide Removal System in Acute Respiratory Distress Syndrome

This pilot randomized controlled trial will evaluate whether catheter size affects the efficacy and performance of ultra-low-flow extracorporeal carbon dioxide removal (ECCO₂R) in mechanically ventilated adults with acute respiratory distress syndrome (ARDS) and hypercapnic respiratory acidosis. Participants will be randomly assigned to receive ECCO₂R using a 12F, 13F, or 15F catheter. The primary outcome is the percentage change in PaCO₂ from baseline during ECCO₂R. Secondary outcomes include achievement and time to correction of hypercapnic respiratory acidosis, changes in PaO₂, circuit lifespan, maximum blood flow, and device- and patient-related complications.