Extracorporeal Carbon Dioxide Removal in Critical Care: Bridging Physiology and Clinical Reality—A State-of-the-Art Review

Extracorporeal carbon dioxide removal (ECCO₂R) has emerged as a refined physiological intervention designed to dissociate the act of ventilation from the work of gas exchange, offering a theoretical pathway toward lung-protective and even ultra-protective ventilatory strategies in patients with severe respiratory failure. Unlike full extracorporeal membrane oxygenation, ECCO₂R operates at lower blood flow rates, facilitating carbon dioxide clearance with smaller cannulas and potentially fewer vascular complications. Yet, as with many technologies that traverse the boundary between salvage therapy and routine support, the clinical evidence to date presents a paradox: ECCO₂R reliably reduces PaCO₂, permits lower tidal volumes, and in many cases enables earlier extubation, but these physiological victories have not consistently translated into reduced hospital length of stay or improved early mortality. This review examines the principles, configurations (arterio-venous versus veno-venous), complications (bleeding, thrombosis, vascular injury, mechanical failures), and clinical applications of ECCO₂R in acute respiratory distress syndrome and chronic obstructive pulmonary disease exacerbations. Particular attention is paid to the gap between mechanistic promise and patient-centered outcomes, the role of ECCO₂R as a bridge to transplantation, and the ongoing regulatory and logistical challenges—including the lack of FDA approval and the intensive interdisciplinary resources required for safe deployment. Ultimately, ECCO₂R remains an investigational but intellectually compelling technology, one that forces clinicians to confront a fundamental question: can superior gas exchange alone improve the trajectory of critical illness, or must we await truly lung-restorative therapies?