Authors' reply: What every intensivist should know about extracorporeal CO₂ removal in ARDS

We thank Tang for the thoughtful comments regarding our review on extracorporeal CO₂ removal (ECCO₂R) in acute respiratory distress syndrome (ARDS). In this reply, we further discuss several key issues related to the physiological rationale and future development of ECCO₂R. While acknowledging the relevance of mechanical power (MP) as an integrative measure of ventilatory energy, we argue that variables such as driving pressure (ΔP) and ventilatory ratio (VR) may provide more actionable physiological information for identifying patients most likely to benefit from ECCO₂R. We review evidence supporting physiology-based patient selection, including predictive enrichment strategies derived from the SUPERNOVA and REST studies, and emphasize the importance of ventilatory burden, dead-space burden, and respiratory mechanics as determinants of treatment response. We also address the biological and physiological heterogeneity of ARDS, highlighting the need for individualized decisionmaking rather than universal selection criteria. Regarding treatment timing, we agree that earlier implementation may be physiologically advantageous, although optimal initiation thresholds remain uncertain. Finally, we discuss the emerging role of hybrid ECCO₂R-continuous renal replacement therapy (CRRT) platforms within the broader framework of multiple organ support therapy. Although the physiological rationale for these approaches is compelling, current evidence remains limited and heterogeneous. Overall, we contend that the future of ECCO₂R will depend on improved physiological patient selection, technological refinement, and a more precise understanding of responder phenotypes.