The role of extracorporeal CO2 removal from pathophysiology to clinical applications with focus on potential combination with RRT: an expert opinion document

Abstract

Technological advancements have facilitated the application of extracorporeal-carbon-dioxide removal (ECCO₂R) in managing acute respiratory-failure (ARF), including both hypoxemic and hypercapnic forms. A non-systematic literature review (PubMed, Medline, Embase, Google Scholar; January 2000-November 2024) identified randomized-controlled-trials (RCTs) and real-world evidence (RWE) on ECCO₂R, alone or combined with continuous renal replacement therapy (CRRT). A multidisciplinary panel of intensivists, anesthesiologists, and nephrologists from Italy, Portugal, and Spain assessed clinical integration of ECCO₂R. Key considerations included identifying ideal candidates, such as patients with acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), asthma exacerbations, alongside initiation timing and discontinuation criteria. For ARDS, recommended initiation thresholds included driving pressure ≥15 cm H₂O, plateau pressure ≥28 cm H₂O, pH < 7.28, and respiratory-rate >25 breaths/min. In COPD or asthma exacerbations at risk of non-invasive ventilation (NIV) failure, triggers included pH ≤ 7.25, RR ≥ 30 breaths/min, Intrinsic-PEEP ≥ 5 cm H₂O, signs of respiratory fatigue, paradoxical abdominal motion, and severe distress. Absolute contraindications were uncontrolled bleeding, refractory hemodynamic instability, or lack of vascular access. Relative contraindications included moderate coagulopathy and limited access. The panel concluded ECCO₂R may support selected adults with ARDS or obstructive lung disease, though further RCTs and high-quality prospective studies are needed to guide practice.

Keywords: acute distress respiratory syndrome; asthma; chronic obstructive pulmonary disease; continuous renal replacement therapy; extracorporeal CO2 removal; mechanical ventilation.

Figure 1

Applications and initiation parameters of extracorporeal CO₂ removal in acute respiratory distress syndrome and obstructive airway diseases in invasive (A) and non-invasive (B) mechanical ventilation. Schematic representation of the clinical applications of ECCO₂R in ARDS and obstructive airway diseases, under both invasive mechanical ventilation (IMV) and non-invasive ventilation (NIV) settings. The diagram details the respiratory parameters and arterial blood gas (ABG) thresholds for treatment initiation, along with the basic initiation parameters of ECCO₂R. ABG, arterial blood gas; ARDS, acute respiratory distress syndrome; ECCO₂R, extracorporeal CO₂ removal; IMV, invasive mechanical ventilation; NIV, non-invasive ventilation; RR, respiratory rate; CIRF, clinical indicators of respiratory failure; PAB, paradoxical abdominal breathing; SRD, severity of respiratory dyspnea.

Figure 2

Applications and initiation parameters of extracorporeal CO₂ removal in combination with continuous renal replacement therapies. Schematic representation of the clinical applications of ECCO₂R in combination with CRRT. The process follows KDIGO 2012 AKI guidelines (See reference 70), emphasizing the importance of clinical context, fluid balance, and laboratory trends over isolated blood urea nitrogen and creatinine thresholds. Key considerations include dose calculation (25–30 mL/kg/h to achieve an effluent dose of ≥20–25 ml/kg/h), dose distribution (diffusive vs. post-dilution convective dose), and the impact of pre-dilution on effective clearance. Clinical insights highlight thresholds for initiating CRRT, the importance of maintaining prescribed vs. administered dose, and minimizing downtime. AKI, acute kidney injury; CRRT, continuous renal replacement therapy; ECCO₂R, extracorporeal CO₂ removal.