Lung-protective ventilation targeting low tidal volumes and plateau pressures is the mainstay of therapy in patients with ARDS. This ventilation strategy limits pulmonary strain, inflammation, and injury, but it may be associated with profound hypercapnic acidosis. In such conditions, extracorporeal CO2 removal can attenuate or normalize hypercapnia and may even facilitate ultraprotective ventilation. Almost half of patients with ARDS develop renal failure. Pathophysiological cross-talk between the injured lung and kidney may aggravate global organ failure and weighs negatively on outcomes. A substantial number of patients with ARDS require continuous renal replacement therapy. Systems adapted from conventional renal replacement platforms with blood flows < 500 mL/min can achieve significant CO2 elimination. Therefore, incorporating low-flow extracorporeal CO2 removal in a continuous renal replacement therapy circuit is an attractive therapeutic option. We reviewed the relevant literature on combining extracorporeal CO2 removal with continuous renal replacement therapy.