Efficient CO2 removal using extracorporeal lung and renal assist device

We developed a novel system comprising acid infusion, membrane lung, and a continuous renal replacement therapy console for efficient CO2 removal at a low blood flow. To evaluate the new system, we used an ex vivo experimental model using swine blood. A liter of aliquoted blood adjusted to pH 7.25 and pCO2 65 mm Hg was mixed with acid (0, 10, or 20 mL of lactic or hydrochloric acid [1 mol/L]) and was immediately delivered to the system in a single pass. We collected blood samples at each point of the circuit and calculated the amount of CO2 eliminated by the membrane lung. The new system removed 13.2 ± 0.8, 32.0 ± 2.1, and 51.6 ± 3.7 mL/min of CO2 (with 0, 10, and 20 mEq/L of lactic acid) and 21.2 ± 1.2, 27.3 ± 0.3, and 42.0 ± 1.3 mL/min (with 0, 10, and 20 mEq/L of hydrochloric acid), respectively. The levels of lactate and Cl− ions for acid–base equilibrium were restored after continuous hemodiafiltration. Thus, the amount of CO2 eliminated by the membrane lung was 3.9 times higher with lactic acid and 2.0 times higher with hydrochloric acid compared with non-acid controls. In conclusion, this easy-to-setup CO2 removal system was safe, effective, and removed CO2 at a low blood flow.