Development of ambulatory arterio-venous carbon dioxide removal (AVCO ₂R): The downsized gas exchanger prototype for ambulation removes enough CO₂ with low blood resistance

We are developing an ultra compact gas exchanger to allow ambulation during arterial-venous CO₂ removal (AVCO₂R). The ambulatory AVCO₂R gas exchanger (135 ml prime volume and 1.3 M² gas exchange surface area) is made of polymethylpentene hollow fibers. The gas exchanger was attached to sheep carotid artery (12F) and jugular vein (14F) by percutaneous cannulae for 6 hours (n = 5). Device CO₂ removal was measured and calculated at a constant blood flow rate of 1 L/min coupled with varying sweep gas from 1 to 15 L/min, and at constant sweep gas flow of 2 L/min coupled with varying blood flow from 0.5 to 1.25 L/min to determine capacity of CO₂ removal at Pa CO₂ = 40-50 mm Hg. Blood gases, CO ₂ removal and hemodynamics were recorded at 0, 3, and 6 hours. CO₂ removal increased with sweep gas flow rate and with increase of device blood flow. Hemodynamics remained unchanged throughout study. Gas exchanger resistance remained stable at 2.3 ± 0.53 mm Hg/L/min. CO ₂ removal with 1 L/min blood flow and 2 L/min sweep gas was 110 ± 12 then stabilized at 85 ± 14 mL/min to 6 hours. The compact ambulatory AVCO₂R gas exchanger achieves stable, near total CO ₂ removal for at least 6 hours with a simple arteriovenous shunt.