DEVELOPMENT OF AMBULATORY ATERIOVENOUS CO2 REMOVAL (AAVCO2R)

Abstract

Using a simple arteriovenous shunt at 1 liter flow, a commercial hollow fiber gas exchanger achieves near total CO2 removal, allowing lung rest and potentially improving survival. We are developing a ultra-compact gas exchanger to allow patient ambulation during AVCO2R. Methods: The AAVCO2R gas exchanger (MC3, Inc.) has a total volume of 340 ml and a fiber surface of 1.3 2. The hollow fibers are OxyPlus PMP 90/200 (Membrana GmbH) with an outer skin to mitigate plasma leakage. Carotid artery and jugular vein cannulated by percutaneous 12F arterial and 14F venous cannulae. AAVCO2R gas exchanger was attached for 6 hours (n=3). The device CO2 removal was measured at a constant flow rate of 1 L/min, varying sweep gas from 1 to 15 L/min, to determine the optimal sweep gas:blood flow ratio. Blood gases, CO2 removal and hemodynamics were recorded at 0, 3 and 6 hours. During data recording, the sheep were sedated to suppress spontaneous breathing, and were hypoventilated to maintain PaO280 mmHg and PaCO2=40–50 mmHg. Results: CO2 removal increased with sweep gas flow rate, with an inflection point occurring at 5 L/min. Hemodynamic parameters were unchanged throughout. Gas exchanger resistance remained stable at 2.3+/−0.53 mmHg/L/min. CO2 removal with 1L/min blood flow and 5 L/min sweep gas was 110 +/−12 then stabilized at 85+/−14 mL/min to 6 hours. Conclusion: The compact AAVCO2R gas exchanger demonstrated an optimal CO2 removal at a 5:1 sweep gas to blood flow rate ratio, achieving stable, near total CO2 removal for at least 6 hours with a simple arteriovenous shunt.