AMBULATORY ARTERIOVENOUS CARBON DIOXIDE REMOVAL

DESCRIPTION (provided by applicant): Chronic Obstructive Pulmonary Disease (COPD) affects 15-17 million people in the United States and is the fourth leading cause of death in the U.S. When COPD reaches end-stage, hypercarbia, not hypoxia, usually limits the COPD patients' ability to ambulate. Lung Volume Reduction Surgery remains investigational. Lung transplantation is available to only 900/year as the average wait for a donor is two years with 30 percent wait-list mortality. An artificial lung is years away. We developed Arteriovenous Carbon Dioxide Removal (AVCO2R) with a low-resistance gas exchanger in a simple percutaneous arteriovenous shunt to achieve near-total extracorporeal removal of CO2 production with only 800-1200 mI/min blood flow. From our animal and patient safety trials, AVCO2R decreases minute ventilation with an increase in PaO2/FiO2 and no significant change in WBC, platelets, or complement while maintaining CO2 and pH homeostasis. Currently, AVCO2R is designed for percutaneous access in a supine patient as treatment for ARDS. A prototype Ambulatory AVCO2R (A-AVCO2R ) gas exchanger was designed and built by MC3 (Ann Arbor, Ml) for high gas exchange efficiency and very low blood flow resistance. The initial A-AVCO2R design was successfully implanted by the University of Texas Medical Branch (UTMB) to provide near total CO2 removal in a normal sheep for 24 hours. At this point, necessary prototype A-AVCO2R modifications include: 1) optimization of the oxygenator design for ambulatory arteriovenous CO2 removal (A-AVCO2R), and 2) implementation of a portable sweep gas control system. The immediate goal of this phase I research plan is to address the major problems in A-AVCO2R design, fabricate the changes into a working prototype, and then test the design chronically (1 week) in ambulatory large animals. For Phase II, we plan a series of long-term (1 month) studies in sheep models of CO2 retention to prepare for clinical trials to achieve our goal of A-AVCO2R as a management technique for long-term survival or as a bridge to lung transplantation.