Stewart Farling, PhD
Postdoctoral Associate
Duke University, United States
Disclosure information not submitted.
Travis Vesel, MD
Pediatric Cardiac Intensivist
Duke University Hospital
Durham, North Carolina, United States
Disclosure information not submitted.
Bruce Klitzman, PhD
Associate Professor in Surgery
Duke University School of Medicine, United States
Disclosure information not submitted.
Marc Deshusses, PhD
Professor of Civil and Environmental Engineering
Duke University, United States
Disclosure information not submitted.
Alexandre Rotta, MD, FCCM
Chair, SCCM Pediatric Section
Duke University Medical Center
Durham, North Carolina, United States
Disclosure information not submitted.
Title: Development of a Novel Intravascular Oxygenator Catheter: Pilot Ex-Vivo Study
Introduction: The ability to oxygenate blood can be lifesaving to patients with refractory hypoxemia. We are developing a hollow fiber membrane (HFM) intravascular catheter capable of delivering clinically significant quantities of O2 directly to the bloodstream through non-porous small diameter hollow fibers. The catheter permits the application of hyperbaric conditions to generate large concentration gradients across the diffusing surface, thereby greatly increasing O2 transfer. This pressure-enhanced diffusive flux combined with our unique mixing method allows for the development of a compact membrane oxygenator suitable for intravascular use. We hypothesized that our HFM catheter system would have the ability to deliver clinically significant quantities of O2 to blood in an ex-vivo perfusion model.
Methods: The HFM catheter consisted of a 16.2 cm bundle composed of thirty hollow fibers (Teflon AF 2400 polymer, OD 406.4 µm, ID 228.6 µm) secured to a central shaft. A stepper motor rotated the bundle across a macro angle step of 22.5° followed by micro-oscillations at 11.25° at 3200 deg s-1. The experimental circuit was primed with porcine whole blood anticoagulated with heparin. The HFM bundle was inserted into the mock vena-cava (2.5 cm ID) with deoxygenated blood (or water) flowing past it at 2 L/min. Test liquid inlet conditions were held constant (temp 37° C, oxyhemoglobin percentage 65 ±5 %, PaCO2 45 ± 5 mmHg, pH 7.35 ± 5 ) using a Maquet Quadrox-I adult oxygenator with a custom sweep gas blend of N2, O2, and CO2. THAM was added to adjust the pH as needed. Pre- and post HFM bundle blood samples were taken and analyzed using a GEM Premiere 3000 blood gas analyzer. Gas exchange was normalized to the fiber bundle surface area.
Results: The O2 flux in water was 200 and 243 mL O2 min-1 m-2 at intraluminal fiber O2 pressures of 2.125 and 5 PSI, respectively. Under identical conditions in porcine whole blood (Hb of 5.4 g/dL), the mean O2 flux was 546 ± 135 and 702 ± 330 mL O2 min-1 m-2 at intraluminal fiber oxygen pressures of 2.125 and 5 PSI, respectively.
Conclusion: This pilot ex-vivo study demonstrates that our apparatus is capable of transferring clinically significant amounts of O2 to the bloodstream. It represents the highest O2 flux reported in the literature for any attempt at intravascular gas exchange.