The Annals of Thoracic Surgery, Vol 57, 1484-1490, Copyright © 1994 by The Society of Thoracic Surgeons
Performance of an intravenous gas exchanger (IVOX) in a venovenous bypass circuit
W Tao, JB Zwischenberger, TT Nguyen, AE Tzouanakis, EJ Matheis, DL Traber and A Bidani
Department of Surgery, University of Texas Medical Branch, Galveston 77555-0528.
To analyze quantitatively the performance of the intravenacaval blood gas
exchanger (IVOX), we developed a right atrium-pulmonary artery venovenous
extracorporeal bypass circuit. Oxygen transfer and carbon dioxide removal
were calculated at different blood flow rates, different hemoglobin levels,
and during permissive hypercapnia. Oxygen transfer increased linearly with
blood flow up to 41 mL/min. Likewise, O2 transfer increased linearly with
hemoglobin levels up to 7.5 g/dL, but no further increases were achieved
above this level. Carbon dioxide removal increased linearly as flow
increased from 1.0 to 3.0 L/min but did not increase further for higher
flows. Carbon dioxide removal was 45 mL/min at blood carbon dioxide tension
of 42 mm Hg but increased to a maximum of 81 mL/min at a carbon dioxide
tension of 90 mm Hg. We conclude that IVOX is a diffusion-limited device
dependent on blood flow, hemoglobin content, and the gas pressure gradient
across the membrane. Further engineering improvements are needed to improve
the gas exchange performance of IVOX.