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THEORETICAL STUDY OF GAS EXCHANGE IN TOTAL LIQUID VENTILATION

Fujioka, Hideki*; Tredici, Stefano; Hirschl, Ronald B.; Bartlett, Robert H.; Grotberg, James B.*†

Poster Presentations
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*Biomedical Engineering Department, †Department of Surgery University of Michigan, Ann Arbor, USA

Adult respiratory distress syndrome and neonatal respiratory distress syndrome are characterized by less compliant lungs, a result of insufficient surfactant production or effectiveness. Total liquid ventilation (TLV) is an artificial ventilation system which uses perfluorocarbon (PFC) liquid to eliminate the air-liquid interface. PFC has high solubilities of oxygen and carbon-dioxide. In TLV, the convection is important for gas transport in the alveolar region because the diffusivities of gases in PFC are four orders of magnitude lower than in air. In this study, a computational model for gas exchange in the lung was developed: a conducting airways branching network was modelled as a trumpet-shaped tube; the terminal alveolar sac was modelled as an oscillating spherical shell; a tissue and capillary blood were modelled as well-mixed compartments; and, mixed-venous gas partial pressures were calculated assuming a constant oxygen consumption and carbon dioxide production. Since the convection dominates the transport in the sac as well as in the conducting airways, steep partial pressure gradients in the sac exist from the middle of inspiration to the beginning of expiration. Our computational results for the arterial gas partial pressures agreed well with the experimental results of TLV for rabbits.

This work is supported by NIH grant HL64373.

Copyright © 2006 by the American Society for Artificial Internal Organs