A Closed Loop Model of Pulmonary Gas Exchange Under Inflammatory Stress

Angela Reynolds
Virginia Commonwealth University

(March 6, 2009 2:30 PM - 3:30 PM)

A Closed Loop Model of Pulmonary Gas Exchange Under Inflammatory Stress

Abstract

To model acute lung injury we previously developed a partial differential equation (PDE) model of gas exchange and inflammation within a cluster of approximately 25 alveoli along a capillary. We refer to this cluster as a respiratory unit (RU). We increased biological fidelity of this model by incorporating metabolism. We created a closed loop lung-scale model by linking multiple RUs under various anatomical and physiological conditions with metabolism effects.

Once metabolism was modeled, our original PDEs model for gas exchange and inflammation on a single RU was simplified mathematically to a more computational feasible model. The model was reduced such that arterial PO2 and PCO2 reflect the combined effects of metabolism and inflammation.

Combining multiple RUs we created a closed loop lung-scale model. Computational gains on the single RU allow the implementation of more accurate heterogeneity within the lung. Therefore, we vary both blood and tidal volumes on the RUs simultaneously.

In the closed loop lung-scale model we see that shunting (the closing of alveoli) is a major contributor to the reduction of PO2 during inflammation. Including metabolism gives rise to more accurate drops in PO2 than in the previous model. This model will be used with a more accurate inflammation model to simulate PO2 changes during specific diseases, i.e. pneumonia.