Advancing Front Oxygen Transfer Model for the Design of Microchannel Artificial Lungs.

Abstract

Microchannel artificial lungs may provide highly efficient, long-term respiratory support, but a robust predictive oxygen transfer (VO2) model is needed to better design them. To meet this need, we first investigated the predictive accuracy of Mikic, Benn, and Drinker's advancing front (AF) oxygen transfer theory by applying it to previous microchannel lung studies. Here, the model that included membrane resistance showed no bias toward overprediction or underprediction of VO2 (median error: -1.13%, interquartile range: [-26.9%, 19.2%]) and matched closely with existing theory. Next, this theory was expanded into a general model for investigating a family of designs. The overall model suggests that, for VO2 = 100 ml/min, fraction of delivered oxygen (FDO2) = 40%, wall shear stress ((Equation is included in full-text article.)) = 30 dyn/cm, and blood channel height = 20-50 μm, a compact design can be achieved with priming volume ((Equation is included in full-text article.)) = 5.8-32 ml; however, manifolding may be challenging to satisfy the rigorous total width ((Equation is included in full-text article.)) requirement ((Equation is included in full-text article.)= 76-475 m). In comparison, 100-200 μm heights would yield larger dimensions ((Equation is included in full-text article.)122-478 ml) but simpler manifolding ((Equation is included in full-text article.)4.75-19.0 m). The device size can be further adjusted by varying FDO2, (Equation is included in full-text article.), or VO2. This model may thus serve as a simple yet useful tool to better design microchannel artificial lungs.