Physical models of the smaller pulmonary airways

Any internalized flow exhibits closely coupled interactions with its confining geometry. Efforts to gain an understanding of in vivo airway transport phenomena, therefore, dictate that careful attention to be paid to those anatomic airway features that constrain and modify regional air movement. We present a series of analyses of human small airway casts to refine and extend the current geometric description of small airway bifurcations. Airway shape factors believed to have a high propensity to alter the fluid dynamics of airflows within this region are specifically addressed. The results of these anatomic and fluidic analyses are used to develop two average symmetrical and asymmetrical bifurcation patterns. Finally, methods for the production of physical bifurcation models conforming to these requirements are presented to develop a rational representation of anatomic as well as flow similitude during airway research.