Heliox respiration: effect on oxygen transport through narrowed airways

We are investigating the respiratory flow of heliox (helium-oxygen mixtures) through models of obstructed airways.
Large and small airways have been studied. In both cases, heliox provides a significant benefit in the pressure-flow
relations versus similar nitrogen-oxygen mixtures. For example, for 80%-20% heliox, the maximum pressure needed
to drive a given flow rate is about 50% less than that for 80%-20% nitrox.
The figure below shows pressure-volume loops obtained in an experiment where an obstruction, of known size,
was placed between a respirator and an artificial lung. Various nitrox and heliox mixtures were tried. It is seen
that the peak inlation pressure decreases dramatically when nitrox is substituted by heliox.
Related publication:
Papamoschou, D. "Theoretical Validation of the Respiratory Benefits of Helium-Oxygen Mixtures," Respiration Physiology, Vol. 99 , 1995.