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Is Aerodynamic Diameter a Good Metric for Understanding Regional Lung Deposition?

Weers JG, Kadrichu N, Rao N.

RDD Europe 2019. Volume 1, 2019: 59-66.

Abstract:

Although cascade impactors classify particles by inertial impaction, it is standard practice to convert the impactor distributions to aerodynamic particle size distributions by making measurements at a constant flow rate. The reliance on particle size leads to many misconceptions that pervade how we conduct our testing and how we evaluate and interpret results. In this manuscript, we propose an alternative way of presenting cascade impactor data that utilizes impaction parameter cutoffs as opposed to size cutoffs. Measurements in terms of a mass median impaction parameter (MMIP) allow for impactor tests to be conducted with realistic breathing profiles without the need of mixing inlets. Data presented in this fashion show improved correlations with in vivo observations in terms of regional deposition in the lungs and flow rate dependence in lung delivery.