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CFD and Hybrid Deposition Modeling: When and Why the Approach is Useful

Longest P.

Respiratory Drug Delivery 2018. Volume 1, 2018: 123-136.

Abstract:

To determine the lung dosimetry of inhaled pharmaceutical aerosols, a large number of deposition models are available across a spectrum of complexity. At the least complex end of the spectrum, algebraic whole-lung models are capable of providing accurate deposition results for the respiratory tract as a whole (including the extrathoracic airways) under a variety of inhalation conditions. On the other end of the spectrum, complete-airway computational fluid dynamics (CFD) models are providing valuable insights into the lung distribution of current inhaled medications and the design of new targeted drug delivery strategies. Model selection often depends on the detail required in the output data. As soon as the airway is divided into two (extrathoracic and lung) or three (extrathoracic, central, and peripheral airway) regions, recent studies show that algebraic whole-lung models struggle to match in vivo data for pharmaceutical (nebulized) aerosols. Complete- airway CFD models have recently shown good agreement with 2D gamma scintigraphy data for pharmaceutical aerosols across multiple inhaler platforms, but at the expense of requiring specialized CFD modelers. This study reviews strengths and weaknesses of airway deposition models and illustrates recent comparisons of newly proposed complete-airway CFD models with in vivo data for pharmaceutical aerosols.