“…To circumvent this limitation, the most common approach for evaluating the delivery of aerosolized drugs relies on the estimation of the lung deposition from in vitro tests [ 11 , 12 , 13 , 14 ], in vivo preclinical studies [ 15 , 16 , 17 , 18 ], or mathematical modeling [ 19 ]. Most of these studies evaluated the overall drug deposition by quantifying the overall amount of aerosol that impacts against the walls of the different extra pulmonary components of the system (i.e., connecting tubes, patient interface, nebulizer chamber, and patients upper airways), the particles exhaled into the expiratory limb of the ventilation circuit, and the particles delivered into the lung [ 12 , 20 , 21 ]. These studies have been useful to investigate the impact of breathing flows, particle size, gravity, geometric characteristics of nebulizers, ventilation–patient interfaces and breathing circuits, and other fluid dynamic factors on the aerosol deposition.…”