Numerical simulation of targeted drug delivery to different regions of realistic human lung model under realistic aerosol breathing condition

In nearly all the previous studies on the particle transport and deposition of aerosols in human lungs, the airflow rate that is inhaled in the lung is assumed to be either constant or sinusoidal function of time, which does not represent the inhalation of aerosols into the lung in reality. This is the first-ever study of the transport and deposition of aerosols in a realistic human lung model employing transient flow rate for realistic aerosol breathing patterns. The measured transient airflow rate is used as the inlet condition in the numerical simulations, and the particles are released immediately when the patient inhales air into the lung, i.e., when the flow velocity starts to increase from zero. We found that the effects of aerosol size on aerosol deposition in different generations of the lung under realistic breathing conditions follow the same trend as those under constant velocity conditions. However, quantitatively, the deposition efficiencies at different parts of the lung model under the two breathing conditions are significantly different from each other. This conclusion signifies the importance of investigating aerosol deposition using realistic breathing conditions. We conducted numerical simulations for aerosol diameters ranging from 1 μm to 10 μm under transient flow conditions. The deposition efficiency in the mouth-throat area increases with aerosol diameter. The deposition efficiency at the trachea increases with increasing aerosol diameter up to 6 μm, and then it remains nearly unchanged. The maximum deposition efficiencies at generations 2 to 5 occur at aerosol diameters between 1 μm and 10 μm. The quantified effect of aerosol size on the deposition efficiency at every generation of the lung provides useful insight for targeted drug delivery.