A model of ventilation distribution in the human lung.

A thorough analysis of aerosol particle deposition in the human lung requires the knowledge of the distribution of inspired air at respiration. In this paper, a mathematical model of ventilation distribution has been developed using a five-lobe airway model. The model accounts for the nonlinear effects of compliance and resistance on airway dynamics. Ventilation distributions were determined under different gravitational force conditions. A larger gravity leads to a greater nonuniformity of ventilation between the upper and lower lobes of the lung. Ventilation distributions in different lobes of the lung at various inspiratory flow rates were also calculated. At slow inspiratory flow rates, ventilation was found to be nonuniform with more air entering the lower lobes. As the flow rate increases, this nonuniformity became smaller. The calculated results compare favorably with existing experimental data. When a different gas is inspired instead of air, a preferential distribution of ventilation to the upper lobes was found if the density of the inspired gas is greater than that of the air.