Aerosol Bolus Inhalation as Technique for the Diagnosis of Various Lung Diseases – A Theoretical Approach

y mathematically extending the former model for the theoretical description of the aerosol bolus dispersion the behavior of particle pulses in diseased lung structures was simulated. The geometry used for healthy lungs was modified in two aspects: First, a modeling of possible airway obstructions, which usually occur in patients with chronic bronchitis, chronic asthma or cystic fibrosis, was carried out and, second, a theoretical approximation of the emphysema, which may be observed in lungs of smokers, but also as an accompanying phenomenon in obstructive diseases, was established. The calibration of single airways within a stochastic lung path as well as single alveoli within the pulmonary compartment was realized using the random number concept, whereby the necessary normal distributions were determined from histological measurements of pathological lung structures. In lungs with airway obstructions, the exhaled bolus exhibits a decreased dispersion with respect to healthy probands, whereas in emphysematous lungs the respective half-width of the peak is increased. Mode shift and skewness of the bolus are influenced significantly by the modified lung architecture, enhancing the diagnostic meaning of the bolus technique.