Article Abstract

Aerosol bolus dispersion in male and female subjects: a theoretical analysis

Authors: Robert Sturm


Background: The main objective of the present contribution consists in a detailed theoretical description of aerosol bolus dispersion in the lungs of male and female probands. The work is founded on the hypothesis that intrapulmonary bolus transport and mixing with the adjacent air volume are characterized by partly significant differences between men and women. In addition, gender-specific particle deposition from the inhaled aerosol boluses has to be expected.
Methods: Behaviour of aerosol boluses transported in male and female lungs was simulated on the assumption of Gaussian peak shape and by application of statistical moments. Based on these mathematical methods the half-width, standard deviation, skewness, and mode-shift of the exhaled bolus were modelled. Computations were conducted for inhaled bolus half-width of 50 mL, symmetric breath-cycles with a length of 8 s and inhalation flow rates of 250 mL/s. Monodisperse particles with diameter of 0.84 µm and a density of 1 g/cm3 were used.
Results: Aerosol bolus behaviour computed for male lungs partly exhibits valuable discrepancies with respect to the behaviour in female lungs. Highest differences could be found for deep boluses, where statistical parameters calculated for males deviate from that predicted for females by 0 to 80%. Deposition of particles transported in the aerosol boluses is characterized by gender-specificity insofar as respective values predicted for females fall below those of males by up to 60%.
Conclusions: The results presented in the contribution give rise to the conclusion that females show another behaviour with regard to aerosol bolus inhalation than males. This difference, which is expressed by gender-specific bolus parameters and deposition fractions, has to be considered in the case of using the bolus technique as non-invasive diagnosis method of lung diseases. Additionally, further experimental studies investigating in detail the gender-related discrepancies of intrapulmonary bolus transport are necessary.