In vitro deposition of micrometer-sized particles in the extrathoracic airways of children during tidal oral breathing

摘要

Nine oral airway replicas of children 6-14 years old were used for measuring deposition of 0.5-6.3 μm diameter particles during inhalation of four representative (sinusoidal) breathing patterns typical of those observed during the use of nebulizers by children. For a given particle size and inhalation flow rate, deposition in the present child replicas is higher than in adults and is not well predicted by adult correlations, even when age-related scaling factors are applied. However, by using subject-specific geometrical dimensions of the airway replicas, dimensionless correlations that predict deposition of micrometer-sized particles in children's oral airways during tidal breathing are presented. Such best fitting correlation gives deposition efficiency η2 = [1-1/(4.99(stk ~(241)Re~(-0.17)) + 1)] × 100, where Re and Stk are Reynolds and Stokes numbers with length scale given by V/A_s where V is airway volume and A_s is airway surface area.