Mucus transport by high-frequency nonsymmetrical oscillatory airflow.
To study air-mucus interaction as a possible mechanism of tracheal mucus transport and to test the validity of using surface tracer displacement to indicate bulk mucus transport, we performed a combined experimental-theoretical study. We hypothesized that the mucus mass is moved by the difference between expiratory and inspiratory velocities. The rate of transport of a layer of simulated mucus lining the bottom of a rectangular trough was measured in two ways during oscillatory air flow. Peak velocity ratios (R) from 1.0 to 2.0, frequencies (f) between 7 and 13 Hz, and tidal volumes (VT) between 50 and 100 ml were generated by a custom-made pump. The experimental results demonstrate that measuring the displacement of a tracer deposited on the surface of the mucus layer is equivalent to measuring bulk mucus movement by weight. Moreover the measured mucus velocities (micron) correlate well with a theoretical model which predicts that micron is proportional to delta VT f1.5 (R-1). These results suggest that shearing at the air-mucus interface could be a significant factor in the enhanced tracheal mucus clearance during high-frequency chest wall oscillation.
Chang
H K
HK
Department of Biomedical Engineering, University of Southern California, Los Angeles 90089-1451.
Weber
M E
ME
King
M
M
D000818:Animals; D001693:Biological Transport, Active; D004548:Elasticity; D006612:High-Frequency Ventilation; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D008962:Models, Theoretical; D009093:Mucus / Q000502:physiology*; D013990:Tidal Volume; D014783:Viscosity