Comparative observations of mucus transport velocity in health and disease

The present study evaluated mucus transport velocity (MTV) in different areas of the tracheobronchial tree in vitro in normal, acute and chronic bronchitic animals. The average MTV in normal animals ranged from 11.5 mm/min in the trachea to 0.64 mm/min in the pre-terminal bronchus. Chronic bronchitic animals showed mucus hypersecretion, areas of ciliary abnormality and mucus stagnation. The mean transport velocities ranged from 21.2 mm/min in the trachea to 4.1 mm/min in the pre-terminal bronchus. In the acutely ill animals, MTV ranged from 2.5 mm/min in the trachea to zero below the upper lobar bronchus. It is postulated that the higher than normal values in chronic bronchitis are due to altered mucus rheology, increased peristalsis and linear acceleration; whereas those in acute bronchitis were attributed to an early phase of viral or bacterial infection.