Interactive Effect of Surface Tension and Viscosity on Displacement of Airway Mucus Inside a Rigid Model Adult Trachea During Cough

Altered surface and viscoelastic properties of mucus during respiratory diseases have a strong influence on its clearance by cilia and cough. Combined effect of the surface tension and viscosity with relatively unchanged storage modulus of simulated airway mucus (simulant) considered as the capillary number on displacement of 0.3mL simulant aliquot during simulated cough through a model adult human trachea at relatively low cough velocity (15±0.5m/s) of 0.3s duration was investigated. Displacement of simulant aliquots decreased significantly with capillary number (p<0.0001). The interactive effects of viscosity and surface properties may give insight into understanding mucus displacement at low cough velocities in patients with chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and asthma.