Numerical Analysis of Airway Mucus Clearance Effectiveness Using Assisted Coughing Techniques

Abstract

Cough is a protective respiratory reflex used to clear respiratory airway mucus. For patients with cough weakness, such as chronic obstructive pulmonary disease, neuromuscular weakness disease and other respiratory diseases, assisted coughing techniques are essential to help them clear mucus. In this study, the Eulerian wall film model was applied to simulate the coughing clearance process through a computational fluid dynamics methodology. Airway generation 0 to generation 2 based on realistic geometry is considered in this study. To quantify cough effectiveness, cough efficiency was calculated. Moreover, simulations of four different coughing techniques applied for chronic obstructive pulmonary disease and neuromuscular weakness disease were conducted. The influences of mucus film thickness and mucus viscosity on cough efficiency were analyzed. From the simulation results, we found that with increasing mucus film thickness and decreasing mucus viscosity, cough efficiency improved accordingly. Assisted coughing technologies have little influence on the mucus clearance of chronic obstructive pulmonary disease models. Finally, it was observed that the cough efficiency of the mechanical insufflation-exsufflation technique (MIE) is more than 40 times the value of an unassisted coughing technique, which indicates that the MIE technology has a great effect on airway mucus clearance for neuromuscular weakness disease models.

Effect of nebulised BromAc® on rheology of artificial sputum: relevance to muco-obstructive respiratory diseases including COVID-19

“…Treatment with Bromelain showed a marked drop in γ in both the treatment groups (0.125 and 250 µg/ml) with a drop of 27 and 36%, respectively in AS model with substantial effect on € (336 and 480%, respectively) indicating the impact of dynamic viscosity on the flow speed of sputa and ciliary clearance [47]. In the case of SS model again there was drop in γ of 8.0 and 8.2% for the two concentrations of Bromelain (125 and 250 µg/ml), with almost no difference.…”

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“…Cough peak expiratory airflow (Figure 2A) has also been correlated with the successful clearance of the airway [41][42][43][44]. The initial expiratory cough airflow rapidly accelerates, reaches a peak and then rapidly declines to a sustained cough expiratory airflow plateau.…”

A simplified tempo-spatial model to predict airborne pathogen release risk in enclosed spaces: An Eulerian-Lagrangian CFD approach

“… 4 Local ambient air velocity [m/s] [0.25–1.5], 21.7, 0- 10 [ 7 , 8 ] 5 Local ambient air direction [deg] [ 9 ] 6 Local ambient air humidity [%] [20–60], 50 [ 6 , 8 ] 7 Local air temperature [ o C] [17–23], 25, [ 7 , 8 ] 8 Temporal profile of exhalation flow rate (for C or S) [m 3 /s] Fig. 5 a [ 8 , 10 , 11 ] 9 Spatial profile of exhalation [−] [ 12 , 13 ] 10 With or without facial mask [with or without] [ 11 ] 11 Gender [−] Man, Woman [ 14 ] 12 Age [year] 19–50 [ 15 ] …”