Application of computational fluid dynamics to investigate pathophysiological mechanisms in exercise-induced laryngeal obstruction

The underlying pathophysiological mechanisms of exercise-induced laryngeal obstruction (EILO) remain to be fully established. It is hypothesized that high inspiratory flow rates can exert a force on laryngeal airway walls that contribute to its inward collapse causing obstruction. Computational fluid dynamics (CFD) presents an opportunity to explore the distribution of forces in a patient-specific upper airway geometry. The current study combined exercise physiological data and CFD simulation to explore differences in airflow and force distribution between a patient with EILO and a healthy matched control. Participants underwent incremental exercise testing with continuous recording of respiratory airflow and laryngoscopic video, followed by an MRI scan. The respiratory and MRI data were used to generate a subject-specific CFD model of upper respiratory airflow. In patient with EILO, the posterior supraglottis experiences an inwardly directed net force, whose magnitude increases nonlinearly with larger flow rates, with slight changes in the direction toward the center of the airway. The control demonstrated an outwardly directed force at all regions of the wall, with a magnitude that increases linearly with larger flow rates. A comparison is made between the CFD results and endoscopic visualization of supraglottic collapse, and a very good agreement is found. The current study presents the first hybrid physiological and computational approach to investigate the pathophysiological mechanisms of EILO, with preliminary findings showing great potential, but should be used in larger sample sizes to confirm findings.<b>NEW & NOTEWORTHY</b> The current study is the first to use a hybrid combined computational fluid dynamics (CFD) and exercise physiology approach to investigate pathophysiology in exercise-induced laryngeal obstruction (EILO). The hybrid methodology is a promising approach to explore the pathophysiological mechanisms underlying the condition. Notable differences occur in the distribution of airflow and wall forces between the EILO and control participants, which align with symptoms and visual observations.