Fiber optic endoscopic optical coherence tomography (OCT) to assess human airways: The relationship between anatomy and physiological function during dynamic exercise

• Published in: Physiological reports Vol. 9; no. 1; pp. e14657 - n/a
• Main Authors: Peters, Carli M., Molgat‐Seon, Yannick, Dominelli, Paolo B., Lee, Anthony M. D., Lane, Pierre, Lam, Stephen, Sheel, Andrew W.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.01.2021; John Wiley and Sons Inc
• Subjects: Adult; Airway Remodeling - physiology; airway size; Anatomy; Balloon catheters; Bronchoscopy; Catheters; Endoscopy; Esophagus; exercise; Exercise - physiology; Exercise Test - methods; Female; Females; Fiber optics; Humans; Lung - diagnostic imaging; Lung - physiology; Male; Mechanical ventilation; Mechanics; Middle Aged; optical coherence tomography; Original Research; Physiology; Respiratory Mechanics; Respiratory tract; Reynolds number; Software; Tomography; Tomography, Optical Coherence - methods; Viscoelasticity; Work of Breathing; Young Adult; airway size; exercise; optical coherence tomography; respiratory mechanics
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.14657

Airway luminal area (Ai) influences respiratory mechanics during dynamic exercise; however, previous studies have investigated the relationship between airway anatomy and physiological function in different groups of individuals. The purpose of this study was to determine the effect of Ai on respiratory mechanics by making in vivo measures of airway dimensions and work of breathing (Wb) in the same individuals. Healthy participants (3F/2M; 23–45 years) completed a cycle exercise test to exhaustion. During exercise, Wb was assessed using an esophageal balloon catheter, while simultaneously assessing minute ventilation (V˙E). On a separate day, subjects underwent a bronchoscopy procedure to capture optical coherence tomography (OCT) measures of three airways in the right lung. Each participant's Wb‐V˙E data were fit to a non‐linear regression equation (Wb = aV˙E3 + bV˙E2) that partitions Wb into its turbulent resistive (a) and viscoelastic (b) components. Measures of Ai and luminal diameter were made for the 4th–6th airway generations. A composite index of airway size was calculated as the sum of the Ai for each generation and the total area of the 4th–6th generation was calculated based on Weibel's model. Constant a was significantly correlated to the Weibel model total airway area (r = −0.94, p = 0.017) and index of airway size (r = −0.929, p = 0.023), whereas constant b was not associated with either measure (both p > 0.05). We found that individuals who had the smallest Ai had the highest resistive Wb and our findings provide the basis for further study of the relationship between airway size and respiratory mechanics during exercise. We made in vivo measures of multiple airways and modeled the work of breathing (Wb)‐minute ventilation (V˙E) relationship during exercise in a group of healthy young adults. We found that individuals with the highest resistive Wb had the smallest 4th–6th generation airways. These findings improve our understanding of the interrelationship between human airway dimensions and respiratory mechanics during exercise.