An in depth study of morphological small airway changes in explant lungs with end stage COPD

Abstract

Although the most known hallmarks of Chronic Obstructive Pulmonary Disease (COPD) are alveolar emphysema and chronic bronchitis also small airways are affected in COPD. We aim to describe the morphological alterations of the small airways occurring in inflated explant lungs with end stage COPD and compare them with non-used donor lungs. Bronchioles morphometrics of 3 samples (cores)/lung of 4 COPD lungs and 3 control lungs were assessed using a high resolution microCT (10µm resolution) and airway segmentation with ITK software. Disease severity was measured by alveolar surface density which gradually decreases in emphysematous samples. Within the control (1 male/ 2 female, mean age of 59y) and COPD lungs (1 male/ 3 female, mean age 63y, mean FEV1 39%), we observed a decrease in number of Terminal Bronchioles/mL (p<0.0001), number of generations/ml (p=0.003) and mean bronchiolar diameter (p=0.084), and an increase (p=0.0009) in mean bronchiolar branch length, with decreasing surface density (fig. 1A). Small airway alterations in end stage COPD include a decrease in number of small airways, next to a stretching (longer) and narrowing of the remaining small airways which will impact on the air flow and eventually result in airflow obstruction (fig 1B).