Airway morphometry in COPD with bronchiectasis: a view on all airway generations

Area of Science:

• Pulmonary Medicine
• Respiratory System Imaging
• Pathophysiology

Background:

• The underlying pathophysiology of bronchiectasis in chronic obstructive pulmonary disease (COPD) remains unclear.
• Both small and large airways are progressively lost in COPD, but the extent of involvement in different airway generations in COPD with bronchiectasis is unknown.

Purpose of the Study:

• To investigate and compare airway generations in COPD explant lungs with and without bronchiectasis.
• To determine the extent of airway involvement across different generations in COPD patients with co-existing bronchiectasis.

Main Methods:

• A multimodal imaging approach was used, including computed tomography (CT) for large airways and microCT for terminal bronchioles and complete airway tree quantification.
• COPD explant lungs with bronchiectasis were compared to COPD explant lungs without bronchiectasis and unused donor lungs.
• Airway segmentation and 3D quantification of the entire airway tree were performed using lobar microCT images.

Main Results:

• COPD lungs with bronchiectasis exhibited significantly more airways than COPD lungs without bronchiectasis (p<0.001), with large airway numbers comparable to controls.
• Lack of airway tapering (p=0.010) and larger airway diameters were observed in lower lobes of lungs with bronchiectasis (p=0.010).
• Terminal bronchioles were equally reduced in both COPD groups compared to controls, despite increased large and small airways in COPD with bronchiectasis.

Conclusions:

• COPD lungs with bronchiectasis demonstrate a significantly higher number of both large and small airways compared to COPD lungs without bronchiectasis.
• While terminal bronchioles are similarly affected in both COPD groups, the increased airway count in COPD with bronchiectasis suggests distinct pathophysiological mechanisms.
• These findings highlight the importance of considering airway எண்ணிக்க in the pathophysiology of COPD with bronchiectasis.