Measuring Airway Remodeling in Patients With Different COPD Staging Using Endobronchial Optical Coherence Tomography

Background

Although FEV₁ remains the gold standard for staging COPD, the association between airway remodeling and airflow limitation remains unclear. Endobronchial optical coherence tomography (EB-OCT) was performed to assess the association between disorders of large and medium to small airways and COPD staging. We also evaluated small airway architecture in heavy smokers with normal FEV₁ (S_NL) and healthy never-smokers.

Methods

We recruited 48 patients with COPD (stage I, n = 14; stage II, n = 15; stage, III-IV, n = 19), 21 S_NL, and 17 healthy never-smokers. A smoking history inquiry, as well as spirometry, chest CT, bronchoscopy, and EB-OCT were performed. Mean luminal diameter (D_mean), inner luminal area (Ai), and airway wall area (Aw) of third- to ninth-generation bronchi were measured using EB-OCT.

Results

Patients with more advanced COPD demonstrated greater abnormality of airway architecture in both large and medium to small airways, followed by S_NL and never-smokers. Abnormality of airway architecture and EB-OCT parameters in S_NL were comparable to those in stage I COPD. FEV₁% predicted correlated with D_mean and Ai of seventh- to ninth-generation bronchi in COPD; however, neither D_mean nor Ai of third- to sixth-generation bronchi correlated with FEV₁% in stage I and stage II COPD and in S_NL.

Conclusions

FEV₁-based COPD staging partially correlates with small airway disorders in stage II-IV COPD. Small airway abnormalities detected by EB-OCT correlate with FEV₁-based staging in COPD and identify early pathologic changes in healthy heavy smokers.