Airway morphological abnormalities of bronchiolitis assessed by endobronchial optical coherence tomography

S. Zhuquan*^a (Dr), L. Shiyue^a (Prof)

^a The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, CHINA

* py1011xiaoquan@163.com

Background: Few studies have reported the medium-sized and small airway morphological abnormalities of bronchiolitis, i.e. bronchiolitis obliterans (BO) and diffuse panbronchiolitis (DPB). Whether impulse oscillometry (IOS) is feasible to reflect small airway remodeling in bronchiolitis remains unclear.

Objectives: Aiming to demonstrate the airway morphological abnormalities of BO and DPB assessed by endobronchial optical coherence tomography (EB-OCT), and elucidate whether spirometric and IOS parameters could reflect the airway remodeling of bronchiolitis.

Methods: We recruited 18 patients with bronchiolitis (BO, n=9; DPB, n=9) and 17 control subjects. Assessments of clinical features, SGRQ, chest CT, spirometry, IOS, bronchoscopy and EB-OCT were performed. The association of EB-OCT and lung function parameters were determined with correlation analysis.

Results: The magnitude of abnormalities of spirometry and IOS parameters were significantly greater in patients with bronchiolitis than in control subjects (all P<0.05). Patients with BO had notably lower FEV₁, FVC, FEV₁/FVC, MMEF% pred and higher Fres and AX than those with DPB (all P<0.05). The EB-OCT measurement in patients with bronchiolitis and Bland-Altman analysis between the bronchus in the left and the right lung demonstrated a heterogeneous distribution of airway calibers, presenting high intra- and inter-individual variability. Patients with bronchiolitis had notably greater airway wall area (Aw%7-9 and Aw%3-9) (both P<0.05) compared to control, while BO presented greater magnitude of airway abnormalities than DPB. Fres and R₅-R₂₀ correlated negatively with medium-sized and small airway inner area (Ai3-6 and Ai7-9), and positively with airway wall area (Aw%3-6 and Aw%7-9) (all P<0.05), whose correlation coefficients were higher than those of spirometric parameters.

Conclusions: Bronchiolitis, BO and DPB, manifested a heterogeneous distribution of airway calibers with significant intra- and inter-individual variability. IOS parameters, rather than spirometry, correlated better with medium-sized and small airway remodeling in bronchiolitis assessed by EB-OCT measurement.

Disclosure of funding source(s): none