Small airway dysfunction may be an indicator of early asthma: findings from high-resolution CT

Increasing attention is now focused on the role of the small airways in asthma. Patients with small airway asthma typically have a preserved forced expiratory volume in 1 second, with disproportionate small airway dysfunction.

The aim of this study was to determine whether there are structural changes in the large airways in patients with small airway asthma.

Nine patients with small airway asthma and 20 healthy controls underwent high-resolution computed tomography (HRCT) scan. The apicoposterior segmental bronchus in the left upper lobe (LB1+2) and the posterior basal segmental bronchus in the left lower lobe (LB10) were identified on HRCT images. The luminal area (LA), wall area (WA), and wall area percentage (WA%) of each bronchus were measured from the 2nd (lobar) to the 6th generation and compared between the patients with small airway asthma and the healthy controls.

The WA% of the 6th generation in the patients with small airway asthma was higher than that in the healthy controls; the difference was statistically significant (LB1 + 2, P = .040; LB10, P = .033).

Structural changes in the large airways of patients with small airway asthma may represent an early stage of asthma.