Small Airway Dysfunction in Children With Controlled Asthma

Abstract Introduction Asthma is characterized by chronic inflammation of the central and distal airways. The aim of this study was to assess the small airway (SA) of children with moderate-severe asthma with normal FEV1. Methods This was an open-label, prospective, observational, cross-sectional study with consecutive inclusion of patients with moderate-severe asthma, receiving standard clinical treatment, with normal baseline FEV 1 . We determined multiflow FEno (CAno), oscillatory resistance and reactance (R5–R20, X5), forced spirometry (FEV1, FEF 25–75 ), total body plethysmography (RV/TLC) and bronchodilation test. SA involvement was defined as: CAno >4.5 ppb, R5–R20 >0.147 kPa/L/s, X5 25–75 z -score, RV/TLC >33%. Poor asthma control was defined as ≤19 points on the ACT questionnaire or ≤20 on the c-ACT. Results In a cohort of 100 cases, 76 had moderate asthma and 24 had severe asthma; 71 children were classified as poorly controlled and 29 were well-controlled. In total, 77.78% of the group with all the correct determinations ( n =72) showed ≥ 1 altered SA parameter and 48.61% ≥ 2 parameters. There were no differences between well-controlled or poorly controlled cases. Conclusions Children with moderate-severe asthma, with normal FEV 1 , show a phenotype of dysfunctional SA. In our series, the evaluation of SA using the techniques described above did not provide information on disease control.