Background: The formulation and particle size of the inhaled medication as well as inhaler characteristics affect pulmonary deposition.

Aim: To compare efficacy of two inhalers with inhaled corticosteroid and long-acting beta-agonist (ICS/LABA) in asthmatic adolescents with chronic bronchial obstruction. 

Methods: 44 asthmatics aged 12-17 years (median 14y, male 59%) with need of regular anti-asthmatic medication for at least 3 months and FEV1/FVC <-1,65SD started fluticasone propionate/formoterol (FP/FORM) in K-haler® or fluticasone furoate/vilanterol (FF/VI) in Ellipta® for two months each in a cross-over study. Lung function was measured with spirometry and impulse oscillometry and symptoms assessed with both Asthma Control Test (ACT) and a question related to exercise-induced symptoms at every visit. 

Results: Baseline median for FEV1 was -1,41SD, for FEV1/FVC -2,37SD, and for ACT 22. In this poster we introduce the results related to the the small airways. AX Z-score and R5-20 Z-score correlated significantly in both groups at every visit (rho 0,750-0,906, p<0,001). No significant correlations were seen between ACT and AX Z-score or R5-20 Z-score. Insignificant differences were seen between exercise-induced symptoms and AX Z-score or R5-20 Z-score, except at the baseline R5-20 Z-score which was higher in patients with exercise-induced symptoms in FP/FORM group (median 0,53SD vs 1,51SD, p=0,014). AX Z-score or ACT did not improve significantly. 

Conclusion: In asthmatic patients with mild symptoms despite of the chronic bronchial obstruction the intervention with the ICS/LABA did not improve small airways indices significantly.