Introduction Small airway obstruction is important in the pathophysiology of cystic fibrosis (CF) lung disease. Additionally, many CF patients lose lung function in the long term as a result of respiratory tract exacerbations (RTEs). No trials have been performed to optimize mucolytic therapy during a RTE. We investigated whether specifically targeting dornase alfa to the small airways improves small airway obstruction during RTEs. Methods In a multi-center, double-blind, randomized controlled trial CF patients hospitalized for a RTE and on maintenance treatment with dornase alfa were switched to a smart nebulizer. Patients were randomized to small airway deposition (n = 19) or large airway deposition (n = 19) of dornase alfa for at least 7 days. Primary endpoint was forced expiratory flow at 75% of forced vital capacity (FEF75). Main Results Spirometry parameters improved significantly during admission, but the difference in mean change in FEF75 between treatment groups was not significant: 0.7 SD, P = 0.30. FEF25-75, FEV1, nocturnal oxygen saturation and diary symptom scores also did not differ between groups. Conclusions This study did not detect a difference if inhaled dornase alfa was targeted to small versus large airways during a RTE. However, the 95% confidence interval for the change in FEF75 was wide. Further studies are needed to improve the effectiveness of RTE treatment in CF. Pediatr Pulmonol. 2014; 49:154-161.

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doi.org/10.1002/ppul.22800, hdl.handle.net/1765/72568
Pediatric Pulmonology
Department of Biostatistics

van den Beukel-Bakker, M., Volpi, S., Salonini, E., Müllinger, B., Kroneberg, P., Bakker, E., … Tiddens, H. (2014). Small airway deposition of dornase alfa during exacerbations in cystic fibrosis; A randomized controlled clinical trial. Pediatric Pulmonology, 49(2), 154–161. doi:10.1002/ppul.22800