Inhaled corticosteroid delivery is markedly affected by breathing pattern and valved holding chamber model

Background There is a scarcity of high‐quality research on the efficient delivery of inhaled corticosteroids using valved holding chambers (VHCs) in children. Methods The delivered dose (DD) of fluticasone from a metered dose inhaler (pMDI) was tested using four VHCs: AeroChamber plus Flow‐Vu (AC), Babyhaler (BH), EasyChamber (EC), and Optichamber Diamond (OD). The in vitro setup included an anatomical child throat model, Next Generation Impactor, and a breathing simulator to generate tidal breathing of a four and a 6‐year‐old child, and adult type single inhalation. Results OD showed the lowest proportion of fluticasone trapped in the throat with all breathing patterns. AC showed similar fine particle dose (FPD) in the respirable range (1–5 µm) irrespective of the breathing pattern. For BH, the median FPD 1–5 µm was highest during adult breathing. OD and EC showed higher overall DD and higher doses in the 1–5 µm range with paediatric breathing profiles compared to adult inhalation. The median DD and FPD 1–5 µm were significantly lower with BH compared to any other VHCs during tidal breathing. Compared to EC, the FPD of the other VHCs were skewed towards