Supplementary Material for: Evidence of an Acinar Response following Treatment for Exacerbation in Adult Patients with Cystic Fibrosis

Background: Treating acute infectious exacerbations in cystic fibrosis (CF) patients with intravenous antibiotic therapy leads to variability in lung function and the ventilation distribution response. Part of the variable lung clearance index (LCI) response could be associated with the variable peripheral effects of intravenous antibiotic administration. Objectives: We explored to what extent the peripheral lung zones of CF patients could contribute to lung function improvements following treatment for infectious exacerbations. Methods: Over a 1-year period, 15 adult CF patients admitted for acute exacerbations were recruited. Lung function and multiple breath washout (MBW) tests were performed on the day of admission and at discharge. From the MBW test, we obtained acinar and conductive indices of ventilation heterogeneity and LCI. Results: The mean age (±SD) was 26 ± 5 years. Upon admission, the FEV₁ was 54 ± 16% predicted and the LCI was 181 ± 26% predicted. After treatment, the average FEV₁ increased to 61 ± 20% predicted (p < 0.001) and the LCI decreased to 173 ± 28% predicted (p = 0.042). The change in LCI was associated with a change in acinar (ρ = +0.54; p = 0.039) but not in conductive ventilation heterogeneity (p > 0.1). Conclusions: In CF patients in whom an improvement in LCI was obtained after treatment for an acute infectious exacerbation, this was paralleled by a decrease in acinar ventilation heterogeneity.