Multicentre feasibility of multiple-breath washout in preschool children with cystic fibrosis and other lung diseases.

Background: Multiple-breath washout (MBW)-derived lung clearance index (LCI) detects early cystic fibrosis (CF) lung disease. LCI was used as an end-point in single- and multicentre settings at highly experienced MBW centres in preschool children. However, multicentre feasibility of MBW in children aged 2-6 years, including centres naïve to this technique, has not been determined systematically.