TY - JOUR T1 - Prospective longitudinal measurements of N<sub>2</sub> multiple breath washout indices in primary ciliary dyskinesia JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P4527 AU - Helene Kobbernagel AU - Kent Green AU - Astrid Madsen AU - Frederik Buchvald AU - Jakob Ejlertsen AU - Per Gustafsson AU - Kim Gjerum Nielsen Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P4527.abstract N2 - Background: Previous studies of multiple breath washout (MBW) indices (lung clearance index (LCI), Sacin*VT and Scond*VT) in primary ciliary dyskinesia (PCD) have demonstrated abnormal values in about 85%, 96% and 78%, respectively, - even with spirometric values within the normal range. Long term variability of N2 MBW indices in PCD has not been reported, although important for the use and interpretation of N2 MBW indices in the clinical management and as outcome measures in interventional studies.Aims and objectives: To assess the overall change in N2 MBW indices during one year and estimate the within- and between-occasion variability in PCD.Methods: N2 MBW (Exhalyzer D, Eco Medics AG) in triplets and standard spirometry were prospectively assessed on three occasions over one year. Occasions with less than two acceptable MBW measurements were excluded.Results: Twenty-six PCD patients, aged 6-18 years (median 12.8) performed 76 N2 MBW test occasions of which 72 (95%) were included. Baseline mean (SD) FEV1 % predicted: 84.8 (11.3); LCI: 9.8 (1.9); Sacin*VT: 0.15 (0.08); and Scond*VT: 0.06 (0.02). Within-occasion SD / CV% (95% CI) of LCI were 0.63 (0.55; 0.70) / 6.6% (6.0%; 7.2%). Scond*VT significantly improved over the study period.View this table: Conclusions: This study reports estimates of short- and long term variability of N2 MBW indices in a cohort of paediatric PCD patients, which is essential for future studies in PCD with MBW indices as outcome measures. ER -