PT  - JOURNAL ARTICLE
AU  - Anders Lindblad
AU  - Monica Rosberg
AU  - Birgitta Houltz
AU  - Per Gustafsson
TI  - Prospective follow up over 1 year with N<sub>2</sub> multiple breath washout (MBW) in children with cystic fibrosis
DP  - 2013 Sep 01
TA  - European Respiratory Journal
PG  - P3610
VI  - 42
IP  - Suppl 57
4099  - http://erj.ersjournals.com/content/42/Suppl_57/P3610.short
4100  - http://erj.ersjournals.com/content/42/Suppl_57/P3610.full
SO  - Eur Respir J2013 Sep 01; 42
AB  - Background: The N2 MBW method is increasingly used in studies to assess ventilation inhomogeneity. It is more sensitive than spirometry in detecting early changes of cystic fibrosis (CF) lung disease. The aim was to evaluate the change and variation of lung clearance index (LCI) over a one-year period in children with CF. Methods: Triplets of N2 MBW were recorded (Exhalyzer D, Eco Medics AG) in 25 CF subjects (15M) aged 6-18 yrs (median 10.2 yrs, mean FEV1.0 92 (17)% (1). Five had chronic P. aeruginosa (PA) infection. The MBW test was done at the patients regular visits to the outpatient clinic. A minimum of two acceptable washouts were required for inclusion. Results: 109 N2 MBW test occasions were undertaken. In 108/109 occasions two or three technically acceptable MBW washouts were recorded, while in 1/109 failed. There was no difference between LCIs at the first and the last N2 MBW test (9.58(2.73) vs 9.60 (2.82)(ns). Patients with chronic PA had higher LCI compared to non-PA (11.96(4.15) vs 8.98(1.98); p=0.026). Median number of tests during one year was 4/patient (range 2-6).The within test occasion CV for LCI was 5.8 (3.5)%. The mean between test standard deviation of LCI for the washouts in each patient was 0.83 (0.46) (absolute units) with a greater variation in patients high LCI. The mean CV for LCI between test was, however, 8.5 (4.2)% with no bias with greater LCI. Conclusion: In this cohort, LCI was stable over a one-year period. In absolute units, variability of LCI was less in patients with relatively low LCIs at start, while the relative variation over time was independent of the initial LCI. 1.Quanjer GLI-2012 Equations, www.lungfunction.org.