TY - JOUR T1 - Comparing analysis software versions in infant multiple breath washout JF - European Respiratory Journal JO - Eur Respir J VL - 42 IS - Suppl 57 SP - P1099 AU - Anne-Marie Ebdon AU - Billy Skoric AU - Colin Robertson AU - Sarath Ranganathan Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/Suppl_57/P1099.abstract N2 - Background: An elevated functional residual capacity (FRC) measured in infants with cystic fibrosis may help identify gas-trapping, frequently identified on chest computed tomography in this population.Aims: To examine the difference in values for FRC and LCI (lung clearance index) measured by multiple breath washout, analysed using 2 different versions of a commercially available software package.Methods: Infant lung function was performed at 3 months, 1 year and 2 years of age under sedation with chloral hydrate. Both FRC and LCI were measured using 4% sulphur hexafluoride (Exhalyzer® D, Eco Medics, Switzerland). Data were acquired using Spiroware Wbreath and analysed using both versions 3.19 and 3.28 (Ndd Medizintechnik AG).Results: 34 infants of mean age 14.9 months (range 3.0-26.5 months) were tested. Using v3.19 the mean (SD) FRC was 20.9 (4.8) mls/kg, coefficient of variation (CV) 4.2%. Using v3.28 the FRC was 22.7 (4.5) mls/kg, CV 3.5%. The mean (SD) difference between the FRC measurements (v3.28-v3.19) was 1.8 (2.1) mls/kg. In most subjects agreement was within ±2SD but in 3/34 agreement for FRC was outside the limits of agreement (>2SD). The mean (SD) difference between the LCI measurements (v3.28-v3.19) was -0.12 (0.3) and in 2/34 subjects agreement was outside the limits of agreement (>2SD).Conclusion: Variability in FRC and LCI values arise when using different versions of the same analysis software package and requires consideration when inter-centre comparisons are made. ER -