Variability of monthly nitrogen multiple-breath washout during one year in children with cystic fibrosis

Abstract

We report between-session variability of LCI using NMBW in school-age children and adolescents with CF. LCI changes exceeding 25% may be considered clinically relevant. TestPoint® and Spiroware® can be used interchangeably in longitudinal studies.

Difference between SF6 and N2 multiple breath washout kinetics is due to N2 back diffusion and error in N2 offset

“…The known variability of both back diffusion (19) and possible drift in technical offset may explain the large intersession variability of N 2 LCI, which recently led authors to conclude that a change of at least 25% in patients with CF is required to be considered clinically relevant (9). The drift in technical offset (observed between the two devices at different time points) makes comparison between LCI data measured at different sites difficult, and this obviously is a challenge for multicenter trials using LCI as an end point.…”

Exercise capacity and ventilation inhomogeneity in cystic fibrosis: A cross‐sectional study

“…LCI 2.5 performed at rest cannot be considered as a surrogate measure of what occurs during exercise, when respiratory physiology changes significantly. Furthermore, considering the 3‐months interval variability reported for LCI 2.5 being up to 25%, MBWN 2 and exercise tests performed on the same day should be considered the only approach to document the impact of ventilation inhomogeneity on exercise tolerance. The distance between MBWN 2 and incremental exercise test measurements in the present study might have determined the lack of association between LCI 2.5 and ppWpeak.…”

Cystic fibrosis year in review 2018, part 1

“…At baseline, median LCI was 9.37 (6.82; 12.08). 85 Over the course of the subsequent year, children had monthly triplicate N 2 MBW measurements before spirometry, regardless of clinical status, demonstrating a between-session variability of up to 25%, indicating changes larger than 25% are likely clinically relevant. During the study, systematic difference between two commonly used commercial software systems were not seen, indicating that they could be used interchangeably for both research and for disease monitoring.…”

“…One study evaluated 14 children with CF over the course of 1 year. At baseline, median LCI was 9.37 (6.82; 12.08) . Over the course of the subsequent year, children had monthly triplicate N 2 MBW measurements before spirometry, regardless of clinical status, demonstrating a between‐session variability of up to 25%, indicating changes larger than 25% are likely clinically relevant.…”