Evaluation of a multiple breath nitrogen washout system in children

Sarah M. Isaac, Renee Jensen, Pinelopi Anagnostopoulou, Jane C. Davies, Monika Gappa, Philipp Latzin, Clare Saunders, Christopher Short, Florian Singer, Sanja Stanojevic, Annelies Zwitserloot, Felix Ratjen*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    Abstract

    Introduction The multiple breath nitrogen washout (MBW) test offers a sensitive measure of airway function. In this study we aim to (a) assess the validity of the EasyOne Pro LAB (MBWndd) in an in vitro lung model, (b) assess the feasibility, repeatability, and reproducibility of MBWndd and (c) compare outcomes with the Exhalyzer D (MBWEM) and body plethysmography.

    Methods In vitro, functional residual capacity (FRC) measurements were assessed using a lung model under quasi-physiological conditions and compared to measured FRC. In vivo plethysmography and MBW were performed in a prospective study of children at two visits (n = 45 healthy; n = 41 cystic fibrosis [CF]). Bland-Altman plots were used to compare agreement between FRC and lung clearance index (LCI) measurements.

    Results In vitro FRCndd measurements were repeatable but lung volumes were underestimated (mean relative difference -5.4% (limits of agreement [LA] -9.6%; -1.1%), 95% confidence interval (CI) -6.27; -4.45). In vivo, compared to plethysmography, FRCndd was consistently lower (-19.3% [-40.5; 1.9], 95% CI [-23.9; -14.7]), and showed a volume dependency. LCIndd values were also higher in children with smaller lung volumes. The within-test coefficient of variation of the FRCndd and LCIndd were 4.9% in health, and 5.6% and 6.9% in CF respectively. LCIndd was reproducible between-visits (mean relative difference [LA] -3.7% [-14.8, -7.5; 95% CI -6.6; -0.73] in health [n = 17] and 0.34% [-13.2, 22.8; 95% CI -5.0; 5.69] in CF [n = 23]). When calculated using the same algorithm, LCIndd was similar to LCIEM in health.

    Conclusions MBWndd measurements are feasible, repeatable, and reproducible, however, MBW-derived outcomes are not interchangeable with MBWEM.

    Original languageEnglish
    Pages (from-to)1-7
    Number of pages7
    JournalPediatric Pulmonology
    Volume55
    Issue number8
    DOIs
    Publication statusPublished - 28-May-2020

    Keywords

    • function pulmonary testing
    • LUNG CLEARANCE INDEX
    • VALIDATION

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