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Evaluation of a multiple breath nitrogen washout system in children
Author(s) -
Isaac Sarah M.,
Jensen Renee,
Anagnostopoulou Pinelopi,
Davies Jane C.,
Gappa Monika,
Latzin Philipp,
Saunders Clare,
Short Christopher,
Singer Florian,
Stanojevic Sanja,
Zwitserloot Annelies,
Ratjen Felix
Publication year - 2020
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.24862
Subject(s) - medicine , repeatability , nitrogen washout , plethysmograph , confidence interval , functional residual capacity , coefficient of variation , lung volumes , reproducibility , washout , spirometry , cystic fibrosis , limits of agreement , lung function , lung , nuclear medicine , cardiology , asthma , mathematics , statistics
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 (MBW ndd ) in an in vitro lung model, (b) assess the feasibility, repeatability, and reproducibility of MBW ndd and (c) compare outcomes with the Exhalyzer D (MBW EM ) 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 FRC ndd 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, FRC ndd was consistently lower (−19.3% [−40.5; 1.9], 95% CI [−23.9; −14.7]), and showed a volume dependency. LCI ndd values were also higher in children with smaller lung volumes. The within‐test coefficient of variation of the FRC ndd and LCI ndd were 4.9% in health, and 5.6% and 6.9% in CF respectively. LCI ndd 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, LCI ndd was similar to LCI EM in health. Conclusions MBW ndd measurements are feasible, repeatable, and reproducible, however, MBW‐derived outcomes are not interchangeable with MBW EM .