DOI:
10.1183/13993003/erj.38.suppl_55.p2022
Authors:
Emilia Viklund, A. Lindblad, P. Robinson, B. Houltz, L. Bergh, Monika Rosberg, P. Gustafsson
Abstract:
Background:
The lung clearance index (LCI) obtained from SF6 multiple breath washout (MBW) is a sensitive index of peripheral airway dysfunction in cystic fibrosis (CF) [1]. SF6 LCI values are lower and show stronger agreement between laboratories than historical N2 LCI using conventional N2 analyzers [1]. Formal comparison between the two types of MBW systems has not been performed to date. This study compared FRC and LCI obtained using both methods: mass spectrometer SF6 MBW and a new indirect N2 MBW system (Exhalyser D, EcoMedics, Duernten, Switzerland) in CF subjects.
Methods:
10 CF subjects, median (range) 17 (15-40) yrs performed MBW in triplicate using an SF6-based mass spectrometer MBW system and an Exhalyzer D indirect N2-based MBW system (main stream infrared CO2 sensor, side stream laser O2 sensor). FRC and LCI were calculated using similar software algorithms. Results expressed as mean (SD) and between-test comparisons made using students t-tests.
Results:
There was no significant difference between FRC values (N2 FRC 2.82 (0.71) vs. SF6 FRC 2.53 (0.70), p=0.37), however N2 LCI, 12.52 (3.14), was significantly higher than SF6 LCI, 9.77 (2.46) (p=0.043). Within-session repeatability (coefficient of variation, CV%) did not differ between the groups: N2 FRC 6.8 (2.9)% vs. SF6 FRC 5.5 (3.1)%, and N2 LCI CV 5.0 (3.6)% vs. SF6 LCI CV 4.7 (2.8)%.
Conclusions:
LCI values obtained with the new indirect N2 MBW system were greater than those obtained with the current gold standard SF6 mass spectrometer based system. FRC values and within-session repeatability were similar.
References:
1
Robinson PD et al. European Respiratory Monograph; 2010. p. 87-104.