Abstract
Background: Lung Clearance Index (LCI) derived from Multiple Breath Washout (MBW) using MS and SF6 is a sensitive measure of ventilation inhomogeneity[1]. Clinical applications of this test should increase now that ultrasonic flowmeter N2 washout (N2-WO) to measure LCI is commercially available but it is important to establish the relationship between these systems[2].
Aim: To compare LCI and FRC measured by the NDD N2-WO system and a custom-built AMIS 2000 MS SF6 system in healthy adults.
Methods: MBW was performed in healthy adults using the two systems on the same day. The mean of 3 acceptable measures on each were compared.
Results: 18 adults aged 19-64y completed assessments. LCI and FRC were significantly lower on the NDD system compared with MS (mean diff (95%CI): -0.4 (-0.1;-0.8) and -0.5L (-0.3;-0.7). The 95% limits of agreement were relatively wide (Fig 1).
Fig1. Bland-Altman graphs of LCI and FRC
Conclusions: These preliminary results suggest that, as expected, MBW results using MS SF6 and NDD N2-WO are not interchangeable. Further comparative and repeatability data collection is in progress both in healthy subjects and children with lung disease to establish if the NDD N2-WO system can discriminate lung disease from health with as much sensitivity as the MS SF6 system.
References:
1. Aurora: Thorax 2010
2. Robinson: Eur Resp J 2013.
- © 2013 ERS