Comparing intra-breath oscillometry and MBW in children with CF

Abstract

Introduction/Aim: Multiple breath washout (MBW) is a useful test for detecting early changes in peripheral airways and in detecting ventilation inhomogeneity in patients with cystic fibrosis (CF). Unfortunately, feasibility of MBW is often low in very young children (30%-40%). Intra-breath oscillometry (IB-OSC) measures respiratory system resistance (Rrs) and reactance (Xrs) during tidal breathing and has high feasibility (>80%) in very young children. Measures of Xrs include the small peripheral airways and thus, may also reflect ventilation inhomogeneity. Our aim was to examine whether measures of Xrs reflect ventilation inhomogeneity as measured by MBW. Method: IB-OSC and MBW were performed on 75 children at the Queensland Children's Hospital, as part of the Early Life Origins of CF (ELO) study. IB-OSC was measured using a 10 Hz signal to track within-breath changes, and MBW was performed using the N2 protocol. MBW results were classified as normal or abnormal (lung clearance index (LCI) >7.9) and measures of Xrs (end-expiratory (XeE), end-inspiratory (XeI) and difference (XeE-XeI) were compared between the MBW groups. Results: Acceptable paired IB-OSC and MBW measurements were achieved by 63 children (male 60%), median age 7 years (IQR 4.7-8.4) and height 121.8cms (IQR 110.1- 134). Abnormal LCI results were reported in n = 33 (52%). There were no differences in gender, age or height between those with normal versus abnormal LCI results. Children with abnormal LCI results had decreased (more negative) Xrs variable compared to children with normal LCI (Table 1). Of those with abnormal LCI, 13 patients (40%) also had XeE-eI values below the lower limit of normal. Conclusion: These preliminary results suggest that IB-OSC Xrs variables reflect ventilation inhomogeneity. As IB-OSC is more feasible than MBW in very young patients with CF, further research is warranted to explore the potential of IBOSC in this cohort. (Table Presented).L6377946112022-04-25 <br />