Bronchodilator response in children using intra-breath oscillometry

Abstract

Introduction/Aim: A bronchodilator response (BDR) is a test of reversible airway obstruction that can be used to define the presence of asthma. This study describes a BDR in children using intra-breath oscillometry (IB-Osc). Methods: Intra-breath respiratory impedance (IB-Zrs) was measured at baseline and 15 min after salbutamol 400 mcg using a single 10 Hz sinusoid in asymptomatic 7-year-old children participating in a community-based cohort study. IB-Zrs outcomes included resistance at end-expiration (ReE), resistance at end-inspiration (ReI), the volume dependence of resistance (ΔR = ReE-ReI), reactance at endexpiration (XeE), reactance at end-inspiration (XeI), and the volume dependence of reactance (ΔX = XeE-XeI). Absolute BDR was calculated as post-bronchodilator minus prebronchodilator value. Relative BDR was expressed as absolute BDR divided by the pre-bronchodilator value (as a percentage). Results: The feasibility of BDR testing was 93.7% (n = 74) including 40 females (54.1%). The mean (SD) absolute BDR for ReE and ReI was -1.28 (0.88) cmH2O.s.L-1 and -1.22 (0.83) cmH2O.s.L-1, respectively. The mean relative BDR for ReE and ReI was -20.28% (12.98) and -20.42% (11.50) respectively. The median (Q3, Q1) absolute BDR for ΔR was -0.04 (0.32, -0.37) cmH2O.s.L-1. The median absolute BDR for XeE and mean absolute BDR for XeI was 0.40 (0.77, 0.21) cmH2O.s.L-1 and 0.44 (0.50) cmH2O.s.L-1, respectively. The median relative BDR for XeE and XeI was 50.80% (18.75, 75.29) and 48.03% (14.95, 64.96) respectively. The median absolute BDR for ΔX was 0.04 (0.19, -0.18) cmH2O.s.L-1. There was no significant difference between children with asthma or wheezing in the last 12 months (n = 9) and healthy children (n = 65) in terms of baseline or BDR for IB-Zrs outcomes. Conclusion: The BDR measured by IB-Zrs was not significantly different in children with stable asthma compared to healthy children. Further studies of IB-Zrs involving intrasession testing variability and short-term repeatability in healthy children are required to better define a BDR.L6377948292022-04-25 <br />