Longitudinal tracking of intrabreath respiratory impedance in preschool children

Abstract

AbstractBackgroundLongitudinal measurements of intrabreath respiratory impedance (Zrs) in preschool‐aged children may be able to distinguish abnormal lung function trajectories in children with a history of wheezing compared to healthy ones.MethodsChildren from a prospective, longitudinal community‐based cohort performed annual intrabreath oscillometry (IB‐OSC) measurements from age 3‐ to 7‐years. IB‐OSC was performed using a single 10 Hz sinusoid while clinically asymptomatic. Linear mixed‐effects models were developed to explore the effects of wheezing phenotypes, growth, and sex on seven IB‐OSC outcome variables over time: resistance at end‐expiration (ReE), resistance at end‐inspiration (ReI), the tidal change in resistance (∆R=ReE‐ReI), reactance at end‐expiration (XeE), reactance at end‐inspiration (XeI), the tidal change in reactance (∆X=XeE‐XeI), and ∆X normalized by tidal volume (∆X/VT).ResultsEighty‐five children produced 374 acceptable IB‐OSC measurements. Subjects were classified into one of three wheeze groups: never (n = 36), transient (n = 34), or persistent (n = 15). After adjusting for height, children with persistent wheezing, compared to those who never wheezed, had +0.814 hPa s L−1 ReE (95% confidence interval [CI] +0.178 to +1.451, p = 0.015), −0.792 hPa s L−1 XeE (95% CI −1.203 to −0.381, p = 0.003), −0.538 hPa s L−1 ∆X (95% CI −0.834 to −0.242, p = 0.007) and −1.672 hPa s L−2 ∆X/VT (95% CI −2.567 to −0.777, p < 0.001). Increasing height had a significant effect on all IB‐OSC resistance and reactance variables when adjusted for the effect of preschool wheezing.ConclusionsIB‐OSC is feasible for tracking lung function growth in preschool‐aged children and may allow abnormal lung function to be identified early in asymptomatic preschoolers with a history of persistent wheezing.