AUTHOR=Barreto Mario , Veneroni Chiara , Caiulo Mariaclaudia , Evangelisti Melania , Pompilio Pasquale Pio , Mazzuca Maria Cristina , Raponi Giorgia , Pagani Jacopo , Parisi Pasquale 

TITLE=Within-breath oscillometry for identifying exercise-induced bronchoconstriction in pediatric patients reporting symptoms with exercise

JOURNAL=Frontiers in Pediatrics

VOLUME=11

YEAR=2024

URL=https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2023.1324413

DOI=10.3389/fped.2023.1324413

ISSN=2296-2360

ABSTRACT=<sec><title>Background</title><p>Evaluating oscillometry parameters separately for the inspiratory and expiratory breath phases and their within-breath differences can help to identify exercise-induced bronchoconstriction (EIB) in pediatric outpatients disclosing exercise-induced symptoms (EIS).</p></sec><sec><title>Aims</title><p>To assess the response in impedance parameters following an exercise challenge in patients reporting EIS.</p></sec><sec><title>Methods</title><p>Sixty-eight patients reporting EIS (34 asthmatics and 34 suspected of asthma, age mean = 10.8 years, range = 6.0–16.0) underwent an incremental treadmill exercise test. Spirometry was performed at baseline and 1, 5-, 10-, 15-, and 20-min post exercise. Oscillometry was performed at baseline and at 3- and 18-min post exercise. Bronchodilator response to 200 µg albuterol was then assessed. EIB was defined as a forced expiratory volume in 1 s (FEV<sub>1</sub>) fall ≥10% from baseline. Expiratory and inspiratory resistance (Rrs) and reactance (Xrs), their <italic>z</italic>-score (Ducharme et al. 2022), and their mean within-breath differences (ΔRrs = Rrs<sub>exp</sub>-Rrs<sub>insp</sub>, ΔXrs =<sub> </sub>Xrs<sub>exp</sub>-Xrs<sub>insp</sub>) were calculated. Receiver operating characteristic (ROC) curves and their areas (AUCs) were used to evaluate impedance parameters’ performances in classifying EIB.</p></sec><sec><title>Results</title><p>Asthmatic patients developed EIB more frequently than those suspected of asthma [18/34 (52.9%) vs. 2/34 (5.9%), <italic>p</italic> &lt; 0.001]. In the 20 subjects with EIB, Rrs<sub>insp</sub>, Rrs<sub>exp</sub>, Xrs<sub>insp</sub>, and Xrs<sub>exp</sub> peaked early (3’), and remained steady except for Xrs<sub>insp,</sub> which recovered faster afterward. ΔXrs widened 18 min following the exercise and reversed sharply after bronchodilation (BD) (−1.81 ± 1.60 vs. −0.52 ± 0.80 cmH<sub>2</sub>O × s/L, <italic>p</italic> &lt; 0.001). Cutoffs for EIB leading to the highest AUCs were a rise of 0.41 in <italic>z</italic>-score Rrs<sub>insp</sub> (Se: 90.0%, Sp: 66.7%), and a fall of −0.64 in <italic>z</italic>-score Xrs<sub>insp</sub> (Se: 90.0%, Sp: 75.0%). Accepting as having “positive” postexercise oscillometry changes those subjects who had both <italic>z</italic>-scores beyond respective cutoffs, sensitivity for EIB was 90.0% (18/20) and specificity, 83.3% (40/48).</p></sec><sec><title>Conclusion</title><p>Oscillometry parameters and their within-breath differences changed markedly in pediatric patients presenting EIB and were restored after the bronchodilator. Strong agreement between <italic>z</italic>-scores of inspiratory oscillometry parameters and spirometry supports their clinical utility, though larger studies are required to validate these findings in a broader population.</p></sec>