Small airway dysfunction is an independent dimension of wheezing disease in preschool children

Abstract

Background Whether small airway dysfunction (SAD), which is prevalent in asthma, helps to characterize wheezing phenotypes is undetermined. The objective was to assess whether SAD parameters obtained from impedance measurement and asthma probability are linked. Methods One hundred and thirty‐nine preschool children (mean age 4.7 years, 68% boys) suffering from recurrent wheezing underwent impulse oscillometry that allowed calculating peripheral resistance and compliance of the respiratory system (markers of SAD) using the extended RIC model (central and peripheral resistance, inertance, and peripheral compliance). Children were classified using the probability‐based approach of GINA guidelines (few, some, and most having asthma). A principal component analysis (PCA) that determined the dimensions of wheezing disease evaluated the links between SAD and asthma probability. Results Forty‐seven children belonged to the few, 28 to the some, and 64 to the most having asthma groups. Whereas their anthropometrics and measured parameters were similar, the most having asthma group exhibited the lowest mean value of airway inertance after bronchodilator probably due to airway inhomogeneities. PCA characterized four independent dimensions including a peripheral resistance (constituted by baseline peripheral compliance, Frs, R5Hz, R5‐20Hz, X5Hz, and AX), a central resistance (baseline central resistance, R20Hz), anthropometrics (age and height), and asthma probability (wheezing patterns and therapeutic steps). Thus, PCA showed that the SAD markers were independent from clinical dimensions and were unable to differentiate wheezing phenotypes. Conclusions Lung function parameters obtained from impulse oscillometry and asthma probability were belonging to independent dimensions of the wheezing disease.

Reference values of impulse oscillometry (IOS) for healthy Chinese children aged 4–17 years

“…With increasing age and height, the total respiratory impedance and airway resistance gradually decreased, while the respiratory system reactance decreased (negative value increased). Recent studies showed that R 5 –R 20 was a direct measure of anatomical narrowing in the small airways and that small airway narrowing had a marked impact on both asthma control and quality of life [ 29 , 30 ]. We found that R 5 –R 20 gradually decreased with increasing age and height, which was similar to airway resistance.…”

Pulmonary function testing for the diagnosis of asthma in preschool children

“…Many previous studies have demonstrated IOS applicability in preschool children and several reference values are available for children of Caucasian and Asian origin [19,21,22]. Studies evaluating IOS parameters for distinguishing between wheezing and healthy children have been contradictory [23 ▪ ,24 ▪ ]. Depending on the patient selection, both significant differences [25] and lack of differences [26] have been reported using a z -score >2 as cut-off for Rrs and Xrs at 5 Hz.…”

Oropharyngeal obstruction and respiratory system compliance are linked to ventilatory control parameters in pediatric obstructive sleep apnea syndrome

“…We used the extended Resistance-Inertance-Compliance model (eRIC) capable of accounting for significant frequency dependence of the respiratory impedance, which has previously been described 16 , 17 . In eRIC (Fig.…”

“…1 A), R is partitioned into central (Rc) and peripheral (Rp) resistance of the respiratory system, while C RS is the compliance of the respiratory system (including parenchymal and conducting airways compliances). The model was fitted to the impedance data (5–35 Hz) and the minimization of a performance index allowed the calculation of model parameters, as previously done 17 . We used the corrected Akaike information criterion to evaluate the goodness of fit of the eRIC model on this particular data set 16 .…”