Plamen Bokov

and 4 more

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 wheeze 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 of the respiratory system). Children were classified using the probability-based approach of GINA guidelines (few, some, 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 nine independent dimensions including a peripheral resistance (constituted by baseline peripheral resistance, AX, R5-20Hz, X5Hz), a central resistance (baseline central resistance, R20Hz) and an airway size dimension (post-bronchodilator inertance and central resistance). PCA showed that the SAD markers were independent from clinical dimensions (control and asthma probability were two other dimensions) and did not help to define wheezing phenotypes. Conclusions. Lung function parameters obtained from impulse oscillometry and asthma probability were belonging to independent dimensions of the wheezing disease.