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 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.