Multifrequency oscillometry for evaluating pediatric patients with exercise-induced symptoms

ABSTRACT
Forced oscillometry (FOT) is valuable for assessing exercise-induced bronchoconstriction (EIB) and bronchodilator response, but newer reference values for comparable FOT devices remain underutilized.
To compare FOT and spirometry parameters after exercise testing and bronchodilation in children reporting exercise-induced symptoms.
We measured resistance (Rrs), its frequency dependence (Fdep 5-19), and reactance (Xrs) at 5, 11, and 19 Hz during inspiration and expiration in 35 patients (ages 6-16). Spirometry, FeNO, blood eosinophils, and skin-prick tests were also assessed. After treadmill exercise, spirometry was repeated at 1′, 5′, 10′, 15′, and 20′, and FOT at 3′ and 18′. EIB was defined by a ≥10% drop in FEV₁, and bronchodilation was evaluated 15′ post-salbutamol.
Fourteen patients with EIB exhibited lower functional values and higher inflammatory indices. Post-exercise, these patients had significant increases in Rrs z-scores and Fdep 5-19, along with decreases in Xrs compared to non-EIB patients. FOT changes correlated with the drop in FEV₁ and FEF_25-75. Bronchodilation was reflected in Rrs at 5 Hz and Xrs across all frequencies.
Multifrequency FOT effectively detects airway changes, with low frequencies key for EIB assessment and the 5-19 Hz range essential for bronchodilation evaluation.

IMMPACT STATEMENT
Z-scored values and changes from device-appropriate reference points allow multifrequency FOT to detect airway alterations during EIB and bronchodilation.

Received: Sep 24, 2024
Accepted: Nov 24, 2024