A62-14 Impulse Oscillometry-based Bronchodilator Response Across Age Groups In Asthma

Background

Objective assessment of reversible airflow obstruction is essential for asthma diagnosis. Impulse oscillometry (IOS) is a noninvasive pulmonary function test performed during tidal breathing, requiring minimal patient cooperation and offering enhanced sensitivity for small airway dysfunction, particularly in young children. This study evaluated age-related patterns of IOS-based bronchodilator responses in patients with clinically diagnosed asthma.

Methods

We retrospectively analyzed patients with clinician-diagnosed asthma who underwent IOS between August 2019 and May 2020 and demonstrated obstructive airflow patterns with a positive bronchodilator test (BDT). Participants were stratified into three age groups: <6 years, 6-20 years, and >20 years. IOS parameters including resistance at 5 Hz (R5), resistance at 20 Hz (R20), R5-R20, and resonance frequency were analyzed before and after bronchodilator administration. A positive BDT was defined as a ≥ 30% reduction in airway resistance in patients <18 years or ≥ 40% in adults.

Results

A total of 225 patients (median age 6 years; male:female = 123:102) were included. At baseline, median R5 was 175.3% (95% CI, 171.7-178.6) and R20 was 121.7% (95% CI, 118.7-127.1) of predicted, with a median R5-R20 of 52.3% (95% CI, 49.9-57.1). Median resonance frequency was 5.11 Hz (95% CI, 4.62-5.35). Post-bronchodilator, median R5 decreased to 123.6% (95% CI, 119.1-126.8), corresponding to a significant median reduction of 52.8% (95% CI, 49.5-56.1; P < 0.0001). Age demonstrated a moderate correlation with R20 (r = 0.51, P < 0.001) and weak correlations with R5, R5-R20, and resonance frequency, while no significant associations were observed for X5 or AX.

Conclusions

IOS-derived proximal airway resistance increases with age in asthma, indicating age-dependent differences in airway mechanics. IOS combined with bronchodilator testing provides a practical, reproducible approach for assessing airflow reversibility across pediatric and adult populations and may enhance asthma phenotyping in clinical practice.

This abstract is funded by: None