Reversible Airway Obstruction on Impulse Oscillometry in Preschool Children with Bronchopulmonary Dysplasia.

Abstract

To assess lung function and bronchodilator reversibility via the impulse oscillometry system (IOS) in 3- to 6-year-old children with bronchopulmonary dysplasia, a population historically difficult to evaluate via spirometry. A retrospective review of IOS in 3- to 6-year-old children was conducted. Clinical data were abstracted from electronic medical records, including a modified St George's Respiratory Questionnaire scored according to symptoms, activity, and impact. We analyzed 103 IOS reports in 73 patients (median age 4.1 years; IQR 3.5-5.0); of these, 52.4% were acceptable and repeatable. At least 1 parameter was abnormal in 78% of reports, including elevated resistance with median z scores for R₇ (1.8; IQR 0.9-2.8) and R_7-20 (1.4; IQR 0.8-2.2) and decreased reactance with median AX (2.6; IQR 0.8-3.3), F_res (1.4 IQR; 0.6-2.4), and X₇ (-2.4 IQR; -3.7 to -1.4]). Median z scores for the cohort normalized after the administration of albuterol. Improved resistance and reactance were observed on clinic follow-up IOS in children treated with inhaled corticosteroid/long-acting beta-agonists. The cohort had increased morbidity, with total St George's Respiratory Questionnaire score of 12.1 (IQR 7.6-25.6), symptom score of 32.5 (IQR 17.2-46.8), activity score of 7.6 (IQR 0-29.8), and impact score of 7.4 (IQR 0-17.1). IOS can be performed by one-half of preschool-aged children with bronchopulmonary dysplasia and reveals abnormal lung function characterized by elevated airway resistance and decreased reactance that is bronchodilator-responsive. IOS is a feasible technique to evaluate objectively the early, critical changes in respiratory health and response to medical therapy in a population in whom other methods are not available.