Normal range for bronchodilation response in impulse oscillometry parameters in healthy adults

Abstract

Impulse oscillometry (IOS) is an effort-independent pulmonary function test. While the normal range of the bronchodilator response for dynamic spirometry has been thoroughly investigated, such studies are scarce for IOS. Pre- and post-bronchodilator IOS and spirometry were measured in Uppsala study participants (n=3,777, age 50 - 64 years) of the Swedish CArdioPulmonary bioImage Study (SCAPIS) cohort. The subjects answered questions on smoking habits, respiratory symptoms and disease.The normal range of post-bronchodilator changes in IOS (resistance at 5 and 20 Hz (R5 and R20), reactance at 5 Hz (X5) and the area under the reactance (AX)) were defined in never-smoking individuals without any respiratory disease or symptoms (n=1,966, whereof 47% females, mean age 57 years). The upper limit of normal (ULN, the 95th percentile) for R5, R20 and AX as well as lower limit of normal (LLN, the 5th percentile) for X5 were defined and further used to study the association with current asthma and wheeze in the total study cohort. The mean (ULN) post-bronchodilation relative change was -10.1% (-28.8) for R5, -9.2% (-26.4) for R20 and -19.4% (-65.4) for AX. The mean LLN post-bronchodilation relative change was 12.9% (44.8) for X5. Subjects with post-bronchodilation changes >ULN in either R5 or AX, or