Fig. 1

Selection of participants. Of the 245 patients diagnosed with bronchial asthma who visited the clinic between April 2017 and June 2019, 137 were excluded and 108 participated. In total, 34 patients with central predominant type, 58 with peripheral predominant type, and 16 with resistless type were enrolled. The definition of the subtypes of bronchial asthma classified using the impulse oscillometry system is shown in Table 1