부산대학교 도서관

Background. In some subjects with suspected asthma who have normal spirometry, administration of bronchodilators (BD) improves expiratory flow rates. The predictive value of this phenomenon in adults is not known. Objectives. To evaluate the predictive value of the response to BD for bronchial hyper-responsiveness (BHR) using the metacholine challenge test (MCT). Patients and methods. The study population included 62 non-smoking adult patients (41.9% women) 29.5 ± 15.5 years of age (range 18-64 years) with suspected asthma with normal spirometry that underwent MCT within 1 week. The response to BD (200 μ g inhaled salbutamol) was compared between subjects with positive and negative MCT using cutoff levels of provocative concentrations of metacholine causing a 20% decrease in forced expiratory volume in 1 second (FEV1) (PC20) of 4 and 8 mg/mL. Results. Mean (± SD) baseline FEV1 was 87.8 ± 12% of predicted. After BD administration the mean FEV1 increased by 4.3 ± 3.9%. The prevalence of BHR was 17.7% and 25.8% for PC20 for PC20 of 4 mg/mL and 8 mg/mL, respectively. The post-BD FEV1 increment for subjects with positive and negative MCT tests was 3.9% ± 3.3% versus 4.4% ± 4.1%, respectively; p = 0.89, using cutoff of 4 mg/mL. The corresponding figures for cutoff of 8 mg/ml were 4.3% ± 3.1% vs. 4.3% ± 4.2%, respectively; p = 0.8465. There was no correlation between post-BD FEV1 increment and PC20 values in patients with positive MCT test for the above-mentioned cutoff levels (correlation coefficient r = 0.1645, p = 0.6289; and r = 0.2417, p = 0.4051, respectively). Conclusions. In adults with suspected asthma who have normal spirometry, the response to BD cannot be used to predict BHR. [ABSTRACT FROM AUTHOR]