Bronchodilator reversibility: What are the differences between asthma and chronic obstructive pulmonary disease?

INTRODUCTION: Currently, the bronchodilator reversibility is not recommended to differentiate asthma from chronic obstructive pulmonary disease (COPD); however, physiopathological specificities of each disease contribute to the differences in response to the drug. OBJECTIVES: The objective of this study is to evaluate the differences in bronchodilator response between asthmatic and COPD patients and to determine which of the bronchodilation criteria have the best ability to detect the positive response in these patients. MATERIALS AND METHODS: This was a cross-sectional study. The sample included 104 patients with asthma or COPD who performed lung function tests between January and March 2018. The whole sample was analyzed according to postbronchodilator variation (Δ) of lung function parameters, and the postbronchodilator reversibility was characterized using a multiple bronchodilation criteria. The drug used in reversibility test was salbutamol. RESULTS: In this study, Δ forced-expiratory volume in the 1st s (ΔFEV1) and a Δ Raw was statistically higher in the group with asthma compared with the group with COPD. In the asthma group, the criteria ↓ functional residual capacity (FRC) ≥10%, ↓Raw ≥ 35%, ↑ forced expiratory flow between 25% and 75% of vital capacity (FEF25%–75%) ≥20% and ↑ FEV1 and / or ↑ forced vital capacity ≥12% and 200 mL were those that presented a greater capacity of detecting a positive response to bronchodilator. The criteria ↑ FEF25%–75%≥20% and ↓ FRC ≥ 10% were those that had the greater ability of detecting airway reversibility in COPD group. CONCLUSION: The analysis of postbronchodilator FEV1 and raw modifications as well as the using of a combination of multiple bronchodilation criteria contribute to a deeper characterization of bronchodilator reversibility in asthma and COPD.