[Contribution of the bronchodilator test in the study of bronchial reversibility]

This study sought to determine the optimum dose of salbutamol and the most useful method for calculating bronchodilator response. Changes in FEV1 after inhalation of 3 doses of salbutamol 200 micrograms were measured in 150 adults (64 healthy individuals, 18 with rhinitis, 53 with asthma and 15 with bronchitis). Bronchodilator response was calculated by 4 different methods: absolute value, percent change form baseline FEV1, from theoretical value and from weighted value. Significant differences in response were observed among the various methods of assessment. Patients with asthma and bronchitis showed the greatest response to salbutamol and their results were used to analyze the usefulness of the reversibility indices. The index that discriminated best was percent of theoretical reference value, although the sensitivity of this index was low and specificity varied from 0.73 to 1 depending on the cut-off point used. This index of reversibility along with absolute value proved to be the least dependent on baseline FEV1. We conclude that bronchodilator response is best assessed by calculating changes in FEV1 in relation to a theoretical reference value. This bronchomotor test, however, does not adequately assess patients with asthma and bronchitis.