[An evaluation of the bronchodilator response with beta agonists in patients with chronic obstructive pulmonary...

The aim of this study was to analyze the functional reversibility and establish the most appropriate index and minimum dose of beta-2-agonist in patients with chronic obstructive pulmonary disease (COPD). Sixty patients with COPD (FEV1/FVC < 70%) in stable phase. After taking baseline forced spirometry readings, we applied the accumulated dose-response technique, administering 0.2 mg salbutamol every 10 minutes up to a maximum dose of 1 mg. Spirometric readings were taken 10 minutes after each dose. Response was evaluated with absolute values of FEV1 and with percent improvement over baseline FEV1 over the theoretical value and over the possible value. We calculated the correlation coefficient between baseline FEV1 and response, as measured by each of the aforementioned indices. No significant improvement was observed for doses higher than 0.4 mg salbutamol in either absolute values or percentage of baseline or theoretical values. Response was not significantly improved over 0.2 mg as measured by percent of possible response. Percent of theoretical value was the index that showed the least dependence on baseline FEV1 for each dose of salbutamol. A minimum dose of 0.4 mg salbutamol, or an equivalent dose of another similar sympathicomimetic drug, should be used for evaluation of bronchodilation response in patients with COPD. Response should be evaluated by percent of theoretical value.