Comparacion entre procaterol y salbutamol mediante dosis-respuesta acumulada en pacientes con limitacion cronica al flujo aereo

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

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.

[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.