Bronchodilator testing: an endless story.

T he history of the bronchodilator test dates back to the late 1950s when airway diseases were classified as reversible or irreversible depending on the response to bronchodilators [1, 2]. The hope to differentiate asthma from chronic obstructive pulmonary disease (COPD) on this basis was such that the test soon gained popularity in clinical practice. Two large trials published in the mid 1980s, however, dimmed the original enthusiasm on such a test because no clear cut-off was found between asthmatic and COPD patients [3, 4]. In addition, the response depended on several factors, such as definition and severity of airflow obstruction and spirometric parameter considered for the functional response to the dilator agent together with its relevant threshold of natural variability. Finally, the test was scarcely reproducible over time in the individual patients. Somehow, these two studies challenged the common notion of that time that airway reversibility was a typical and unique feature of bronchial asthma.