[Responder and non-responder in the bronchodilator test?]

In 15 patients with chronic airflow obstruction 0.2 mg salbutamol was administered to determine reversibility within 15 minutes ("test effect"). Subsequently, maximum 24-hour effects of three beta 2-agonists (fenoterol 0.2 mg, salbutamol 0.2 mg, salmeterol 0.05 mg, each by MDI) were determined in random order ("best effect"). Airways obstruction was measured by FEV1, MEF50, MEF25, airway resistance Raw and thoracic gas volume TGV. "Best effects" were compared with "test effects". As a whole test effects were significantly smaller than best effects, often not reaching a 15% change, normally achieved during the 24-hour observation. Significant correlations existed between FEV1 and the corresponding values of Raw, MEF50 and MEF25, although there were considerable individual differences between test results. The reduction of TGV after a beta 2-agonist was significantly related to TGV-baseline values. We conclude in line with other authors that tests of acute reversibility of airways obstruction cannot reliably differentiate between "responders" and "non-responders" and that such tests may mislead if used for the differentiation of asthma and COPD.