Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by limited reversibility to bronchodilator therapy and progressive airway obstruction. Reversibility test is widely used to assess the “reversible” and “irreversible” airway obstruction, which is very important in the differential diagnosis of COPD and asthma. Bronchodilator response is found in 10% to 30% of patients with COPD. Although many different methods for performing and evaluating the reversibility have been used, it is usually suggested to obtain spirometry before and 20 minutes after inhalation of salbutamol 400 µg by a metered dose inhaler connected to a spacer or 5 mg via a nebuliser. The best way to define the bronchodilator response is to find a change in forced expiratory volume in one second (FEV1) of more than 12% of the predicted level and of 200 ml increase as an absolute difference. Assessment of the late reversibility by oral prednisolone 30-40 mg per day for two weeks or at least 1000 µg beclomethasone dipropionate for four to six weeks is used for evaluating the effectiveness of adding inhaled steroids to the treatment. Reversibility test is also useful in defining the prognosis in COPD. Patients with a higher bronchodilator response were shown to have a decreased annual rate of FEV1 decline and positive reversibility is a predictor of good prognosis. Besides, instead of prebronchodilator, it is proposed to use postbronchodilator FEV1 for calculating the annual rate of decline in FEV1. In conclusion, reversibility test is a practical and easily performed method in the diagnosis, treatment, prognosis and follow-up of the patients with COPD.