- Positive response to the reversibility test in the screening visit, defined as an increase of at least 12% (or, alternatively, of 200mL) from baseline value in the measurement of FEV1 30 minutes following 2 puffs (2 ´ 100 µg) of inhaled salbutamol administered via pMDI. The reversibility test can be avoided in patients having a documented positive response in the previous 6 months.