Lung function
The lung function test was evaluated by a spirometer (Koko DigiDoser,
Louisville, KY, USA) coupled with a microcomputer. The technical
procedure, eligibility criteria, and reproducibility were established in
accordance with the American Thorax Society and European Respiratory
Society recommendations (11). The following variables were assessed:
FEV1, FVC, and the FEV1/FVC ratio.
Spirometry was performed before and after 400 µg of salbutamol inhaled
with an interval of 10 to 15 minutes to evaluate the BD response (11). A
positive BD response was considered if a post-BD increase in
FEV1 of >12% was predicted from the pre-BD
value (11). Values were compared with the values predicted based on data
from a Brazilian population, and the LLN was evaluated by a program
provided by the Global Lung Initiative (11).