1GOLD Executive Committee. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease (Re- vised 2011) IEB/OL] . www. goldcopd, corn.
2Jing JY, Huang TC, Cui W, et al. Should FEV1/FEV replace FEV1/FVC ratio to detect airway obstruction? A meta analysis [ J . Chest, 2009, 135 (4): 991-998.
