Pulmonary function is usually assessed by measurement of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the ratio of FEV1 to FVC. The measurements are integral to the diagnosis of chronic obstructive pulmonary disease (COPD), and also are important long term predictors of population morbidity and mortality [1]. Reduced FEV1/FVC defines airways obstruction; whereas reduced FEV1 grades the severity of obstruction [2].
