Use of forced inspiratory vital capacity to identify bronchodilator reversibility in obstructive lung disease

The objective of this study was to assess the utility of forced inspiratory vital capacity, (FIVC) to identify, bronchodilator reversibility (BDR) for patients with obstructive lung disease (OLD) in relation to customary BDR criteria as defined by the American Thoracic Society (ATS). Concurrent data analysis was used in an academic medical center setting. Two hundred patie nts with OLD (including chronic obstructive lung disease and asthma) underg oing testing at the Pulmonary Function Laboratory at Cedars-Sinai Medical C enter from January 1995 to December 1996 were identified. These 200 patient s were categorized into four grades of obstruction by ATS-defined forced ex piratory volume in I see (FEV1) criteria (severe, moderately severe, modera te, and mild). Each of these groups was further subdivided into equal subgr oups according to the presence (+) or absence (-) of BDR. Inspiratory flow- volume loops and FIVC were analyzed for each of these subgroups. Of the pat ients exhibiting BDR on the forced expiratory, maneuver (FEM), FIVC correct ly identified 53% of the cases. For patients not exhibiting BDR on FEM, FIV C identified an additional 12 cases. In 72% of cases, the maximal FIVC was not obtained from the maximal FEM flow-volume loop. FIVC inspection of the data (which were already available from standard spirometric testing) ident ified a subgroup of OLD patients with BDR not appreciated by FEV1 or FVC cr iteria, which may respond to bronchodilator therapy. The maximal FIVC value should be obtained by manual inspection to identify the best inspiratory f low-volume loop.