The role of FEV6 in the detection of airway obstruction.

Objectives: There are recent reports regarding the use of forced expiratory volume in 6 s (FEV6) in place of forced expiratory vital capacity (FVC) in the detection of airway obstruction. We aimed to investigate the role of FEV6 in comparison with FVC in the evaluation of airway obstruction.

Methods: The pulmonary function tests (PFT) results of all 5114 patients, who had been tested in the pulmonary function laboratory between 1998 and 2003, were retrospectively analyzed to investigate the relationship between FEV6 and FVC.

Results: We have found a mean difference of 95.35+/-121.7 (min=0, max=1050) ml (3.37%) when FVC and FEV6 values (FVC-FEV6) of all cases were compared. This difference was found to be higher (180 ml, 7.3%) in patients with airway obstruction. When FEV1/FVC is taken as the gold standard, FEV1/FEV6 had negative predictive value of 92.24% and a sensitivity of 86.09% in the detection of airway obstruction.

Conclusions: Although it is easier to use FEV6 in place of FVC, relatively low sensitivity in that setting may result in the underestimation of airway obstruction. This drawback should be kept in mind when FEV6 is utilized to detect airway obstruction.