Abstract
Forced expiratory volume in 6 seconds (FEV6) could complement forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) for detecting airflow obstruction in chronic obstructive pulmonary disease (COPD). Our aim is to evaluate the use of the FEV1/ FEV6 and FEV6 as an alternative for FEV1/FVC and FVC in the detection of dynamic hyperinflation during six minute walk test (6MWT).
Sixty-two ambulatory and clinically-stable COPD patients were randomized to this cross-over study. One group of 31 patients performed the spirometry by FVC first, then measuring FEV6, before and after 6MWT. The other 31 patients initiated the maneuver of FEV6 first, then followed by FVC, during the 6MWT. FVC, FEV1, inspiratory capacity (IC), FEV6 and FEV1/FEV6 were recorded.
FEV6 and FEV1/FEV6 were strongly correlated with FVC (r=0.907, n=62, p<0.0001) and FEV1/FVC (r=0.865, n=62, p<0.0001) before 6MWT. Values of FEV6 and FEV1/FEV6 were also strongly related to FVC (r=1.00, n=62, p<0.0001) and FEV1/FVC (r=0.809, n=62, p<0.0001) after 6MWT. We found that FVC showed good correlation to pre-exercise IC (r=0.697, n=62, p<0.0001) and post-exercise IC (r=0.642, n=62, p<0.0001). The value of FEV6 also have similar correlation with pre-exercise IC (r=0.593, n=62, p<0.0001) and post-exercise IC (r=0.584, n=62, p<0.0001). The delta IC was correlated with delta FEV6 (r=-0.357, n=62, p=0.004), however, was not related to delta FVC (r=-0.093,n=62, p=0.470).In conclusion, FEV6 and FEV1/FEV6 can be used as a valid alternative for FVC and FEV1/FVC to detect airway limitation or dynamic hyperinflation during 6MWT.
- © 2013 ERS