Open AccessRole of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest
Author(s) -
Diaz O.,
Villafranca C.,
Ghezzo H,
Borzone G,
Leiva A,
MilicEmil J,
Lisboa C
Publication year - 2000
Publication title -
european respiratory journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.021
H-Index - 241
eISSN - 1399-3003
pISSN - 0903-1936
DOI - 10.1034/j.1399-3003.2000.16b14.x
Subject(s) - dynamic hyperinflation , medicine , copd , cardiology , vital capacity , ventilation (architecture) , tidal volume , hyperinflation , pulmonary function testing , incremental exercise , lung volumes , physical therapy , respiratory system , lung function , lung , diffusing capacity , heart rate , blood pressure , mechanical engineering , monetary policy , engineering , monetary economics , economics
Abstract Expiratory flow limitation promotes dynamic hyperinflation during exercise in chronic obstructive pulmonary disease (COPD) patients with a consequent reduction in inspiratory capacity (IC), limiting their exercise tolerance. Therefore, the exercise capacity of patients with tidal expiratory flow limitation (FL) at rest should depend on the magnitude of IC. The presented study was designed to evaluate the role of FL on the relationship between resting IC, other respiratory function variables and exercise performance in COPD patients. Fifty‐two patients were included in the study. Negative expiratory pressure (NEP) technique was employed to assess FL. Maximal work rate ( W Rmax) and oxygen uptake ( V ′O 2 ,max) were measured during an incremental symptom‐limited cycle exercise. Twenty‐nine patients were FL at rest. The IC was normal in all non‐FL patients, while in most FL subjects it was decreased. Both W Rmax and V ′O 2 ,max were lower in FL patients (p<0.001, each). A close relationship of W Rmax and V ′O 2 ,max to IC was found (r=0.73 and 0.75, respectively; p<0.0001, each). In the whole group, stepwise regression analysis selected IC and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (% predicted) as the only significant contributors to exercise tolerance. Subgroup analysis showed that IC was the sole predictor in FL patients, and FEV1/FVC in non‐FL patients. Detection of flow limitation provides useful information on the factors that influence exercise capacity in chronic obstructive pulmonary disease patients. Accordingly, in patients with flow limitation, inspiratory capacity appears as the best predictor of exercise tolerance, reflecting the presence of dynamic hyperinflation.