Lung function, dyspnoea, and exercise tolerance in stable chronic obstructive pulmonary disease patients

摘要

During the last 50 years, the correlation of exercise tolerance with routine pulmonary function testing in patients with chronic obstructive pulmonary disease (COPD) has been investigated in many studies. In almost all instances, the degree of airway obstruction was assessed in terms of FEV_1. Since, a weak correlation was found between exercise tolerance and FEV_1 (% predicted), it has been concluded that other factors than lung function impairment (e.g., deconditioning and peripheral muscle dysfunction) play a predominant role in limiting exercise capacity in COPD patients. Recent studies, however, have shown that in moderate to very severe COPD patients the inspiratory capacity, a marker of hyperinflation, is a better predictor of exercise tolerance than FEV_1 and forced vital capacity (FVC), suggesting that the main cause of exercise intolerance in these patients is dynamic pulmonary hyperinflation due to concurrent expiratory flow limitation (FL).