Chest
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Multicenter Study
Decline of resting inspiratory capacity in COPD: the impact on breathing pattern, dyspnea, and ventilatory capacity during exercise.
To better understand the interrelationships among disease severity, inspiratory capacity (IC), breathing pattern, and dyspnea, we studied responses to symptom-limited cycle exercise in a large cohort with COPD. ⋯ Progressive reduction of the resting IC with increasing disease severity was associated with the appearance of critical constraints on Vt expansion and a sharp increase in dyspnea to intolerable levels at a progressively lower ventilation during exercise.