The enigma of dyspnoea in COPD: A physiological perspective.

Dyspnoea (perceived breathing discomfort) is the most common symptom experienced by patients with chronic obstructive pulmonary disease (COPD) and is associated with progressive physical inactivity and poor quality of life. Exertional dyspnoea ratings in COPD have been shown to consistently correlate with a number of physiological ratios that ultimately point to demand/capacity imbalance of the dynamic respiratory system.[1] These include ventilatory output, tidal oesophageal pressure and tidal diaphragmatic electromyography (EMG) (all expressed relative to respective maxima). Studies using bronchodilators or inspiratory muscle training (IMT) to relive dyspnoea have confirmed the importance of high IND in dyspnoea causation in COPD. [Extracted from the article]