Mechanisms of dyspnea in chronic lung disease

To discuss three emerging areas of research triggering new hypotheses for mechanisms of dyspnea.

There has been an emphasis on the importance of lung volumes in evaluating symptoms and lung function in patients with chronic obstructive pulmonary disease. Dyspnea intensity seems to more closely correlate with measures of hyperinflation than airflow limitation, highlighting the importance of neuromechanical dissociation in the development of dyspnea. Inhaled furosemide has demonstrated a beneficial effect in laboratory-induced dyspnea, and the sensation of air hunger has been ameliorated by this therapy, possibly via activation of pulmonary stretch receptors. There appear to be distinct affective and sensory components of dyspnea, and the affective dimension may be modifiable, although this has not been fully studied.

Dyspnea in chronic obstructive pulmonary disease is clearly related to hyperinflation, and lung volumes are valuable for characterizing disease. It remains unclear whether a limitation in tidal volume due to dynamic hyperinflation is the key factor in exertional dyspnea in this disease. Research of inhaled furosemide demonstrates the importance of afferent sensory input in modifying dyspnea, and deserves further study. The contributions of the affective and sensory components of dyspnea remain unclear, but should be studied further.