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The article reviews some studies on the mechanisms for the perception of dyspnea in order to consider, after optimal treatment of the underlying disease, the possibility of interventions that palliate the condition. Studies indicate that a neurophysiological model provides a conceptual framework for understanding the mechanism of dyspnea. The studies also suggest that endogenous opioids, nebulized furosamide, antiinflammatory therapy and chest wall vibration are potential approaches for modulating lung and chest wall receptors to relieve dyspnea.

Purpose: To examine the responsiveness of a new computerized method for patients to provide continuous ratings of dyspnea during exercise in patients with chronic obstructive pulmonary disease (COPD)., Methods: In this randomized, double-blind study the effects of an inhaled bronchodilator (BD), albuterol/ipratropium bromide solution, were compared with normal saline (NS) in 30 patients with COPD (age, 66+/-9 yr; forced expiratory volume in 1 s, 48+/-14% pred). At visit 1, patients were familiarized with the cycle ergometer and computer, monitor, and mouse system to provide continuous ratings of dyspnea during exercise. At subsequent visits 2-3 d apart, patients performed pulmonary function tests followed by incremental ramp (15 W.min-1) and, 1 h later, constant work (at 55% of maximal work capacity) exercise tests., Results: During incremental exercise the slopes of VO2:dyspnea and VE:dyspnea regressions were significantly lower, and patients exercised longer (Delta=0.4 min; P=0.003) with BD therapy compared with NS. During constant work exercise there was a significant reduction in dyspnea at the same exercise duration (5.0+/-2.8 vs 6.2+/-2.8 units on the 0-10 category-ratio scale; P=0.02) and patients exercised longer (Delta=0.9 min; P=0.04) with BD therapy. Changes in lung function at rest did not correlate significantly with changes in dyspnea ratings during exercise., Conclusions: Continuous ratings of dyspnea were responsive to inhaled bronchodilator therapy during both incremental and constant work exercise tests in patients with symptomatic COPD.

Purpose: The purpose of this study was to examine whether patients with chronic obstructive pulmonary disease (COPD) would report similar ratings of dyspnea at the same relative exercise intensity after participation in pulmonary rehabilitation., Methods: Forty-two patients with COPD performed incremental cardiopulmonary exercise testing before and after completion of a 6-wk exercise-training program. Subjects rated dyspnea on the 0-10 category-ratio (CR-10) scale each minute of the exercise test., Results: Both responders (21 patients who exhibited an increase in [OV0312]O(2peak) after pulmonary rehabilitation) and nonresponders (21 patients who had no increase in [OV0312]O(2peak)) reported slightly lower ratings of dyspnea ( approximately 0.5 on the CR-10 scale) at the same relative (50% and 75% of [OV0312]O(2peak)) exercise intensities. These changes in dyspnea ratings after pulmonary rehabilitation were not significantly different between responders and nonresponders., Conclusion: The study suggests that patients with COPD can use the same ratings of dyspnea to monitor training at the same relative exercise intensity whether they achieve a physiological training response or not.