Components of dyspnoea during incremental exercise across the COPD continuum

Abstract

<b>Background:</b> Evaluation of the intensity and quality of exertional dyspnoea is potentially useful in patients with COPD. The present study examined associations between dyspnoea intensity and quality, dynamic respiratory mechanics, and exercise capacity during CPET in patients with COPD. <b>Methods:</b> In this cross-sectional study, 261 patients with mild-to-very severe COPD and 94 age- and sex-matched controls completed an incremental cycle CPET to symptom limitation. Throughout exercise, expired gas, operating lung volumes and dyspnoea intensity were assessed. At peak exercise, dyspnoea quality was assessed using a modified 15-item questionnaire. <b>Results:</b> Logistic regression revealed that amongst 15 dyspnoea descriptors, those alluding to the clusters “unsatisfied inspiration”, “tight chest”, and “rapid breathing” discriminated patients from controls (all p&lt;0.05). However, only “unsatisfied inspiration” was consistently associated with an increased likelihood for both critical inspiratory mechanical constraints and reduced exercise capacity in COPD (odds ratio [95% confidence interval]=3.26 [1.40-7.60] and 3.04 [1.24-7.45], respectively, both p&lt;0.05). Thus, patients reporting “unsatisfied inspiration” (n=177) had an increased frequency of critical inspiratory mechanical constraints and low exercise capacity, compared with those who did not select this descriptor, regardless of COPD severity or peak dyspnoea intensity scores. <b>Conclusion:</b> In patients with COPD, regardless of disease severity, reporting descriptors in the unsatisfied inspiration cluster complemented traditional assessments of dyspnoea during CPET and helped identify patients with critical mechanical abnormalities germane to exercise intolerance.