The Relationship Between Dyspnea and Pulmonary Functions, Arterial Blood Gases and Exercise Capacity in Patients with COPD

SUMMARY Dyspnea is described as a sensation of awareness of difficulty in breathing. Clinical techniques for rating dyspnea include Medical Research Council (MRC) scale, Baseline Dyspnea Index (BDI) and Borg scale. The aim of this study was to investigate the relationship between clinical dyspnea ratings and pulmonary functions, exercise capacity. 20 patients with moderate COPD (group 1) and 12 healthy controls (group 2) were included to the study. MRC scale, BDI and Borg scales were applied to all patients and pulmonary function tests, maximal inspiratory pressure (Pimax), mouth occlusion pressure (P 0.1 ), breathing pattern (BP), arterial blood gases (ABG) and symptom-limited exercise on a cycle ergometer were performed. All patients with COPD terminated the test because of dyspnea. The patients with COPD had moderate COPD [FEV1(pred%): 56.00 ± 15.03%]. The clinical dyspnea ratings of the patients were; MRC scale: 2.10 ± 0.55, BDI: 5.65 ± 1.60 and Borg scale: 4.55 ± 1.23. The BDI showed significant correlation with airflow rates, PaO2 and SaO2 (p< 0.05, p< 0.01), Borg scale showed significant correlation with airflow rates (p< 0.01), whereas they did not show significant correlation with Pimax and P 0.1 . There was a only significant correlation between MRC scale and peak oxygen uptake [VO 2 /kg (pred%)]; other dyspnea scales lacked any correlation with exercise testing parameters. In this study, clinical dyspnea scales and ratings during exercise were correlated with mainly airflow rates and ABG parameters. But they were not significant correlation with exercise capacity.