Physiologic limitations during daily life activities in COPD patients

Introduction: Patients with COPD are known to be limited in their performance of activities of daily life (ADL). This observational study aims to investigate the ventilatory and metabolic demand of ADL in home settings of patients and evaluate possible mechanisms involved in physiological limitation during ADL in COPD. Methods: In their home settings, 21 stable patients with COPD (GOLD II-IV, mean FEV1 43% predicted) were asked to perform their most dyspnea causing activities at their usual pace until symptoms discouraged further performance. Ten healthy control subjects, matched for age and gender, performed comparable activities. Ventilatory and metabolic demands of the ADL were studied using a portable breath-by-breath system. Results: Compared with healthy controls, ADL time was shorter in patients (530 +/- 38 s vs. 318 +/- 37 s respectively) and activities resulted in important complaints of dyspnea. Oxygen consumption ((V) over dotO(2)) during the activities was higher in patients compared to healthy subjects (957 +/- 51 vs. 768 +/- 63 mL/min resp.). Ventilatory demand ((V) over dotE) for comparable activity (at iso-(V) over dotO(2)) was higher in patients and went together with complaints of dyspnea in patients, but not in healthy subjects. Ventilatory constraints like low ventilatory reserve and inspiratory reserve volume and dynamic hyperinflation occurred in more than 80% of the patients, especially in (very) severe patients. Conclusion: Patients with COPD experience limitations in the performance of ADL, which lead to reductions in ADL time and dyspnea complaints. There appears to be an important role for ventilatory limitations, which become more prominent as disease progresses. (C) 2010 Elsevier Ltd. All rights reserved.