Background:~In spite of oxygen therapy, desaturations frequently occur during exercise in COPD patients. Although current recommendations are to add 1 L/min to the baseline oxygen flow during exertion, a new closed-loop system (FreeO2) automatically and continuously adjusts the oxygen flow to the patient's needs based on the oxygen saturation by pulse oximetry (SpO2), end-tidal CO2 (EtCO2) and respiratory rate. A preliminary study showed significant improvement in exercise tolerance in COPD patients not needing oxygen therapy. Although oxygen flow could be two fold increased during exercise, a worsening hypercapnia is plausible in severe COPD.~Aim of this study is to evaluate this system during endurance shuttle walking test in COPD patients with oxygen therapy and hypercapnia.~Methods: The investigators proposed to conduct a controlled, randomized cross-over study comparing the efficacy of a Closed-loop System for Oxygen Delivery (FreeO2) as compared with fixed oxygen flow during an endurance shuttle walking test in patients with COPD, oxygen therapy and hypercapnia.
The purpose of this study is to investigate the benefit of Closed-loop System for Oxygen Delivery (FreeO2) as compared with fixed oxygen flow during endurance shuttle walking test in patients with Chronic obstructive pulmonary disease (COPD), oxygen therapy and hypercapnia.~The study was designed to test the following hypotheses:~As compared with fixed oxygen flow, the FreeO2 Oxygen Delivery system leads to higher exercise tolerance (distance during ESWT) and lower desaturation events without increase in hypercapnia in patients with COPD, oxygen therapy and hypercapnia.~As compared with fixed oxygen flow, the FreeO2 Oxygen Delivery system leads to lower dyspnea and leg fatigue scores at a given endurance time during the shuttle walking test in patients with COPD, oxygen therapy and hypercapnia.~As compared with fixed oxygen flow, the FreeO2 Oxygen Delivery system leads to lower cardiac and respiratory frequencies at a given endurance time during the shuttle walking test in patients with COPD, oxygen therapy and hypercapnia.