Oxygen Supplementation In Copd Patients With Exercise Induced Denaturation - A Rct Study

Background: Knowledge about the physiological responses to oxygen supplementation in patients with COPD who have normal oxygen saturation (SaO2) at rest but desaturate during exercise are scarce. Aims: To evaluate the effects of oxygen supplementation during exercise on cardiorespiratory responses and dyspnea score in COPD patients who desaturate during exercise (SaO2<88%). Methods: In a double-blinded, randomized crossover study 16 COPD patients (FEV1 50±14% pred, age 65±8 yrs) performed a maximal treadmill test and thereafter two constant work load (CWL) tests at 85% of peak work load. During the CWL-tests, the patients breathed 21% and 30% oxygen in random order on a facemask from a reservoir. Oxygen uptake (VO2), carbon dioxide output (VCO2), ventilation (VE), heart rate, blood pressure and dyspnea score (Borg CR10) were measured pre-exercise and at iso-time at 5 min. Results: All patients completed both CWL-tests. SaO2 at iso-time increased significantly from 84±5% to 96±1% with 30% O2, p<0.001. VO2 was significantly higher (1386±535 vs 1168±457mL/min, p=0,002). Dyspnea score was significantly reduced from 6.3±1.9 to 3.6±1.8 (p=0.003) with 30% O2. Breathing frequency (31±7 to 28±5, p=0.008), heart rate (126±20 to 119±18, p<0.001) and systolic blood pressure (192±16 to 179±17 mmHg, p=0.002) were lower. VE, VCO2 and the change in inspiratory capacity from rest to iso-time did not change significantly. Conclusions: Supplemental oxygen significantly improved cardiorespiratory responses to exercise and reduced exercise induced discomfort in COPD patients who desaturate during exercise.