COPD and oxygen supplementation: Improvement in inspiratory capacity and dyspnea during exercise

Background: Ambulatory oxygen is recommended for COPD patients with long term oxygen treatment (LTOT), but the benefit in patients who only desaturate during exercise is uncertain. The aim of this study was to evaluate effects of oxygen supplementation during exercise on inspiratory capacity (IC) and thereby dynamic hyperinflation (DH) and dyspnea in COPD patients without resting hypoxia, who desaturate to SpO 2 Methods: In a double-blind, randomized crossover study 11 COPD patients (FEV 1 : 51.6±14.4%pred, age: 65±8 yrs, DL,CO: 46.7±20.6%pred) performed a maximal treadmill exercise test and thereafter two constant work load (CWL) tests at 85% of peak work load with measurement of oxygen uptake and ventilation. Iso-time was set to 5 min. During the CWL-tests the patients received an air mix (21% and 30% FIO 2 in random order) on a facemask through a reservoir (Douglas bag). IC and dyspnea (Borg CR10) were recorded pre-exercise and every min during the CWL-tests. Results: All patients finished both CWL-tests. FIO 2 30% compared to 21% improved IC at iso-time in all but two patients and dyspnea in all but one patient. IC was1.7L with 21% O 2 and 2.0L with 30% O 2 ; an improvement in IC of 0.3±0.3L (p= 0.010). Dyspnea was 6.5±1.5 with 21% O 2 and 3.6±1.8 with 30% O 2 ; a reduction in dyspnea of 3.1±2.4 (p=0.003). Arterial oxygen tension (PaO 2 ) and saturation (SaO 2 ) increased from 7.2±1.1 kPa and 84±5% (21% O 2 ) to 11.8±1.7 kPa and 96±2% (30% O2), respectively (p Conclusions: The study revealed that short term oxygen, given in a therapeutic dose, significantly improved IC, and thereby DH, as well as dyspnea in COPD patients with exercise desaturation.