%0 Journal Article %A A. Somfay %A J. Porszasz %A S.M. Lee %A R. Casaburi %T Dose-response effect of oxygen on hyperinflation and exercise endurance in nonhypoxaemic COPD patients %D 2001 %R 10.1183/09031936.01.00082201 %J European Respiratory Journal %P 77-84 %V 18 %N 1 %X Dynamic hyperinflation contributes to exertional breathlessness and reduced exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. This study examined whether oxygen supplementation results in a dose-dependent decrease in hyperinflation associated with functional and symptomatic improvement.Ten severe COPD patients without clinically significant oxygen (O2) desaturation during exercise, and seven healthy subjects, performed five exercise tests at 75% of maximally tolerated work rate. Inspired oxygen fraction (FI,O2) was varied (0.21, 0.3, 0.5, 0.75 and 1.0) among tests in a randomized order. Ventilation (V'E) was measured, and end-inspiratory (EILV) and end-expiratory (EELV) lung volume changes were assessed from inspiratory capacity manoeuvres.In the patients, compared to room air, endurance time increased with FI,O2=0.3 (mean±sem 92±20%) and increased further with FI,O2=0.5 (157±30%). At isotime, compared to room air, there were significant reductions in dyspnoea score, EELV, EILV, V'E and respiratory frequency (fR) with FI,O2=0.3. Improved endurance time negatively correlated with change in EELV (r=0.48, p=0.002) and EILV (r=043, p=0.005). The dyspnoea rating decrease correlated with fR decrease. In healthy subjects, smaller V'E and fR decreases were observed at FI,O2=0.5, accompanied by more modestly increased endurance.Oxygen supplementation during exercise induced dose-dependent improvement in endurance and symptom perception in nonhypoxaemic chronic obstructive pulmonary disease patients, which may be partly related to decreased hyperinflation and slower breathing pattern. This effect is maximized at an inspired oxygen fraction of 0.5.A. Somfay is a visiting scientist from the Dept of Pulmonology, Albert Szent-Györgyi Medical University, Szeged-Deszk, Hungary and is partly supported by the Hungarian Soros Foundation (Budapest), the Foundation for Hungarian Pulmonology (Budapest) and the Foundation for Quality Care of Patients with Lung and Heart Diseases (Deszk). J. Porszasz is a visiting scientist from the National Institute of Occupational Hygiene and Health (Budapest). S.M. Lee is a visiting scientist from the Dept of Internal Medicine, Eulji Medical College, Seoul, Korea and is the recipient of a World Health Organization fellowship. %U https://erj.ersjournals.com/content/erj/18/1/77.full.pdf