Dose-response effect of oxygen on hyperinflation and exercise endurance in nonhypoxaemic COPD patients

• Published in: The European respiratory journal Vol. 18; no. 1; pp. 77 - 84
• Main Authors: Somfay, A, Porszasz, J, Lee, S.M, Casaburi, R
• Format: Journal Article
• Language: English
• Published: Leeds Eur Respiratory Soc 01.07.2001; Maney
• Subjects: Aged; Ambulatory Care; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Dyspnea - physiopathology; Dyspnea - therapy; Emergency and intensive respiratory care; Exercise Test; Female; Humans; Intensive care medicine; Lung - physiopathology; Lung Volume Measurements; Male; Medical sciences; Middle Aged; Oxygen - blood; Oxygen Inhalation Therapy; Physical Endurance - physiology; Prognosis; Pulmonary Disease, Chronic Obstructive - physiopathology; Pulmonary Disease, Chronic Obstructive - therapy; Single-Blind Method; Work of Breathing - physiology; Physical exercise; Human; Oxygenotherapy; Lung disease; Chronic; Lung function; Treatment; Respiratory disease; Bronchus disease; Exploration; Obstructive pulmonary disease; Resuscitation
• ISSN: 0903-1936; 1399-3003; 1399-3003
• DOI: 10.1183/09031936.01.00082201

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 (O 2 ) desaturation during exercise, and seven healthy subjects, performed five exercise tests at 75% of maximally tolerated work rate. Inspired oxygen fraction ( F I,O 2 ) 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 F I,O 2 =0.3 (mean±sem 92±20%) and increased further with F I,O 2 =0.5 (157±30%). At isotime, compared to room air, there were significant reductions in dyspnoea score, EELV, EILV, V ' E and respiratory frequency ( f R ) with F I,O 2 =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 f R decrease. In healthy subjects, smaller V ' E and f R decreases were observed at F I,O 2 =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.