Acute effects of hyperoxia on resting pattern of ventilation and dyspnoea in COPD.
OBJECTIVE
Hyperoxia has been shown to reduce resting ventilation, hyperinflation and dyspnoea in patients with severely hypoxaemic COPD. This study assessed the effects of hyperoxia on these resting measures in patients with COPD of varying disease severity and characterized those patients who responded.


METHODS
Measurements of dyspnoea (Borg score), oxyhaemoglobin saturation (SpO(2)), inspiratory capacity (IC), minute ventilation, tidal volume, breathing and cardiac frequency were performed at rest in 51 patients with COPD while they breathed air and 44% oxygen, in a randomized double-blinded fashion.


RESULTS
Hyperoxia induced significant reductions in cardiac frequency and dyspnoea and a significant increase in SpO(2). No significant change was noted in IC for the group overall, and there was substantial inter-subject variation in this measurement. No significant changes were found in ventilation, and there was no correlation between change in dyspnoea and change in IC. In patients with moderate to severe airflow obstruction (FEV(1) < 70% predicted), a significant association was found between the degree of airflow obstruction and change in IC induced by hyperoxia.


CONCLUSIONS
Hyperoxia improved dyspnoea but did not significantly alter resting pulmonary hyperinflation in a group of patients with COPD of varying severity. However, in a subset patients with moderate to severe airflow obstruction a relationship existed between the severity of airflow obstruction and volume response to hyperoxia.
Moore
Rosemary
R
Northern Clinical Research Centre, The Northern Hospital, Epping, Australia.
Berlowitz
David
D
Pretto
Jeffrey
J
Brazzale
Danny
D
Denehy
Linda
L
Jackson
Bruce
B
McDonald
Christine
C
D000368:Aged; D000369:Aged, 80 and over; D004311:Double-Blind Method; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology; D007320:Inspiratory Capacity / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*; D012123:Pulmonary Ventilation / Q000502:physiology; D012146:Rest / Q000502:physiology; D012720:Severity of Illness Index; D016896:Treatment Outcome