title: Sex differences in exertional dyspnea in patients with mild COPD: physiological mechanisms.
abstract: The purpose of this study was to evaluate the physiological basis for sex-differences in exercise-induced dyspnea in patients with mild COPD. We compared operating lung volumes, breathing pattern and dyspnea during incremental cycling in 32 men (FEV(1)=86±10% predicted) and women (FEV(1)=86±12% predicted) with mild COPD and 32 age-matched controls. There were no sex differences in dyspnea in the control group at any work-rate or ventilation (V(E)). Women with COPD had significantly greater dyspnea than men at 60 and 80 W. At 80 W, dyspnea ratings were 5.7±2.3 and 3.3±2.5 Borg units (P<0.05) and the V(E) to maximal ventilatory capacity ratio was 72% and 55% in women and men, respectively (P<0.05). Comparable increases in dynamic hyperinflation were seen in both male and female COPD groups at symptom limitation but women reached tidal volume constraints at a lower work rate and V(E) than men. Superimposing mild COPD on the normal aging effects had greater sensory consequences in women because of their naturally reduced ventilatory reserve.
authors.affiliation: Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston General Hospital, Kingston, ON, Canada.
authors.forename: Jordan A
authors.initials: JA
authors.lastname: Guenette
authors.forename: Dennis
authors.initials: D
authors.lastname: Jensen
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Webb
authors.forename: Dror
authors.initials: D
authors.lastname: Ofir
authors.forename: Natya
authors.initials: N
authors.lastname: Raghavan
authors.forename: Denis E
authors.initials: DE
authors.lastname: O'Donnell
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D002245:Carbon Dioxide / Q000378:metabolism; D016022:Case-Control Studies; D004417:Dyspnea / Q000209:etiology*; D015444:Exercise; D005080:Exercise Test / Q000009:adverse effects*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D013990:Tidal Volume / Q000502:physiology
chemical_list: D002245:Carbon Dioxide