Chronic obstructive pulmonary disease (COPD) is characterized by an expiratory flow limitation, as well as an evident reduced exercise capacity compared to that of healthy age-matched individuals. Clearly, the expiratory flow limitation plays a significant role in this exercise intolerance; however, the extent of the contributions of other systemic factors remains unclear. More specifically, there is little data thus far on the role of blood flow delivery as a possible exercise limitation in COPD, especially in light of the potential interactions between cardiac output (Qc) and pulmonary hyperinflation. Thus, the purpose of this study was to compare the slope of the Qc versus oxygen uptake (VO 2) response through several submaximal cycling loads in patients with moderately severe COPD with that of age-matched healthy control subjects (CTRL). Also examined was the possibility that ventilatory constraints such as dynamic hyperinflation contribute to an abnormal Qc response. Cardiac output was measured using the CO2-rebreathing equilibrium technique during baseline conditions and cycling at 20, 40 and 65% of peak power in 17 COPD (Age: 64 +/- 8 yrs; FEV1/FVC: 37 +/- 11%; FEV1: 41 +/- 15% predicted) and 10 age-matched CTRL subjects. Inspiratory capacity (IC) was also measured for the determination of dynamic hyperinflation during the steady state exercise bouts. The results indicate that while the absolute Qc values are lower in COPD than in CTRL during moderately intense (65% peak power) cycling (11.30 +/- 2.38 vs. 15.63 +/- 2.15 L⋅min -1, p < 0.01), likely due to their lower exercise metabolic demand, the Qc/VO2 response to increasing levels of exercise intensity is normal or hyperdynamic in COPD. Indeed, the majority of patients with COPD exhibited Qc/VO2 slopes greater than 7.0, which may be indicative of a peripheral muscle bioenergetic disturbance that may drive the need for greater oxygen delivery, and thus result in an exaggerated ce
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84021 |
| Date | January 2005 |
| Creators | De Souza, Melissa |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Kinesiology and Physical Education.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002271936, proquestno: AAIMR22713, Theses scanned by UMI/ProQuest. |
Page generated in 0.0076 seconds