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Systemic oxygen extraction during incremental exercise in patients with severe chronic obstructive pulmonary disease
- Source :
- European Journal of Applied Physiology. 78:201-207
- Publication Year :
- 1998
- Publisher :
- Springer Science and Business Media LLC, 1998.
-
Abstract
- To determine if decreased systemic oxygen (O2) extraction contributes to the exercise limit in severe chronic obstructive pulmonary disease (COPD), 40 consecutive incremental cycle ergometer exercise tests performed by such patients, from which a "log-log" lactate threshold (LT) was identified, were compared to those of 8 patients with left ventricular failure (LVF) and 10 normal controls. Pulmonary gas exchange and minute ventilation were measured continuously and arterial blood gas tensions, pH, and lactate concentrations were sampled each minute. Cardiac output (Qc) was measured by first-pass radionuclide ventriculography. The systemic O2 extraction ratio (O2ER) was calculated as arterial - mixed venous O2 content difference (CaO2 - CvO2)/CaO2. Peak exercise O2 uptake (VO2peak) was markedly reduced in both COPD and LVF [41 (3) and 42 (3)% predicted, respectively], compared to controls [89 (2)% predicted, P0.0001 for each]. Similarly, the LT occurred at a low percentage of predicted maximal oxygen consumption in both COPD and LVF [25 (2) and 27 (3)%] compared to normals [46 (3)%, P0.0001 for each]. The systemic O2ER at peak exercise was severely reduced in COPD [0.36 (0.02)] compared to the other groups [P0.0001 for each], for whom it was nearly identical [0.58 (0.03) vs 0.63 (0.04), LVF vs control, P0.05]. In the COPD group, an early LT correlated with reduced systemic O2ER at peak exercise (r = 0.64, P0.0001), but not with any index of systemic O2 delivery. These data suggest that lactic acidemia during exercise in patients with severe COPD is better related to abnormal systemic O2 extraction than to its delivery and contributes to the exercise limit.
- Subjects :
- Male
medicine.medical_specialty
Physiology
Radionuclide ventriculography
Physical exercise
Incremental exercise
Oxygen Consumption
Physiology (medical)
Internal medicine
Humans
Medicine
Orthopedics and Sports Medicine
Lung Diseases, Obstructive
Exercise physiology
Exercise
Aged
COPD
business.industry
Lactate threshold
Hemodynamics
Public Health, Environmental and Occupational Health
General Medicine
Middle Aged
medicine.disease
Respiratory Function Tests
Surgery
Exercise Test
Cardiology
Arterial blood
Acidosis, Lactic
Female
Blood Gas Analysis
business
Respiratory minute volume
Subjects
Details
- ISSN :
- 14396327 and 14396319
- Volume :
- 78
- Database :
- OpenAIRE
- Journal :
- European Journal of Applied Physiology
- Accession number :
- edsair.doi.dedup.....137bbb78079e74fabc940c86290a9d5e