Back to Search
Start Over
Reproducibility of the parameters of the on-transient cardiopulmonary responses during moderate exercise in patients with chronic obstructive pulmonary disease.
- Source :
- European Journal of Applied Physiology; Sep2001, Vol. 85 Issue 5, p434-441, 8p
- Publication Year :
- 2001
-
Abstract
- To be clinically useful as indices reflective of altered physiological function consequent to interventions in patients with chronic obstructive pulmonary disease (COPD), the time constant (τ) and steady-state amplitude of the kinetic responses for oxygen uptake (VO<subscript>2</subscript>) carbon dioxide output (VCO<subscript>2</subscript>) ventilation (V<subscript>E</subscript>) and heart rate (HR) have to be appropriately differentiable and reproducible. We therefore assessed the reproducibility of τ and steady state amplitude values in 41 patients with severe COPD [mean (SD)] [forced expiratory volume in 1 s=41 (7)% predicted], aged 64 (5) years. Of the total, 6 of the patients (15%) did not produce breath-by-breath data of sufficient quality to warrant kinetic analysis. The remaining 35 patients completed two moderate-intensity 10 mm square-wave exercise tests separated by 2 h, both before and after an endurance training programme. Tests were conducted on an electromagnetically-braked cycle ergometer at an exercise intensity corresponding to 80% of the estimated lactate threshold (θ<subscript>La</subscript>) or 50% of peak oxygen uptake if °La was insufficiently differentiable. Breath-by-breath measurements of VO<subscript>2</subscript>, VCO<subscript>2</subscript>, V<subscript>E</subscript> and HR were averaged into 10 s bins and the on-transient response kinetics were estimated using a mono-exponential model. Analysing the pre-training and the post-training test 1 and test 2 comparisons together, the test 1-test 2 differences were not significantly different from 0 for either τ or A. The standard deviation of the test 1-test 2 differences allowed us to define the magnitude of change that would reach statistical significance. For τ, this averaged some 8, 10, 11 and 8 s, for VO<subscript>2</subscript>, VCO<subscript>2</subscript>, VE and HR, respectively, for a one-tailed paired-comparisons test (i.e. appropriate for assessing hypothesised improvements resulting from an intervention); for a two-tailed comparison, the differences were approximately 2 s greater. The corresponding one-tailed values for A were 100 ml·min<superscript>-1</superscript>, 95 ml·min<superscript>-1</superscript>, 2.5 1 mm<superscript>-1</superscript> and 4 beats·min<superscript>-1</superscript>, respectively; the two-tailed values were 10%-15% greater. We therefore conclude that both τ and A for moderate-intensity exercise can be reproducibly estimated in patients with COPD when the data set provides a sufficiently large amplitude of response and sufficiently low sample variability to allow appropriate parameter estimation. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14396319
- Volume :
- 85
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- European Journal of Applied Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 16127537
- Full Text :
- https://doi.org/10.1007/s004210100486