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Continuous measurement of breathlessness during exercise: validity, reliability, and responsiveness
D A Mahler1, R Mejia-Alfaro, J Ward
1Section of Pulmonary and Critical Care Medicine, Dartmouth-Hitchcock Medical Center, Lebanon 03756-0001, USA. donald.a.mahler@hitchock.org
Journal of Applied Physiology (Bethesda, Md. : 1985)
|May 18, 2001
Summary
A new continuous method for measuring breathlessness (dyspnea) during exercise is as reliable as the traditional discrete method. The continuous approach offers superior responsiveness to respiratory load changes and better identifies relationships between breathlessness and physiological variables in COPD patients.
Area of Science:
- Exercise Physiology
- Respiratory Medicine
- Psychophysics
Background:
- Assessing breathlessness (dyspnea) during exercise is crucial for understanding cardiorespiratory function and disease.
- Traditional discrete methods involve infrequent, single judgments, potentially missing dynamic changes.
- A continuous method using a computer interface may offer a more sensitive approach to quantifying subjective respiratory sensations.
Purpose of the Study:
- To introduce and compare a continuous method of recording breathlessness during exercise with the traditional discrete method.
- To evaluate the reliability and responsiveness of both methods in healthy individuals and patients with chronic obstructive pulmonary disease (COPD).
Main Methods:
- Three studies were conducted involving healthy young females and males, and patients with COPD.
- Subjects performed exercise on a cycle ergometer, rating breathlessness using either a discrete (minute-by-minute) or continuous (real-time mouse-controlled scale) method.
- Physiological variables including work, oxygen consumption, and minute ventilation were recorded; respiratory loads were introduced in specific protocols.
Main Results:
- Both discrete and continuous methods yielded statistically similar psychophysical results relating breathlessness to work, oxygen consumption, and minute ventilation in healthy subjects.
- Both methods demonstrated high reliability across test sessions.
- The continuous method uniquely allowed for the assessment of responsiveness to the onset and offset of respiratory loads and better identified significant relationships between breathlessness and physiological variables in COPD patients.
Conclusions:
- The continuous method for assessing breathlessness during exercise is a reliable alternative to the discrete method.
- The continuous method provides enhanced insights into dynamic respiratory responses and the relationship between subjective breathlessness and physiological parameters, particularly in clinical populations like COPD.
- This method holds potential for more nuanced clinical assessments and research in respiratory physiology.