Abstract
Assessment of dyspnoea severity during incremental cardiopulmonary exercise testing (CPET) has long been hampered by the lack of reference ranges as a function of work rate (WR) and ventilation (V′E). This is particularly relevant to cycling, a testing modality which overtaxes the leg muscles leading to a heightened sensation of leg discomfort.
Reference ranges based on dyspnoea percentiles (0–10 Borg scale) at standardised work rates and V′E were established in 275 apparently healthy subjects aged 20–85 years (131 men). They were compared with values recorded in a randomly selected “validation” sample (n=451; 224 men). Their usefulness in properly uncovering the severity of exertional dyspnoea were tested in 167 subjects under investigation for chronic dyspnoea (“testing sample”) who terminated CPET due to leg discomfort (86 men).
Iso-work rate and, to a lesser extent, iso-V′E reference ranges (5th–25th, 25th–50th, 50–75th and 75th–95th percentiles) increased as a function of age, being systematically higher in women (p<0.01). There were no significant differences in percentiles distribution between “reference” and “validation” samples (p>0.05). Submaximal dyspnoea-work rate scores fell within the 75th–95th or >95th percentiles in 108 out of 118 (91.5%) subjects of the “testing” sample who showed physiological abnormalities known to elicit exertional dyspnoea, i.e. ventilatory inefficiency and/or critical inspiratory constraints. In contrast, dyspnoea scores typically fell in the 5th–50th range in subjects without those abnormalities (p<0.001).
This frame of reference might prove useful to uncover the severity of exertional dyspnoea in subjects who otherwise would be labelled as “non-dyspnoeic” while providing mechanistic insights into the genesis of this distressing symptom.
Abstract
Iso-power and iso-ventilation reference ranges for exertional dyspnoea were prospectively established in men and women aged 20 to 85. This is the first set of normative values to objectively assess the burden of dyspnoea during incremental cycle ergometry. https://bit.ly/2yfftY6
Footnotes
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Author contributions: All authors played a role in the content and writing of the manuscript. All authors were involved in data collection. In addition, J.A. Neder and D.E. O'Donnell shared the original idea for the study; these authors and D.C. Berton performed data analysis and prepared it for presentation. J.A. Neder wrote the first draft of the manuscript.
Conflict of interest: J.A. Neder has nothing to disclose.
Conflict of interest: D.C. Berton has nothing to disclose.
Conflict of interest: L.E. Nery has nothing to disclose.
Conflict of interest: W.C. Tan reports grants from Canadian Respiratory Research Network, AstraZeneca Canada Ltd, Boehringer Ingelheim Canada Ltd, GlaxoSmithKline Canada Ltd, Novartis, Canadian Institutes of Health Research, Respiratory Health Network of the Fonds de la recherche en santé du Québec, Merck, Nycomed, Pfizer Canada Ltd and Theratechnologies, during the conduct of the study.
Conflict of interest: J. Bourbeau reports grants from CIHR, Canadian Respiratory Research Network (CRRN), Foundation of the MUHC and Aerocrine, personal fees for consultancy and lectures from Canadian Thoracic Society and CHEST, grants and personal fees for advisory board work and lectures from AstraZeneca, Boehringer Ingelheim, Grifols, GlaxoSmithKline, Novartis and Trudell, outside the submitted work.
Conflict of interest: D.E. O'Donnell has nothing to disclose.
Support statement: J.A. Neder has been funded by the New Clinician Scientist Program from the Southeastern Ontario Academic Medical Association (SEAMO), Canada. The funder had no role in the study design, data collection and analysis, or preparation of the manuscript.
- Received January 29, 2020.
- Accepted May 12, 2020.
- Copyright ©ERS 2020