Abnormal Exertional Breathlessness on Cardiopulmonary Cycle Exercise Testing in Relation to Self-Reported and Physiologic Responses in Chronic Airflow Limitation

Chest. 2024 Jul;166(1):81-94. doi: 10.1016/j.chest.2024.02.034. Epub 2024 Feb 27.

Abstract

Background: Exertional breathlessness is a cardinal symptom of cardiorespiratory disease.

Research question: How does breathlessness abnormality, graded using normative reference equations during cardiopulmonary exercise testing (CPET), relate to self-reported and physiologic responses in people with chronic airflow limitation (CAL)?

Study design and methods: An analysis was done of people aged ≥ 40 years with CAL undergoing CPET in the Canadian Cohort Obstructive Lung Disease study. Breathlessness intensity ratings (Borg CR10 scale [0-10 category-ratio scale for breathlessness intensity rating]) were evaluated in relation to power output, rate of oxygen uptake, and minute ventilation at peak exercise, using normative reference equations as follows: (1) probability of breathlessness normality (probability of having an equal or greater Borg CR10 rating among healthy people; lower probability reflecting more severe breathlessness) and (2) presence of abnormal breathlessness (rating above the upper limit of normal). Associations with relevant participant-reported and physiologic outcomes were evaluated.

Results: We included 330 participants (44% women): mean ± SD age, 64 ± 10 years (range, 40-89 years); FEV1/FVC, 57.3% ± 8.2%; FEV1, 75.6% ± 17.9% predicted. Abnormally low exercise capacity (peak rate of oxygen uptake < lower limit of normal) was present in 26%. Relative to peak power output, rate of oxygen uptake, and minute ventilation, abnormally high breathlessness was present in 26%, 25%, and 18% of participants. For all equations, abnormally high exertional breathlessness was associated with worse lung function, exercise capacity, self-reported symptom burden, physical activity, and health-related quality of life; and greater physiologic abnormalities during CPET.

Interpretation: Abnormal breathlessness graded using CPET normative reference equations was associated with worse clinical, physiological, and functional outcomes in people with CAL, supporting construct validity of abnormal exertional breathlessness.

Keywords: dyspnea; exercise capacity; exercise test; reference values.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Canada
  • Dyspnea* / diagnosis
  • Dyspnea* / etiology
  • Dyspnea* / physiopathology
  • Exercise Test* / methods
  • Exercise Tolerance / physiology
  • Female
  • Forced Expiratory Volume / physiology
  • Humans
  • Male
  • Middle Aged
  • Oxygen Consumption / physiology
  • Pulmonary Disease, Chronic Obstructive* / complications
  • Pulmonary Disease, Chronic Obstructive* / diagnosis
  • Pulmonary Disease, Chronic Obstructive* / physiopathology
  • Self Report*