Ekström M; Faculty of Medicine, Lund University, Lund, Sweden.
Li PZ; Lewthwaite H; Bourbeau J; Tan WC; Jensen D;
Chest [Chest] 2025 Mar 11.
Date of Electronic Publication: 2025 Mar 11.
Background: Exertional breathlessness is a cardinal symptom of people with chronic airflow limitation (CAL) and can be evaluated using cardiopulmonary exercise testing (CPET).
Research Question: Does abnormally high exertional breathlessness in relationship to the rate of oxygen uptake (V’O 2 ) and minute ventilation (V’ E ) indicate different underlying pathophysiologic mechanisms and clinical characteristics in people with CAL?
Study Design and Methods: Analysis of people ≥ 40 years of age with CAL (FEV 1 to FVC ratio after bronchodilation less than lower limit of normal) undergoing symptom-limited incremental cycle CPET in the Canadian Cohort Obstructive Lung Disease study. Using published normative references, breathlessness phenotypes at peak exercise were categorized as abnormal (Borg 0-10 scale intensity rating more than upper limit of normal) by V’O 2 alone, abnormal by both V’O 2 and V’ E , or normal by both V’O 2 and V’ E . Exercise physiologic responses and clinical characteristics were compared between groups.
Results: We included 325 people (44% women) with CAL (mean (SD) FEV 1 , 75.4 (17.5)% predicted). Compared with the normal by both V’O 2 and V’ E group (n = 237 [73%]), the abnormal by V’O 2 only group (n = 29 [9%]) showed lower pulmonary diffusing capacity and greater exercise ventilatory inefficiency, whereas the abnormal by both V’O 2 and V’ E group (n = 50 [15%]) showed even worse lung function, dynamic critical inspiratory constraints, and exertional breathlessness along with greater symptom burden in daily life, lower physical activity, and worse health status.
Interpretation: Exertional breathlessness phenotyped in relationship to V’O 2 and V’ E using normative reference equations enable multivariable analyses of underlying symptom mechanisms and associated clinical characteristics.
Competing Interests: Financial/Nonfinancial Disclosures The authors have reported to CHEST the following: J. B. and W. C. T. report receiving institutional funding for the CanCOLD study from Astra Zeneca Canada, Ltd., Boehringer-Ingelheim Canada, Ltd., GlaxoSmithKline Canada, Ltd., Merck, Novartis Pharma Canada, Inc., as well as Nycomed Canada, Inc. (W. C. T.), Pfizer Canada, Ltd. (W. C. T.), Trudell (J. B.), and Grifolds (J. B.). None declared (M. E., P. Z. L., H. L., D. J.).