1. Effects of chronic obstructive pulmonary disease (COPD) severity on different parameters of ventilatory inefficiency during incremental cardiopulmonary exercise testing (CPET). a) Minute ventilation (V′E)–carbon dioxide output (V′CO2) intercept increased an...
Effects of chronic obstructive pulmonary disease (COPD) severity on different parameters of ventilatory inefficiency during incremental cardiopulmonary exercise testing (CPET). a) Minute ventilation (V′E)–carbon dioxide output (V′CO2) intercept increased and b) V′E–V′CO2 slope diminished as the disease progressed from Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1–4. c) As the V′E/V′CO2 nadir depends on both slope and intercept, it remained elevated (compared with controls) across disease stages. d) Increasing nadir–slope differences from GOLD stages 1–4 reflects the impact of a progressively higher intercept. *: p<0.05 COPD versus controls (panel b) or controls versus all COPD groups (panel c). Reproduced from [19] with permission.
Denis E. O'Donnell et al. Eur Respir Rev 2016;25:
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