Structural determinants of exercise ventilatory inefficiency in mild-to-moderate COPD

Background: Exercise ventilatory inefficiency (e.g., increased ventilation (VE) / CO 2 output (VCO 2 ) nadir) has been consistently found in moderate-to-severe COPD. It remains unknown a) whether this holds true for patients with largely preserved FEV 1 and, if so, b) whether it would be associated with structural findings suggestive of “wasted” ventilation (i.e., emphysema). Methods: 45 subjects of both genders (19 with COPD) prospectively underwent incremental cardiopulmonary exercise testing. % Emphysema in COPD was established by high resolution CT. Results: The groups were well-matched by age, gender and body dimensions. As shown in the Table , patients presented with lower peak exercise capacity and greater VE/VCO 2 nadir compared to controls (p Peak oxygen uptake and power were inversely related to VE/VCO 2 nadir (r=-0.57 and r=-0.46, respectively; p 2 nadir was strongly related to % emphysema ( Figure ). Conclusion: COPD is associated with poor ventilatory efficiency even in patients with largely preserved FEV 1 . Imaging features of mild emphysema may have functional relevance for these patients under the stress of exercise.