Inspiratory Capacity during Exercise: Measurement, Analysis, and Interpretation
Figure 5
Operating lung volume plots during constant work rate cycle exercise in COPD patients following acute high-dose anticholinergic therapy versus placebo (a) and hyperoxia versus room air (b). The operating lung volumes (i.e., end-expiratory and end-inspiratory lung volumes) were reduced at rest (0 min) following anticholinergic therapy and resulted in a downward shift in operating lung volumes throughout exercise. The magnitude of dynamic hyperinflation at peak exercise (calculated as the difference in EELV from resting values) did not change following bronchodilation. The magnitude of dynamic hyperinflation was also similar at peak exercise (~0.2 L) during hyperoxia compared with room air in hypoxemic patients with COPD. Data for these graphs are based on previously published studies from our laboratory [43, 74]. IRV, inspiratory reserve volume; , tidal volume; DH, dynamic hyperinflation; TLC, total lung capacity.
