Increased oxygen pulse after LVRS is associated with reduced dynamic hyperinflation

Stroke volume augmentation during exercise is limited in COPD patients because of decreased preload from dynamic hyperinflation (DH). We hypothesized that O2 pulse and pulse pressure (PP) improve following LVRS and the magnitude of improvement correlates with reduction in DH.We compared 16 emphysema patients undergoing LVRS with 6 emphysema patients not undergoing LVRS. O2 pulse and PP were calculated from maximal cardiopulmonary exercise tests at baseline and six months later. End-expiratory lung volume to total lung capacity (EELV/TLC) represented DH. Comparisons were made between baseline and 6 months at metabolic isotimes (%VCO2max).At baseline, the LVRS group was older with higher FEV1, but had similar hyperinflation to the non-LVRS group. At 6 months, O2 pulse (50%, 75%, and 100%VCO2max) and PP (50% and 75%VCO2max) increased in LVRS, but not in the non-LVRS group. Baseline FRC/TLC inversely correlated with resting O2 pulse (r= -0.449,p=0.04). Decreased EELV/TLC correlated with increased O2 pulse at 75% (r= -0.487,p=0.02) and 100%VCO2max (r= -0.548,p=0.008).LVRS led to increased O2 pulse and PP during exercise at metabolic isotimes 6 months following surgery. Reductions in DH correlated with increases in O2 pulse during exercise. Reduction in lung volume may improve stroke volume response to exercise by decreasing dynamic hyperinflation