Effects of Lung Volume Reduction Surgery on Exercise Pulmonary Hemodynamics in Severe Emphysema

Abstract

To clarify the effects of lung volume reduction surgery (LVRS) on pulmonary hemodynamics in severe emphysema and to evaluate the role of pulmonary circulation in the increased exercise performance after LVRS. In eight male patients with severe emphysema, we measured pulmonary artery (Ppa) and occlusion (Pop) pressures and cardiac output through a Swan-Ganz thermodilution catheter, and we calculated cardiac index (CI), pulmonary vascular resistance index, and driving pressure. The study was performed at rest and during exercise using a supine bicycle ergometer at 25 W, under room air and O2 inhalation. Exercise performance was expressed as endurance time in minutes. Pulmonary function tests were performed. The patients underwent an identical study before and 6 months after LVRS. The patients' exercise performance was significantly increased after LVRS (5.9+/-1.8 min) compared with that before LVRS (3.6+/-0.9 min). LVRS resulted in a significant increase in FEV1 and a significant decrease in residual volume. Before LVRS, Ppa was increased both at rest and during exercise. LVRS did not change rest or exercise Ppa. LVRS significantly decreased Pop during exercise from 24+/-10 mm Hg to 18+/-7 mm Hg. CI at rest and during exercise were significantly increased after LVRS. O2 administration significantly decreased Ppa during exercise both before and after LVRS. These findings suggest that LVRS does not improve pulmonary hypertension at rest or during exercise in patients with severe emphysema and that elevated Pop during exercise before LVRS is probably related to lung mechanic abnormalities.