Effect of lung volume reduction surgery on gas exchange and pulmonary hemodynamics at rest and during exercise

Lung volume reduction surgery (LVRS) has become an extended surgery for emphysema in order to improve the dyspnea of severely affected patients. Because resection of lung areas may reduce the vascular bed, which is an important factor of pulmonary hypertension in emphysematous patients, especially during exercise, the aim of our study was to assess the outcome of pulmonary hemodynamics and gas exchange at rest and during exercise after LVRS. Nine patients had right heart catheterization before and 3 to 12 mo (mean, 4.5 mo) after LVRS. FEV1 increased from 705 to 1,005 ml (p < 0.05) after LVRS. Pa-O2, Pa-CO2 and mean pulmonary artery pressure ((Ppa) over bar) did not change after LVRS, either at rest or during exercise. However, a significant overall decrease of the respiratory swings of the pulmonary artery diastolic pressure (Delta Pd) at rest (median value, from 12 to 8 mm Hg, p < 0.01) and during exercise (from 20 to 15 mm Hg, p < 0.05) was observed. There was a significant correlation between the change in resting (Ppa) over bar ((Ppa) over bar before minus (Ppa) over bar after LVRS) and the change in resting Delta Pd (r = 0.73, p < 0.03), and also between the change in exercising (Ppa) over bar and the change in resting Delta Pd (r = 0.80, p < 0.02). Significant correlations were also found between the change in exercising (Ppa) over bar and the change in exercising Pa-O2 (r = -0.70, p < 0.05), and between the change in exercising (Ppa) over bar and the change in exercising Pa-CO2 (r = 0.76, p < 0.03). We conclude that pulmonary hemodynamics in most cases are not impaired by LVRS either at rest or during exercise. The possible mechanisms influencing hemodynamics after a lung volume reduction procedure are discussed.