Study objective: To evaluate serial lung function studies, including elastic recoil, in patients with severe emphysema who undergo lung volume reduction surgery (LVRS). To determine mechanism(s) responsible for changes in airflow limitation.
Methods: We studied 12 (10 male) patients aged 68±9 years (mean±SD) 6 to 12 months prior to and at 6-month intervals for 2 years after thoracoscopic bilateral LVRS for emphysema.
Results: At 2 years post-LVRS, relief of dyspnea remained improved in 10 of 12 patients, and partial or full-time oxygen dependency was eliminated in 2 of 7 patients. There was significant reduction in total lung capacity (TLC) compared with pre-LVRS baseline, 7.8±0.6 L (mean±SEM) (133±5% predicted) vs 8.6±0.6 L (144±5% predicted) (p=0.003); functional residual capacity, 5.6±0.5 L (157±9% predicted) vs 6.7±0.5 L (185±10% predicted) (p=0.001); and residual volume, 4.9±0.5 L (210±16% predicted) vs 6.0±0.5 L (260±13% predicted) (p=0.000). Increases were noted in FEV1, 0.88±0.08 L (37±6% predicted) vs 0.72±0.05 L (29±3% predicted) (p=0.02); diffusing capacity, 8.5±1.0 mL/min/mm Hg (43±3% predicted) vs 4.2±0.7 mL/min/mm Hg (18±3% predicted) (p=0.001); static lung elastic recoil pressure at TLC (Pstat), 13.7±0.5 cm H2O vs 11.3±0.6 cm H2O (p=0.008); and maximum oxygen consumption, 8.7±0.8 mL/min/kg vs 6.9±1.5 mL/min/kg (p=0.03). Increase in FEV1 correlated with the increase in TLC Pstat/TLC (r=0.75, p=0.03), but not with any baseline parameter.
Conclusion: Two years post-LVRS, there is variable clinical and physiologic improvement that does not correlate with any baseline parameter. Increased lung elastic recoil appears to be the primary mechanism for improved airflow limitation.