Endoscopic lung volume reduction in COPD: improvements in gas transfer capacity are associated with improvements in ventilation and perfusion matching

Background: Endoscopic lung volume reduction (ELVR) has been shown to improve lung function, quality of life, and exercise tolerance in patients with severe heterogeneous emphysema. Our study aims to determine the effect of ELVR on gas transfer capacity corrected for alveolar volume (KCO) and investigate the relationship between KCO and ventilation and perfusion (VQ) matching. We speculate on possible mechanisms for the observed changes Methods: Patients with severe chronic obstructive pulmonary disease were prospectively recruited and underwent unilateral upper lobe ELVR between 2012 and 2014. Each had respiratory function test and differential VQ scans at baseline, 1-, 3-, and 12-month post-ELVR. Results: In total, 11 patients had 3 sets of respiratory function test (at baseline, 1, and 3 mo), whereas 7 had 4 sets (at baseline, 1, 3, and 12 mo). KCO improved by 10.3 (± 7.5)% at 1 month (P = NS) and 39.8 (± 15.4)% at 12 months (P < 0.05). VQ of the nontargeted lung increased by 12.8 (± 5.6)% and 7.9 (± 2.3)%, respectively at 1 month, whereas those of the targeted lung both decreased (P < 0.05). At 3 and 12 months, the VQ changes were similar to those at 1 month, though some were not statistically significant. Conclusions: ELVR results in improved KCO for at least 12 months. This may be explained by the VQ redistribution to the nontargeted and less emphysematous lung with improved VQ matching.