Endoscopic lung volume reduction (ELVR) in COPD: Improvements in gas transfer capacity correlate with improvements in ventilation and perfusion (VQ) matching

Abstract

Introduction: We previously reported improvements in gas transfer factor (KCO) in patients undergoing ELVR for severe heterogeneous emphysema. The mechanism is unknown but we postulate improved VQ matching. Aim: To investigate the relationship between KCO and VQ matching. Methods: Patients with severe COPD were prospectively recruited and underwent unilateral upper lobe ELVR between 2012 and 2014. Each had RFTs and differential VQ scans at baseline, 1, 3 and 12 mths post-ELVR. We report on 11 patients with complete 3 mth data, 7 of whom had 12 mth data. Results: Mean age was 65(SEM ±1.7) yrs. Baseline post-bronchodilator FEV1 was 31.6(±1.6)% predicted, TLC 133.5(±4.6)%, RV 215.1(±11.1)% and KCO 60.2(±5.9)% pred. Targeted lobes were LUL (n=8) and RUL (n=3). KCO improved by 10.3(±7.5)% at 1 mth (p=NS), 21.7(±9.6)% at 3 mths (p<0.05) and 39.8(±15.4)% at 12 mths (p<0.05). Ventilation and perfusion of the non-targeted lung increased by 12.8(±5.6)% and 7.9(±2.3)% respectively at 1 mth whilst those of the targeted lung decreased by 11.5(±4.3)% and 28.4(±5.9)% respectively (all p<0.05). At 3 mths and at 12 mths, the changes to ventilation and perfusion were similar to those at 1 mth, though some of the VQ changes were no longer statistically significant. Conclusions: ELVR results in improved KCO for at least 12 mths. This may be explained by the overall improvements in ventilation and perfusion of the non-targeted lung and reduction in ventilation and perfusion to the targeted side with improved VQ matching.