Background: Bronchoscopic lung volume reduction (BLVR) via valve implantation can be achieved by targeting severely hyperinflated and emphysematously destructed lung areas in patients with chronic obstructive lung disease. Lack of collateral ventilation (CV) is important for good outcomes with BLVR. CV can be measured using the catheter-based Chartis system. The aim of this study was to evaluate the correlation between total exhaled volume drained from the target lobe measured by Chartis and clinical outcomes after BLVR in CV-negative patients. Methods: From January 2016 to March 2019, 60 patients were included in this retrospective single-center analysis. Drained volume (TVol) measured by Chartis was recorded and compared with lung function and physical performance parameters. Outcome variables included the percentage change in lung function [forced expiratory volume in 1 s (FEV1), residual volume (RV), and inspiratory vital capacity (IVC)]. Secondary outcomes were the degree of target lobe volume reduction (TLVR), change in 6-min walk distance (6MWD), and change in chronic obstructive pulmonary disease (COPD) assessment test (CAT) score. Results: Drained volume correlated significantly with post-BLVR change in FEV1 ( r = 0.663), IVC ( r = 0.611), RV ( r = −0.368), and TLVR ( r = 0.635) (all p < 0.05). In a priori-defined patient subgroups based on drained volume [<100 ml ( n = 19), 100−400 ml ( n = 33), and >400 ml ( n = 8)]; mean changes in FEV1 were 2.6%, 17.4%, and 51.3%; in RV were −3.9%, −10.6%, and −23.8%; in IVC were −4.0%, 10.6%, and 62.4%; and in TLVR were 525 ml (39%), 1375 ml (73%) and 1760 ml (100%), respectively. There were no significant correlations between absolute and percentage changes in 6MWD and the CAT score. Lung volume reduction was diagnosed in 32 (53%) cases. Conclusion: Drained volume measured by the Chartis system correlated with functional improvement in CV-negative patients undergoing BLVR. The reviews of this paper are available via the supplemental material section.

Background Bronchoscopic lung volume reduction (BLVR) with endobronchial valves (EBV) can be a successful treatment for end-stage emphysema patients. The reduction of hyperinflation enhances ventilatory mechanics and diaphragm function. Understanding predictors for treatment success is crucial for further improvements. Purpose The aim of this study was to assess the effect of the target lobe volume reduction (TLVR) in relation to the ipsilateral lung volume reduction (ILVR), affected by the compensatory expansion of the adjacent lobe, on the outcome after BLVR with valves. Patients and Methods The volumetric relationship of ILVR% to TLVR%, addressed as R eduction R atio ( R ), was recorded in 82 patients and compared to changes in lung function, physical performance and quality of life. A small value for R implies a relatively low volume reduction of the ipsilateral lung (ILVR) compared to the volume reduction of the target lobe (TLVR). Additionally, the minimal clinically important difference (MCID) for R was calculated. Results Patients with a smaller Reduction Ratio ( R <0.2) showed minor improvements at the 3 months follow-up compared to patients with R ≥0.2 (mean changes of 39 mL (5.8%), –395 mL (–4.9%) and 96 mL (7.1%) versus 231 mL (33%), –1235 mL (–20%) and 425 mL (29%) in the forced expiratory volume in 1s (FEV 1 ), residual volume (RV) and inspiratory vital capacity (IVC), respectively, and –3 m and 0 points versus 20.4 m and –3.4 points in the 6-minute-walking-distance (6MWD) and COPD assessment test (CAT) score respectively). With a combined value of 0.185, a MCID for R was calculated with established anchors (FEV 1 , RV, and 6MWD) for emphysema patients. Conclusion Extensive compensatory hyperinflation of the adjacent non-treated lobe after BLVR results in decreased ILVR, which is responsible for a lack of meaningful improvements in ventilatory mechanics and clinical outcome, despite technically successful lobe volume reduction.

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