Clinical Impact of Compensatory Hyperinflation of the Nontreated Adjacent Lobe After Bronchoscopic Lung Volume Reduction with Valves

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 Reduction Ratio (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.