Early Trends in Bronchoscopic Lung Volume Reduction: A Systematic Review and Meta-analysis of Efficacy Parameters

Bronchoscopic Lung Volume Reduction: A Review

Bronchoscopic lung volume reduction (BLVR) is an established treatment modality for the management of advanced chronic obstructive pulmonary disease complicated by severe emphysema and hyperinflation refractory to other therapies. BLVR aims to reduce hyperinflation and residual volume, thereby improving pulmonary function, symptom control, and quality of life. Multiple distinct devices and technologies, including endobronchial coils, thermal vapor ablation, bio-lung volume reduction, and airway bypass stenting, have been developed to achieve lung volume reduction with varying degrees of accessibility and evidence. The most promising BLVR treatment modality to date has been the placement of one-way endobronchial valves (EBVs), with more than 25,000 cases performed worldwide. Identifying symptomatic patients who would benefit from BLVR is challenging and can be time and resource intensive, and candidacy may be limited by physiologic parameters. Additional new technologies may be able to improve the identification and evaluation of candidates as well as increase the portion of evaluated patients who ultimately qualify for BLVR. In this review, we aim to provide historical context to BLVR, summarize the available evidence regarding its use, discuss potential complications, and provide readers with a clear guide to patient selection and referral for BLVR, with a focus on EBV placement. In addition, we will highlight potential future directions for the field.

Bronchoscopic Lung Volume Reduction

Since the publication of the National Emphysema Treatment Trial study, lung volume reduction (LVR) has been considered a therapeutic alternative for patients with advanced obstructive lung disease. The high complication rate of surgical LVR has led to the development of bronchoscopic LVR (BLVR). Of the currently available BLVR alternatives, coils and unidirectional endobronchial valves lead the list. The choice of each device depends on emphysema characteristics and presence of collateral ventilation. Evaluation of these patients at centers with expertise in interventional pulmonology and management of BLVR is strongly recommended.

Efficacy and Safety of Stent, Valves, Vapour ablation, Coils and Sealant Therapies in Advanced Emphysema: A Meta-Analysis

Bronchoscopic lung volume reduction (BLVR) methods have emerged as a new treatment option for patients with severe emphysema. Endobronchial valves and coils have been extensively studied. This review assesses efficacy, safety, and cost effectiveness of the BLVR procedures (stent, valves, vapor ablation, endobronchial coils, lung sealant) in patients with severe emphysema. Databases were searched until October 2016, and randomized controlled trials (RCTs) comparing available BLVR procedures to standard medical care or sham bronchoscopy were included. Random effect model and generic inverse variance approach were used for meta-analysis. Out of 381 identified records, 16 RCTs were included. As compared to recommended medical care or sham bronchoscopy, the BLVR procedures are more effective in improving quality of life [SGRQ score (WMD=-6.38; -9.12 to -3.65)] and 6MWT (WMD=24.21; 9.68-38.74) and percentage FEV₁ (WMD=10.48; 7.07-13.89). Increased risk of serious adverse events (RR=2.18; 1.63-2.93), specifically for chronic pulmonary obstructive disease exacerbations and lower respiratory tract infection combined (RR=1.37; 1.07-1.75), were observed with bronchoscopic interventions, while there was no difference in number of deaths (RR=1.25; 0.79-1.99) and respiratory failure (RR=1.13; 0.57-2.21). The BLVR procedures, especially endobronchial coils, were found to be effective in the management of patients with severe emphysema irrespective of collateral ventilation. However, characterization of patients who would be most benefited from these procedures is required, and effectiveness of these procedures in long run needs to be established.

Efficacy and safety of bronchoscopic lung volume reduction therapy in patients with severe emphysema: a meta-analysis of randomized controlled trials

BACKGROUND

Increasing randomized controlled trials (RCTs) indicate that bronchoscopic lung volume reduction (BLVR) is effective for severe emphysema. In this meta-analysis, we investigated the efficacy and safety of BLVR in patients with severe emphysema.

METHODS

PubMed, Embase and the Cochrane Library and reference lists of related articles were searched, and RCTs that evaluated BLVR therapy VS conventional therapy were included. Meta-analysis was performed only when included RCTs ≥ 2 trials.

RESULTS

In total, 3 RCTs for endobronchial coils, 6 RCTs for endobronchial valves (EBV) and 2 RCTs for intrabronchial valves (IBV) were included. Compared with conventional therapy, endobronchial coils showed better response in minimal clinically important difference (MCID) for forced expiratory volume in 1s (FEV1) (RR = 2.37, 95% CI = 1.61 - 3.48, p < 0.0001), for 6-min walk test (6MWT) (RR = 2.05, 95% CI = 1.18 - 3.53, p = 0.01), and for St. George's Respiratory Questionnaire (SGRQ) (RR = 2.32, 95% CI = 1.77 - 3.03, p < 0.00001). EBV therapy also reached clinically significant improvement in FEV1 (RR = 2.96, 95% CI = 1.49 - 5.87, p = 0.002), in 6MWT (RR = 2.90, 95% CI = 1.24 - 6.79, p = 0.01), and in SGRQ (RR = 1.53, 95% CI = 1.22 - 1.92, p = 0.0002). Both coils and EBV treatment achieved statistically significant absolute change in FEV1, 6MWT, and SGRQ from baseline, also accompanied by serious adverse effects. Furthermore, subgroup analysis showed there was no difference between homogeneous and heterogeneous emphysema in coils group. However, IBV group failed to show superior to conventional group.

CONCLUSIONS

Current meta-analysis indicates that coils or EBV treatment could significantly improve pulmonary function, exercise capacity, and quality of life compared with conventional therapy. Coils treatment could be applied in homogeneous emphysema, but further trials are needed.