Airway granulation response to lung-implantable medical devices:a concise overview

Increasing numbers of endoscopically implantable devices are implanted in the airways, such as airway stents, one-way valves and coils, to treat both malignant and benign diseases. They significantly improve patient outcomes, but their long-term effectiveness and sustainability is hampered by the reaction of the formation of granulation tissue. Factors including procedural-related tissue injury; micro-organism presence; device-related factors, such as the material, design and sizing in relation to the airway; and patient-related factors, including genetic susceptibility, comorbidities and medication use, might all effect the severity of the tissue response and the subsequent degree of granulation tissue formation. However, research into the underlying mechanism and risk factors is scarce and therefore our knowledge is limited. Joint efforts from the scientific community, both pre-clinical and clinical, are needed to gain a deeper understanding and eventually improve the long-term treatment effectiveness of lung-implantable devices

Safety and Considerations of the Anaesthetic Management during Bronchoscopic Lung Volume Reduction Treatments

Background: Different bronchoscopic lung volume reduction approaches are available for a select group of patients with advanced COPD. General anaesthesia is the recommended method of sedation during these procedures. However, this patient population is at an increased risk of anaesthetic complications, and the best approach to general anaesthesia and mechanical ventilation is unknown.Objectives: The aims of this study were to describe the anaesthetic management techniques used during bronchoscopic lung volume reduction procedures and to investigate the number of anaesthesia-related events.Methods: Data were retrospectively collected from all endobronchial valve and lung volume reduction coil procedures performed between January 2018 and March 2020 in our hospital. Primary outcomes measures were anaesthetic technique including airway management; ventilation mode and settings; and the incidence of anaesthesia-related events, classified as catastrophic, severe, significant, or moderate.Results: 202 procedures were included. One procedure was performed under procedural sedation, 198 (98%) under general anaesthesia with endotracheal intubation, and 3 (1.5%) under general anaesthesia with laryngeal mask airway. Volume-controlled ventilation was used in 64% of the procedures and pressure-controlled in 36%. Patients were ventilated with a median respiration rate of 9.9 (IQR: 9.6-10.6) breaths per minute, mean tidal volume of 5.8 ± 1.4 mL/kg, and median inspiratory to expiratory (I:E) ratio of 1:2.8 (IQR: 1:2.1-1:3.2). No catastrophic anaesthesia-related events were observed. Hypotension was the most observed anaesthesia-related event.Conclusions: Despite the presence of advanced COPD, general anaesthesia and mechanical ventilation are well tolerated by patients undergoing endobronchial valve or lung volume reduction coil treatment. This is presumably strongly linked to the strict selection criteria. Other important considerations are using a low respiratory rate, low tidal volume, and high I:E ratio.</p

Revision Bronchoscopy After Endobronchial Valve Treatment for Emphysema:Indications, Findings and Outcomes

Background: Endobronchial valve (EBV) treatment is an effective treatment for patients with severe emphysema. Revision bronchoscopies after endobronchial valve treatment can be essential to prolong the effect of treatment or address long-term complications. Purpose: To evaluate the indications, endoscopic findings and outcomes of revision bronchoscopies and investigate if any predictors for granulation tissue formation, after EBV treatment, can be identified. Patients and Methods: Patients who underwent EBV treatment between 2016 and 2019 in our hospital, as routine care, were included. If a patient underwent a revision bronchoscopy, data regarding revision bronchoscopies, including indication, finding, intervention and pulmonary function testing (PFT) after revision bronchoscopy were analysed. Results: One hundred seventy-nine patients were included of which 41% required at least one revision bronchoscopy. In 43% of the revision bronchoscopy patients, the indication was loss of initial treatment effect. In 53% of the revision bronchoscopy patients, granulation tissue was found to be the underlying cause. Valve replacement(s) were performed in 51% of the revision bronchoscopy cases. Permanent valve removal was required in 13% of all patients. Overall, revision bronchoscopies led to improvements in PFT outcomes for patients experiencing no or a loss of initial treatment effect. No clinically relevant predictors for granulation tissue formation were identified. Conclusion: Performing a revision bronchoscopy after EBV treatment is a useful procedure leading to an improved treatment effect in most patients. Granulation tissue formation, causing valve dysfunction, is the most common cause of longer term problems

Bronchoscopic Lung Volume Reduction Coil Treatment for Severe Emphysema:A Systematic Review and Meta-Analysis of Individual Participant Data

BACKGROUND: Lung volume reduction coil (LVR-coil) treatment provides a minimally invasive treatment option for severe emphysema patients which has been studied in multiple clinical trials. OBJECTIVES: The aim of the study was to assess the effect of LVR-coil treatment on pulmonary function, quality of life, and exercise capacity using individual participant data. METHOD: PubMed, Web of Science, and EMBASE were searched until May 17, 2021. Prospective single-arm and randomized controlled trials that evaluated the effect of LVR-coil treatment on forced expiratory volume in 1 s (FEV1), residual volume (RV), St. George Respiratory Questionnaire (SGRQ) total score, and/or 6-min walk distance (6MWD) and were registered in an official clinical trial database were eligible for inclusion. Individual patient data were requested, and a linear mixed effects model was used to calculate overall treatment effects. RESULTS: Eight trials were included in the final analysis, representing 680 individual patients. LVR-coil treatment resulted in a significant improvement in FEV1 at 3- (0.09 L [95% confidence interval (95% CI): 0.06-0.12]) and 6-month follow-up (0.07 L [95% CI: 0.03-0.10]), a significant reduction in RV at 3- (-0.45L [95% CI: -0.62 to -0.28]), 6- (-0.33L [95% CI: -0.52 to -0.14]), and 12-month follow-up (-0.36L [95% CI: -0.64 to -0.08]), a significant reduction in SGRQ total score at 3- (-12.3 points [95% CI: -15.8 to -8.8]), 6- (-10.1 points [95% CI: -12.8 to -7.3]), and 12-month follow-up (-9.8 points [95% CI: -15.0 to -4.7]) and a significant increase in 6MWD at 3-month follow-up (38 m [95% CI: 18-58]). CONCLUSIONS: LVR-coil treatment in emphysema patients results in sustained improvements in pulmonary function and quality of life and shorter lived improvements in exercise capacity. Since the owner of this LVR-coil has decided to stop the production and newer generations LVR-coils are currently being developed, these results can act as a reference for future studies and clinical guidance

The impact of emphysema heterogeneity on treatment response after endobronchial valve treatment

Background Lung volume reduction with endobronchial valves can significantly improve functional outcomes in patients with advanced emphysema. The extent and spatial distribution pattern of emphysema shows considerable heterogeneity, which might affect response to endobronchial valve treatment. Our aim was to study the effect of emphysema heterogeneity on change in clinical outcomes after endobronchial valve treatment. Methods Data were collected from our national registry of patients who received endobronchial valve treatment between 2016 and 2020. We assessed the association between the heterogeneity index, absolute difference in destruction between the target and ipsilateral lobe, and relative change in forced expiratory volume in 1 s (FEV1), residual volume (RV), St George's Respiratory Questionnaire (SGRQ) and 6-min walk distance (6MWD) at 6-week, 6-month and 12-month follow-up. Results In total, 236 patients were included. Heterogeneity index was significantly associated with improvements in FEV1, RV and 6MWD at all follow-up visits, and in SGRQ at the 6- and 12-month follow-up visits. The majority of patients, independent of heterogeneity index, showed clinically meaningful improvements based on minimal important difference thresholds. Conclusions Heterogeneity index influences the degree of clinical improvement after endobronchial valve treatment where in general a more heterogeneous distribution translates to larger improvements. However, patients with a more homogeneous distribution also showed clinically meaningful improvements. Therefore, we believe emphysema heterogeneity alone should not be used as a decisive patient selection criterion, but should be weighed in the context of all other relevant patient and target lobe characteristics when deciding on a patient's treatment eligibility

Endobronchial Valve Treatment Does Not Cause Significant Nickel Deposition in Lung Tissue

Bronchoscopic lung volume reduction using endobronchial valves (EBVs) is a treatment option for patients with severe emphysema. These EBVs are made out of a nitinol mesh covered by a silicone layer. Nitinol is an alloy of nickel and titanium and is commonly used in implantable medical devices because of its biocompatibility and memory-shape properties. However, there are some concerns that nickel ions can be released from nitinol-containing devices which might cause adverse health effects, especially in patients with a known nickel hypersensitivity. In vitro, it was found that EBV release significant amounts of nickel in the first hours. Our aim was to assess the nickel concentration in lung tissue from a patient who previously underwent EBV treatment but, due to treatment failure, underwent lung volume reduction surgery and to compare this to a reference sample. We found no significant difference in the median nickel concentration between the EBV-treated patient and the non-EBV-treated patient (0.270 vs. 0.328 μg/g, respectively, p = 0.693) and these concentrations were also comparable to previously published nickel concentrations in human lung tissue samples not having any medically implanted devices in the lung. Our results suggest that there is no significant long-term nickel deposition in lung tissue after EBV treatment

Response to endobronchial valve treatment: it's all about the target lobe

Background Bronchoscopic lung volume reduction using endobronchial valves (EBV) has been shown to be beneficial for severe emphysema patients. The most important predictor of treatment response is absence of collateral ventilation between the treatment target and ipsilateral lobe. However, there are still a substantial number of nonresponders and it would be useful to improve the pre-treatment identification of responders. Presumably, predictors of response will be multifactorial, and therefore our aim was to explore whether we can identify response groups using a cluster analysis. Methods At baseline and 1 year follow-up, pulmonary function, exercise capacity and quality of life were measured. A quantitative chest computed tomography scan analysis was performed at baseline and 2–6 months follow-up. The cluster analysis was performed using a hierarchical agglomerative method. Results In total, 428 patients (69% female, mean±sd age 61±8 years, forced expiratory volume in 1 s 27±8% predicted, residual volume 254±50% pred) were included in our analysis. Three clusters were generated: one nonresponder cluster and two responder clusters. Despite solid technical procedures, the nonresponder cluster had significantly less clinical response after treatment compared to the other clusters. The nonresponder cluster was characterised by significantly less emphysematous destruction, less air trapping and a higher perfusion of the target lobe, and a more homogeneous distribution of emphysema and perfusion between the target and ipsilateral lobe. Conclusions We found that target lobe characteristics are the discriminators between responders and nonresponders, which underlines the importance of visual and quantitative assessment of the potential treatment target lobe when selecting patients for EBV treatment

Improved exercise capacity results in a survival benefit after endobronchial valve treatment

Background: Bronchoscopic lung volume reduction using endobronchial valves (EBV) is a treatment option for selected patients with advanced emphysema. The treatment significantly improves pulmonary function, exercise capacity, quality of life, and potentially improves survival. Our main aim was to assess whether treatment response significantly influences survival time after EBV treatment. Methods: We evaluated treatment response at 6-week and 1-year follow-up of all patients treated with EBVs between 2008 and 2020. Survival status was retrieved on December 1, 2021. Patients were defined as responders or non-responders based on known minimal important differences for FEV1, residual volume (RV), RV/Total Lung Capacity (TLC) ratio, 6-min walk distance (6MWD), St. George's Respiratory Questionnaire (SGRQ), target lobe volume reduction (TLVR), and complete lobar atelectasis. Uni- and multivariate cox regression models were used to evaluate the effect of response on survival time. Results: A total of 428 patients were included. EBV treatment resulted in significant improvements in pulmonary function, exercise capacity and quality of life. Median survival was 8.2 years after treatment. SGRQ and 6MWD response were independent predictors for improved survival time (Hazard Ratio (HR) 0.50 [0.28–0.89], p =.02 and HR 0.54 [0.30–0.94], p =.03, respectively). The presence of a complete lobar atelectasis did not significantly affect survival, neither did pulmonary function improvements. Conclusions: Our results suggest that improvement in exercise capacity and quality of life after EBV treatment are associated with a survival benefit, independent of improvements in pulmonary function, reduction in target lobe volume or the presence of complete lobar atelectasis

Supplementary Material for: Bronchoscopic Lung Volume Reduction Coil Treatment for Severe Emphysema: A Systematic Review and Meta-Analysis of Individual Participant Data

Background: Lung volume reduction coil (LVR-coil) treatment provides a minimally invasive treatment option for severe emphysema patients which has been studied in multiple clinical trials. Objectives: The aim of the study was to assess the effect of LVR-coil treatment on pulmonary function, quality of life, and exercise capacity using individual participant data. Method: PubMed, Web of Science, and EMBASE were searched until May 17, 2021. Prospective single-arm and randomized controlled trials that evaluated the effect of LVR-coil treatment on forced expiratory volume in 1 s (FEV1), residual volume (RV), St. George Respiratory Questionnaire (SGRQ) total score, and/or 6-min walk distance (6MWD) and were registered in an official clinical trial database were eligible for inclusion. Individual patient data were requested, and a linear mixed effects model was used to calculate overall treatment effects. Results: Eight trials were included in the final analysis, representing 680 individual patients. LVR-coil treatment resulted in a significant improvement in FEV1 at 3- (0.09 L [95% confidence interval (95% CI): 0.06–0.12]) and 6-month follow-up (0.07 L [95% CI: 0.03–0.10]), a significant reduction in RV at 3- (−0.45L [95% CI: −0.62 to −0.28]), 6- (−0.33L [95% CI: −0.52 to −0.14]), and 12-month follow-up (−0.36L [95% CI: −0.64 to −0.08]), a significant reduction in SGRQ total score at 3- (−12.3 points [95% CI: −15.8 to −8.8]), 6- (−10.1 points [95% CI: −12.8 to −7.3]), and 12-month follow-up (−9.8 points [95% CI: −15.0 to −4.7]) and a significant increase in 6MWD at 3-month follow-up (38 m [95% CI: 18–58]). Conclusions: LVR-coil treatment in emphysema patients results in sustained improvements in pulmonary function and quality of life and shorter lived improvements in exercise capacity. Since the owner of this LVR-coil has decided to stop the production and newer generations LVR-coils are currently being developed, these results can act as a reference for future studies and clinical guidance