Airway Stents from Now to the Future: A Narrative Review.

Airway stent insertion is important for patients with airway stenosis. Currently, the most widely used airway stents in clinical procedures are silicone and metallic stents, which offer patients effective treatment. However, these stents composed of permanent materials need to be removed, subjecting patients to invasive manipulation once more. As a result, there is a growing demand for biodegradable airway stents. Biodegradable materials for airway stents are now available in two types: biodegradable polymers and biodegradable alloys. Polymers that include poly (l-lactic acid), poly (D, l-lactide-co-glycolide), polycaprolactone, and polydioxanone are the ultimate metabolites which are generally carbon dioxide and water. Magnesium alloys are the most often utilized metal biodegradable materials for airway stents. The stent's mechanical properties and rate of degradation vary as a result of the different materials, cutting techniques, and structural configurations. We summarized the information above from recent studies on biodegradable airway stents conducted in both animals and humans. There is great potential for clinical applications for biodegradable airway stents. They avoid damage to the trachea during removal and reduce complications to some extent. However, several significant technical difficulties slow down the development of biodegradable airway stents. The efficacy and safety of different biodegradable airway stents still need to be investigated and proved.

Effectiveness of endobronchial coil treatment for lung volume reduction in patients with severe heterogeneous emphysema and bilateral incomplete fissures: a six-month follow-up.

BACKGROUND: Treatment with lung volume reduction coils (LVRC) may be effective in patients with severe heterogeneous emphysema and incomplete fissures. OBJECTIVE: We hypothesized that LVRC placement improves pulmonary function, exercise tolerance and quality of life in these patients. METHODS: Twenty-six patients with chronic obstructive pulmonary disease (COPD), 13 males and 13 females, aged 66 ± 8 years with heterogeneous emphysema and incomplete fissures were included in this retrospective analysis. The coils were implanted unilaterally in the upper or lower lobe. Patients were followed up at 30, 90 and 180 days after treatment and changes in pulmonary function test and 6-minute-walk-test (6MWT) values as well as scores for the modified Medical Research Council (mMRC) dyspnea scale and the St. George's Respiratory Questionnaire (SGRQ) were recorded. RESULTS: FEV1 improved significantly at 90 days and tended to decrease at the 180-day follow-up (0.67 ± 0.17 vs. 0.78 ± 0.25 vs. 0.73 ± 0.21 liters, respectively, p < 0.001). The 6MWT score had improved significantly at 90 days and had tended to decrease at the 180-day follow-up (216 ± 107 vs. 262 ± 97 vs. 262 ± 112 m, respectively, p = 0.001). SGRQ was significantly improved at 90 days. Multivariate analysis showed that worse 6MWT performance at baseline was independently associated with a greater improvement in 6MWT at the 90-day follow-up. The total complication rate was 54% (n = 14) and included light hemorrhage in 6 patients, COPD exacerbation in 6, pneumothorax in 1 and both COPD exacerbation and pneumothorax in 1 patient. CONCLUSIONS: This is the first study to show that LVRC in patients with heterogeneous emphysema and incomplete fissures improves exercise capacity, quality of life and lung function up to 90 days after the intervention. Further studies are needed to assess the long-term effects of LVRC in these patients.

Effect of fissure integrity on lung volume reduction using a polymer sealant in advanced emphysema.

RATIONALE: Interlobar fissure integrity has previously correlated with responsiveness to endobronchial lung volume reduction therapy in patients with advanced emphysema. OBJECTIVE: This report summarises the effect of interlobar fissure integrity on responses to treatment with a novel endoscopic tissue sealant (AeriSeal emphysematous lung sealant (ELS)) that collapses hyperinflated lung. METHODS: Fissure status, lung volumes, tissue density and disease heterogeneity were assessed radiographically in 28 patients (age 63.4±6.1 years, 20 men) with advanced upper lobe predominant emphysema (density=888.0±18.2 HU; upper lobe tissue density < -950 = 2.62±1.74). Post-treatment changes in lobar volume, pulmonary function, exercise capacity, symptoms and quality of life were compared in patients with complete fissures (CFs) and incomplete fissures (ICFs). RESULTS: ELS therapy reduced lung volumes independent of interlobar fissure integrity. In patients with upper lobe emphysema and CFs, lobar volume reduction was 214±127 ml/treatment compared with 256±175 ml/treatment in those with ICFs (p=0.453). Reductions in gas trapping and improvements in spirometry, functional capacity and quality of life were similar in patients with CFs and ICFs. Stepwise multiple regression modelling confirmed that fissure integrity did not contribute to post-treatment changes in forced expiratory volume in 1 s, residual volume/total lung capacity ratio or lobar volume measured by CT analysis. CONCLUSIONS: Interlobar fissure integrity, an important determinant of responsiveness to endobronchial lung volume reduction therapy in prior studies, had minimal impact on physiological and functional responses to ELS therapy in patients with severe upper lobe predominant emphysema. CLINICAL TRIAL REGISTRATION NUMBER: Registration numbers for trials contributing to datasets in this report: NCT00884962, NCT01051258 and NCT01181466.

Airway stabilization with silicone stents for treating adult tracheobronchomalacia: a prospective observational study.

RATIONALE: It is postulated that in patients with severe tracheobronchomalacia (TBM), airway stabilization with stents may relieve symptoms. OBJECTIVES: To evaluate the effect of silicone stents (tracheal, mainstem bronchus, or both) on symptoms, quality of life, lung function, and exercise capacity in these patients. METHODS: A prospective observational study in which baseline measurements were compared to those obtained 10 to 14 days after stent placement. MEASUREMENTS AND MAIN RESULTS: Of 75 referred patients, 58 had severe disease and underwent therapeutic rigid bronchoscopy with stent placement. Mean age was 69 years (range, 39 to 91 years), 34 were men, 33 had COPD, and 13 had asthma. Almost all patients (n = 57) had dyspnea as a sole symptom or in combination with cough and recurrent infections; four patients required mechanical ventilation for respiratory failure. In 45 of 58 patients, there was reported symptomatic improvement; quality of life scores improved in 19 of 27 patients (p = 0.002); dyspnea scores improved in 22 of 24 patients (p = 0.001); functional status scores improved in 18 of 26 patients (p = 0.002); and mean exercise capacity improved from baseline, although not significantly. The 49 complications included mainly 21 partial stent obstructions, 14 infections, and 10 stent migrations. Most patients with concomitant COPD also improved on most measures. CONCLUSIONS: In the short term, airway stabilization with silicone stents in patients with severe TBM can improve respiratory symptoms, quality of life, and functional status. Coexisting COPD is not an absolute contraindication to a stenting trial in this population. Stenting is associated with a high number of short-term and long-term but generally reversible complications.