Chronic obstructive pulmonary disease (COPD) is a common and prevalent respiratory disease with high prevalence and mortality rates, especially in patients with severe COPD, where lung function is significantly reduced, seriously affecting their workforce and quality of life, and it is difficult to achieve the desired outcome with pharmacological treatment. In recent years, the minimally invasive technique of transbronchoscopic lung volume reduction (BLVR) has become a hot research topic, which involves placing a one-way valve plug (EBV, also known as an airway overlay stent) into the corresponding target lobe or lung segment bronchus of severe emphysema through bronchoscopy, causing it to atrophy while the volume of functional lung tissue increases relatively, thereby improving lung function. The study of BLVR is based on the theory of surgical lung volume reduction surgery (LVRS) in the treatment of emphysema: by removing the overinflated and non-functional part of the lung tissue, the elastic retraction force of the lung is restored, the adjacent relatively normal lung tissue is expanded, the airway expansion is maintained during expiration, and the airway resistance is reduced; the diseased lung tissue is removed, the lung volume is reduced, and the overly flattened diaphragm is changed. It also improves pulmonary compliance by removing emphysematous tissue, improving ventilation, reducing ineffective ventilation, and improving ventilation/blood flow ratio; relieving the compression of blood vessels by diseased tissue, lowering total vascular resistance and pulmonary artery pressure, and improving right heart function. Through the above actions to correct a series of pathophysiological changes caused by lung overinflation, the purpose of improving respiratory function is ultimately achieved. However, BLVR has the potential to be superior to LVRS in the following aspects: less invasive, less costly, shorter postoperative recovery time, fewer complications, and the ability to adjust the position of the placed valve or remove it. Based on these advantages, BLVR has the potential to broaden the indications for LVRS, and patients with severe emphysema who cannot tolerate surgery may potentially undergo BLVR. Methods of BLVR and its mechanisms The ideal device for BLVR should have the following characteristics: 1) effective and sustained lung decompensation can be obtained; 2) reproducible results; 3) the device is suitable for patient placement through bronchoscopy under local anesthesia; 4) the device Easy to remove using the bronchoscope; 5. The device is constructed so that it does not move within the airway; 6. It allows bronchial secretions to be expelled; 7. There are no lung infections due to sputum retention. The more experimental research and clinical method of BLVR is to place a unidirectional valve in the target area, and there are two main types: spiral umbrella stent (spiral intra-bronchial valve, IBV) and Emphasys unidirectional valve stent (emphasys endobronchial valve, EBV). The spiral umbrella stent is a unidirectional valve that can be placed into the bronchus via bronchoscopy. It is composed of a basic framework of nickel-titanium alloy with five anchors at the distal end and a radiolucent stent at the proximal end, which is covered by a polymer compound to form an umbrella structure. EBV is an endobronchial valve stent developed by Emphasys, Inc. that has been tested in animal and initial clinical trials and has achieved good clinical results. Compared to bioprotein gel plugging and IBV, EBV allows gas and secretions to escape from the target area and prevents gas from entering the target lung, thus easily occluding the non-functional emphysema site and achieving volume reduction, and secretions can be easily drained and drained without causing infection. Unidirectional valve method is to implant a unidirectional valve into the target bronchus through bronchoscopy, so that the bronchus is ventilated in one direction, i.e., allowing the exhalation of gas in the lung tissue and preventing the inhalation of gas, with the aim of causing the lung tissue in the emphysema area to become non-hypertensive. The smaller size of the atelectasis reduces the volume of the lung and the dead space for ventilation on the one hand, and reduces the compression of relatively normal lung tissue on the other hand, resulting in an improved ventilation/blood flow ratio. The one-way valve also allows secretions to drain from obstructed lung tissue, reducing the likelihood of infection and obstructive pneumonia.The key to post-exercise limitation of ventilation in COPD patients is dynamic lung hyperinflation, where expiratory flow rate limitation leads to an increase in end-expiratory lung volume during exercise, subsequently limiting the achievable tidal volume.Hopkinson et al. suggested that one-way valve placement reduced dynamic lung hyperinflation, with no reduction in static lung volume. Although there was no reduction in static lung volume, patients showed clinical efficacy by improving both symptoms and exercise tolerance, confirming that BLVR improved exercise capacity in patients due to reduced dynamic lung hyperinflation. Status of clinical application of BLVR abroad Snell et al. placed a total of 66 valve devices within each segment and subsegment of the unilateral upper lobe of the lung in 10 patients with severe emphysema, with 4 to 11 valve devices implanted in each patient, and the average operation time was 1 hour and 55 minutes (±24.5 minutes). Changes in preoperative and postoperative X-rays, nuclear scans, arterial blood gas analysis, pulmonary function, carbon monoxide diffusion capacity (DLCO), and 6-minute walk test were observed. Patients’ FEV1, FVC, RV, TLC and 6-minute walk test were not significantly different after 30 days, but DLCO improved significantly from 7.47 ± 2 ml/min/mmHg to 8.26 ± 2.6 ml/min/mmHg, with a small amount of pulmonary distension insufficiency seen in the target area.Yim et al. placed a total of 87 live valves in 20 patients under rigid bronchoscopy. involving the bronchi of the lung segments within the right upper lobe, right lower lobe, left upper lobe, and left lower lobe, of which 8 patients were placed bilaterally. There was a significant improvement in FEV1, FVC, FVC%, and 6-minute walk test at 90 days postoperatively, as well as a significant improvement in the Quality of Life Survey Scale and the Shortness of Breath Rating Scale at 30 and 90 days postoperatively compared with the preoperative period. 17 patients underwent CT evaluation of the target areas, and at 90 days postoperatively, there was no pulmonary atrophy in 13 target areas, less than 25% atrophy in 6 target areas, and greater than 75% atrophy in only 4 target areas. Wan and Toma et al. in Hong Kong, China, reviewed a multicenter population-based study of 98 patients with end-stage emphysema who underwent BLVR with EBV. This included a total of 98 patients with end-stage emphysema from 9 centers in 7 countries. The inclusion and exclusion criteria were the same for all patients, but there were no uniform criteria for the target area and number of EBVs placed and the anesthetic modality for bronchoscopic manipulation. A total of 396 EBV one-way valves were placed, with placement predominantly in the unilateral lobe (49.0%) and mostly in the right upper lobe (39.8%). Follow-up after 90 days of EBV placement showed the greatest improvement in patients with unilateral whole lobe decompensation, while improvement was more pronounced in those with FEV1 <30% and RV >22.5%. During the 90-day observation, eight patients developed serious complications, including one death. The results of the study showed that the application of EBV for BLRV significantly improved lung function and exercise tolerance. Recently, de Oliveira reported the results of 24-month clinical observations in patients with EBV placement. The major complication of first-generation EBV after 24 months of placement was peripheral mucosal granuloma, while EBV functioned normally. There was no statistical difference in the improvement of pulmonary function and BODE index at 12 and 24 months after EBV placement, however, 1/5 and 3/5 of the 5 patients followed up to 24 months maintained an improvement in FEV1 and FVC of >12% or ≥150 mL. The number of patients in this study is small and further studies are needed to determine the long-term efficacy of the study. The number of patients in this study is small, and long-term outcomes need to be further investigated, and large, prospective, multicenter, randomized controlled studies are needed to confirm which patients are more suitable for EBV treatment. The common complications include restrictive pneumothorax, the mechanism of which remains unclear and may be related to the atrophy of the lung tissue in the target area before the rest of the lung tissue can compensate for expansion to form a restrictive pneumothorax; other complications include acute exacerbation of COPD, lung infection, sputum retention, and bronchospasm. Current status of domestic BLVR research and application In recent years, several scholars in China have conducted experimental animal studies on BLVR. Dong Yonghua et al. used a mixture of anhydrous ethanol and iodine oil to inject into the target area and blocked the proximal bronchi with bone cement, and achieved good lung decongestion effect. Wang Wansheng et al. used pingyangmycin iodine oil emulsion combined with proximal bronchial bone cement sealing for pulmonary decongestion. Zhang Qian et al. injected bioprotein gel into a rabbit model of New Zealand emphysema for lung decongestion and achieved recent efficacy. Shen Ning et al. reported for the first time the application of a unidirectional valve made of silicone as a bronchial embolus for BLVR in dogs, and CT and histopathological examination showed that the placement of the valve in the bronchus could lead to partial atrophy of the lung tissue and achieve pulmonary decongestion. The one-way valve plug (EBV, also known as airway lamina stent, is an airway lamina stent developed and produced by Beijing Puyi Shengji Technology Co., Ltd.) recently adopted by our hospital has achieved satisfactory results in the clinical treatment of COPD patients with indications. The one-way valve plug is made of medical stainless steel, nickel-titanium alloy wire and polyurethane material, and the combination of airway stent delivery system sheath, loader and transmission rod. The unique design is not only easy for doctors to operate safely but also can achieve the purpose of treatment. The product has applied for the patent of invention in 2007, and passed the product registration test in 2008 in the supervision and inspection institution designated by the State Food and Drug Administration, and the indicators meet the requirements and pass the test. The product has good physical and mechanical properties, chemical stability, biocompatibility and safety. The unique design is not only easy for doctors to operate safely but also can achieve the purpose of treatment.