Fiberoptic bronchoscopy plays an important role in the diagnosis and differential diagnosis of lung diseases. However, in clinical work, there are a significant number of patients with lesions outside the mediastinum or tracheal cavity, which prevent conventional bronchoscopy from reaching the lesions and therefore cannot provide the biopsy and brush-off specimens needed for clinical diagnosis. For this reason, ultrasound tracheoscopy was born from clinical needs, and this technology is a cutting-edge technology in the international and domestic arenas. Our hospital is one of the first units in China to carry out this technology, and the number of ultrasound bronchoscopy cases has reached more than 1000, which is the first-class in China in terms of safety, diagnosis rate and number of cases. The principle of ultrasonic bronchoscopy: Combining bronchoscopy and ultrasound probe, the ultrasound probe is installed at the front of the bronchoscope to directly observe the lesions under the mucosa of the trachea and bronchi, the extra-tracheal lesions and the enlarged lymph nodes outside the trachea. It is a new technique of tracheoscopic biopsy with high safety, high diagnostic rate, high repeatability and very low surgical trauma. Trans-ultrasound bronchoscopic needle aspiration biopsy (EBUS-TBNA) can obtain mediastinal lymph that is not available with conventional bronchoscopy. The biopsy is performed directly under endotracheal ultrasound guidance, with accurate site, satisfactory sampling, few complications, and minimal trauma. Clinical application of ultrasonic bronchoscopy (EBUS) in lung cancer diagnosis and treatment Current situation of lung cancer diagnosis: 75% of lung cancer patients are clinically diagnosed as having advanced tumor, and many patients have no obvious symptoms at the initial stage. Some patients develop lung shadows, severe cough and even cough up blood. One examination can take several months, which often delays the disease. Many examinations need to remove samples from the body under general anesthesia to complete, which is risky, and the examination procedure can also cause wounds to the patient and have a high misdiagnosis rate. Mediastinal lymph nodes: Mediastinal lymph node enlargement is often a diagnostic challenge for lung oncologists. 28% specificity, 75% sensitivity, 51% accuracy for CT; 100%, 89%, 94% for EBUS. In the past, the diagnosis of such diseases was usually made by transbronchial lymph node biopsy or mediastinoscopy under bronchoscopy, but these two modalities suffer from poor accuracy, unsatisfactory sampling, high risk, trauma, and long hospital stay. The features of ultrasound tracheoscopy: it can show the intraluminal and extraluminal structures through dual channels, and it can also observe and examine the blood flow, submucosal lesions, evaluate the depth of tumor infiltration in the trachea, and whether it can be treated intraluminally, as well as guide the biopsy of perihilar lung lesions. EBUS-guided lymph node biopsy (EBUS-TBNA) can observe the size of lesions and the extent of lymph node invasion, and provide more accurate information for It can provide a more accurate basis for the staging of lung cancer and guide the selection of the most correct treatment plan. Indications for ultrasound bronchoscopy: u submucosal lesions in the trachea and bronchi (to understand the extent of tumor spread in the submucosa and the distance from the bulge, to predict the surgical margins and avoid incomplete surgical resection); u tracheal and bronchial stenosis; u normal surface mucosa but suspected wall or extra-tubular infiltrative disease (to assess the depth of tumor tracheobronchial wall infiltration); u intradiastinal lesions: mainly the identification of the nature of lymph node enlargement ( u the nature of hilar and mediastinal masses or enlarged lymph nodes) u mediastinal, tracheal and bronchial lesions requiring puncture localization; u assessment of efficacy after treatment of tracheal and bronchial lesions; u lung cancer for mediastinal and hilar lymph node staging; u understanding the relationship between lung lesions and mediastinal structures to determine whether surgery is indicated; u distinguishing between mediastinal tumors and tracheobronchial primary tumors, especially to determine whether solid tumors are externally compressed in the ductal wall or infiltrating the u distinguish between mediastinal tumors and tracheobronchial primary tumors, especially to determine whether solid tumors are externally pressing the wall or infiltrating the wall, and to further clarify the cause of extrapulmonary changes in the airway (tumors, lymph nodes, pleural fluid or abnormally enlarged cardiovascular chambers) Application scope: mainly used for biopsy of mediastinal occupancy and pathological staging of lung cancer. n It has high sensitivity and specificity in determining mediastinal lymph node metastasis of malignant tumors; n It also has high accuracy and sensitivity in determining benign mediastinal lesions such as nodular disease; n It elevates the standardized treatment of lung cancer and the diagnosis of mediastinal disease to a new level; n For lung cancer patients preparing for surgery, this examination is especially important because it can determine whether the tumor is metastatic and accurately predict the postoperative effect to avoid unnecessary surgery, and the whole examination process is non-invasive and less painful for patients. For the diagnosis of epithelial carcinoma of the lung, EBUS-TBNA is expected to replace mediastinoscopy as the preferred method; for benign mediastinal lesions including granulomatous lesions, the diagnostic value of EBUS-TBNA is still limited by diagnostic equipment and technology, but there is much room for improvement; for special lesions such as lymphoma, there is no alternative to mediastinoscopy, but EBUS-TBNA is expected to become a diagnostic method. How to reduce the false negative rate of EBUS-TBNA; how to use EBUS-TBNA specimens for immunohistochemistry and other molecular biology studies to provide more theoretical basis for individualized comprehensive treatment of lung cancer will be one of the key research directions in the future.