1. Brief medical history: Male, 51 years old, was admitted to the hospital for one week with a right middle lung occupancy found on physical examination. Chest CT suggested: right middle lung occupancy with peripheral obstructive inflammation. Bronchoscopy revealed neoplasia in the middle lobe lumen with incomplete obstruction of the lumen. Pulmonary function tests were approximately normal. Preoperative diagnosis: right middle lung heterogeneous shadow, consider malignant possibility. Proposed surgery: thoracoscopic right middle lobe resection with mediastinal lymph node dissection. 2. Brief description of the operation: Right middle lung lobectomy was performed under routine lumpectomy. Since the preoperative tracheoscopy suggested that neoplasm was seen in the middle lobe lumen and did not completely obstruct the lumen, the middle stem bronchus might be invaded. During the operation, the bronchus was handled last: after freeing the middle lobe bronchus, the airway was opened and the middle stem bronchus was found to be invaded, so an intraoperative decision was made to perform a middle and lower lobe resection. Surgical sequence: 7 groups of lymph nodes – lower lobe – 2 and 4 groups of lymph nodes. The thoracic cavity was flushed and tested for leaks without abnormalities, and the bleeding was carefully stopped in preparation for chest closure. Before closing the chest, we again examined the situation in the chest cavity under the lumpectomy and found that the right lower pulmonary ligament, the inferior ramus, and group 2 and 4 lymph nodes were leaking bloody fluid at a faster rate. The hemostatic gauze placed to the above mentioned areas was removed and carefully explored again, no obvious bleeding spots were seen and no obvious lymphatic fluid exudation was seen. Potential possible foci of bleeding and capillary lymphatic ducts in the above mentioned areas were carbonized with ultrasonic knife, and then multiple pieces of hemostatic gauze were used to fill and compress them again. When the lung lobes were explored, it was found that there was an oozing spot on the coarse surface of the horizontal fissure of the upper lobe of the right lung, and the bleeding was stopped by continuous sutures with 3-0 Prilling sutures, and 100 ml of 50% glucose solution was instilled into the chest cavity before closing the chest. The whole hemostasis procedure lasted about 2 hours. A small amount of bloody fluid was still leaking at a rate of approximately 35 ml per hour during 30 minutes of observation. According to the director’s opinion, we temporarily ate after the operation, carefully observed the chest tube drainage and recorded the hourly chest drainage volume. This morning’s checkup: good mental status, normal vital signs, 12-hour chest drainage volume of about 100 ml, dark red. Orthopantomogram of the chest suggests: no obvious fluid in the right chest cavity, poor expansion of the right upper lung. The director instructed: the patient was instructed to cough effectively, and to aspirate tracheoscopically if necessary, while suction could be given appropriately to increase the negative pressure in the right thoracic cavity. 3. Summary of experience: The hemostasis process took a long time yesterday, and it was not clear in the end what caused the above results. During the operation, the director of the major department was asked to consult intraoperatively again, and the possible causes of the above situation were analyzed, which I summarize here: ① bleeding, possible bleeding sites: capillaries at the mediastinal lymph node clearance site, bronchial arteries, coarse surface of the remaining lung, broken end of the adhesion zone, vascular injury of the remaining lung, broken end of the vessel of the resected lung. ② Lymphatic fluid, broken ends of capillary lymph vessels at the site of mediastinal lymph node dissection, injury to the variant thoracic duct, injury to small branches of the thoracic duct. ③ A deep venous catheter left in place by the anesthesiologist has punctured the vessel wall and entered the thoracic cavity. ④ The upper pulmonary vein is severed or partially severed. ⑤ The fibrous pericardium has been cut open.