2.1 Collection of clinical data
This study was approved by the ethics committee of The Children’s Hospital of Zhejiang University School of Medicine, and all patients were informed of the relevant research and provided their written consent. A total of 194 children who were operated TFBA surgery in The Children’s Hospital of Zhejiang University School of Medicine from June 01, 2019 to April 30, 2020 was researched. The general characteristic, clinical symptoms, operative records, cervicothoracic CT, type and retention time of TFBA and weight were collected. The diagnosis of cervicothoracic CT was made by two senior attending doctors in our department according to clinical history. LRTI is defined as infection and inflammation of trachea, main bronchus and lung bronchi. Imaging basis includes preoperative cervicothoracic CT and intraoperative rigid bronchoscopy10. Clinical diagnosis is based on relevant clinical guidelines11,12.