The pediatric nasopharynx is characterized by abundant lymphoid tissue (also called adenoids), which proliferates significantly in childhood and can be significantly enlarged, especially in children with recurrent upper respiratory tract infections. Excessive enlargement of the adenoids can cause obstructive dyspnea and sleep disorders. The characteristics of pediatric trachea and bronchi are: narrow lumen, soft tracheal cartilage, many tracheal mucosal vessels, poorly developed luminal elastic tissue and relatively weak cilia function. Therefore, the susceptibility of pediatric patients to respiratory infections is determined by anatomical and physiological characteristics. The diameter of pediatric trachea varies greatly by age. The total tracheal diameter of newborns is only 5-6 mm, while that of adults is 20-25 mm. the transverse diameter of the trachea is 0.5-0.9 cm until 2 years of age, and 0.7-1.5 cm from 2 to 10 years of age. from newborns to adults, the length of the trachea increases 3 times and the diameter increases 4 times. Comparison of pediatric and adult trachea