Bronchi with a diameter of <2 mm are anatomically referred to as fine bronchi, and the inflammation that occurs in the fine bronchi is called acute bronchiolitis. Acute bronchiolitis is a common and frequent disease in pediatrics, mostly seen in infants and young children within 2 years of age, and is caused by 80% of respiratory syncytial virus infections. Early symptoms of upper respiratory tract infection, 2-3 days later may appear cough, breathing difficulties, serious respiratory rate up to more than 60 times per minute, heart rate of about 180 times per minute, and even respiratory failure, is a more serious disease of infants and children.