IOE groups were given systematic therapy according to the routine treatment plan for PRS for 4 weeks. The main intervention measures included: 1) non-invasive ventilator treatment, generally at least once every night and typically not exceeding continuous daily usage.; 2) attention to feeding and sleeping positions, with a recommended sleeping position of lateral recumbent and the head of the bed raised by 20-30°; 3) swallowing function training, such as tongue muscle stretching training, assisted anterior jaw protrusion training, lemon ice stimulation to the soft palate, pharyngeal wall, etc., generally 5 days per week, twice per day, 5-20 minutes each time; 4) pulmonary ultrashort wave therapy, generally at least 2-3 times a week, and not more than once a day; 5) physical therapy, such as intensive training for gross motor functions including lifting the head, turning over, sitting, crawling, standing, etc., generally 3-5 days per week, 1-2 times per day, 5-20 min each time.

PNG groups were given systematic therapy according to the routine treatment plan for PRS for 4 weeks. The main intervention measures included: 1) non-invasive ventilator treatment, generally at least once every night and typically not exceeding continuous daily usage.; 2) attention to feeding and sleeping positions, with a recommended sleeping position of lateral recumbent and the head of the bed raised by 20-30°; 3) swallowing function training, such as tongue muscle stretching training, assisted anterior jaw protrusion training, lemon ice stimulation to the soft palate, pharyngeal wall, etc., generally 5 days per week, twice per day, 5-20 minutes each time; 4) pulmonary ultrashort wave therapy, generally at least 2-3 times a week, and not more than once a day; 5) physical therapy, such as intensive training for gross motor functions including lifting the head, turning over, sitting, crawling, standing, etc., generally 3-5 days per week, 1-2 times per day, 5-20 min each time.

The specific procedure was as follows: the infant was placed in a semi-recumbent or sitting position with the head fixed. Before each feeding, the infant's oral and nasal secretions were to be cleared. An intermittent oro-esophageal tube (Appendix) was appropriately lubricated with water on the head part. The professional medical staff held the tube and slowly inserted it through one side of the mouth into the upper part of the esophagus. The depth of insertion depended on the patient's age and height. After each feeding, the tube was immediately removed, and the patient was held upright for at least 30 minutes in case of reflux.

Once the symptoms of respiratory tract infection such as fever, cough, sputum, dyspnea, and respiratory distress were observed, the medical staffs would conduct the future exam. With the presence of rales on auscultation of both lungs, examination by CT, the routine blood test, and blood culture, the patients would be diagnosed as the pulmonary infection "Positive".

The relevant indicators include total protein (TP, g/L) from the blood test within 24h after admission and the last day of treatment, generally, with empty-stomach infants and in the morning.