Invasive ventilation(IV) remains one key cornerstone to reduce neonatal mortality for preterm infants with respiratory distress syndrome(RDS) and/or acute respiratory distress syndrome(ARDS). However, it is also related to increased risks of ventilator-associated lung injury and escalation of pulmonary inflammation, and which finally result in bronchopulmonary dysplasia (BPD). Early weaning from IV in newborn infants with BPD is therefore a key procedure to reduce these risks above.

Supplying with the combined advantages of NCPAP and high-frequency oscillatory ventilation (HFOV) with high carbon dioxide(CO2) removal, no need for synchronisation, non-invasion, less volume/barotraumas, and increased functional residual capacity, nasal HFOV(NHFOV) was considered as a strengthened version of NCPAP. Furthermore, the superimposed oscillations of NHFOV could avoid gas-trapping, and allowed to obviously up-regulate mean airway pressure (MAP) more than NCPAP. Thus, NHFOV might be more beneficial as post-extubation respiratory support strategy to avoid re-intubation and subsequent complications and/or sequelae as compared with NCPAP in preterm infants. Nowadays, NHFOV was increasingly used in neonatal intensive care unit (NICU) around the world due to its convenient operation. A retrospective review has reported the beneficial effects of NHFOV in preterm infants as a remedial measure after failing to other noninvasive modes, including reducing the number of apneas, bradycardias or oxygen desaturations. However, there were rare randomized controlled studies comparing NHFOV with NCPAP in preterm infants with BPD.

We have found that NHFOV is superior to NCPAP in avoiding re-intubation in very preterm infants with the first extubation. The purpose of the present study was to compare NHFOV with NCPAP as post-extubation respiratory support strategies on the need for endotracheal ventilation, as well as pressure of CO2(PCO2) level in preterm infants with BPD.

Inclusion Criteria:

Eligibility requirements for neonates:

• The gestational age is less than 32 weeks
• The preterm neonates are diagnosed with BPD and need invasive ventilation
• Extubation and subsequent noninvasive ventilation is ready to be carried out

Exclusion Criteria:

one of the following conditions is needed:

• there were no intraventricular hemorrhage(IVH) grades 3 or 4
• major congenital anomalies
• parents' decision not to participate

After documenting parental consent, these ventilated infants with BPD were randomly assigned to either NHFOV or NCPAP using a table of random numbers and sealed opaque envelopes when they were eligible for extubation. Blinding to doctor was not possible due to the nature of the intervention, is not necessary to participant.