To very low birth weight infant(VLBW) with respiratory disease syndrome(RDS) who need mechanical ventilation,early extubation may have more benefits.Early extubation may decrease the ventilation-associated pneumonia(VAP),sepsis and decrease the incidence of severity bronchopulmonary dysplasia(BPD).But often fail attempts at extubation because of apnea,atelectasis,hypercapnia,hypoventilation or other illnesses.~High frequency oscillatory ventilation is benefit to lung.Initial ventilation with HFOV in preterm with RDS may reduce the incidence of BPD and improve the neurodevelopment.Compared HFOV with conventional ventilation in preterm infants showed that HFOV had superior lung function when 11 to 14 years age.Whether nasal high frequency oscillatory ventilation(NHFOV) also have those advantages in non-invasive mode? Null D M et al do a experiment on preterm lambs,the result suggest that NHFOV may promotes alveolarization.But there was no clinical trials to prove.~The nasal intermittent positive pressure ventilation (NIPPV) group fail definition：1、 Fraction of inspired oxygen (FiO2)>40%、MAP>12 centimeter water column (cm H2O),but arterial oxygen saturation (SaO2)<90%.2、significant abdominal distension.3、PaCO2>60millimeter of mercury(mmHg)or partial pressure of arterial oxygen (PaO2)<45 millimeter of mercury(mmHg).4、severe apnea( definition:>6 episodes requiring stimulation in 6 hours or requiring >1 episodes of positive-pressure ventilation) 5.potential of hydrogen (PH)<7.2 The~The NHFOV group fail definition：1、FiO2>40%、MAP>14 mbar,but SaO2<90%.2、significant abdominal distension.3、PaCO2>60millimeter of mercury(mmHg) or PaO2<45millimeter of mercury(mmHg).4、severe apnea 5.PH<7.2.
To evaluate the efficacy and safety of nasal high frequency oscillatory ventilation(NHFOV) in preterms with respiratory disease syndrome(RDS) after extubation.