Selective High Frequency Oscillatory Ventilation (HFOV) for Neonates

Neonatal respiratory distress syndrome (RDS) remains a major respiratory disorder for the increasing preterm population, and its incidence has been confirmed to be increased gradually with decreased gestational age. Previous studies demonstrated incidences of 90% at 24 weeks', 80% at 28 weeks', 57% at 30-31 weeks', and 25% at 35-36 weeks' gestational age(GA). However, these figures were mainly performed in the pre-neonatal acute respiratory distress syndrome (ARDS) era, in which ARDS was usually considered as RDS, and surfactant was therefore used repeatedly. In fact, no studies have indicated beneficial effects of surfactant for adult and pediatric ARDS, and therefore, its exact action for neonatal ARDS was needed to be further elucidated. In 2017, the international ARDS collaborative group provided the first consensus definition for neonatal ARDS, and the exact incidence of neonatal ARDS and mortality were unknown.

Similarities to adult and pediatric ARDS, no special pharmacologic therapy for neonatal ARDS has been shown to reduce either short-term or long-term mortality and morbidity, the risk of death therefore remains high for preterm infants. Study reported that 50% chance of death with neonatal intensive care appeared at 24 weeks in most high-income countries and 34 in low-income and middle-income countries. Among the survivors, bronchopulmonary dysplasia(BPD), neurologic impairment and retinopathy of prematurity(ROP) were the main causes of secondary death, rehospitalization and medical resource use. How to reduce rate of mortality and severe complications constitutes a challenge for neonatologists.

An interesting result was that HFOV did reduce the incidence of mortality as compared with CMV(2:9 vs 3:3, 95%confidence intervel(CI) 0.09-0.89, P=0.03) (4:177 vs 13:179, 95%CI 0.10-0.94, P=0.04). The results suggested that, excluding preterm infants with RDS, HFOV could also reduce other primary outcomes, such as the risk of death, BPD, IVH and neurologic impairment.

Eligibility Criteria:
Inclusion Criteria:

subgroup 1: For a neonate to be included, the following four criteria must be fulfilled:

1. gestational age (GA) between 26+0 and 33+6 weeks (estimated on the postmenstrual date and early gestation ultrasonographic findings);
2. birth weight less than 2000g;
3. diagnosis with ARDS and/or RDS;
4. assisted with CMV within 12 h after birth;
5. stabilization before randomization within 12 h after birth: FiO2\<0.40, Paw\<12 cmH2O, 90%-95% of SpO2, pH\>7.20, PaCO2\<60 mmHg(these may be evaluated by arterial blood gas analysis).

subgroup 2 For a neonate to be included, the following four criteria must be fulfilled:

1. gestational age (GA) more than 33+6 weeks (estimated on the postmenstrual date and early gestation ultrasonographic findings);
2. birth weight more than 2000g;
3. diagnosis with ARDS and/or RDS;
4. assisted with CMV within 12 h after birth;
5. stabilization before randomization within 12 h after birth: FiO2\<0.40, Paw\<12 cmH2O, 90%-95% of SpO2, pH\>7.20, PaCO2\<60 mmHg(these may be evaluated by arterial blood gas analysis).

Exclusion Criteria:

Neonates with at least one of the following criteria are not eligible for the study:

1. neonates who only needed noninvasive ventilation;
2. major congenital anomalies or chromosomal abnormalities;
3. neuromuscular diseases;
4. upper respiratory tract abnormalities;
5. need for surgery known before the first extubation;
6. grade Ⅲ-IV-intraventricular hemorrhage (IVH);
7. congenital lung diseases or malformations or pulmonary hypoplasia.
8. parents reject to join