We previously used a hyperoxia-hyperventilation strategy. However, we currently adopt a strategy of early CPAP-`gentle' ventilation (abbrev: vent) as advocated by Columbia Babies Hospital, New York. This is a retrospective study to evaluate the outcomes using the 2 different strategies. METHODS: Inclusion criteria: All babies ≥ 2 kg, FiO2 ≥ 0.5 for ≥ 1 day/or ventilatory assistance. The study period of hyperoxia-hypervent is Dec '91 to Jan '93. Babies are kept hyperoxic (PaO2 ≥ 120 mmHg) with high Hood O2. Intermittent mandatory vent. (IMV) is indicated when PaO2 < 120 mmHg on FiO2 ≥ 0.8 Hood O2. Rarely CPAP is used when IMV is not indicated but baby has severe respiratory distress. On IMV, hypervent is used, keeping PaCO2 low and pH alkalotic. The aim is PaO2 ≥ 80 mmHg. Tolazoline, surfactant and/or paralysis are used in severe cases. The study period of early CPAP-`gentle' vent. is July '94 to Aug '95. Babies with significant respiratory distress are placed on nasal prong CPAP + 5cm H2O. IMV is indicated when PaO2≤ 50mmHg on FiO2 ≥ 0.8 CPAP. 2 main IMV techniques are used: 1) Low Vent Rate 20-40/min {PIP 20-30 cm H2O, PEEP + 5cm H2O, Inspiratory Time (IT) 0.5s}, 2) High Vent. Rate 100/min {PEEP O, IT 0.3s}. High PIP is avoided. When PIP ≥ 30-35 cm H2O, tolazoline, surfactant and/or high frequency interruptor are considered. Nitric oxide and ECMO are not available. The aim is PaO2 ≥ 50mmHg. No attempt is made to achieve a low PaCO2 or alkalotic pH. Paralysis is not used. The 2 study groups do not differ statistically in BW, GA, Sex, race, diagnoses and Apgar Scores. Results: There were 8702 and 8537 live-births ≥ 2kg for the hyperoxia-hypervent. and CPAP-`gentle' vent. study periods respectively.Table

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Our data suggests that early CPAP-`gentle' vent. decreases mortality from PPHN. Early CPAP also significantly reduces the need for IMV. In PPHN cases,`gentle' vent. also improves survival (p=0.03).