High frequency oscillatory ventilation and extracorporeal membrane oxygenation in severe persistent pulmonary hypertension of the newborn

We report on 50 term and near-term neonates (birth weight > 1800 g, gestational age > 33 weeks) with severe persistent pulmonary hypertension of the newborn (PPHN), referred to us from January 1987 to July 1991 after failure of maximum conventional treatment. All infants had paO₂<45 mm Hg when ventilated with peak inspiratory pressure >38 cm H₂O and FiO₂=1.0, hence meeting entry criteria for extracorporeal membrane oxygenation (ECMO). High frequency oscillatory ventilation (HFOV) was tried in all patients. If sufficient oxygenation could not be achieved (paO₂<40 mm Hg for at least 2 h), ECMO therapy was begun, which was the case in 25 children. Neonates responding to HFOV (n=25) were of a slightly younger gestational age (37.0 weeks vs 38.8 weeks,P<0.05), had higher Apgar scores and were less hypoxaemic before HFOV (paO₂ 36.6 mm Hg vs 28.8 mm Hg,P<0.01); during HFOV there was a significant rise in paO₂ (> 150 mm Hg;P<0.001) and a fall in pCO₂ to 21.6 mm Hg (P<0.001). Due to air leaks, which was the main complication of HFOV (52%), ECMO therapy had to be begun in two additional infants after an initial positive effect. HFOV tended to be successful in cases of primary PPHN, meconium aspiration and sepsis, but not in infants with lung hypoplasia as a result of diaphragmatic hernia or other reasons. Success or failure of HFOV could not be reliably predicted by any parameter. Mean duration of HFOV was 37.8 h vs 84.9 h of ECMO. PPHN could be overcome in 88% of the HFOV-treated and in 76% of the ECMO-treated infants; overall survival rate was 74% (predicted probability of survival using maximum conventional treatment <10%). There were no significant differences between HFOV/ECMO groups with regard to duration of ventilation following HFOV/ECMO, total time in hospital, rate of bronchopulmonary dysplasia and neurological complications (intracranial haemorrhage, brain infarction). Among the survivors, the rate of mentally handicapped children was equal in both groups (overall 18.9%). Our analysis shows that about 50% of neonates with PPHN who fail to respond to conventional ventilatory support and maximum treatment can be treated successfully with HFOV, thus avoiding ECMO. By applying both forms of therapy, the survival rate of infants with severe PPHN can be increased from an estimated rate of <10% up to 80%.