Objectives: We hypothesized that the absence of an increase in the Doppler-derived aortopulmonary pressure gradient (APPG) across the ductus arteriosus, which reflects pulmonary artery pressure during the first day of life, can predict clinical complications in preterm infants with neonatal respiratory distress syndrome (RDS) STUDY DESIGN: Twenty-nine healthy preterm infants weighing 2210 +/- 244 gm (mean +/- SEM) and 63 infants with RDS weighing 1645 +/- 86 gm were studied with the Doppler ultrasound technique for measurement of the mean APPG at 2, 24, 48, and 72 hours of age. Of infants with RDS, 67% were treated with synthetic surfactant.
Results: Spontaneous closure of the ductus arteriosus on the first day of life led to exclusion of 11 infants with RDS and 17 control subjects from the study. Of the remaining 52 infants with RDS, 26 had an increase in the APPG from 2 to 24 hours of age, and APPG values remained low in the other 26 infants. Neonatal complications appeared more frequently (p < 0.001) in distressed infants with little change in APPG values (delta APPG) (22/26) than in infants with high delta APPG (6/26). Six of the infants with high delta APPG values (23%) needed medical or surgical closure of the ductus, but no other acute neonatal complications occurred; 14 (54%) of the infants with low delta APPG required ductal closure. Between the ages of 24 and 58 hours, five of the latter 26 infants had severe pulmonary hemorrhage, which was fatal in two cases. Severe (grade III or IV) intraventricular hemorrhage was seen in three infants with RDS and a low delta APPG; one of these infants also had severe pulmonary bleeding. Pneumothorax occurred in six infants with a low delta APPG. Infants without an increase in the APPG value during the first day of life required a significantly higher fraction of inspired oxygen.
Conclusions: Noninvasive measurement of the change in APPG during the first day of life may provide a useful method for identifying infants with RDS at high risk of neonatal complications.