The contribution of PDA in the neonate with severe RDS

Abstract

We have compared the actual contribution of surfactant deficiency in respiratory distress syndrome to left-to-right shunting across a patent ductus arteriosus in premature infants with severe RDS by performing serial phospholipid analysis of tracheal aspirates and echocardiograms, and we have correlated these findings with the infants' clinical courses and management of ventilation. This analysis was combined with surgical or pharmacologic closure of PDA if a significant shunt existed. Qualitative surfactant abnormalities at birth and the subsequent maturation of phospholipids after birth were similar in all three groups of infants (Group 1, RDS alone; Group 2, RDS+PDA in infants weighing >1.2 kg; Group 3, RDS+PDA in infants ≤ 1.2 kg). The largest infants had isolated RDS (Group 1) and, after a brief period of stabilization after birth, had declining ventilatory and oxygen requirements. Infants in Group 2 had a gradual decrease in ventilatory and oxygen requirements which was accelerated markedly by cessation of PDA shunting. Infants in Group 3 had increasing ventilatory and oxygen requirements despite a maturing tracheal aspirate phospholipid pattern; their course, especially if they were asphyxiated, was characterized by early development of a significant left-to-right shunt and worsening clinical condition which improved following ablation of the shunt. The data suggest that severe RDS presents as a developmental spectrum and provides the justification for a controlled trial of very early closure of the PDA in the very low-birth-weight infant with severe RDS.