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Review of studies evaluating ductal patency in the premature infant
M D Reller1, M J Rice, R W McDonald
1Oregon Health Sciences University, Department of Pediatrics, Portland 97201.
Insights
Physiologic closure of the ductus arteriosus typically occurs by day four in premature infants. Persistent ductal patency after this time is abnormal, even in preterm infants without respiratory distress syndrome.
Area of Science:
- Neonatal Physiology
- Pediatric Cardiology
Background:
- The ductus arteriosus is a fetal blood vessel that normally closes shortly after birth.
- Premature infants, especially those with respiratory distress syndrome (RDS), are at risk for persistent patent ductus arteriosus (PDA).
Purpose of the Study:
- To determine the normal timing of physiologic closure of the ductus arteriosus in premature infants.
- To identify risk factors for persistent PDA in this population.
- To evaluate the effect of exogenous surfactant on ductal patency.
Main Methods:
- Observational studies assessing ductal patency in premature infants with and without RDS.
- Analysis of normative data for ductal closure rates.
- Evaluation of ductal patency in a randomized trial of exogenous surfactant.
Main Results:
- Physiologic closure of the ductus arteriosus is expected by the fourth day of life.
- Prematurity alone, without RDS, does not increase the risk of persistent PDA.
- Persistent PDA is uncommon in larger premature infants (≥30 weeks gestation) with RDS.
- Exogenous surfactant administration did not increase the risk of delayed ductal closure or the need for indomethacin.
Conclusions:
- Ductal patency beyond four days of life is considered abnormal, regardless of gestational age.
- Respiratory distress syndrome is a more significant factor than prematurity alone in persistent PDA.
- Exogenous surfactant therapy is safe concerning ductal patency in premature infants with severe RDS.
Abstract:
A series of investigations has been performed to assess the timing of physiologic closure of the ductus arteriosus in premature infants with and without respiratory distress syndrome. The data from these studies emphasize the concept of physiologic ductal patency and give normative data for expected closure rates through the fourth day of life. On the basis of these data, patency on or beyond the fourth day of life is abnormal irrespective of gestational age, and prematurity, in the absence of respiratory distress syndrome, is not a risk factor for persistent patent ductus arteriosus. We also found that persistent patent ductus arteriosus in larger premature infants (> or = 30 weeks of gestation) with respiratory distress syndrome is relatively uncommon. Last, ductal patency was evaluated in a group of low birth weight infants with severe respiratory distress syndrome in a randomized, double-blind trial of exogenous surfactant administration. We concluded that the beneficial effects of exogenous surfactant are not associated with either a greater clinical need for indomethacin or any increased risk of delayed closure of the ductus arteriosus.