The influence of the timing of surfactant replacement therapy for the treatment of neonatal respiratory distress syndrome was evaluated in a study of 182 neonates of less than 30 weeks' gestation who were randomly assigned prior to delivery to one of three study groups: control (dummy instillation of air given at birth), early surfactant (surfactant given at birth), or late surfactant (surfactant given at <6 hours of age). Subjects in the late surfactant group could avoid treatment if they had a clear chest roentgenogram and required no supplemental oxygen at a mean airway pressure of less than 7 cm of water. All treated neonates were eligible to receive up to three additional doses during the first 5 days of life. The three groups were comparable with respect to birth weight, gestational age, and other perinatal parameters with the exception of a lower cord arterial pH and 1-minute Apgar score in the early surfactant group. Of the 60 neonates randomly assigned to late treatment, 29 (48%) were deemed surfactant sufficient and thereby avoided treatment; the other 31 received their first dose at a mean age of 2.9 hours. There was a significant improvement in gas exchange during the first week of life in both surfactant groups compared with the control group, reflected by differences in fraction of inspired oxygen, arterial/alveolar Po2, and ventilation index (peak pressure x rate on the ventilator) (P < .001). Surfactant therapy also resulted in a lower incidence of pulmonary air leak and severe chronic lung disease (defined as requirement for respiratory support beyond 36 weeks post-conceptional age). There were no differences between early and late surfactant groups in any of these parameters. The only statistically significant difference between the surfactant groups was that the early group had a higher incidence of mild chronic lung disease (respiratory support beyond 28 days of age) than the late treatment group (P < .005). Neonates in the late treatment group were extubated earlier and had a shorter neonatal intensive care unit stay than control neonates (P < .05), whereas those in the early group were not significantly different from control neonates in these parameters. It is concluded that replacement therapy with bovine lung surfactant extract in neonates of less than 30 weeks' gestation results in decreased oxygen and ventilatory requirements during the first week of life and a lower incidence of pulmonary air leak and severe chronic lung disease. Comparable short-term effects were seen whether a prophylactic or treatment approach was used, but there was a lower incidence of mild chronic lung disease with late treatment. There appears to be no clinical justification for routinely using a prophylactic approach to surfactant replacement therapy in this population of neonates.
- Received August 20, 1990.
- Accepted October 23, 1990.
- Copyright © 1991 by the American Academy of Pediatrics