Effectiveness of surfactant treatment and retreatment in moderately preterm infants.

Background: Respiratory distress syndrome (RDS) is commonly treated in preterm infants with surfactant and artificial respiratory support. However, their effects have been demonstrated in infants born before 30 weeks of gestational age, while there are no data on the efficacy of surfactant treatment and retreatment in the subgroup of moderately preterm infants (MPIs). We aimed to assess changes in oxygenation indices and RDS severity after surfactant administration in MPIs and to identify possible risk factors for the need for multiple doses of surfactant in these patients. Methods: We conducted a retrospective study on 60 MPIs born between 30+0 and 33+6 weeks of gestational age who were affected by RDS and required surfactant treatment. Peripheral oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) ratio and arterial/alveolar partial pressure of oxygen (a/APO2) ratio before and after the administration of the first and second surfactant doses were calculated. Clinical characteristics of infants who required one or more doses of surfactant were compared. Results: A total of 48 infants (80%) received a single dose of surfactant, while 12 infants (20%) received multiple doses. Both the SpO2/FiO2 ratio and the a/APO2 ratio significantly increased after the first and second doses of surfactant. However, we did not identify any clinical predictors for the need of surfactant retreatment in this population. Receiver operating characteristic (ROC) analysis indicated that the SpO2/FiO2 ratio measured 1 h after administration of the first dose is a significant predictor of the need for additional doses. Conclusions: The first and second doses of surfactant improved the oxygenation indices and reduced the severity of RDS in MPIs. The post-surfactant SpO2/FiO2 ratio can be a useful adjunct in determining the need for additional doses of surfactant. These findings help further our understanding of the effects of surfactant treatment in MPIs.