Patent Ductus Arteriosus (PDA) and Response to Late Surfactant Treatment in Premature Infants Running Title: Ductus Arteriosus and Late Surfactant Treatment

Abstract Objective To determine clinical/echocardiography (ECHO) phenotype of response to late surfactant, according to patent ductus arteriosus (PDA) status. Study Design Infants ≤26+6 weeks gestational age (GA), who received ≥1 surfactant dose after postnatal day 6 with known PDA status, were enrolled. Response to surfactant, based on change in respiratory severity score, and relationship with PDA status were evaluated via univariate analysis. Results In total, 35 patients were enrolled (total of 71 doses of surfactant), whose mean weight and GA at birth were 595g(508, 696) and 23.3(22.7, 25) weeks. Positive response to late surfactant was independently associated with absence of PDA [OR 26(2, 334), p=0.01] whereas presence of PDA was associated with negative response [OR 12(1.1, 126), p=0.04]. Conclusions In neonates ≤26+6 weeks gestation response to late surfactant is influenced by PDA status. Future trials should consider PDA status when refining patient selection for late surfactant treatment.