Intervention
Two types of surfactants were used for intervention in this study. One group received BLES 135 mg/kg (produced by Blesbiochemical, Canada) and the other group received Survanta (Beraksurf®) 100 mg/kg (produced by Tekzima, Iran). Drug administration in both groups was performed intratracheally for 10 min. The first dose was given immediately after hospitalization, and if it was not required at that time, it was prescribed in the hospitalization period and with deterioration of RDS (this deterioration was not justifiable with other causes).Chest radiography was performed in both groups 6 h after the first dose. Based on radiographic findings and neonate clinical condition, second and third dose were either prescribed or unfixed.