Surfactant Replacement Therapy for

Neonatal respiratory distress syndrome is one of the most common complication seen in premature infant, It occurs after the onset of breathing and is associated with an insufficiency of pulmonary surfactant .It is caused by lack of a slippery protective substance surfactant which helps the lungs to inflate with air and keeps the air sacs from collapsing. or genetic problems with lung development .The surfactant prevents atelectasis by reducing surface tension at low lung volumes when it is concentrated at end expiration as the alveolar radius decreases.Also it contributes to lung recoil by increasing surface tension at larger lung volumes when it is diluted during inspiration as the alveolar radius increases.Without surfactant, surface tension forces are not reduced and atelectasis develops during end expiration as the alveolus collapses .Surfactant deficiency induces atelectasis which leads to cycle of hypoxia, hypercapnia, and acidosis, acts on type two cells to reduce surfactant synthesis and in some infant on the pulmonary arterioles to produce pulmonary hypertension.Infants at greatest risk for RDS are the premature who have an immature L/S ratio .The use of Surfactant has reduced neonatal mortality and lowered costs for intensive care in developed countries