To examine whether changes of oxygenation index (OI) by postnatal age were different by the number of surfactant administration, and different between subgroups of survival and death.

From January 2005 to June 2006, preterm infants (n=84) diagnosed as respiratory distress syndrome (RDS) and treated with surfactant and ventilator were included. They were divided into two groups: Group I (n=54) was infants received surfactant, one time and Group II (n=30) was infants received surfactant, two times. We also categorized group I & II infants into two subgroups in each group: survival group and death group. We calculated OI at birth, 24 hr, 48 hr and 72 hr after birth.

Gestational age (30.1±2.6 wk vs 28.4±3.4 wk) and birth weight (1,478±442 g vs 1,199±495 g) were different between group I and group II. In preterm infants with RDS, the changes of OI by postnatal age were different between groups ( P =0.001) and different with time change ( P <0.001). In group I, the OI of survival subgroup showed decreasing by postnatal age compared with death subgroup, but was not significantly different between subgroups. In group II, the change of OI was not different between survival and death.

These findings suggest that OI helps to predict the respiratory condition in preterm infants with RDS.