Inhaled Iloprost for the Treatment of Persistent Pulmonary Hypertension in the Term and Near Term Infants.

Infants eligible for the study will be divided into two arms according to oxygenation index: Infants in arm A (OI \<20) will receive nebulized Iloprost in a lower dose (50 ng/kg/min) for one hour, and a higher dose (100 ng/kg/min) for another hour. Infants in arm B (OI\>20) will receive NO, and in addition will receive nebulized Iloprost in a lower dose for one hour and a higher dose for another hour.