This feasibility trial was designed to test the safety of using the intravenous form of Prostaglandin E1 in an inhaled form (iPGE1) on infants born at 34 0/7ths weeks gestational age or greater diagnosed with hypoxemic respiratory failure and on assisted ventilation. The intravenous form of PGE1 was to be aerosolized and administered via a nebulizer attached to the infant's ventilator. The goal was to enroll 50 subjects within 6-9 months, in preparation for a larger, multi-center randomized control trial; however, the study was withdrawn for lack of recruitment.