Respiratory failure occurs in near term and term infants as a complication of perinatal aspiration syndromes, pneumonia, sepsis, respiratory distress syndrome and primary pulmonary hypertension. Recently a collaborative trial of the NICHD Neonatal Research Network and the Canadian Inhaled Nitric Oxide Study Group (the NINOS trial) demonstrated that inhaled nitric oxide (iNO) reduced the number of deaths and the need for extracorporeal membrane oxygenation (ECMO) therapy -- a lung bypass mechanism -- from 64 percent to 46 percent. The standard recommended threshold for initiation of iNO therapy, based on this trial, was an oxygenation index (OI) >=25.