Methods:
The birth weight and the gestational age of infants 				were 3125.5 ± 794 g (mean ± SD) and 39 ± 2.4 weeks, respectively. All 				neonates were ventilated for an average of 137.5 min (range 90-180 min) prior to 				NO therapy. The mean oxygenation index (OI) of all neonates prior to NO was 				46.3 ± 5 (mean ± SEM). NO was initially administered at 20 parts per 				million (ppm) for at least 2 h and increased gradually by 2 ppm to a maximum of 				80 ppm.