Inhaled nitric oxide in persistent pulmonary hypertension of the newborn refractory to high-frequency ventilation

Abstract

Background: This study was designed to evaluate the effect of nitric oxide (NO) on the management of neonates with severe persistent pulmonary hypertension refractory to high-frequency oscillatory ventilation. 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. Results: Eighteen infants (75%) responded and six (25%) did not respond to the treatment. Three neonates died in the responding group, while all the non-responders died (P=0.0001). The survival rate was 62.5% among all neonates. NO significantly decreased OI (P<0.0001) and improved the arterial/alveolar (a/A) oxygen ratio (P<0.0001) within the first 2 h of NO therapy in 61.1% of the responders. However, the OI and the a/A oxygen ratio remained almost the same throughout the treatment in the non-responders and the non-survivors. Conclusion: Inhaled NO at 20 ppm, following adequate ventilation for 2 h without significant response, could be used to identify the majority of the nonresponders in order to seek other alternatives.