Abstract
Inhaled nitric oxide (iNO) is a potent local vasodilator. Numerous case reports describe its efficacy in treating persistent pulmonary hypertension of the newborn (PPHN). This report describes experience at the authors' institution with iNO therapy in 10 consecutive infants with PPHN of a number of etiologies. Infants received iNO at doses of 0.2 to 80 ppm for 1 to 481 h. Five infants were classified as responders (20 torr or greater rise in PaO2) and one as a partial responder (PaO2 rise of 10 to 19 torr). The remaining four did not respond. Overall observed mortality was three of 10, with two of four of nonresponders and the only partial responder dying. Survivors required ventilation for 18±18 days and oxygen for 29±30 days, and they remained in hospital 40±30 days (mean ± SD). Although improvement in oxygenation with iNO was primarily due to reduction in pulmonary pressure, in selective patients, changes in ventilation-perfusion relationships could account for some of the increase in oxygenation. The presence of significant methemoglobinemia in two patients (7% and 4.5%) when the infants' iNO dose was increased to 80 ppm highlights the importance of careful monitoring for toxicity. Further studies are needed to define the best dosage and duration of iNO. While iNO shows great promise in the treatment of PPHN, randomized controlled trials are needed to delineate in which infants iNO use is indicated.