Inhaled Nitric Oxide therapy in neonates with PPHN: The diagnosis of PPHN is based on clinical (labile hypoxemia and differential cyanosis) or echocardiographic findings. Optimal oxygenation and lung recruitment with optimal lung inflation and surfactant in the presence of parenchymal lung disease is the initial step in the management of PPHN. An OI of 20 is a reasonable threshold to initiate iNO. The presence of hemodynamic instability and severe hypoxemia (OI ~ 40 range) is an indication for ECMO. See text for details. (copyright Satyan Lakshminrusimha).