Inhaled nitric oxide in neonates with persistent pulmonary hypertension

To investigate the oxygenation and haemodynamic dose response to inhaled ni tric oxide in neonates with persistent pulmonary hypertension (PPHN), we ga ve seven neonates nitric oxide and measured directly pulmonary arterial pre ssure. Inhaled nitric oxide produced peak improvement in oxygenation at 5 p arts per million (ppm) whereas peak improvement in the pulmonary-to-systemi c arterial pressure ratio did not occur until a nitric oxide dose of 20 ppm , which suggests that an initial dose of 20 ppm is optimum for the treatmen t of PPHN.