CLINICAL-RESPONSES TO PROLONGED TREATMENT OF PERSISTENT PULMONARY-HYPERTENSION OF THE NEWBORN WITH LOW-DOSES OF INHALED NITRIC-OXIDE

We studied the efficacy of low-dose nitric oxide inhalation in nine co nsecutive patients with severe persistent pulmonary hypertension of th e newborn (PPHN) who were candidates for extracorporeal membrane oxyge nation (ECMO). All patients had marked hypoxemia despite aggressive ve ntilator management and echocardiographic evidence of pulmonary hypert ension. Associated diagnoses included meconium aspiration syndrome (3 patients), sepsis (3 patients), and congenital diaphragmatic hernia (2 patients). Infants were initially treated with inhaled nitric oxide a t 20 ppm for 4 hours and then at 6 ppm for 20 hours. In all infants, o xygenation promptly improved (arterial/alveolar oxygen ratio, 0.077 +/ - 0.016 at baseline vs 0.193 +/- 0.030 at 4 hours; p <0.001) without a decrease in systemic blood pressure. Sustained improvement in oxygena tion was achieved in eight patients treated with inhaled nitric oxide for 24 hours at 6 ppm (arterial/alveolar oxygen ratio, 0.270 +/- 0.053 at 24 hours; p <0.001 vs baseline). One patient with overwhelming sep sis had an initial improvement of oxygenation with nitric oxide but re quired ECMO for multiorgan and cardiac dysfunction. We conclude that l ow doses of nitric oxide cause sustained clinical improvement in sever e PPHN and may reduce the need for ECMO. However, immediate availabili ty of ECMO is important in selected cases of PPHN complicated by sever e systemic hemodynamic collapse.