Low dose inhaled nitric oxide causing selective pulmonary vasodilation in child with idiopathic pulmonary hypertension.

Low dose (3 ppm) inhaled nitric oxide caused selective pulmonary vasodilation with improved systemic arterial pressure, cardiac index and arterial oxygenation in an infant with primary pulmonary hypertension. Methaemoglobin levels did not exceed 0.6%, and nitrogen dioxide concentrations remained within 0.05 ppm.