The therapeutic effect of inhaled nitric oxide in neonatal persistent pulmonary hypertension with and without Congenital Heart Disease

Objectives: To assess the therapeutic effect of inhaled nitric oxide (iNO) for persistent pulmonary hypertension of the newborn (PPHN) in infants without congenital heart disease and infants with severe acyanotic congenital heart disease. Methods: Thirty-three patients with persistent pulmonary hypertension were enrolled in this study. All cases were compatible with the diagnostic criteria of PPHN and were divided into two groups - Group 1 was neonates without congenital heart disease (n=21) and Group 2 was neonates with severe acyanotic congenital heart disease (n=12). All patients underwent iNO therapy from 20 to 60 ppm after definite diagnosis of pulmonary hypertension. Improvement in pulse oximetry (SpO₂) and the oxygenation index (OI) served as indicators of the therapeutic effect. We also recorded changes in the mean arterial pressure (MAP) to investigate the possible side effects of iNO therapy. Results: The mean baseline SpO₂ was 75.5±7.9% in Group 1 and 75.9±9.8% in Group 2. After administration of iNO for three hours, the SpO₂ in Group 1 increased significantly to 91.6±10.2% (p<0.01) but remained low in Group 2 (SPO₂ was 77.5±11.8% and p=0.762). The OI was also significantly reduced in Group 1 after iNO therapy (p<0.01). The MAP in the two groups showed no significant change before and after iNO treatment. The nitrogen dioxide concentration was below 3 ppm in all cases. Conclusions: In neonates with PPHN, early iNO therapy improves oxygenation without short-term side effect. Nevertheless, patients with PPHN complicated by congenital heart disease did not achieve the same excellent results.