Inhaled nitric oxide and intravenous magnesium sulphate for the treatment of persistent pulmonary hypertension of the newborn.

Introduction: The aim of this study was to compare the response and survival rates of term infants with persistent pulmonary hypertension of the newborn (PPHN) on high frequency oscillatory ventilation (HFOV) treated with either inhaled nitric oxide (iNO) or intravenous magnesium sulphate (MgSO4).

Methods: This was a randomised controlled study. The inclusion criteria were infants with respiratory distress, oxygen index equal to or greater than 25 despite HFOV support, and echocardiographic evidence of PPHN. Infants in the MgSO4 group (n is 13) were loaded with MgSO4 200 mg/kg infused over half an hour, followed by continuous infusion at 50-150 mg/kg/hour to attain a serum magnesium level of 5.0-7.0 mmol/L. Infants in the iNO group (n is 12) were administered nitric oxide at an initial concentration of 20 ppm. Analysis was done on an intention-to-treat basis.

Results: There was no significant difference in the median age when the vasodilators were commenced (MgSO4 group: 14.0 hours, interquartile range [IQR]: 7.5, 27.0; iNO group: 14.8 hours, IQR: 12.5, 35.3, p is 0.8). There was no significant difference in the proportion of infants who responded primarily to either vasodilator (MgSO4: 23.3%, iNO: 33.3%, p is 1.0) . After switching over to iNO following a failed MgSO4 therapy, a significantly higher proportion (9 out of 10) of the non-respondents in the MgSO4 group recovered from PPHN and survived compared to the non-respondents in the iNO group (1 out of 8) who switched over to intravenous MgSO4 (p is less than 0.03).

Conclusion: Infants who were administered iNO following a failed MgSO4 therapy were associated with a better outcome than those who were administered MgSO4 following a failed iNO therapy.