Nitric oxide (NO) is an endogenous vasodilator that is responsible for regulating smooth muscle tone via changes in cyclic guanosine monophosphate (cGMP). Inhaled NO (iNO) causes pulmonary vasodilatation without affecting systemic vascular resistance. The aim of this study was to evaluate the efficacy and adverse effects of iNO therapy for the treatment of term infants with persistent pulmonary hypertension of the newborn (PPHN).
METHODS:
From June 1998 to June 2000, 26 term infants with PPHN were given iNO therapy. Another 21 term infants with PPHN who did not receive iNO therapy served as the control group. All patients had an oxygenation index (OI) of more than 25 at the beginning of the study. iNO was started at a dose of 20 ppm and weaned according to the response achieved within the 3 hours of treatment.
RESULTS:
The OI decreased rapidly after 30 minutes of iNO therapy and was significantly lower in the iNO group than in the control group at 30 minutes, 3, 12, and 24 hours after iNO therapy (p < 0.01). All cases in the iNO therapy group had serum methemoglobin levels of less than 2.5% and nitric dioxide (NO2) concentrations less than 2 ppm.
CONCLUSIONS:
We conclude that iNO therapy produces rapid improvement in oxygenation for 24 hours without short-term side-effects in term infants with PPHN. If a high dose of NO (80 ppm) is used, serum methemoglobin and NO2 values should be monitored.
