Introduction: Inhaled nitric oxide (INO) offers advantages of selective pulmonary vasodilation and rapid inactivation compared to intravenous vasodilators. These advantages make INO an attractive agent for the treatment of pulmonary hypertension (PHTN). The efficacy of INO has been studied in persistent fetal circulation, acute respiratory distress syndrome(ARDS), and congenital heart disease (CHD). Potential adverse effects of INO include: nitrogen dioxide (NO2) toxicity, methemoglobinemia, and platelet dysfunction. Our objective was to evaluate the safety of INO in pediatric patients (pts).
Methods: Pediatric pts. with PHTN and ARDS or CHD were studied under an established protocol approved by our IRB and conforming to FDA guidelines for an investigational new drug. Informed consent was obtained for each child prior to treatment. INO was sequentially titrated from 10 parts per million (ppm) to 20, 40, 60, and 80 ppm at ten minute intervals. Parameters monitored before and during therapy included nitric oxide (NO) and NO2 concentrations, mean arterial blood pressure (MAP), and percent methemoglobin(MHG). NO and NO2 levels were continuously monitored using an in-line Dräger electrochemical detection device. MAP was continuously measured with an indwelling arterial catheter. MHG was measured by co-oximetry. A decrease in the MAP of 10%, MHG≥5%, or NO2 concentration > 5 ppm were considered adverse effects by study criteria. Pretreatment MAP was compared to MAP at 80 ppm INO using a paired t-test. A p value < 0.05 was considered statistically significant.
