Objective: The purpose of this study was to analyze the clinical evolution, acute toxicity and factors which influence the response to nitric oxide treatment in children.
Patients and methods: We studied prospectively 25 children, 14 boys and 11 girls, between 15 days and 16 years of age. Seventeen patients were diagnosed with ARDS and 8 with PHT. All patients presented hypoxemia and/or PHT refractory to conventional therapy and were treated with inhaled NO (1.5 to 45 ppm) between 45 minutes to 47 days. We studied the secondary effects, morbidity and mortality, and analyzed the relationship between NO effects and age, sex, diagnosis, infection, previous PaO2/FiO2 ratio, previous oxygenation index and previous mean pulmonary arterial pressure (mPAP)/mean systemic arterial pressure (mSAP).
Results: The effect of NO was maintained during the time of administration without tachyphylaxis. There were no secondary effects of NO administration. NO2 was always < 2 ppm and metahemoglobinemia was below 3.5%. There was no relationship between the effect of NO and the rest of the factors analyzed. Twelve patients (48%) survived, 9 of the children with ARDS (53%) and 3 of the children with PHT (38%). Eleven of the 21 patients who improved with NO treatment survived (52%), as did 1 of the 4 patients who did not improve (25%).
Conclusions: Prolonged administration of inhaled NO at low concentrations maintains the improvement of oxygenation and pulmonary hypertension without acute secondary effects. We have not found factors that could predict the clinical response to NO.