Response to inhaled nitric oxide in persistent pulmonary hypertension of the newborn: relationship to baseline oxygenation.

OBJECTIVE: We hypothesized that the magnitude of response to inhaled nitric oxide in persistent pulmonary hypertension of the newborn would correlate with the degree of baseline hypoxemia. STUDY DESIGN: We performed a retrospective chart review of 15 consecutive newborn infants with persistent pulmonary hypertension of the newborn treated with inhaled nitric oxide as part of a pilot study. Oxygenation index was calculated for each patient at baseline and 0.5 and 24 hours after the start of therapy and findings were compared by repeated-measures analysis of variance. Correlation was determined between baseline oxygenation index and 24-hour change in oxygenation index. RESULTS: Patients had a rapid and sustained decrease in oxygenation index (66.7 +/- 14.8 vs 26.3 +/- 5.0 vs 12.9 +/- 2.8, baseline vs 0.5 hour vs 24 hours; p < 0.001) during the study period, and the change in oxygenation index was highly correlated with baseline oxygenation index (r2 = 0.98). Two patients were placed on extracorporeal membrane oxygenation support before the 24-hour time point because of overwhelming sepsis and severe cardiac dysfunction. CONCLUSIONS: In patients with severe persistent pulmonary hypertension of the newborn, we conclude that the clinical response to inhaled nitric oxide is most dramatic in those patients with the most severe hypoxemia.