The efficacy of inhaled nitric oxide treatment in premature infants with acute pulmonary hypertension

Abstract

Background: Although inhaled nitric oxide (iNO) therapy in term infants with pulmonary hypertension (PHT) has demonstrated definite benefit, the use of iNO in preterm infants remains inconclusive.

Aims: To evaluate the impact of iNO treatment in premature infants with acute PHT.

Study design: Retrospective cohort.

Subjects: Infants < 34 weeks' gestational age, admitted during 2010-2016 to two neonatal units, having treated with iNO for confirmed PHT. A positive response was defined by FiO₂ reduction ≥20% within 3-h post iNO initiation. Early PHT was defined when developed within the first 72 h of age.

Outcome measures: The primary outcome was the evaluation of the acute response to iNO administration. Secondary outcomes included the comparison of neonatal characteristics and outcomes between positive and negative responders, and early or late PHT infants.

Results: Of the 55 infants of our cohort, 39 (71%) had a positive response to iNO administration. No differences noted regarding bronchopulmonary dysplasia, intraventricular haemorrhage or other morbidities; however, positive responders had significantly higher survival rate in overall (77 vs 21%, p = 0.001) and within early PHT subgroup (74 vs 33%, p = 0.044). Regression analysis revealed that oligohydramnios (OR 2.834, 95%CI 1.652-6.070) and early PHT (OR 1.953, 95%CI 1.377-2.930) were significantly related with a positive response.

Conclusions: Preterm infants with confirmed acute PHT respond in significant proportion to the iNO administration, especially in the background of oligohydramnios or the development of early PHT.

Keywords: Inhaled nitric oxide; Premature infant; Pulmonary arterial hypertension.