Response to Inhaled Nitric Oxide and Mortality Among Very Preterm Neonates With Pulmonary Hypertension

Importance: Clinical observations of immediate improvement in fraction of inspired oxygen (FiO2) in a proportion of cases is often cited as the rationale for using inhaled nitric oxide (iNO) in the management of acute pulmonary hypertension among very preterm neonates (gestational age, <32 weeks). However, the clinical effectiveness of such a response pattern remains underinvestigated. Objective: To identify factors associated with predischarge mortality among very preterm neonates receiving iNO for acute pulmonary hypertension, with specific a priori emphasis on iNO responsiveness. Design, Setting, and Participants: This prospective observational cohort study was conducted from January 1, 2018, to December 31, 2022, at 12 Canadian tertiary neonatal intensive care units. Consecutive very preterm neonates who received iNO for a diagnosis of acute pulmonary hypertension and pretreatment FiO2 of 0.50 or more were included. Neonates with congenital anomalies or those who were treated for chronic pulmonary hypertension with iNO were excluded. Early acute pulmonary hypertension (≤72 hours of age) and late acute pulmonary hypertension (>72 hours of age) cohorts were analyzed separately. Statistical analysis was performed from January 2023 to January 2024. Exposure: Treatment with iNO for acute …