P2C178: Short Term Respiratory Effects of Inhaled Nitric Oxide in Preterm Infants

Background: Inhaled Nitric Oxide (iNO) has been found effective for hypoxemic respiratory failure from persistent pulmonary hypertension (PPHN) in term neonates, however its use and benefits in preterm infants has not been well studied. This project studied the respiratory effects of inhaled Nitric Oxide in preterm infants with hypoxemic respiratory failure. We hypothesize that inhaled nitric oxide is beneficial in preterm infants suffering from hypoxemic respiratory failure.

Methods: An IRB approved retrospective study analyzed infants admitted to the NICU from 1/2010 to 6/2022 who were less than 34 weeks and treated with 20 ppm of iNO. Ventilatory parameters were collected prior to, at initiation and for 24 hours after initiation of iNO and included ventilator settings, oxygen saturation, fraction of inspired oxygen (FiO2) and oxygenation index (OI). Values were documented every 1 hour for the first 4 hours, then every 2 hours for 8 hours, and every 4 hours for the next 12 hours of iNO use.

Results: A total of 98 preterm newborns were studied, with average gestational age 25.7 (± 2.9 weeks) and average birth weight of 797 (± 390 grams). Baseline FiO2 requirement immediately prior to initiation of iNO was 0.91 (± 0.18). Patients with PPHN confirmed on ECHO (N= 44) comprised 44.9%. Most of the surviving patients with PPHN on ECHO developed bronchopulmonary dysplasia. There was a significant decrease in FiO2 requirement (p < 0.001) and oxygen saturation (p=0.007) after 24 hours of iNO. There was no significant change in the Mean Airway Pressure (MAP) as a result of iNO treatment during the 24 hours (p= 0.768). There was also a significant improvement in Oxygenation Index (OI) over time while on iNO (p < 0.001).

Conclusion: Among preterm infants with hypoxemic respiratory failure, iNO use improved oxygen saturation, FiO2 requirement and OI in the first 24 hours. There was no improvement in MAP or other ventilator settings.