Aim: We aim to describe some characteristics of premature neonates which may predict response to inhaled nitric oxide (iNO).
Methods: Neonates < 37 weeks without congenital abnormalities who received a single episode of iNO between January 2002 to December 2016 were included in this retrospective chart review. For the purposes of this study, we defined a response to iNO as being any reduction in fraction of inhaled oxygen (FiO2) at the time of iNO weaning.
Results: 52 infants with a 57.7% overall survival were included. There was no significant difference in survival between gender or birth weight groups. Responders were found to be of older gestational age (p = 0.045), had a longer duration of iNO treatment (p = 0.004), longer time to weaning (p = 0.014) and earlier initiation of treatment (p = 0.010). Infants < 1,000 g were less likely to respond to iNO therapy (p = 0.006) and had a higher FiO2 at weaning (p = 0.037). Gender had no effect on response to iNO therapy (p = 0.176). Infants with preterm premature rupture of membranes (PPROM) were treated for longer prior to weaning (p = 0.025), treated for longer overall (p = 0.005) and had a lower FiO2 at weaning (p = 0.018). There was no significant correlation between methaemoglobin level and duration of iNO (R = -0.08; p = 0.57).
Conclusions: We found that premature infants with birth weight > 1,000 g and older gestational age were more likely to respond to iNO therapy. Our findings also suggest that infants with PPROM may benefit from the use of iNO for respiratory distress. As a result, these findings support the individualized use of iNO in select premature infants whose premorbid characteristics deem them more likely to have a positive response.