(51) Characteristics of Extremely Low Gestational Age Newborns at High Risk of Developing Adverse Reaction Following Milrinone Administration and Associated Risk Factors

Background: Recently, there has been an increase in milrinone utilization in management of preterm neonates including in acute pulmonary hypertension and prevention of hemodynamic instability following patent ductus arteriosus (PDA) closure. However, the safety and dosing of milrinone among preterm population is poorly investigated.

Objectives: The primary aim was to characterize the safety of milrinone administration in the first 4 postnatal weeks.

Design/Methods: A retrospective cohort study was conducted at University of Iowa Neonatal Intensive Care Unit [2018 to 2020]. Infants born at a gestational age between 22 0/7-28 6/7 weeks who received milrinone administration in the first 4 postnatal weeks were included. The primary outcome was milrinone associated hypotension (diastolic BP [DBP] < 3rd percentile, drop in DBP >50% or need to initiate new cardiovascular agents in the 1st 6h after milrinone). Univariate analyses between hypotensive and non-hypotensive patients was performed.

Results: Thirty-four patients were included of whom 8 developed hypotension or needed initiation of new vasoactive agents following milrinone administration. Baseline neonatal characteristics suggested that those in hypotensive group were younger at the time of milrinone initiation [postmenstrual age (PMA) 27.3 vs 28.8 wk., (p=0.015)] and were on more likely to be on cardiovascular support prior to milrinone. Moreover, their disease trajectories showed worse oxygenation efficacy with higher respiratory severity score (RSS) during the first 4 hours of milrinone initiation (p=0.039).

Conclusions: In this cohort study, the use of milrinone in extremely preterm infants already receiving significant cardiovascular support was associated with systemic hypotension, particularly at younger PMA. These findings highlight the importance of close hemodynamic monitoring and physiologic based targeted utilization of milrinone in such vulnerable populations. Further studies are warranted to better define the safety profile and optimal use parameters of milrinone in extremely preterm infants.