129 - Transitional Hypotension in Extremely Premature Neonates and Biomarkers of Brain Injury: Prospective Cohort Pilot Study

Current definitions of transitional hypotension (THN) in extremely premature neonates (EPNs) lack consensus. Management of THN may be associated with adverse neurodevelopmental outcomes. Little is known regarding biomarkers of neurologic injury (BNI) among EPNs with THN.

Objective: Characterize THN in EPNs using high-resolution mean arterial pressure (hrMAP) and determine whether relationships exist between THN and BNI.

Design/Methods: We conducted a pilot, prospective, cohort study from July 2021 through June 2022 among EPNs admitted to the Johns Hopkins All Children’s Hospital NICU. This report aims to describe the feasibility of enrollment and collection of urine specimens. We also aim to report clinical characteristics and hrMAP (sampled through indwelling umbilical arterial catheter) of the cohort. Urine samples were collected at < 12 hours, 24-, 48- and 72-hours of life (HOL) in EPN. Biospecimens were cryopreserved for future analysis of BNI S100B, Adrenomedullin and Activin A using commercially available ELISA kits. Descriptive statistics were employed.

Results: A total of 24 EPNs were enrolled (12.5% consented prenatally and 87.5% postnatally) of 26 eligible. For the study sample, 12(50%) were male with mean (standard deviation) gestation of 25.3(1.6) weeks and weight 763.96(217.16) grams, 18.2% were growth restricted. Antenatally, 45.8% received complete betamethasone course, 75% magnesium sulfate and 79.2% antibiotics. In the delivery room, delayed cord clamping occurred in 58.3% and 87.5% were endotracheally intubated with mean Apgar scores of 3.1 and 4.9 at 1- and 5- minutes respectively. 14(58%) received fluid resuscitation (blood products and/or crystalloid infusion) in the first 24 HOL while 7(29.2%) received inotropes. hrMAP was collected for the first 72 HOL and analyzed on both a cohort and individual patient level. hrMAP was stratified per 24-hour increment with lowest MAP occurring in the first 24 HOL. 7(29%) neonates suffered from severe outcomes (grade III/IV IVH and/or death). Those with severe outcomes spent 18.1% of the first 24 HOL at MAP < 25 compared to 3.7% of those without. 74 of anticipated 96 urine samples (77%) were collected with 17/24 (71%) patients having at least 3 samples, all within the pre-specified timeframe for BNI analysis.

Conclusion(s): We found high enrollment rates facilitated by prenatal and delayed consenting and limited protocol deviations related to urine sampling. High resolution physiometric data revealed lowest MAP occurred in the first 24 HOL corresponding with multiple blood pressure interventions, primarily in the form of volume resuscitation.