269 - Blood Pressure Trajectories and Brain Injury in Neonates with Hypoxic-Ischemic Encephalopathy Undergoing Therapeutic Hypothermia

Publication Number: 4265.269

Clara I. McNair MacNeil, The University of Western Ontario - Arthur Labatt Family School of Nursing, London, ON, Canada; Ahmed Al Farsi, LHSC, LONDON ONTARIO CANADA, NY, United States; Abdullah Aljughaiman, KSAU-HS, Al Ahsa, Ash Sharqiyah, Saudi Arabia; Andrea C. De La Hoz, London Health Sciences Center Research Institute, London, ON, Canada; Yasmine Sallam, McMaster University Michael G. DeGroote School of Medicine, Burlington, ON, Canada; Lilian M. N. Kebaya, University of Toronto Temerty Faculty of Medicine, Toronto, ON, Canada; Michael Miller, The University of Western Ontario - Schulich School of Medicine & Dentistry, London, ON, Canada; Renjini Lalitha, University of Western Ontario, London, ON, Canada; Soume Bhattacharya, Western University, London, ON, Canada

Background: Hypoxic-ischemic encephalopathy (HIE) is a leading cause of neonatal mortality and long-term neurodevelopmental impairment. Therapeutic hypothermia (TH) is the standard treatment for moderate-to-severe HIE, yet 40–50% of treated infants still demonstrate abnormal brain MRI findings. Optimal blood pressure (BP) targets during TH remain uncertain. Early inotrope exposure has been associated with brain injury; however, causal relationships and BP trajectory differences among affected neonates are not well understood.

Objective: To compare blood pressure trajectories during TH and rewarming between neonates with and without MRI-confirmed brain injury and examine associations among inotrope use, BP parameters, and cumulative exposure to low BP states with presence of MRI-defined brain injury.

Design/Methods: This retrospective cohort study included term and near-term neonates with HIE treated with TH at a Canadian tertiary NICU (2002–2019). Demographic and clinical data were extracted. Hourly BP measurements were recorded during 72-hour cooling and 6-hour rewarming phases, converted to centiles using published reference charts. Brain MRI performed on days 3–4 was scored using a standardized system. Associations between BP exposure and MRI-defined injury were analyzed using linear mixed-effects and multivariate regression models, adjusting for encephalopathy severity and covariates.

Results: Among 104 infants, 43 (41%) demonstrated MRI evidence of brain injury.( Table 1 ) The injury group had significantly lower systolic BP (SBP) throughout cooling and rewarming despite greater inotrope use; and spent more time below the 5th and 25th BP centiles. (Table 2) Among inotrope-treated infants, those with brain injury had lower SBP at 48–72 hours (61.8 ± 8 vs. 68.5 ± 7 mmHg, p = 0.046). In infants not receiving inotropes, those with injury also had lower mean SBP (64.7 ± 7 vs. 67.9 ± 6.3 mmHg, p = 0.043). Multivariate analysis identified gestational age (OR 0.60, 95% CI 0.41–0.88, p = 0.009) and cumulative time below the 5th BP centile (OR 1.053, 95% CI 1.01–1.10, p = 0.011) as independent predictors of brain injury.

Conclusion(s): Neonates with HIE who develop MRI-confirmed brain injury exhibit persistently lower BP during TH and rewarming. Regardless of inotrope use, lower SBP between 48–72 hours was seen in neonates brain injury. Prolonged exposure to BP below the 5th centile independently predicted MRI-defined injury. These findings will help refine hemodynamic management and BP targets during TH to enhance neuroprotection in this vulnerable population.

Table 1. Baseline clinical and demographic data in neonates with and without brain injury .
BP MRI Table 1.pdf

Table 2: Blood pressure differences during therapeutic hypothermia and rewarming in patients with brain injury and without brain injury
Table 2 BP and MRI injury.pdf

Figure 1 :Proportion of Time Spent in Pre – Specified Blood pressure centile.
Figure 1.pdf