169 - Prognostic Value of Early Resistive Index in Neonates with Hypoxic-Ischemic Encephalopathy

Friday, April 28, 2023

5:15 PM – 7:15 PM ET

Poster Number: 169
Publication Number: 169.136

Erika E. Bartschat, Creighton University School of Medicine, Omaha, NE, United States; Elizabeth Lyden, University of Nebraska Medical Center, Omaha, NE, United States; Eric S. Peeples, University of Nebraska Medical Center, Omaha, NE, United States

Presenting Author(s)

Erika E. Bartschat (she/her/hers)

Student
Creighton University School of Medicine
Omaha, Nebraska, United States

Background: Head ultrasonography (HUS) is often used in infants with hypoxic-ischemic encephalopathy (HIE) to detect brain abnormalities that may alter management of the patient, but can also be used to measure resistive index (RI) which can be indicative of cerebral blood flow abnormalities. Prior to the standard use of therapeutic hypothermia, anterior cerebral artery RI was determined to be a strong predictor of outcomes after HIE, especially when performed within the first few hours after injury. Specifically, an RI < 0.6 was associated with increased death or severe neurodevelopmental disability. Recent studies have questioned the benefit of RI when obtained during hypothermic conditions but have only measured the RI at 12 hours or greater after injury.

Objective: To evaluate if RI measurements retain their efficacy as a prognostic indicator of negative outcomes when measured at NICU admission (≤6 hours of life).

Design/Methods: This retrospective cohort study included all infants born between 2012 and 2022, diagnosed with HIE and treated with therapeutic hypothermia. Patient demographics and clinical interpretation of the HUS and Doppler were recorded, including anterior cerebral artery RI values. RI values were analyzed both as a continuous variable as well as binary with RI< 0.6 versus ≥0.6. Recorded short-term outcomes included seizure incidence (determined by electroencephalography), clinical MRI interpretation, and death.

Results: Data were collected from 42 infants who met inclusion criteria. Demographic data were compared between those infants with RI< 0.6 and those with RI≥0.6 with no significant differences between groups. There were also no differences in the rates of brain injury on MRI, seizures, or death prior to discharge between newborns with RI< 0.6 compared to RI≥0.6. Mean RI values were not different between those with and without brain injury on MRI, seizures, or death (Fig. 1), though there was a trend toward lower RI values in infants with hemorrhage on MRI (p=0.076). There was also no significant correlation between the core body temperature at the time of HUS and the RI value, or between initial HUS results and the MRI results.

Conclusion(s):

No statistical difference was found in incidence of negative outcomes between infants with RI< 0.6 and those with RI≥0.6, nor clear correlation between initial HUS and MRI results. Although RI was not strongly correlated with body temperature at the time of HUS, this study suggests that the prognostic abilities of RI are decreased by hypothermia even when obtained early after injury.