311 - Therapeutic Hypothermia in Preterm Infants with Presumed Hypoxic-Ischemic Encephalopathy: A Comparative Cohort Study at a Neurocritical Care Unit

Publication Number: 311.6593

Alejandra Martinez Valderrama, The Hospital for Sick Children, Toronto, ON, Canada; Brian T. Kalish, Boston Children's Hospital, Boston, MA, United States; Amr El Shahed, The hospital for Sick Chikdren, Toronto, ON, Canada; Vann Chau, The Hospital for Sick Children, Toronto, ON, Canada; Emily W.Y.. Tam, The Hospital for Sick Children, Toronto, ON, Canada; Rhandi Christensen, The Hospital for Sick Children, Toronto, ON, Canada; Diane Wilson, Hospital for Sick Children, Toronto, ON, Canada; Anjana Ravi Chandran, The Hospital for Sick Children, Toronto, ON, Canada; Benjamin Banh, The Hospital for Sick Children, Toronto, ON, Canada; Ignacio Beamonte Arango, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Canarias, Spain; Wael Abdelmageed, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada; Linh G. Ly, University of Toronto Temerty Faculty of Medicine, Toronto, ON, Canada; Mehmet N.. Cizmeci, The Hospital for Sick Children, Toronto, ON, Canada

Background: In infants with perinatal hypoxic-ischemic encephalopathy (HIE) born at < 36 weeks, the efficacy and safety of therapeutic hypothermia (TH) remain unclear.

Objective: To compare the mortality rates, laboratory parameters, systemic complications, electrographic data, and neurodevelopmental outcomes at 18 months corrected age between two cohorts of neonates with perinatal HIE treated with TH.

Design/Methods: This observational comparative cohort study included all infants admitted to the neurocritical care unit from January 2015 to December 2023. The cohort was divided into two groups: Group 1 consisted of preterm infants born between 33 0/7 and 35 6/7 weeks GA, while Group 2 comprised early-term to near-term infants born between 36 0/7 and 37 6/7 weeks GA. Data collected included mortality rate, hemodynamic instability requiring inotropes, hypoxic respiratory failure, documented hypoglycemia, hyperglycemia, coagulopathy, acute kidney injury, elevated liver enzymes, normalization time of electrographic background and the emergence of sleep-wake cycling on amplitude-integrated electroencephalogram (aEEG), and presence of electrographic seizures on cEEG. Neurodevelopmental outcomes were evaluated at 18 months corrected age using standardized tests.

Results: A total of 123 infants were included, with 64 in Group 1 and 59 in Group 2 (median 35.14 weeks [IQR 0.71] vs. 37.14 weeks [IQR 1.0]; p< 0.001; respectively). Group 1 showed a lower cord arterial pH (median 6.9 [IQR 0.27] vs. 7 [IQR 0.28]; p=0.03), a higher Thompson score (median 10 [IQR 2] vs. 9 [IQR 3]; p=0.01), higher rates of hemodynamic instability (66% vs. 32%; p< 0.001), hypoglycemia (56% vs. 36%; p=0.03), and longer hospitalization (median 8 days [IQR 8] vs. 6 days [IQR 4]; p=0.02). Although the aEEG backgrounds within the first 24 hours and normalization of the background rates were similar between groups (p=0.1 for both), Group 1 had lower rates of sleep-wake cycling on aEEG within 72 hours (20% vs. 46%; p=0.01). There was a trend toward higher mortality in Group 1 (25% vs. 12%; p=0.06). Neurodevelopmental outcomes were similar between groups for all domains (p>0.05 for all), and the rate of cerebral palsy was comparable (7% vs. 3%; p=0.5).

Conclusion(s): Preterm infants with HIE treated with TH and born at an earlier gestational age experienced more systemic complications compared to those born at a later gestational age. Although, these infants may face greater challenges than their more mature counterparts, they likely do not show significant differences in neurodevelopmental outcomes.

Table 1: Clinical characteristics and comorbidities of the study population
Table 1.2.pdfaMann-Whitney U test, bFisher’s exact test.
Data are presented as median (interquartile range) or number (%).


Table 2: Electrographic findings and neurodevelopmental outcomes.
Table 2.2.pdfaFisher’s exact test, bMann-Whitney U test. Data are numbers (%) or median (interquartile range)
aEEG: Amplitude-integrated electroencephalography, cEEG: Continuous electroencephalography.


Table 1: Clinical characteristics and comorbidities of the study population
Table 1.2.pdfaMann-Whitney U test, bFisher’s exact test.
Data are presented as median (interquartile range) or number (%).


Table 2: Electrographic findings and neurodevelopmental outcomes.
Table 2.2.pdfaFisher’s exact test, bMann-Whitney U test. Data are numbers (%) or median (interquartile range)
aEEG: Amplitude-integrated electroencephalography, cEEG: Continuous electroencephalography.