Objective To examine the influence of timing of initiation of therapeutic hypothermia (TH) on brain injury on MRI and on neurodevelopmental outcomes at 18 months.
Design Retrospective cohort study.
Setting Tertiary neonatal intensive care unit in Ontario, Canada.
Patients Ninety-one patients with hypoxic ischaemic encephalopathy (HIE) were included, 54 in the early TH group and 37 in the late TH group.
Intervention Whole-body hypothermia administered for 72 hours, initiated either before 3 hours of life (early TH) or between 3 and 6 hours of life (late TH).
Main outcome measures Brain injury on MRI after TH (assessed by two neuroradiologists), and neurodevelopmental outcomes at 18 months old.
Results TH was initiated at a median time of 1.4 hours (early TH) and 4.4 hours (late TH). Sixty-four neonates (early TH=36, late TH=28) survived and completed neurodevelopmental assessment at 18 months. Neonates in the early TH group received more extensive resuscitation than neonates in the late TH group (p=0.0008). No difference was observed between the two groups in the pattern or severity of brain injury on MRI, or in the neurodevelopmental outcomes at 18 months. The non-survivors (n=16) had lower Apgar scores at 10 min, more extensive resuscitation, suffered from more severe HIE and had significantly more abnormal cerebral function monitoring.
Conclusion In this retrospective cohort study, TH initiated early was associated neither with a difference in brain injury on MRI nor better neurodevelopmental outcomes at 18 months.
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Contributors MG collected, analysed and interpreted the data, and drafted and revised the manuscript. MP collected the data and reviewed the manuscript. EM, JD, NBF and SR conceptualised and designed the study, acquired and interpreted the data, and reviewed the manuscript. NJB and MAH analysed and interpreted the data, and reviewed the manuscript. BL conceptualised and designed the study, collected and interpreted the data, provided study supervision, and reviewed and revised the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the Institutional Research Ethics Board.
Provenance and peer review Not commissioned; externally peer reviewed.
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