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Efficacy of refrigerated gel packs for therapeutic hypothermia in neonatal retrieval: a retrospective cohort study
  1. Rachel Morris1,2,
  2. Alex Harris1,
  3. Michael Stewart1,3,4,
  4. Rosemarie Boland1,5,6,
  5. Arun Sett1,4,5,7,8
  1. 1 Paediatric Infant Perinatal Emergency Retrieval, Royal Children's Hospital, Parkville, Victoria, Australia
  2. 2 Department of Neonatal Intensive Care, Singleton Hospital, Swansea, UK
  3. 3 Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
  4. 4 Neonatal Research, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
  5. 5 Department of Obstetrics, Gynaecology and Newborn Health, The University of Melbourne, Melbourne, Victoria, Australia
  6. 6 Clinical Sciences, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
  7. 7 Newborn Research Centre, Royal Women's Hospital, Melbourne, Victoria, Australia
  8. 8 Newborn Services, Joan Kirner Women's and Children's Sunshine Hospital, St Albans, Victoria, Australia
  1. Correspondence to Dr Rachel Morris, Neonatal Department, Singleton Hospital, Swansea, SA2 8QA, UK; rachel.morris6{at}


Objective To determine the efficacy of refrigerated gel packs in achieving and maintaining target temperature in neonates receiving therapeutic hypothermia (TH) for hypoxic ischaemic encephalopathy during neonatal retrieval.

Design Retrospective cohort study.

Setting Paediatric Infant Perinatal Emergency Retrieval, Victoria, Australia.

Patients 200 neonates treated with TH during retrieval between 1 January 2015 and 31 December 2020.

Interventions Active cooling with refrigerated gel packs or passive cooling.

Main outcome measures The primary outcomes were the proportion of neonates who achieved therapeutic cooling rectal temperature (33–34°C) within 6 hours of birth and maintained target temperature range once TH was achieved. Secondary outcomes included need for respiratory support, inotropes, anticonvulsant therapy, sedation and survival at 7 days of life.

Results 200 neonates received TH. Median gestational age was 39 weeks and median birth weight 3300 g. 120 (60%) were actively cooled with refrigerated gel packs and the remainder passively cooled. 121 neonates (61%) reached target temperature within 6 hours and 14 (7%) after 6 hours of birth. Of those who achieved target temperature, 38% were maintained in therapeutic cooling range for the remainder of the retrieval.

Conclusions Achieving and maintaining TH during neonatal retrieval with gel packs is challenging. Target temperature was not maintained in most neonates in this study. These findings support existing evidence favouring the use of servo-controlled cooling devices to optimise TH in the retrieval setting.

  • Neonatology
  • Neurology

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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  • X @ArunSett

  • Presented at These data were presented in abstract form during 2023 at the following conferences: Joint European Neonatal Societies, Perinatal Society of Australia and New Zealand, Australian and New Zealand Neonatal Network and the Jo Kent-Biggs NETS Retrieval Seminar.

  • Contributors RM and RB developed the concept and designed the study. RM and AH extracted the data and performed the analysis. All authors participated in data interpretation. RM, AH and AS wrote the first draft and all authors contributed to redrafting the manuscript and provided approval for the final version to be published. RM is responsible for the overall content as the guarantor.

  • Funding This study was supported by the Victorian Government Operational Infrastructure Support Program (Melbourne, Australia). AS is supported by a research grant from the Australasian Society of Ultrasound in Medicine (grant ID RG 2022/1), a PhD Scholarship from the Centre of Research Excellence in Newborn Medicine (NHMRC, Australia; GNT1153176) and the Research Training Program, University of Melbourne, Victoria, Australia.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.