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Neonatal asphyxia is a major health issue globally. In developed countries asphyxia affects 3-5 per 1000 live births. Subsequent development of moderate to severe hypoxic-ischaemic encephalopathy (HIE) occurs in 0.5- 1 per 1000 live births, with up to 60% of these babies dying during the neonatal period and 25% of survivors having major long term neurodevelopmental problems.
Many experimental animal models and systematic reviews of randomised controlled trials have shown that both whole-body hypothermia and selective head cooling has a neuroprotective effect. It modifies the cells programmed for apoptosis leading to their survival.
Hypothermia may also protect neurons by reducing cerebral metabolic rate. Therapeutic hypothermia aims to lower the temperature of the vulnerable deep brain structures to 33-34°C. Hypothermia is not without risk and thus it is important to manage the patient safely during induction and maintenance of hypothermia and during the rewarming process.
The aim of this guideline is to describe the management of a patient undergoing therapeutic hypothermia in the NICU.
≥ 35 weeks gestational age and more than 1.8kgs.
< 6hrs post birth
Evidence of asphyxia as defined by the presence of at least two of the following four criteria:
Assessment of relative contraindications/not moribund and with plans for full care. For example: uncontrolled pulmonary hypertension, uncontrolled clinical coagulopathy (i.e. active bleeding), major congenital abnormalities, survival appears unlikely (this should be discussed with a tertiary neonatologist or a PIPER Consultant). PPHN should not be considered a contraindication to commencing therapeutic hypothermia for HIE.
Clinically defined moderate or severe HIE (stage 2 or 3 based on modified Sarnat Classification). The presence of moderate/severe HIE is defined as seizures OR presence of signs in at least three of the six categories below:
Scale for Hypoxic Ischemic Encephalopathy
Table adapted from Sarnat el al Pediatric Neurology 113 (2020) 75-79
6. Moderate to severely abnormal background activity on amplitude-integrated EEG i.e. discontinuous, burst suppression or low voltage +/-
7. At the neonatal consultant’s discretion to commence therapeutic cooling
The aim of cooling is to achieve the target temperature within 1 hour of commencement (rectal temperature between 33.0°C – 34.0°C). The total period of cooling and rewarming is for 84 hours, consists of 2 phases:
Continuous ECG, BP, SaO2, ETCO2 monitoring
Close neurological observation
Access: Site lines prior to cooling as perfusion will diminish: Preferably double lumen UVC and UAC/ peripheral arterial line.
Blood tests: ABG, Electrolytes, LFTS, Glucose, Coagulation, FBE
Fluids: Most infants are fluid restricted to avoid fluid overload and cerebral oedema.
Sedation: Infants may require a low dose morphine infusion to optimise comfort and efficacy of the cooling process. Monitor comfort using modified pain assessment tool (mPAT).
Complications are more likely to occur or worsen with lower temperatures. Avoid overcooling the patient.
Explain to family the reasoning for using hypothermia and the expected length of treatment. Explain to family that their baby will feel cold for the duration of the treatment and reassure them that their baby will be kept comfortable during the treatment. Encourage bonding by allowing parents to touch their baby, do
nappy changes etc.
The evidence table for this guideline can be found here.
Please remember to read the
The development of this nursing guideline was coordinated by Alison Kendrick, Clinical Nurse Educator, Butterfly Ward, and approved by the Nursing Clinical Effectiveness Committee. Updated January 2023.