Hypothermia

Disclaimer

These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.

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Aim

To guide Emergency Department (ED) staff with the assessment and management of hypothermia.

Definition¹

Hypothermia is core temperature < 35°C. Young children are at risk due to high body surface area to weight ratio.

Background

Hypothermia is usually due to environmental causes e.g. immersion and exposure.
Check core temperature using a rectal or oesophageal thermometer.
Be aware that sepsis may present with hypothermia. Refer to Sepsis Recognition and Management (ED Guideline)
Younger children are more susceptible to hypothermia than adults due to large body surface area to mass ratio, different physiological responses to cold and lower stores of glycogen.
Hypothermia may complicate other presentations – for example leading to a worsening coagulopathy in trauma related presentations.
Consider toxins or endocrine dysfunction as a cause of unexplained hypothermia.

Effects of hypothermia²

Temperature	Clinical effects
32°C	Decreased pulse, respiratory rate, blood pressure and/or conscious state Shivering stops. Muscle rigidity (may mimic rigor mortis) Atrial arrhythmias appear – usually innocent and revert when rewarmed
28°C	Ventricular arrythmias (including VF) Fixed dilated pupils
26°C	Comatose Absent reflexes Apnoea
20°C	Asystole
15°C	Temperature of the coldest known survivor

Hypothermia in resuscitation

Hypothermia substantially reduces effectiveness of defibrillation and resuscitation drugs. It is reasonable to attempt defibrillation, but if unsuccessful, continue cardiac compression until core temperature is > 30°C, when defibrillation / drugs are more likely to be effective.
Drugs are generally withheld until core temperature is >30°C, as accumulation may occur while cold, with resultant toxicity when rewarmed.
Never diagnose death and thus stop resuscitation until the patient is rewarmed to at least 32°C or cannot be rewarmed despite active measures. Discuss eligibility for extracorporeal membrane oxygenation with Paediatric Critical Care.³

Assessment

Monitor core temperature
Monitor heart rate and rhythm with a 12-lead ECG and rhythm followed by continuous cardiac monitoring.
Check glucose.
Laboratory tests – Full Blood Count (FBC), Urea, Electrolytes and Creatinine (UEC), calcium, magnesium, phosphate, lipase, coagulation profile. If anticipating extracorporeal warming requires blood group and crossmatch.
Unexplained or resistant hypothermia – consider endocrine disorders and screen with thyroid function, Adrenocorticotropic hormone (ACTH) and serum cortisol levels.

Management^1,2,4,5,6

Important Principles

Follow Advanced Paediatric Life Support
Actively rewarm to 32°C, then allow passive rewarming. Once above the fibrillation threshold (32°C) there is no urgency in rewarming
Mild brain hypothermia may limit reperfusion injury
Avoid hyperthermia (keep temperature < 36.5°C)
Beware: rewarming may lead to vasodilation and hypotension (so-called 'after shock'), which can contribute significantly to mortality. Aim to warm no faster than 1-2 ºC per hour
Beware: Peripheral rewarming and vasodilation can result in cold, acidotic blood being shunted to the core, with a drop in core temperature (so-called 'after drop') and an increased risk of arrhythmias
Hypokalaemia is common, even in the presence of marked acidosis
Treat hypoglycaemia with intravenous (IV) dextrose.
Check blood gases, potassium, glucose, and haematocrit with every few degrees of warming.

External rewarming (for temperature > 32°C)

Passive external rewarming:
- remove wet clothes, dry patient
- warm blankets
- cover with sheet of foil / space blankets
Active external rewarming (truncal areas only):
- overhead warmers
- warm air system e.g. 3M^™ Bair Hugger^™
- thermal mattresses.

Active core rewarming (for temperature < 32°C)

Warm IV fluids to 39°C with blood warmer (slow) - start with pre-warmed IV sodium chloride 0.9% at 40°C
Gastric or bladder lavage with sodium chloride 0.9% at 40°C
Peritoneal lavage with potassium-free dialysate or sodium chloride 0.9% at 40°C. Use 20 mL/kg cycled every 15 minutes
Ventilation with humidified gas heated to 42°C
Pleural or pericardial lavage
Haemodialysis, extra-corporeal blood warming.

Nursing considerations

Aim to warm no faster than 1-2 ºC per hour (NB: Rapid rewarming may cause vasodilation and consequently hypotension.)^1,2
Monitor the patient’s temperature 15-30 minutely via axilla / tympanic thermometer or continuously with the CovidienTM Mon-A-ThermTM General Purpose Temperature Probes available in ED or reusable or single use Phillips™ oesophageal temperature probe available in Paediatric Critical Care (PCC) (refer to PCC targeted temperature management).
Lower the temperature setting of the Bair Hugger™ if the patient is warming too quickly.
Turn off Bair Hugger™ once normothermia is reached. The blanket may be left in situ.
Skin must be inspected 1-2 hourly for potential thermal and pressure injury.
Patients must be kept dry as warming will be less effective if patient is damp³
Eyes should be protected by lubricant or patches when overhead warming devices in use ³

References

Corneli HM, Kadish H, Hypothermia in Children. UpToDate. Clinical Manifestations and Diagnosis. UpToDate. ] [cited 08 Jun 2026]. Available from: Hypothermia in children: Clinical manifestations and diagnosis - UpToDate
Hazinski, M F. Nursing Care of the Critically Ill Child. 3rd Ed. Missouri: Elsevier Mosby; 2013.
Acworth J, Nuthal G, Aickin R (2021) ANZCOR Guideline 12.4 – Paediatric resuscitation in special circumstances. [Cited 08 Jun 2026]. Available from: guideline-12-4-paediatric-resuscitation-in-special-circumstances-257.pdf
Hockenberry, M J, Wilson, D. Wong’s Nursing Care of Infants and Children. Ed 12. Missouri: Elsevier Mosby; 2023.
McCullough L, Arora S. 2004. [Cited 08 Jun 2026]. "Diagnosis and treatment of hypothermia". Am Fam Physician. Available from: Diagnosis and Treatment of Hypothermia | AFP
Cameron, P, Brown G, Biswadev M, Dalzel S, Craig S. Textbook of Paediatric Emergency Medicine 4th Ed.Elselvier. 2023.
Kliegman, R, Geme III, J. Nelson Textbook of Pediatrics: 21st Ed.Elseliver. 2019

Endorsed by:	Co-director, Surgical Services (Nursing)	Date:	Jun 2026
		Review date:	Jun 2029

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