Paediatric Acute care Guidelines PMH Emergency Department

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

Background

  • Hypothermia 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

General

Effects of hypothermia

32oC
  • Decreased pulse / respiratory rate / BP / conscious state
  • Shivering stops. Muscle rigidity (may mimic rigor mortis)
  • Atrial arrhythmias appear – usually innocent and revert when rewarmed
28oC
  • Ventricular arrythmias (including VF)
  • Fixed dilated pupils
26oC
  • Comatose
  • Absent reflexes
  • Apnoea
20oC
  • Asystole
15oC
  • 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.

Assessment

  • Monitor core temperature
  • Monitor heart rate and rhythm
  • Check electrolytes and glucose

Management

Initial management

Important Principles:

  • Actively rewarm to 32oC, then allow passive rewarming.  Once above the fibrillation threshold (32oC) there is no urgency in rewarming
  • Mild brain hypothermia may limit reperfusion injury
  • Avoid hyperthermia (keep temperature < 36.5oC)
  • Never diagnose death and thus stop resuscitation until the patient is rewarmed to at least 32°C, or cannot be rewarmed despite active measures
  • Beware: rewarming may lead to vasodilation and hypotension (so-called “after shock“), which can contribute significantly to mortality
  • 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
  • Check blood gases, potassium, glucose, and haematocrit with every few degrees of warming

Further management

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. 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 0.9% saline at 40ºC
  • Gastric or bladder lavage with 0.9% saline at 40°C
  • Peritoneal lavage with potassium-free dialysate or 0.9% saline 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

Routine nursing care.

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