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CDHB

Hypothermia

Definition:

• Mild: temperature 32-35^oC (shivering)
• Moderate: temperature 30-32^oC (unable to shiver)
• Severe: temperature 25-30^oC (<28^oC high risk for ventricular fibrillation)

A low reading core temperature probe is required (e.g., rectal). Standard thermometers do not go below 35^oC.

Initial assessment and resuscitation

• Airways, Breathing, Circulation: warmed, humidified oxygen
  • Warmed IV fluid may be required but be cautious as fluid overload can occur.
  • Defibrillation and antiarrhythmic drugs are less effective at low body temperatures.
  • Vital organs are protected by hypothermia.
  • CPR should not be abandoned until the patient has been warmed beyond 32^oC (the patient is not dead until he or she is "warm and dead").
  • Remove any wet/cold clothes.
• Simple rewarming is the method of choice:
  • Warmed dry blankets. The "Bair Hugger" warm air blanket is available in ICU and in ED.
  • Warmed humidified oxygen.
  • Warmed IV fluids - contribute little to rewarming but will help prevent further cooling by cold IV fluids. Limit the IV fluid volume unless hypovolaemic.
  • Overhead warming device e.g., Fisher & Paykel.
  • Active internal rewarming - invasive methods of warming (cardiopulmonary bypass is the ideal in this circumstance; warmed gastric lavage is the most practical), are only indicated in the patient with severe hypothermia and refractory cardiac arrest in whom an adequate circulation cannot be maintained. Use only at the discretion of the Consultant.

Complete assessment

History - three general types

• The healthy person with exposure to extreme cold e.g., immersion.
• The healthy person with exposure to cold after ingestion of drugs or alcohol.
• The patient with underlying disease who may have been exposed to only moderate cold e.g., the elderly, occult sepsis, the inactive, cerebrovascular disease, trauma, cardiovascular disease, diabetic ketoacidosis, hypoglycaemia etc.

Examination, Investigations: for traumatic injuries, underlying disease and complications of cold. Complications may include pulmonary oedema, bradycardia, hypotension and ventricular arrhythmias.

Definitive management

• Moderate/severe hypothermia is best managed in ICU.
• Treatment of the underlying disease and complications, including antibiotics if suspicious of sepsis.
• Hypothermia is 100% reversible, i.e., the patient has the potential to return to exactly the condition they were in prior to becoming cold.

Topic Code: 1276