Hypothermia, Accidental

Author: Michelle Lin, MD
Updated: 2/4/2011

Hypothermia, Accidental

Stages of Hypothermia


32.2-35°C (90-95°F)

Early Stage Decompensated Stage
Hypertenstion Apathy/Impaired Judgment
Tachycardia Ataxia
Shivering Cold diuresis-kidneys unable to concentrate urine
Vasoconstriction Hypovolemia


28-32.2°C (82.4-90°F)

Clinical Findings
Atrial dysrhythmias
J wave on ECG
Hypotension, bradycardia
Diminished gag reflex
Loss of shivering

J-wave example


<28°C (<82.4°F)

Clinical Findings
No activity on EEG
Fixed pupils
Pulmonary edema
Ventricular dysrhythmias


  • Many thermometers do not measure below 34.4°C (94°F). Need special low-tempsensing rectal or bladder thermometers.
  • Avoid jostling the hypothermic patient too much because of myocardial irritability and consequent arrhythmias.

Direct complications from hypothermia and rewarming

  • Rhabdomyolysis
  • Acute tubular necrosis and renal failure
  • Electrolyte shifts, especially K+ because of acid-base changes during rewarming
  • Hypoglycemia from depleted glycogen stores
  • Functional coagulapathy: May have normal coag studies because have to be rewarmed to run the assay

Rewarming approaches

  1. Passive Rewarming: Remove cold, damp clothes. Wrap with blankets.
  2. Active External Rewarming: Apply heat to skin

    • Heating blanket or radiant heat
    • Hot water bottles or heating pads to truncal surfaces. Caution-- do not burn skin.
    • Risk of “Core Temperature Afterdrop”, vasodilation with active external rewarming causes cold peripheral blood to return to heart. Give warm IV fluid beforehand.
    • Risk of “Rewarming Acidosis”. Lactate from periphery returns to core circulation. May cause transient shock during rewarming.
  3. Active Core Rewarming

    • Humidified air, 40°C (104°F) – increases core temp by 1-2.5°C (1.8-4.5°F) per hr
    • Warm IV fluids at 40-45°C
    • Cardiopulmonary bypass or hemodialysis, Increases core temp by 1-2°C (1.8-3.6°F) every 3-5 minutes
    • Warm fluid lavage of stomach, colon, bladder, pleural space
    • Peritoneal dialysis. Normal saline at 40-45°C at 6-10 L/hr increases core temp by 1-3°C (1.8-5.4°F) per hour when combined with heated oxygen.
    • Mediastinal lavage via open thoracotomy

Choosing a rewarming approach

General approach

  • Check glucose.
  • Consider thiamine 100 mg IV, esp if chronic EtOH at risk for Wernicke’s
  • Treat underlying etiology for hypothermia
  • Give antibiotics +/- steroids, as appropriate

If patient in cardiopulmonary arrest

  • Intubate, CPR, ACLS protocol
  • Warm IVF
  • Heated humidified oxygen
  • Extracorporeal rewarming (i.e. cardiopulmonary bypass), if not immediately available, do active core rewarming measures
  • Rewarm to target temperature >30°C (86°F)

If NOT in cardiopulmonary arrest AND temperature <32°C (89.6°F)

  • Active External Rewarming (i.e. Bair Hugger, warm blankets), and
  • Minimally invasive Active Core Rewarming (warm IVF, warm air)

If NOT in cardiopulmonary arrest AND temp ≥32°C (89.6°F)

  • Passive external rewarming measures


  • McCullough L, Arora S. Diagnosis and treatment of hypothermia. Am Fam Physician. 2004 Dec 15;70(12):2325-32. [PubMed]