Accidental Hypothermia Management

Aka: Accidental Hypothermia Management, Hypothermia Management

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II. Precautions

  1. ECMO is preferred management for severe Hypothermia (<28 C) or severe Cardiac Dysrhythmia (e.g. Asystole)
  2. See Hypothermia for related complications (e.g. Rhabdomyolysis)
  3. There is no single core Temperature cut-off that contraindicates Resuscitation (13.7 C patient has survived)
  4. Anticipate malignant Arrhythmia on rewarming (rescue collapse)
    1. Avoid measures that provoke Arrhythmias (e.g. jostling or moving patient)
    2. Be prepared for recurrent Arrhythmia
    3. Continuous monitoring and Defibrillator pads kept in place
    4. Most non-lethal Arrhythmias (e.g. Atrial Fibrillation) resolve with rewarming

III. Management: Field Triage

  1. Initial measures
    1. Immediately move to warm environment
    2. Cut off or remove all wet and cold clothing and apply warm blankets
    3. Start warmed IV fluids and warmed, humidified oxygen
  2. Mild Hypothermia
    1. Initiate Passive Rewarming and Active External Rewarming
    2. Transport to hospital if any associated injury (e.g. Frostbite, Trauma, Drowning)
  3. Moderate to severe Hypothermia
    1. Initiate passive and Active External Rewarming
    2. Patient should remain supine and avoid exertion (to prevent core Temperature after-drop)
    3. Transport to hospital capable of invasive rewarming
    4. If hemodynamic instability or core Temperature <82 F (28 C)
      1. Transport to ECMO capable facility if available (otherwise to nearest hospital with ICU)

IV. Management: Severe Hypothermia

  1. Hypothermic patient in pulseless arrest
    1. Consider contraindications to Resuscitation below (futile circumstances)
    2. Follow cardiopulmonary arrest algorithm below
    3. Expedite transfer to ECMO center
    4. Initiate rewarming as per protocol below
    5. Consider adjunctive measures (e.g. Intravenous Fluids) as described below
  2. Hypothermic patient with perfusing rhythm
    1. Consider transfer to ECMO center (see indications below)
    2. Initiate rewarming as per protocol below
    3. Consider adjunctive measures (e.g. Intravenous Fluids) as described below
    4. Treat Hypotension with warmed Intravenous Fluids
      1. Hypotension is typically due to Vasoconstriction and cold diuresis
      2. Significant Fluid Replacement (2-5 Liters) may be required to Restore normotension
      3. Vasopressors should only be considered after aggressive rehydration has failed to correct Hypotension

V. Contraindications: Pulseless, asystolic patients for whom Resuscitation efforts are futile

  1. Cardiac Arrest occurred prior to cooling (based on good history)
  2. Core Temperature >89.6 F (32 C) and still in asystolic rhythm
  3. Patient is so frozen that the chest can not be compressed
  4. Serum Potassium >12 mEq/L and pulseless
  5. Blunt Traumatic pulseless arrest (<1% survival)
  6. Complete SubmersionDrowning in pulseless adults (Hypoxia precedes cooling)
    1. Case reports of children surviving Submersion for >1 hour, core Temperature 66 F (19 C) with CPR, ECMO
    2. Immersion Drowning in water (head above water, not hypoxic) has a better prognosis
  7. Pulseless Avalanche victim buried less than 35 minutes or with massive Trauma or airway impacted with snow
    1. Body cooling under an Avalanche occurs at a rate of 18 F/hour (10 C/hour)
    2. Patients buried for greater than 35 minutes will have a core Temperature <89.6 F (32 C)
      1. May achieve ROSC with rewarming

VI. Management: ECMO or Cardiopulmonary Bypass (CPB)

  1. Indications
    1. Hypothermia (core Temperature <32 C or 89.6 F) and cardiac instability (including Cardiac Arrest)
    2. Systolic Blood Pressure <90 mmHg
    3. Ventricular Arrhythmia (including Asystole)
    4. Core Temperature <28 C (82.4 F)
  2. Efficacy
    1. Preferred method with best outcomes
    2. Raises core Temperature by 1.8 - 3.6 F (1-2 C) per 5 minutes (or 12 to 18 F, 7 to 10 C per hour)
    3. Best evidence of any intervention in severe Hypothermia
      1. Pulseless hypothermic patients have 50% survival with ECMO (especially if transport to ECMO Center <6 hours)
      2. Contrast with 10% survival rate in pulseless arrest hypothermic patients treated without ECMO
  3. Modalities
    1. Cardiopulmonary bypass
    2. Arteriovenous or venovenous rewarming
    3. Hemodialysis

VII. Management: Cardiopulmonary Arrest

  1. Feel for a pulse for 1 minute at femoral or carotid (weak, slow pulses are common)
  2. Start CPR Immediately unless Resuscitation is clearly futile (see contraindications above)
    1. Maintain high quality CPR until adequately perfusing rhythm or Resuscitation efforts halted (after rewarming)
    2. Do not delay CPR while seeking a weak pulse (previously recommendations were to palpate pulse for 45 seconds)
    3. Benefits of perfusion from high quality CPR outweigh the risks of induced Arrhythmia
  3. Pulseless Dysrhythmia management while hypothermic (<32 C or 89.6 F)
    1. Defibrillation (when indicated) is often unsuccessful at core Temperature <86 F (30 C)
      1. Attempt Defibrillation at maximum joules at lower Temperature
      2. Reattempt Defibrillation once Temperature increases above 86 F (30 C)
    2. Follow ACLS algorithm but do not persist with unsuccessful interventions until Temperature >32 C or 89.6 F
      1. Resume standard ACLS protocol once core Temperature >32 C or 89.6 F
      2. Hypothermia should no longer be the sole cause of Asystole, once core Temperature is above 32 C or 89.6 F
    3. Asystole
      1. Trial Epinephrine dose every 6 to 10 minutes or repeat after core Temperature increase of 5-10 C
      2. Resume standard ACLS protocol with Epinephrine every 3-5 minutes once core Temperature > 32 C or 89.6 F
    4. Ventricular Fibrillation or Pulseless Ventricular Tachycardia
      1. Trial Epinephrine dose every 6 to 10 minutes or repeat after core Temperature increase of 5-10 C
      2. Defibrillation trial at presentation
        1. Next repeat up to 3 times for every 1 to 2 C (or 1.8 to 3.6 F) increase
        2. Next repeat after core Temperature increase of 5-10 C
      3. Resume standard ACLS protocol for Defibrillation once core Temperature > 32 C or 89.6 F
  4. Rewarming
    1. Transfer to facility with ECMO or cardiopulmonary bypass capabilty (preferred, best outcomes) even if ROSC achieved
    2. See rewarming protocol below
    3. See Rewarming in Hypothermia
  5. Other measures
    1. See precautions above
    2. Advanced Airway (e.g. Endotracheal Intubation)
    3. Amplify QRS Complex on highest setting (typically low amplitude spikes in Hypothermia)
    4. Monitoring with End-Tidal CO2, Bedside Ultrasound
    5. Anti-arrhythmics are ineffective when core Temperature <86 F (30 C)
    6. Cardiac pacing may be used in refractory Bradycardia with Hypotension despite rewarming

VIII. Management: General Resuscitation

  1. Advanced Airway Management
    1. Secured airway and adequate oxygenation and ventilation are critical (but avoid hyperoxia)
    2. Same Advanced Airway indications for normothermic patients (regardless of myocardial irritability)
    3. Trismus refractory to paralytics may require Nasotracheal Intubation or Cricothyrotomy
    4. Endotracheal Tube cuff should be underinflated to allow for expansion with re-heating
    5. Use lower doses and longer intervals of Anesthetic and neuromuscular agents
    6. Decrease ventilation rates to 4-5 breaths per min with Advanced Airway (8-10 without)
      1. Maintains cerebral Blood Flow, and oxygen demand, CO2 retention is lower in Hypothermia
  2. Intravenous Access
    1. Femoral Central Line is preferred over IJ or Subclavian (less myocardial irritability risk)
    2. Initiate prompt volume replacement (preferably with warmed fluid)
      1. Most hypothermic patients are significantly hypovolemic
      2. Initiate dextrose containing fluids (e.g. D5LR or D5NS)
  3. Medications
    1. Medications should be delivered intravenously (not IM, SQ or PO/NG due to poor absorption)
  4. Hyperkalemia
    1. See Hyperkalemia Management
    2. Expect Hyperkalemia with rewarming
  5. Spontaneous Arrhythmia
    1. Reducing Risk
      1. Supplemental Oxygen (and adequate preoxygenation prior to intubation)
      2. Correct Electrolyte disturbance (e.g. Hyperkalemia) and acid-base disturbance
      3. Optimize acid-base status
    2. Atrial Arrhythmias
      1. Expect atrial Arrhythmias
      2. Atrial Arrhythmias resolve spontaneously on rewarming
    3. Ventricular Arrhythmias
      1. Transient ventricular Arrhythmias require no treatment
      2. Magnesium 100 mg/kg IV appears safe and may be effective
      3. Avoid class Ia and Ib agents (e.g. Procainamide, Lidocaine) due to worse outcomes in CT of Hypothermia
      4. Amiodarone has not been shown effective (but appears safe)
  6. Coagulopathy
    1. Clotting function significantly decreases at Body Temperature below 34 C (93.2 F)
    2. Risk of Disseminated Intravascular Coagulation, Gastrointestinal Bleeding and Pulmonary Embolism
    3. Coagulopathy improves with rewarming

IX. Management: Rewarming in mild to moderate Hypothermia (>28 C) without serious dyrhythmia

  1. See Rewarming in Hypothermia
  2. Remove wet clothing and apply warm blankets
  3. Do not suppress shivering
    1. Shivering is reflexive, effective method of rewarming
  4. Passive external rewarming
    1. May be all that is needed if core >89.6 F (32 C)
  5. Minimally-invasive active rewarming (see measures and protocols below)
    1. Warmed IV fluids
    2. Warmed, humidified oxygen
  6. Consider Active External Rewarming
    1. Forced air warming systems (e.g. bair hugger) are preferred

X. Management: Rewarming in Severe Hypothermia (<28 C) or severe Cardiac Dysrhythmia (e.g. Asystole)

  1. See Rewarming in Hypothermia
  2. ECMO planned within 6 hours
    1. See Indications above
    2. Avoid other invasive active rewarming methods if ECMO planned
    3. Active External Rewarming
      1. Forced-air warming systems (e.g. Bair Hugger)
    4. Minimally-invasive active rewarming
      1. Warmed IV fluids
      2. Warmed, humidified oxygen
  3. ECMO not available within 6 hours
    1. Consider expert Consultation
    2. See invasive active rewarming methods listed below
    3. Body cavity rewarming (Bladder lavage)
    4. Other methods to consider if available
      1. Peritoneal Dialysis (Peritoneal Lavage)
      2. Closed Thoracic Lavage
      3. Open thoracic lavage

XI. Management: Other measures

  1. Empiric Antibiotics if Sepsis suspected
    1. Elderly
    2. Neonatal Sepsis
    3. Immunocompromised patients
  2. Empiric therapies in a patient found down
    1. Thiamine if Alcohol Abuse suspected
    2. Dextrose if Glucose testing not immediately available
    3. Do not use empiric Corticosteroids
      1. Only indicated in suspected Adrenal Insufficiency
      2. May be used if Hypothermia refractory to all other measures

XII. References

  1. Bazzoli (2024) Crit Dec Emerg Med, Winter Edition, p 4-11
  2. Civitarese and Sciano (2018) Crit Dec Emerg Med 32(2): 3-16
  3. Herbert and Brown in Herbert (2014) EM:Rap 14(1):1-4
  4. Danzl in Marx (2002) Rosen's Emergency Med, p. 1979-96
  5. Danzl in Auerbach (2001) Wilderness Med, p. 135-77
  6. Zink (2020) Crit Dec Emerg Med 34(3): 19-27
  7. Brown (2012) N Engl J Med 367(2): 1930-8 [PubMed]
  8. McCullough (2004) Am Fam Physician 70:2325-32 [PubMed]

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