Accidental hypothermia: Difference between revisions

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==Complications==
==Complications==
#Aspiration PNA
*[[Acid-base disorders]]
#DIC/Bleeding
*[[Aspiration pneumonia and pneumonitis|Aspiration pneumonia ]]
##Clotting factors are less effective
*Bleeding
#Ineffective Drugs
**Decreased platelet function and inhibition of coagulation cascade
##Protein binding increases as body temperature drops, and most drugs become ineffective
*[[Cold injuries]]
##Pharmacologic manipulation of the pulse and blood pressure generally should be avoided
*[[Dysrhythmias]]
##Orally meds poorly absorbed because of decreased gastrointestinal motility
*[[Disseminated Intravascular Coagulation (DIC)|Disseminated Intravascular Coagulation]]
##Intramuscular route avoided due to poor absorption from vasoconstricted sites
*[[Pancreatitis]]
*[[Rhabdomyolysis]]
*[[Thromboembolism]]
**Secondary to hemoconcentration, increased blood viscosity, and poor circulation
*Ineffective Drugs
**Protein binding increases as body temperature drops, and most drugs become ineffective
**Pharmacologic manipulation of the pulse and blood pressure generally should be avoided
**Orally meds poorly absorbed because of decreased gastrointestinal motility
**Intramuscular route avoided due to poor absorption from vasoconstricted sites


==See Also==
==See Also==

Revision as of 20:21, 25 August 2015

Background

Definition: Core Temp <35C (95F)

  • 50% who die of hypothermia are >65 years old

Swiss Hypothermia Staging System[1]

Classification Temperature Signs/Symptoms
I / Mild 32-35°C (90-95°F) Shivering, awake
II / Moderate 28-32°C (82-90°F) Shivering, depressed mental status
III / Severe 20-28°C (68-82°F) unconscious/severely depressed mental status, shivering ceases
IV / Profound <20°C (68°F) unobtainable VS

Differential Diagnosis

Impaired thermoregulation

Increased heat loss

Diagnosis

ECG

  • Typical sequence is sinus brady > a fib with slow ventricular response > v-fib > asystole
  • Other ECG findings:

Treatment

General

  • Handle pt gently
    • V-fib may be induced by rough handling of pt due to irritable myocardium (anecdotal)
  • O2
    • Hypothermia causes leftward shift of oxyhemoglobin dissociation curve
  • IVF
    • Reasons:
      • Hypothermia > impaired renal concentrating ability > cold diuresis
      • Pts are prone to rhabdo
      • Intravascular volume is lost due to extravascular shift
  • CPR
    • Only perform if pt truly does not have a pulse (unnecessary CPR may lead to V-fib)
    • Spend 30-45s attempting to detect respiratory activity and pulse before starting CPR
  • Dysrhythmias
    • Occur once temp <30C (86F)
    • Rewarming is treatment of choice
      • Most dysrhythmias (e.g. sinus brady, a-fib/flutter) require no other therapy
        • Activity of antiarrhythmics is unpredictable in hypothermia
        • Hypothermic heart is relatively resistant to atropine, pacing, and countershock
    • V-fib
      • May be refractory to therapy until pt is rewarmed
      • Attempt a single defibrillation attempt
        • If unsuccessful continue CPR and attempt defibrillation again once temp >30C (86F)
  • Antibiotics
    • Give if suspect sepsis (e.g. hypothermia fails to correct w/ rewarming measures)
  • Thiamine
    • Consider if Wernicke disease is possible cause of hypothermia (e.g. alcoholic pt)
  • Hydrocortisone
    • Consider if pt has history of adrenal suppression or insufficiency
  • Thyroxine

Rewarming

  • Passive
    • Consider in pt w/ mild hypothermia who is able to generate intrinsic heat
    • Techniques
      • Removal from cold environment
      • Insulation
  • Active
    • Consider in:
      • Moderate-severe hypothermia
      • Mild hypothermia in pt who is unstable or cannot generate intrinsic heat
      • Failure to respond to passive external rewarming
      • May be ineffective in pts w/ poor perfusion or in cardiac arrest
    • Techniques
      • Rewarm trunk BEFORE the extremities
        • Otherwise may lead to hypotension ("core temperature afterdrop")
          • Warmed vasodilated peripheral tissue allows cooler blood in extremities to circulate back to core
      • Warm water immersion
      • Heating blankets
      • Radiant heat
      • Forced air - Bair hugger
      • Warm humidified air
  • Active Internal
    • Consider alone or along with active external warming in:
      • Cardiovascular instability / life-threatening dysrhythmias
      • Severe hypothermia
      • Moderate hypothermia which fails to respond to less aggressive measures
    • Techniques
      • Heated IV fluids: 65°C > 45°C more efficacious
        • If central line is placed avoid irritating the heart
      • GI tract lavage
      • Bladder lavage
      • Pleural lavage
      • Peritoneal lavage
      • Bypass/ECMO[2]/AV Dialysis

Complications

See Also

References

  1. ↑ Brown et al., Accidental Hypothermia. N Engl J Med 2012; 367:1930-1938
  2. ↑ Ginty C, et al. Extracorporeal membrane oxygenation rewarming in the ED: an opportunity for success. American Journal of Emergency Medicine. 2014 December 3 (ahead of print).
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