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**[[PVC]]s
**[[PVC]]s


==Management==
==General Management==
===General===
===Handling===
*Handle pt gently
*Handle pt gently
**[[V-fib]] may be induced by rough handling of pt due to irritable myocardium (anecdotal)
*[[V-fib]] may be induced by rough handling of pt due to irritable myocardium (anecdotal)
*O2
===O2===
**Hypothermia causes leftward shift of oxyhemoglobin dissociation curve
*Hypothermia causes leftward shift of oxyhemoglobin dissociation curve
*[[Intubation]]
*[[Intubation]]
**same indications as normothermic patients
*Intubate gently
**RSI medications may be ineffective at temperatures <30C
*if RSI is given medications may act at a slower rate
*[[IVF]]
===[[IVF]]===
**Reasons:
*Patients are also hypovolemic since Hypothermia > impaired renal concentrating ability > cold diuresis
***Hypothermia > impaired renal concentrating ability > cold diuresis
*Patients are prone to [[Rhabdomyolysis|rhabdomyolysis]] and will need hydration
***Pts are prone to [[Rhabdomyolysis|rhabdomyolysis]]
*Intravascular volume is lost due to extravascular shift
***Intravascular volume is lost due to extravascular shift
===[[CPR]]===
*[[CPR]]
*Only perform if patient  truly does not have a pulse (unnecessary CPR may lead to [[V-fib]])
**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
**Spend 30-45s attempting to detect respiratory activity and pulse before starting CPR
===[[Dysrhythmias]]===
*[[Dysrhythmias]]
*May occur spontaneously if temp <30C (86F)
**Occur once temp <30C (86F)
*Rewarming is treatment of choice
**Rewarming is treatment of choice
*Most dysrhythmias (e.g. sinus brady, [[a-fib]]/[[flutte]]r) require no other therapy
***Most dysrhythmias (e.g. sinus brady, [[a-fib]]/[[flutte]]r) require no other therapy
*Activity of antiarrhythmics is unpredictable in hypothermia
****Activity of antiarrhythmics is unpredictable in hypothermia
*Hypothermic heart is relatively resistant to atropine, pacing, and countershock
****Hypothermic heart is relatively resistant to atropine, pacing, and countershock
*[[Ventricular tachycardia]] or [[Ventricular fibrillation]] are most common
**[[Ventricular tachycardia]] or [[Ventricular fibrillation]]
**May be refractory to therapy until patient is rewarmed
***May be refractory to therapy until pt is rewarmed
**Attempt defibrillation
***Attempt defibrillation
**Value of deferring repeat defibrillation until a target temperature is reached is uncertain<ref>Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861</ref>
****Value of deferring repeat defibrillation until a target temperature is reached is uncertain<ref>Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861</ref>
**Reasonable to perform further defibrillation attempts concurrent with rewarming<ref>Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861</ref>
****Reasonable to perform further defibrillation attempts concurrent with rewarming<ref>Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861</ref>
===[[Antibiotics]]===
*[[Antibiotics]]
*Give if suspect [[sepsis]] (e.g. hypothermia fails to correct w/ rewarming measures)
**Give if suspect [[sepsis]] (e.g. hypothermia fails to correct w/ rewarming measures)
===[[Thiamine]]===
*[[Thiamine]]
*Consider if [[Wernicke disease]] is possible cause of hypothermia (e.g. alcoholic pt)
**Consider if [[Wernicke disease]] is possible cause of hypothermia (e.g. alcoholic pt)
===[[Hydrocortisone]]===
*[[Hydrocortisone]]
*Consider if pt has history of adrenal suppression or insufficiency
**Consider if pt has history of adrenal suppression or insufficiency
**100mg Hydrocortisone
**100mg Hydrocortisone
*[[Thyroxine]]
===[[Thyroxine]]===
**Consider if any suspicion for [[hypothyroidism]]/[[myxedema coma]]
*Consider if any suspicion for [[hypothyroidism]]/[[myxedema coma]]
**Could cause dysrhythmia or cardiac ischemia if not in myxedema coma
*Could cause dysrhythmia or cardiac ischemia if not in myxedema coma
*[[Artificial Surfactant]]
**Believed washed out with drowning
**No current evidence for, but case studies


===Rewarming===
==Rewarming==
*Passive
===Passive===
**Consider in pt w/ mild hypothermia who is able to generate intrinsic heat
Perform in all patients with hypothermia who is able to generate intrinsic heat
**Techniques
#Removal from cold environment which includes removal of wet clothing
***Removal from cold environment
#Insulation with warm blankets and warming devices
***Insulation
===Active===
*Active  
Perform in patients with moderate to severe hypothermia or those who have failre response to passive rewarming
**Consider in:
*Rewarm trunk BEFORE the extremities otherwise you cause further hypotension ("core temperature afterdrop")  
***Moderate-severe hypothermia
*Afterdrop: warmed vasodilated peripheral tissue allows cooler blood in extremities to circulate back to core
***Mild hypothermia in pt who is unstable or cannot generate intrinsic heat
#Warm water immersion
***Failure to respond to passive external rewarming
#Heating blankets
***May be ineffective in pts w/ poor perfusion or in cardiac arrest
#Radiant heat
**Techniques
#Forced air - Bair hugger
***Rewarm trunk BEFORE the extremities
#Warm humidified air via facemask or endotracheal tube
****Otherwise may lead to hypotension ("core temperature afterdrop")  
===Active Internal===
*****Warmed vasodilated peripheral tissue allows cooler blood in extremities to circulate back to core
*Consider alone or along with active external warming in:
***Warm water immersion
**Cardiovascular instability / life-threatening dysrhythmias
***Heating blankets
**Severe hypothermia
***Radiant heat
**Moderate hypothermia which fails to respond to less aggressive measures
***Forced air - Bair hugger
#Heated IV fluids: 38°C -42°C.
***Warm humidified air
#*Two animal studies have showed 65°C IVF via central line warmed subjects faster without side effects, but this has not been tested in humans<ref>Fildes J, Sheaff C, and Barrett J. Very hot intravenous fluid in the treatment of hypothermia. J Trauma. 1993; 35(5):683-686.</ref><ref>Sheaff CM, Fildes JJ, Keogh P, et al. Safety of 65 degrees C intravenous fluid for the treatment of hypothermia. Am J Surg. 1996; 172(1):52-55.</ref>
*Active Internal
#*If central line is placed avoid irritating the heart
**Consider alone or along with active external warming in:
#GI tract lavage
***Cardiovascular instability / life-threatening dysrhythmias
#Bladder lavage
***Severe hypothermia
#[[Thoracic Lavage]]
***Moderate hypothermia which fails to respond to less aggressive measures
#Peritoneal lavage
**Techniques
#Bypass/ECMO<ref>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).</ref>/AV Dialysis
***Heated IV fluids: 38°C -42°C.
==Rewarming Rates==
****Two animal studies have showed 65°C IVF via central line warmed subjects faster without side effects, but this has not been tested in humans<ref>Fildes J, Sheaff C, and Barrett J. Very hot intravenous fluid in the treatment of hypothermia. J Trauma. 1993; 35(5):683-686.</ref><ref>Sheaff CM, Fildes JJ, Keogh P, et al. Safety of 65 degrees C intravenous fluid for the treatment of hypothermia. Am J Surg. 1996; 172(1):52-55.</ref>
Various measures of rewarming cause different core body increases per hour<ref>Kempainen, R. R. and Brunette, D. D. The Evaluation and Management of Accidental Hypothermia. Respir.Care 2004;49(2):192-205 </ref>
****If central line is placed avoid irritating the heart
*IV fluids - no net change
***GI tract lavage
*Shivering - 1.5°C/hr
***Bladder lavage
*Warming Blanket - 2°C/hr
***[[Thoracic Lavage]]
*Peritoneal Lavage - 3°C/hr
***Peritoneal lavage
*Thoracic Lavage - 3-6°C/hr
***Bypass/ECMO<ref>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).</ref>/AV Dialysis
*Hemodialysis 3-4°C/hr
*Cardiac Bypass 7-10°C/hr


*Rewarming Rates <ref>Kempainen, R. R. and Brunette, D. D. The Evaluation and Management of Accidental Hypothermia. Respir.Care 2004;49(2):192-205 </ref>
==External Links==
**IV fluids - no net change
[http://dhss.alaska.gov/dph/Emergency/Documents/ems/documents/Alaska%20DHSS%20EMS%20Cold%20Injuries%20Guidelines%20June%202014.pdf Alaska Cold Injury Guidelines]
**Shivering - 1.5°C/hr
**Warming Blanket - 2°C/hr
**Peritoneal Lavage - 3°C/hr
**Thoracic Lavage - 3-6°C/hr
**Hemodialysis 3-4°C/hr
**Cardiac Bypass 7-10°C/hr


==Complications==
==Complications==

Revisión del 02:51 29 ene 2016

Background

Definition: Core Temp <35C (95F)

  • 50% who die of hypothermia are >65 years old[1]

Clinical Features

Swiss Hypothermia Staging System[2]

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

  • Use low-reading thermometer
    • Some standard thermometers record only to 34C

ECG

Osborn wave.gif
  • Typical sequence is sinus brady > a fib with slow ventricular response > v-fib > asystole
  • Other ECG findings:
    • Osborn (J) wave
    • T-wave inversions
    • PR, QRS, QT prolongation
    • Muscle tremor artifact
    • AV block
    • PVCs

General Management

Handling

  • 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
  • Intubation
  • Intubate gently
  • if RSI is given medications may act at a slower rate

IVF

  • Patients are also hypovolemic since Hypothermia > impaired renal concentrating ability > cold diuresis
  • Patients are prone to rhabdomyolysis and will need hydration
  • Intravascular volume is lost due to extravascular shift

CPR

  • Only perform if patient 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

  • May occur spontaneously if 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
  • Ventricular tachycardia or Ventricular fibrillation are most common
    • May be refractory to therapy until patient is rewarmed
    • Attempt defibrillation
    • Value of deferring repeat defibrillation until a target temperature is reached is uncertain[3]
    • Reasonable to perform further defibrillation attempts concurrent with rewarming[4]

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
    • 100mg Hydrocortisone

Thyroxine

Rewarming

Passive

Perform in all patients with hypothermia who is able to generate intrinsic heat

  1. Removal from cold environment which includes removal of wet clothing
  2. Insulation with warm blankets and warming devices

Active

Perform in patients with moderate to severe hypothermia or those who have failre response to passive rewarming

  • Rewarm trunk BEFORE the extremities otherwise you cause further hypotension ("core temperature afterdrop")
  • Afterdrop: warmed vasodilated peripheral tissue allows cooler blood in extremities to circulate back to core
  1. Warm water immersion
  2. Heating blankets
  3. Radiant heat
  4. Forced air - Bair hugger
  5. Warm humidified air via facemask or endotracheal tube

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
  1. Heated IV fluids: 38°C -42°C.
    • Two animal studies have showed 65°C IVF via central line warmed subjects faster without side effects, but this has not been tested in humans[5][6]
    • If central line is placed avoid irritating the heart
  2. GI tract lavage
  3. Bladder lavage
  4. Thoracic Lavage
  5. Peritoneal lavage
  6. Bypass/ECMO[7]/AV Dialysis

Rewarming Rates

Various measures of rewarming cause different core body increases per hour[8]

  • IV fluids - no net change
  • Shivering - 1.5°C/hr
  • Warming Blanket - 2°C/hr
  • Peritoneal Lavage - 3°C/hr
  • Thoracic Lavage - 3-6°C/hr
  • Hemodialysis 3-4°C/hr
  • Cardiac Bypass 7-10°C/hr

External Links

Alaska Cold Injury Guidelines

Complications

  • Acid-base disorders
  • "Afterdrop"
    • Initial drop in temp and MAP as rewarming is started
      • Due to loss of vasoconstriction/AV shunting peripheral tissues are colder than where central blood flow had been
  • Aspiration pneumonia
  • Bleeding
    • Decreased platelet function and inhibition of coagulation cascade
  • Cold injuries
  • Dysrhythmias
  • Disseminated Intravascular Coagulation
  • 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

External Links

See Also

References

  1. ↑ 1. Centers for Disease Control and Prevention: Hypothermia-related deaths—United States, 2003–2004. MMWR Morb Mortal Wkly Rep 54: 173, 2005
  2. ↑ Brown et al., Accidental Hypothermia. N Engl J Med 2012; 367:1930-1938
  3. ↑ Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861
  4. ↑ Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861
  5. ↑ Fildes J, Sheaff C, and Barrett J. Very hot intravenous fluid in the treatment of hypothermia. J Trauma. 1993; 35(5):683-686.
  6. ↑ Sheaff CM, Fildes JJ, Keogh P, et al. Safety of 65 degrees C intravenous fluid for the treatment of hypothermia. Am J Surg. 1996; 172(1):52-55.
  7. ↑ 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).
  8. ↑ Kempainen, R. R. and Brunette, D. D. The Evaluation and Management of Accidental Hypothermia. Respir.Care 2004;49(2):192-205
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