Accidental hypothermia: Difference between revisions

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==Background==
==Background==
'''Definition: Core Temperature <35C (95F)'''
[[File:Windchill21.gif|thumb|Whid chill chart]]
*Unintentional hypothermia (core cooling <35C) is associated with significant morbidity and mortality.  Roughly 1500 persons die of accidental hypothermia in the US annually.<ref>Baumgartner EA, Belson M, Rubin C, Patel M. [[Hypothermia]]and other cold-related morbidity emergency department visits: United States, 1995-2004. Wilderness Environ Med 2008;19:233-237</ref>   
===Definition: Core Temperature <35°C (95°F)===
*Despite the high mortality associated with pre-hospital arrest, well directed treatment can result in complete neurologic recovery in the hypothermic patient.<ref>Friberg H, Rundgren. Submersion, accidental hypothermia,and cardiac arrest, mechanical chest compressions as a bridge to final treatment: a case report. Scand J Trauma Resusc Emerg Med. 2009; 17: 7</ref>
*Unintentional hypothermia (core cooling <35°C) is associated with significant morbidity and mortality.  Roughly 1500 persons die of accidental hypothermia in the US annually.<ref>Baumgartner EA, Belson M, Rubin C, Patel M. [[Hypothermia]]and other cold-related morbidity emergency department visits: United States, 1995-2004. Wilderness Environ Med 2008;19:233-237</ref>   
*Despite the high mortality associated with pre-hospital arrest, well-directed treatment can result in complete neurologic recovery in the hypothermic patient.<ref>Friberg H, Rundgren. Submersion, accidental hypothermia, and cardiac arrest, mechanical chest compressions as a bridge to final treatment: a case report. Scand J Trauma Resusc Emerg Med. 2009; 17: 7</ref>
*50% who die of hypothermia are >65 years old<ref>Centers for Disease Control and Prevention: Hypothermia-related deaths—United States, 2003–2004. MMWR Morb Mortal Wkly Rep 54: 173, 2005</ref>
*50% who die of hypothermia are >65 years old<ref>Centers for Disease Control and Prevention: Hypothermia-related deaths—United States, 2003–2004. MMWR Morb Mortal Wkly Rep 54: 173, 2005</ref>
*Risk of cardiac arrest increased with temperature <32C, as stable cardiac rhythms can quickly degenerate into unstable rhythms.  Hypothermic patient patient without a pulse must be managed differently due to physiology changes that occur at low temperatures.  
*Risk of cardiac arrest increased with temperature <32°C, as stable cardiac rhythms can quickly degenerate into unstable rhythms.  Hypothermic patient without a pulse must be managed differently due to physiology changes that occur at low temperatures. Defibrillation and many medications may be ineffective until the core temperature is above 30.0°C. If defibrillation is warranted but unsuccessful, active rewarming should be initiated while CPR is continued.  


====Causes of hypothermia====
===Causes===
*Increased heat loss
*Increased heat loss
**Environmental exposure
**Environmental exposure
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***Homeless population
***Homeless population
***Elderly patients → particularly low income during winter months
***Elderly patients → particularly low income during winter months
***Submersion injuries
***[[Submersion injuries]]
**Induced vasodilation
**Induced vasodilation
***Drugs
***Drugs
***Carbon monoxide
***[[Carbon monoxide]]
***Alcohol
***[[Alcohol intoxication]]
*Decreased heat production
*Decreased heat production
**Endocrine
**Endocrine
***Hypopituitarism  
***[[Hypopituitarism]]
***Hypothyroidism
***[[Hypothyroidism]]
***Hypoadrenalism
***[[adrenal insufficiency|Hypoadrenalism]]
***Hypoglycemia
***[[Hypoglycemia]]
**Neuromuscular inefficiency
**Neuromuscular inefficiency
***Extremes of age
***Extremes of age
***Impaired shivering
***Impaired shivering
**Erythrodermas
**Erythrodermas
***Psoriasis
***[[Psoriasis]]
***Exfoliative dermatitis
***[[exfoliative erythroderma|Exfoliative dermatitis]]
***Ichthyosis
***Ichthyosis
***Eczema
***[[Eczema]]
***Burns
***[[Burns]]
**Impaired Thermoregulation
**Impaired Thermoregulation
**Other
**Other
***Sepsis
***[[Sepsis]]
***Trauma
***[[Trauma]]


==Clinical Features==
==Clinical Features==
[[File:1024px-Medical students take to the water to learn about hypothermia 150407-G-NW142-051.jpg|thumb|Medical students learning about the effects of hypothermia on the body.]]
[[File:US Navy 090408-N-3714M-289 A SEAL Qualification Training candidate looks out from a two-man tent during a re-warming exercise in which he spent five minutes in near freezing water.jpg|thumb|Man being rewarmed after spending five-minutes in near freezing water.]]
{{Swiss staging system}}
{{Swiss staging system}}
===Associated Problems===
*[[Cold injuries]]
*Cardiac dysfunction
**[[Dysrhythmias]]
***May occur spontaneously if temperature <30°C (86°F)
**Afterdrop: Initial drop in temperature and MAP as rewarming is started due to loss of vasoconstriction/AV shunting colder peripheral tissues
*[[Coagulopathy]]
**Decreased clotting function
***platelet function and inhibition of coagulation cascade
***Part of the [[Trauma_(main)#Lethal_Triad_of_Major_Trauma|lethal triad of trauma]]
**[[Thromboembolism]]
***Secondary to hemoconcentration, increased blood viscosity, and poor circulation
***[[Disseminated intravascular coagulation]]
*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
**Oral meds poorly absorbed because of decreased gastrointestinal motility
**Intramuscular route avoided due to poor absorption from vasoconstricted sites
*Other
**[[Acid-base disorders]]
**[[Aspiration pneumonia and pneumonitis|Aspiration pneumonia]]
**[[Pancreatitis]]
**[[Rhabdomyolysis]]


==Differential Diagnosis==
==Differential Diagnosis==
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==Evaluation==
==Evaluation==
*'''Use low-reading thermometer'''
*'''Use low-reading thermometer'''
**Some standard thermometers record only to 34C
**Some standard thermometers record only to 34°C
**Measure core temperature with esophageal probe if intubated (most accurate)
**Measure core temperature with esophageal probe if intubated (most accurate)
*Check blood glucose as can be very high in [[DM]] or [[CVA]] or low when metabolized to keep warm
*Check blood glucose as can be very high in [[DM]] or [[CVA]] or low when metabolized to keep warm
*Potassium >10-12 mEq/L not compatible with life
*Potassium >10-12 mEq/L not compatible with life
*Coagulopathy:  clotting factor activity and platelet function significantly reduced at temperature < 34C
*Coagulopathy:  clotting factor activity and platelet function significantly reduced at temperature < 34°C
**Blood is rewarmed for lab testing so results may appear normal
**Blood is rewarmed for lab testing so results may appear normal
*If ABG is rewarmed before analysis, results will be different from patient's actual acid/base state
*If ABG is rewarmed before analysis, results will be different from patient's actual acid/base state
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===[[ECG]]===
===[[ECG]]===
[[File:Osborn wave.gif|thumb]]
[[File:Osborn wave.gif|thumb]]
[[File:HypothermiaECG.jpg|thumb|Atrial fibrillation and Osborn J waves in a person with hypothermia.]]
*Typical sequence is sinus bradycardia → atrial fibrillation with slow ventricular response → ventricular fibrillation → asystole
*Typical sequence is sinus bradycardia → atrial fibrillation with slow ventricular response → ventricular fibrillation → asystole
*Other ECG findings:
*Other ECG findings:
**Osborn (J) wave
**Osborn (J) wave - Size of wave correlates with degree of hypothermia. No prognostic value.
**Muscle tremor artifact
**Muscle tremor artifact
**T-wave inversions
**T-wave inversions
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==General Management==
==General Management==
===Handling===
===Basic Measures===
*Handle patient gently
*Handling
*[[V-fib]] may be induced by rough handling of patient due to irritable myocardium (anecdotal)
**Handle patient gently
===O2===
**[[V-fib]] may be induced by rough handling of patient due to irritable myocardium (anecdotal)
*[[Hypothermia]]causes leftward shift of oxyhemoglobin dissociation curve
*[[Oxygen therapy]]
*[[Intubation]]
**[[Hypothermia]] causes leftward shift of oxyhemoglobin dissociation curve
*Intubate gently
**[[Intubation]]
*if [[RSI]] is given medications may act at a slower rate
**Intubate gently
**If [[RSI]] is given medications may act at a slower rate
*[[IVF]]
**Patients are also hypovolemic since [[hypothermia]] causes impaired renal concentrating ability, in turn causing cold diuresis
**Patients are prone to [[Rhabdomyolysis|rhabdomyolysis]] and will need hydration
**Intravascular volume is lost due to extravascular shift
**[[Normal saline]] preferred over [[Lactated Ringers]], as cold liver poorly metabolizes LR


===[[IVF]]===
*Patients are also hypovolemic since [[Hypothermia]]> impaired renal concentrating ability > cold diuresis
*Patients are prone to [[Rhabdomyolysis|rhabdomyolysis]] and will need hydration
*Intravascular volume is lost due to extravascular shift
*NS preferred over LR as cold liver poorly metabolizes LR
===[[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]]===
===[[Dysrhythmias]]===
*May occur spontaneously if temperature <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]]/[[flutter]]) require no other therapy
*If the patient requires central venous access, femoral is recommended to avoid irritating the myocardium
*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
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**Reasonable to perform further defibrillation attempts concurrent with rewarming<ref name=Hoek />
**Reasonable to perform further defibrillation attempts concurrent with rewarming<ref name=Hoek />


===[[Antibiotics]]===
===Medications for Unexplained Hypothermia in Specific Patient Populations===
*Give if suspect [[sepsis]] (e.g. hypothermia fails to correct with rewarming measures)
*[[Antibiotics]]
 
**Give if suspect [[sepsis]] (e.g. hypothermia fails to correct with rewarming measures)
===[[Thiamine]]===
*[[Thiamine]]
*Consider if [[Wernicke disease]] is possible cause of hypothermia (e.g. alcoholic patient)
**Consider if [[Wernicke disease]] is possible cause of hypothermia (e.g. alcoholic patient)
 
*[[Hydrocortisone]]
===[[Hydrocortisone]]===
**Consider if patient has history of adrenal suppression or insufficiency
*Consider if patient has history of adrenal suppression or insufficiency
***100mg hydrocortisone
**100mg Hydrocortisone
*[[Levothyroxine]]
 
**Consider if any suspicion for [[hypothyroidism]]/[[myxedema coma]]
===[[Thyroxine]]===
**Could cause dysrhythmia or cardiac ischemia if not in myxedema coma
*Consider if any suspicion for [[hypothyroidism]]/[[myxedema coma]]
*[[Hyperglycemia]]
*Could cause dysrhythmia or cardiac ischemia if not in myxedema coma
**Hyperglycemia common in hypothermia:
 
***Stimulates catecholamine induced glycogenolysis
===[[Hyperglycemia]]===
***Inhibits insulin release and uptake by cell membranes
*Hyperglycemia common as hypothermia:
**Rebound hypoglycemia during rewarming can occur if clinicians too aggressively deliver exogenous insulin
**Stimulates catecholamine induced glycogenolysis
**Inhibits insulin release and uptake by cell membranes
*Rebound hypoglycemia during rewarming can occur if clinicians too aggressively deliver exogenous insulin


==Rewarming==
==Rewarming==
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| '''Stage of Hypothermia''' || '''Recommended rewarming modality'''
| '''Stage of Hypothermia''' || '''Recommended rewarming modality'''
|-
|-
| I/ Mild: 32-35C (90-95F) || Passive external
| I/ Mild: 32-35°C (90-95°F) || Passive external
|-
|-
| II/ Moderate: 28-32C (82-90F) || Active external
| II/ Moderate: 28-32°C (82-90°F) || Active external
|-
|-
| III/ Severe: 20-28C (68-82F) || Active internal
| III/ Severe: 20-28°C (68-82°F) || Active internal
|-
|-
| IV/ Profound: <20C (68F) || As severe + modified ACLS
| IV/ Profound: <20°C (68°F) || As severe + modified ACLS
|}
|}


===Passive External===
===Passive External===
*Prevent additional losses → remove wet clothes
*Prevent additional heat loss → Remove wet clothes
*Heated room
*Heated room
*Blankets - If patient still shivering, capable of rewarming 0.5C/hr
*Blankets - If patient still shivering, capable of rewarming 0.5°C/hr
*Hypothermia cap


===Active External===
===Active External===
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**Afterdrop: warmed vasodilated peripheral tissue allows cooler blood in extremities to circulate back to core
**Afterdrop: warmed vasodilated peripheral tissue allows cooler blood in extremities to circulate back to core
*Options:
*Options:
**Warm water immersion (Capable of 2-4C/Hr rewarming)
**Warm water immersion (Capable of 2-4°C/Hr rewarming)
**Heating blankets
**Heating blankets
**Radiant heat
**Radiant heat
**Forced air - e.g. Bair hugger (Up to 1-2.5C/Hr rewarming)
**Forced air - e.g. Bair hugger or Arctic Sun (Up to 1-2.5°C/Hr rewarming)
**Warm humidified air via facemask or endotracheal tube
**Warm humidified air via facemask or endotracheal tube


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*[[Peritoneal lavage]]
*[[Peritoneal lavage]]
*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
*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
**[https://www.hypothermiascore.org/ HOPE score] can predict probability of survival with ECMO


===Rewarming Rates===
===Rewarming Rates===
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| '''Active External'''||||
| '''Active External'''||||
|-
|-
| Warm IV fluids (47C)||1-3||Highly variable; Limited by tubing distance, requires large volumes with risk of volume overload
| Warm IV fluids (47°C)||1-3||Highly variable; Limited by tubing distance, requires large volumes with risk of volume overload
|-
|-
| Forced air  (Bair hugger)||1-2.5||
| Forced air  (Bair hugger)||1-2.5||
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|}
|}


==Management of the coding hypothermic patient==
==[[Cardiac Arrest]]==
*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
*Rhythms can quickly degenerate into unstable rhythms
*Rhythms can quickly degenerate into unstable rhythms
*Be careful when inserting guidewires, persistent shocks can degenerate fib into asystole
*Be careful when inserting guidewires, persistent shocks can degenerate fib into asystole
*Standard [[ACLS]] guidelines may not apply:
*Standard [[ACLS]] guidelines may not apply:
*Any organized rhythm should be assumed to be perfusing the patient adequately
**Any organized rhythm should be assumed to be perfusing the patient adequately
*Starting [[CPR]] may precipitate fatal ventricular rhythms
**Starting [[CPR]] may precipitate fatal ventricular rhythms
*Modified vs. Standard ACLS:
*Modified vs. Standard ACLS:
**ERC recommends up to 3 defibrillations with [[epi] held until temperature >30C, then [[epinephrine]] interval of 6 min until temperature >35C
**ERC recommends up to 3 defibrillations with [[epi]] held until temperature >30°C, then [[epinephrine]] interval of 6 min until temperature >35°C
**AHA recommends 3 defibrillations and 3 rounds of [[epinephrine]] with further dosing guided by clinical response
**AHA recommends 3 defibrillations and 3 rounds of [[epinephrine]] with further dosing guided by clinical response
**Recent consensus suggest only one [[defibrillation]] and round of ACLS meds → rewarm 5C → one defib/meds → Repeat
**Recent consensus suggest only one [[defibrillation]] and round of ACLS meds → rewarm 5°C → one defib/meds → Repeat


===Termination of CPR===
===Termination of [[CPR]]===
*Should be considered if:
*Should be considered if:
**K > 12 mmol<ref>Schaller M, Fischer AP, Perret CH. Hyperkalemia: A Prognostic Factor During Acute Severe Hypothermia. JAMA. 1990;264(14):1842–1845. doi:10.1001/jama.1990.03450140064035</ref><ref name="Paal">Paal P, Gordon L, Strapazzon G, et al. Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Scand J Trauma Resusc Emerg Med. 2016;24(1):111. Published 2016 Sep 15. doi:10.1186/s13049-016-0303-7</ref>
**K > 12 mmol<ref>Schaller M, Fischer AP, Perret CH. Hyperkalemia: A Prognostic Factor During Acute Severe Hypothermia. JAMA. 1990;264(14):1842–1845. doi:10.1001/jama.1990.03450140064035</ref><ref name="Paal">Paal P, Gordon L, Strapazzon G, et al. Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Scand J Trauma Resusc Emerg Med. 2016;24(1):111. Published 2016 Sep 15. doi:10.1186/s13049-016-0303-7</ref>
**[[Asystole]] persists beyond >32C
**[[Asystole]] persists beyond >32°C
*''Lactate and pH have less consistent prognostic significance in hypothermia''
*''Lactate and pH have less consistent prognostic significance in hypothermia''


==Disposition==
==Disposition==
 
*ICU for severe cases
==Complications==
*[[Acid-base disorders]]
*"Afterdrop"
**Initial drop in temperature and MAP as rewarming is started due to loss of vasoconstriction/AV shunting colder peripheral tissues
*[[Aspiration pneumonia and pneumonitis|Aspiration pneumonia]]
*Bleeding
**Decreased platelet function and inhibition of coagulation cascade
*[[Cold injuries]]
*[[Dysrhythmias]]
*[[Disseminated Intravascular Coagulation (DIC)|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
**Oral meds poorly absorbed because of decreased gastrointestinal motility
**Intramuscular route avoided due to poor absorption from vasoconstricted sites


==External Links==
==External Links==
*[http://lifeinthefastlane.com/ecg-library/basics/hypothermia/ LITFL Hypothermia]
*[http://lifeinthefastlane.com/ecg-library/basics/hypothermia/ LITFL Hypothermia]
*[http://dhss.alaska.gov/dph/Emergency/Documents/ems/documents/Alaska%20DHSS%20EMS%20Cold%20Injuries%20Guidelines%20June%202014.pdf Alaska Cold Injury Guidelines]
*[http://dhss.alaska.gov/dph/Emergency/Documents/ems/documents/Alaska%20DHSS%20EMS%20Cold%20Injuries%20Guidelines%20June%202014.pdf Alaska Cold Injury Guidelines]
*[https://emcrit.org/ibcc/hypothermia/ IBCC Hypothermia]


==See Also==
==See Also==
*[[Cold injuries]]
*[[Therapeutic hypothermia]]
*[[Therapeutic hypothermia]]
*[[Water-related injuries]]
*[[Water-related injuries]]

Latest revision as of 01:56, 28 April 2024

Background

Whid chill chart

Definition: Core Temperature <35°C (95°F)

  • Unintentional hypothermia (core cooling <35°C) is associated with significant morbidity and mortality. Roughly 1500 persons die of accidental hypothermia in the US annually.[1]
  • Despite the high mortality associated with pre-hospital arrest, well-directed treatment can result in complete neurologic recovery in the hypothermic patient.[2]
  • 50% who die of hypothermia are >65 years old[3]
  • Risk of cardiac arrest increased with temperature <32°C, as stable cardiac rhythms can quickly degenerate into unstable rhythms. Hypothermic patient without a pulse must be managed differently due to physiology changes that occur at low temperatures. Defibrillation and many medications may be ineffective until the core temperature is above 30.0°C. If defibrillation is warranted but unsuccessful, active rewarming should be initiated while CPR is continued.

Causes

Clinical Features

Medical students learning about the effects of hypothermia on the body.
Man being rewarmed after spending five-minutes in near freezing water.

Swiss Hypothermia Staging System[4]

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

Associated Problems

  • Cold injuries
  • Cardiac dysfunction
    • Dysrhythmias
      • May occur spontaneously if temperature <30°C (86°F)
    • Afterdrop: Initial drop in temperature and MAP as rewarming is started due to loss of vasoconstriction/AV shunting colder peripheral tissues
  • Coagulopathy
  • 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
    • Oral meds poorly absorbed because of decreased gastrointestinal motility
    • Intramuscular route avoided due to poor absorption from vasoconstricted sites
  • Other

Differential Diagnosis

Cold injuries

Evaluation

  • Use low-reading thermometer
    • Some standard thermometers record only to 34°C
    • Measure core temperature with esophageal probe if intubated (most accurate)
  • Check blood glucose as can be very high in DM or CVA or low when metabolized to keep warm
  • Potassium >10-12 mEq/L not compatible with life
  • Coagulopathy: clotting factor activity and platelet function significantly reduced at temperature < 34°C
    • Blood is rewarmed for lab testing so results may appear normal
  • If ABG is rewarmed before analysis, results will be different from patient's actual acid/base state

ECG

Osborn wave.gif
Atrial fibrillation and Osborn J waves in a person with hypothermia.
  • Typical sequence is sinus bradycardia → atrial fibrillation with slow ventricular response → ventricular fibrillation → asystole
  • Other ECG findings:
    • Osborn (J) wave - Size of wave correlates with degree of hypothermia. No prognostic value.
    • Muscle tremor artifact
    • T-wave inversions
    • PR, QRS, QT prolongation
    • ST segment elevation or depression
    • AV block
    • PVCs

General Management

Basic Measures

  • Handling
    • Handle patient gently
    • V-fib may be induced by rough handling of patient due to irritable myocardium (anecdotal)
  • Oxygen therapy
    • 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 causes impaired renal concentrating ability, in turn causing cold diuresis
    • Patients are prone to rhabdomyolysis and will need hydration
    • Intravascular volume is lost due to extravascular shift
    • Normal saline preferred over Lactated Ringers, as cold liver poorly metabolizes LR

Dysrhythmias

  • Rewarming is treatment of choice
  • Most dysrhythmias (e.g. sinus brady, a-fib/flutter) require no other therapy
  • If the patient requires central venous access, femoral is recommended to avoid irritating the myocardium
  • 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[5]
    • Reasonable to perform further defibrillation attempts concurrent with rewarming[5]

Medications for Unexplained Hypothermia in Specific Patient Populations

  • Antibiotics
    • Give if suspect sepsis (e.g. hypothermia fails to correct with rewarming measures)
  • Thiamine
    • Consider if Wernicke disease is possible cause of hypothermia (e.g. alcoholic patient)
  • Hydrocortisone
    • Consider if patient has history of adrenal suppression or insufficiency
      • 100mg hydrocortisone
  • Levothyroxine
  • Hyperglycemia
    • Hyperglycemia common in hypothermia:
      • Stimulates catecholamine induced glycogenolysis
      • Inhibits insulin release and uptake by cell membranes
    • Rebound hypoglycemia during rewarming can occur if clinicians too aggressively deliver exogenous insulin

Rewarming

Recommendations on Rewarming Modality based on Temperature and Clinical picture

Stage of Hypothermia Recommended rewarming modality
I/ Mild: 32-35°C (90-95°F) Passive external
II/ Moderate: 28-32°C (82-90°F) Active external
III/ Severe: 20-28°C (68-82°F) Active internal
IV/ Profound: <20°C (68°F) As severe + modified ACLS

Passive External

  • Prevent additional heat loss → Remove wet clothes
  • Heated room
  • Blankets - If patient still shivering, capable of rewarming 0.5°C/hr
  • Hypothermia cap

Active External

  • 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
  • Options:
    • Warm water immersion (Capable of 2-4°C/Hr rewarming)
    • Heating blankets
    • Radiant heat
    • Forced air - e.g. Bair hugger or Arctic Sun (Up to 1-2.5°C/Hr rewarming)
    • Warm humidified air via facemask or endotracheal tube

Active Internal

Options:

  • Heated IV fluids: 38-42°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[6][7]
    • If central line is placed, avoid irritating the heart
  • GI tract lavage
    • Can cause fluid and electrolyte fluctuations, also risk of pulmonary aspiration
  • Bladder lavage
    • Small surface area available for heat exchange
  • Thoracic lavage
  • Peritoneal lavage
  • Bypass/ECMO[8]/AV Dialysis
    • HOPE score can predict probability of survival with ECMO

Rewarming Rates

Mode °C/Hr Comments
Passive External
Shivering[9] 1.5
Warming Blanket[9] 2
Active External
Warm IV fluids (47°C) 1-3 Highly variable; Limited by tubing distance, requires large volumes with risk of volume overload
Forced air (Bair hugger) 1-2.5
Warm water immersion 2-4
Active Internal
Warm Humidified Air (intubated) 0.5-1.2 Low heat transport capacity
Peritoneal Lavage[9] 3
Thoracic Lavage[9] 3-6
Hemodialysis[9] 3-4
Open thoracotomy lavage Up to 8 (median 3) Highly invasive. 71% survival in 1 study
Cardiac Bypass[9] 7-10

Cardiac Arrest

  • 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
  • Rhythms can quickly degenerate into unstable rhythms
  • Be careful when inserting guidewires, persistent shocks can degenerate fib into asystole
  • Standard ACLS guidelines may not apply:
    • Any organized rhythm should be assumed to be perfusing the patient adequately
    • Starting CPR may precipitate fatal ventricular rhythms
  • Modified vs. Standard ACLS:
    • ERC recommends up to 3 defibrillations with epi held until temperature >30°C, then epinephrine interval of 6 min until temperature >35°C
    • AHA recommends 3 defibrillations and 3 rounds of epinephrine with further dosing guided by clinical response
    • Recent consensus suggest only one defibrillation and round of ACLS meds → rewarm 5°C → one defib/meds → Repeat

Termination of CPR

  • Should be considered if:
  • Lactate and pH have less consistent prognostic significance in hypothermia

Disposition

  • ICU for severe cases

External Links

See Also

References

  1. ↑ Baumgartner EA, Belson M, Rubin C, Patel M. Hypothermiaand other cold-related morbidity emergency department visits: United States, 1995-2004. Wilderness Environ Med 2008;19:233-237
  2. ↑ Friberg H, Rundgren. Submersion, accidental hypothermia, and cardiac arrest, mechanical chest compressions as a bridge to final treatment: a case report. Scand J Trauma Resusc Emerg Med. 2009; 17: 7
  3. ↑ Centers for Disease Control and Prevention: Hypothermia-related deaths—United States, 2003–2004. MMWR Morb Mortal Wkly Rep 54: 173, 2005
  4. ↑ Brown et al., Accidental Hypothermia. N Engl J Med 2012; 367:1930-1938
  5. ↑ 5.0 5.1 Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861
  6. ↑ Fildes J, Sheaff C, and Barrett J. Very hot intravenous fluid in the treatment of hypothermia. J Trauma. 1993; 35(5):683-686.
  7. ↑ 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.
  8. ↑ 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).
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 Kempainen, R. R. and Brunette, D. D. The Evaluation and Management of Accidental Hypothermia. Respir.Care 2004;49(2):192-205
  10. ↑ Schaller M, Fischer AP, Perret CH. Hyperkalemia: A Prognostic Factor During Acute Severe Hypothermia. JAMA. 1990;264(14):1842–1845. doi:10.1001/jama.1990.03450140064035
  11. ↑ Paal P, Gordon L, Strapazzon G, et al. Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Scand J Trauma Resusc Emerg Med. 2016;24(1):111. Published 2016 Sep 15. doi:10.1186/s13049-016-0303-7
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