Accidental hypothermia: Difference between revisions
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==Background== | ==Background== | ||
[[File:Windchill21.gif|thumb|Whid chill chart]] | |||
*Unintentional hypothermia (core cooling < | ===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> | ||
*50% who die of hypothermia are >65 years old<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> | ||
*Risk of cardiac arrest increased with | *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 <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=== | ||
*Avalanche victims | *Increased heat loss | ||
*Homeless population | **Environmental exposure | ||
* | ***Avalanche victims | ||
*Elderly patients | ***Homeless population | ||
*Submersion injuries | ***Elderly patients → particularly low income during winter months | ||
***[[Submersion injuries]] | |||
**Induced vasodilation | |||
***Drugs | |||
***[[Carbon monoxide]] | |||
***[[Alcohol intoxication]] | |||
*Decreased heat production | |||
**Endocrine | |||
***[[Hypopituitarism]] | |||
***[[Hypothyroidism]] | |||
***[[adrenal insufficiency|Hypoadrenalism]] | |||
***[[Hypoglycemia]] | |||
**Neuromuscular inefficiency | |||
***Extremes of age | |||
***Impaired shivering | |||
**Erythrodermas | |||
***[[Psoriasis]] | |||
***[[exfoliative erythroderma|Exfoliative dermatitis]] | |||
***Ichthyosis | |||
***[[Eczema]] | |||
***[[Burns]] | |||
**Impaired Thermoregulation | |||
**Other | |||
***[[Sepsis]] | |||
***[[Trauma]] | |||
==Clinical Features== | ==Clinical Features== | ||
{{Swiss staging system}} | {{Swiss staging system}} | ||
==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]] | |||
*[[coagulopathy|Bleeding]] | |||
**Decreased platelet function and inhibition of coagulation cascade | |||
*[[Cold injuries]] | |||
*[[Dysrhythmias]] | |||
*[[Disseminated Intravascular Coagulation (DIC)|Disseminated Intravascular Coagulation]] | |||
*Hypothermia induced [[coagulopathy]] | |||
*[[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 | |||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
{{Cold injuries DDX}} | {{Cold injuries DDX}} | ||
== | ==Evaluation== | ||
*'''Use low-reading thermometer''' | *'''Use low-reading thermometer''' | ||
**Some standard thermometers record only to | **Some standard thermometers record only to 34°C | ||
**Measure core | **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 | *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 | |||
**Refer to [[therapeutic hypothermia]] for over and underestimations | |||
===[[ECG]]=== | ===[[ECG]]=== | ||
[[File:Osborn wave.gif|thumb]] | [[File:Osborn wave.gif|thumb]] | ||
*Typical sequence is sinus | [[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 | |||
*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 | |||
**T-wave inversions | **T-wave inversions | ||
**PR, QRS, [[QT prolongation]] | **PR, QRS, [[QT prolongation]] | ||
** | **[[ST segment elevation]] or depression | ||
**AV block | **AV block | ||
**[[PVC]]s | **[[PVC]]s | ||
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*Handle patient gently | *Handle patient gently | ||
*[[V-fib]] may be induced by rough handling of patient due to irritable myocardium (anecdotal) | *[[V-fib]] may be induced by rough handling of patient 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]] | ||
*Intubate gently | *Intubate gently | ||
*if RSI is given medications may act at a slower rate | *if [[RSI]] is given medications may act at a slower rate | ||
===[[IVF]]=== | ===[[IVF]]=== | ||
*Patients are also hypovolemic since | *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 | *Patients are prone to [[Rhabdomyolysis|rhabdomyolysis]] and will need hydration | ||
*Intravascular volume is lost due to extravascular shift | *Intravascular volume is lost due to extravascular shift | ||
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*Only perform if patient truly does not have a pulse (unnecessary CPR may lead to [[V-fib]]) | *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 | *Spend 30-45s attempting to detect respiratory activity and pulse before starting CPR | ||
===[[Dysrhythmias]]=== | ===[[Dysrhythmias]]=== | ||
*May occur spontaneously if | *May occur spontaneously if temperature <30°C (86°F) | ||
*Rewarming is treatment of choice | *Rewarming is treatment of choice | ||
*Most dysrhythmias (e.g. sinus brady, [[a-fib]]/[[ | *Most dysrhythmias (e.g. sinus brady, [[a-fib]]/[[flutter]]) 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 | ||
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**May be refractory to therapy until patient is rewarmed | **May be refractory to therapy until patient 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 name=Hoek>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 | **Reasonable to perform further defibrillation attempts concurrent with rewarming<ref name=Hoek /> | ||
===[[Antibiotics]]=== | ===[[Antibiotics]]=== | ||
*Give if suspect [[sepsis]] (e.g. hypothermia fails to correct | *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 | *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]] | *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 | ||
===[[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== | ==Rewarming== | ||
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| '''Stage of Hypothermia''' || '''Recommended rewarming modality''' | | '''Stage of Hypothermia''' || '''Recommended rewarming modality''' | ||
|- | |- | ||
| I/ Mild: 32- | | I/ Mild: 32-35°C (90-95°F) || Passive external | ||
|- | |- | ||
| II/ Moderate: 28- | | II/ Moderate: 28-32°C (82-90°F) || Active external | ||
|- | |- | ||
| III/ Severe: 20- | | III/ Severe: 20-28°C (68-82°F) || Active internal | ||
|- | |- | ||
| IV/ Profound: < | | IV/ Profound: <20°C (68°F) || As severe + modified ACLS | ||
|} | |} | ||
===Passive External=== | ===Passive External=== | ||
*Prevent additional | *Prevent additional heat loss → Remove wet clothes | ||
*Heated room | *Heated room | ||
*Blankets - If patient still shivering, capable of rewarming 0. | *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- | **Warm water immersion (Capable of 2-4°C/Hr rewarming) | ||
**Heating blankets | **Heating blankets | ||
**Radiant heat | **Radiant heat | ||
**Forced air - Bair hugger (Up to 1-2. | **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 | ||
===Active Internal=== | ===Active Internal=== | ||
Options: | Options: | ||
*Heated IV fluids: | *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<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> | **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> | ||
**If central line is placed, avoid irritating the heart | **If central line is placed, avoid irritating the heart | ||
*GI tract lavage | *GI tract lavage | ||
**Can cause fluid and electrolyte fluctuations, also risk of pulmonary aspiration | |||
*[[Bladder lavage]] | *[[Bladder lavage]] | ||
**Small surface area available for heat exchange | |||
*[[Thoracic lavage]] | *[[Thoracic lavage]] | ||
*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 | ||
===Rewarming Rates=== | ===Rewarming Rates=== | ||
Line 130: | Line 196: | ||
| Shivering<ref name=Kempainen>Kempainen, R. R. and Brunette, D. D. The Evaluation and Management of Accidental Hypothermia. Respir.Care 2004;49(2):192-205 </ref>||1.5|| | | Shivering<ref name=Kempainen>Kempainen, R. R. and Brunette, D. D. The Evaluation and Management of Accidental Hypothermia. Respir.Care 2004;49(2):192-205 </ref>||1.5|| | ||
|- | |- | ||
| Warming Blanket<ref name=Kempainen | | Warming Blanket<ref name=Kempainen />||2|| | ||
|- | |- | ||
| '''Active External'''|||| | | '''Active External'''|||| | ||
|- | |- | ||
| Warm IV fluids ( | | 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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| Warm Humidified Air (intubated)||0.5-1.2||Low heat transport capacity | | Warm Humidified Air (intubated)||0.5-1.2||Low heat transport capacity | ||
|- | |- | ||
| Peritoneal Lavage<ref name=Kempainen | | Peritoneal Lavage<ref name=Kempainen />||3|| | ||
|- | |- | ||
| Thoracic Lavage<ref name=Kempainen | | Thoracic Lavage<ref name=Kempainen />|| 3-6|| | ||
|- | |- | ||
| Hemodialysis<ref name=Kempainen | | Hemodialysis<ref name=Kempainen />||3-4|| | ||
|- | |- | ||
| Open thoracotomy lavage||Up to 8 (median 3)||Highly invasive. 71% survival in 1 study | | Open thoracotomy lavage||Up to 8 (median 3)||Highly invasive. 71% survival in 1 study | ||
|- | |- | ||
| Cardiac Bypass<ref name=Kempainen | | Cardiac Bypass<ref name=Kempainen />||7-10|| | ||
|} | |} | ||
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*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 | **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 [[ | **AHA recommends 3 defibrillations and 3 rounds of [[epinephrine]] with further dosing guided by clinical response | ||
**Recent consensus suggest only one [[defibrillation]] and | **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 | **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 > | **[[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 | |||
* | |||
==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]] |
Revision as of 19:52, 3 November 2021
Background
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 of Hypothermia
- Increased heat loss
- Environmental exposure
- Avalanche victims
- Homeless population
- Elderly patients → particularly low income during winter months
- Submersion injuries
- Induced vasodilation
- Environmental exposure
- Decreased heat production
- Endocrine
- Neuromuscular inefficiency
- Extremes of age
- Impaired shivering
- Erythrodermas
- Psoriasis
- Exfoliative dermatitis
- Ichthyosis
- Eczema
- Burns
- Impaired Thermoregulation
- Other
Clinical Features
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 |
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
- Bleeding
- Decreased platelet function and inhibition of coagulation cascade
- Cold injuries
- Dysrhythmias
- Disseminated Intravascular Coagulation
- Hypothermia induced coagulopathy
- 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
Differential Diagnosis
Cold injuries
- Generalized
- Freezing
- Non-freezing
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
- Refer to therapeutic hypothermia for over and underestimations
ECG
- 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
Handling
- Handle patient gently
- V-fib may be induced by rough handling of patient 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 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
- 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
- May occur spontaneously if temperature <30°C (86°F)
- 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
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
- Consider if any suspicion for hypothyroidism/myxedema coma
- Could cause dysrhythmia or cardiac ischemia if not in myxedema coma
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.
- 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
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 |
Management of the coding hypothermic patient
- 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
- ↑ 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
- ↑ 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
- ↑ Centers for Disease Control and Prevention: Hypothermia-related deaths—United States, 2003–2004. MMWR Morb Mortal Wkly Rep 54: 173, 2005
- ↑ Brown et al., Accidental Hypothermia. N Engl J Med 2012; 367:1930-1938
- ↑ 5.0 5.1 Hoek T. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. 122:5829-5861
- ↑ Fildes J, Sheaff C, and Barrett J. Very hot intravenous fluid in the treatment of hypothermia. J Trauma. 1993; 35(5):683-686.
- ↑ 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.
- ↑ 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).
- ↑ 9.0 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
- ↑ 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
- ↑ 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