Accidental Hypothermia

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AccidentalHypothermia
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The BasicsClinical QuestionsTreatment
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Who gets hypothermia?
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Case25 M Ice climberTemp 31 degrees
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How would you classify this pts hypothermia?
31 degrees C
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Mild Core temp. 32 to 35ºC Moderate Core
temp. 28 to 32ºCSevere Core temp. below 28ºC
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Mild34 - amnesia and dysarthria begin33 -
ataxia and apathy developModerate32 -
stupor31 - shivering stops30 - dysrhythmias, CO
drops, insulin ineffectiveSevere28 - high
risk for VF27 - lose reflexes and voluntary
movement26 - major A/B disturbanceProfound19
- flat EEG18 - asystole
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Pretend there is no history of exposurewhy else
could this patient be hypothermic?
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Differential Diagnosis
Increased Heat Loss
Impaired Heat Regulation
Decreased Heat Production
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What mechanisms contribute to heat loss in our
patient?
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Evaporation, radiation, conduction, convection.
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How is the cold affecting this patient?At the
body level?At the organ system level?
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Increase HRProgressive bradycardiaVentricular
ArrhythmiasAsystole
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The J Wave
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Cold diuresisReduced renal flow
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Progressive depressionperfusion maintained
until 25 degrees19 degrees flat EEG
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Initial stimulationProgressive decreaseCO2
retention and Acidosis
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Case continued.
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What is the most accurate method of measuring his
temperature?
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Rectal temperature (insert to 15 cm)- ?
Accurately reflect brain/heart temperature-
Influenced by adjacent frozen stool- lags behind
core temperature changesOral- Often do not
measure below 34 degrees C.Tympanic-
accurately reflect hypothalamus if true
tympanicAxilla- easily affected by external
factorsEsophogeal (insert to 24 cm)-can be
affected by warm airway temperature in tubed
patient
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ChemstripElectrolytesCreatinine, BUNHg, WBC,
PltLactateEKGABGOther CK, fibrinogen, INR,
cortisol, thyroid
Blood Work
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Chemstrip-Insulin ineffective below 30 degrees
-persistent elevation despite rewarming signals
secondary causeHct-Increases 2 for every
drop by 1 degree C-Beware of the hypothermic
patient with a normal/low hematocritABG-Histor
ically controversial-Use uncorrected values
Blood Work
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How can you rewarm him?
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Passive External Rewarming (PER)

• Providing blankets
• Moving to a warm environment
• Heated IV fluids/oral fluids
• pt must be able to produce their own heat
• slow rise in temperature

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Active External Rewarming

• Applying heat to the skin
• Warm blankets
• Bear Hugger
• Immersion warming
• Brokeback Hug?

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Active Internal Rewarming

• Peritoneal dialysis
• Bladder, gastric, or colonic lavage
• Heated intravenous fluids
• Heated humidified oxygen
• Thoracic cavity lavage
• Extracorporeal blood rewarming
• Hemodialysis

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• Recipe
• Warmed NS
• Place 1L NS in 650 W microwave
• Cook on high for 120s, turning and shaking it
  once at midcycle
• Agitate before infusion

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Inhaled warmed O2

• Use warmed air at 45 degrees celcius
• Up to 2 degrees/hr

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Peritoneal Lavage

• Use Arrow peritoneal lavage kit
• Up to 3 degrees C/hour

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GI and bladder rewarming

• 1.5-2.0 degrees/hour

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Thoracic Cavity Lavage

• Up to 6 or 7 degrees/hour reported

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Cardiac Bypass

• Need to consult CV surgery
• Up to 2 degrees/5 mins

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Hemodialysis

• Up to 4.5 degrees/hour

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Comparison of Rewarming Rates
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Case Continued
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• Why has this patient become more hypothermic
  despite your warming measures?

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Approach to rewarming
Mild Hypothermia Passive External
Rewarming /- Active External Rewarming
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Approach to rewarming

• Moderate Hypothermia
• Active External Rewarming
• Active Internal Rewarming

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Approach to Rewarming

• Severe Hypothermia
• Level 1 callout
• If Stable, treat as moderate but be prepared for
  ecmo
• If Unstable, ACLS and prepare for ecmo

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ACLS guidelines?
BLS -prevent heat loss, rewarm -mild AH
passive rewarming -moderate AH AER -Severe
Stable AER or AIR -Severe Unstable bypass
or AIR -Do not withhold ABCs to
rewarm ACLS -If in VF or pulseless VT, attempt
defibrillation -Might be reasonable to perform
further defibs -Might be reasonalbe to
administer vasopressor
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Cold and Dead?
Patients with severe accidental hypothermia and
cardiac arrest may benefit from resuscitation
even in cases of prolonged downtime and prolonged
cpr
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The Obvious-Decapitation-Non-compressible
chest-Ice in mouth and nose-DNR orderThe
Unreliable-rigor or livor mortis-fixed
pupils-tissue deterioration
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RosensSignificant predictors of
outcome asphyxia, prehospital arrest, low or no
BP, high BUN, need for intubation in
ERLiterature Mt. Hood only survivors had
signs of life on scene, temps were above 20
degrees, K lt 7 Mair et al. 1994 K gt 10, pH lt
6.5, Others fibrinogen lt50mg/dL, ammonia
gt250mmol/L
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Frostbite
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CaseIn minor ER63 M
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Pernio

• Local, inflammatory, bluish-red lesions
• Caused by prolonged vasoconstriction
• Gentle drying and massaging.

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Immersion Injury (Trench Foot)
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Cold Injury

• Non-Freezing
• Pernio
• Immersion Injury
• Cold Urticaria

• Freezing
• Frostnip
• Frostbite

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Frostnip

• Reversible and superficial
• No tissue loss
• Pale and discomfort and tingling

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Case27 F Car broke down on a rural
road.Decided to walk outWhile walking through
wooded area, she gets lost, at one point ending
up knee deep in a stream.She wanders through
the forest for 12 hours lost.Eventually she is
spotted by a hunter who calls EMS.
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Frostbite
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Classification
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Treatment

• Remove wet clothing
• Rapid rewarming with warm water (40 degrees)
• Analgesia!!
• NSAIDs?
• Td

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Treatment

• Thawing
• 40 degrees
• Until part feels soft, erythema present
• Usually requires 10-30 minutes
• Active motion by patient

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Treatment

• Post-thaw
• Elevate
• Sterile, bulky dressing
• Aloe Vera?
• Blisters?
• TPA?
• Heparin?
• Abx?
• Hyperbaric O2?, Pentoxifylline?

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Treatment

• Surgery?
• Admission?

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Summary

1. Spectrum of freezing and non-freezing injuries
2. Treat by rapid rewarming
3. Aloe, ibuprofen, and Td (others are controversial)

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