Accidental Hypothermia

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Accidental Hypothermia. The Basics Clinical Questions Treatment. Who gets hypothermia?. Case: 25 M Ice climber… Temp: 31 degrees. How would you classify this pt’s hypothermia?. 31 degrees C. Mild: Core temp. 32 to 35ºC Moderate: Core temp. 28 to 32ºC Severe: Core temp. below 28ºC. - PowerPoint PPT Presentation

Transcript of Accidental Hypothermia

  • AccidentalHypothermia

  • The Basics

    Clinical Questions


  • Who gets hypothermia?

  • Case:

    25 M Ice climber

    Temp: 31 degrees

  • How would you classify this pts hypothermia?31 degrees C

  • Mild: Core temp. 32 to 35C

    Moderate: Core temp. 28 to 32C

    Severe: Core temp. below 28C

  • Mild:34 - amnesia and dysarthria begin33 - ataxia and apathy develop

    Moderate:32 - stupor31 - shivering stops30 - dysrhythmias, CO drops, insulin ineffective

    Severe:28 - high risk for VF27 - lose reflexes and voluntary movement26 - major A/B disturbance

    Profound:19 - flat EEG18 - asystole

  • Pretend there is no history of exposurewhy else could this patient be hypothermic?

  • Differential DiagnosisIncreased Heat LossDecreased Heat ProductionImpaired Heat Regulation

  • What mechanisms contribute to heat loss in our patient?

  • Evaporation, radiation, conduction, convection.

  • How is the cold affecting this patient?

    At the body level?

    At the organ system level?

  • Increase HR

    Progressive bradycardia

    Ventricular Arrhythmias


  • The J Wave

  • Cold diuresis

    Reduced renal flow

  • Progressive depression

    perfusion maintained until 25 degrees

    19 degrees flat EEG

  • Initial stimulation

    Progressive decrease

    CO2 retention and Acidosis

  • Case continued.

  • What is the most accurate method of measuring his temperature?

  • Rectal temperature (insert to 15 cm)- ? Accurately reflect brain/heart temperature- Influenced by adjacent frozen stool- lags behind core temperature changes

    Oral- Often do not measure below 34 degrees C.

    Tympanic- accurately reflect hypothalamus if true tympanic

    Axilla- easily affected by external factors

    Esophogeal (insert to 24 cm)-can be affected by warm airway temperature in tubed patient

  • ChemstripElectrolytesCreatinine, BUNHg, WBC, PltLactateEKGABG

    Other: CK, fibrinogen, INR, cortisol, thyroid

    Blood Work

  • Chemstrip:-Insulin ineffective below 30 degrees -persistent elevation despite rewarming signals secondary cause

    Hct:-Increases 2% for every drop by 1 degree C-Beware of the hypothermic patient with a normal/low hematocrit

    ABG:-Historically controversial-Use uncorrected values

    Blood Work

  • How can you rewarm him?

  • Passive External Rewarming (PER)Providing blanketsMoving to a warm environmentHeated IV fluids/oral fluids

    **pt must be able to produce their own heat***slow rise in temperature

  • Active External RewarmingApplying heat to the skin:

    Warm blanketsBear HuggerImmersion warmingBrokeback Hug?

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

  • Recipe:

    Warmed NS

    Place 1L NS in 650 W microwaveCook on high for 120s, turning and shaking it once at midcycleAgitate before infusion

  • Inhaled warmed O2Use warmed air at 45 degrees celciusUp to 2 degrees/hr*

  • Peritoneal LavageUse Arrow peritoneal lavage kit

    Up to 3 degrees C/hour

  • GI and bladder rewarming1.5-2.0 degrees/hour

  • Thoracic Cavity LavageUp to 6 or 7 degrees/hour reported

  • Cardiac BypassNeed to consult CV surgery

    Up to 2 degrees/5 mins

  • HemodialysisUp to 4.5 degrees/hour

  • Comparison of Rewarming Rates

  • Case Continued

  • Why has this patient become more hypothermic despite your warming measures?

  • Approach to rewarming

    Mild Hypothermia

    Passive External Rewarming

    +/- Active External Rewarming

  • Approach to rewarmingModerate Hypothermia

    Active External Rewarming

    Active Internal Rewarming

  • Approach to RewarmingSevere Hypothermia

    Level 1 callout

    If Stable, treat as moderate but be prepared for ecmo

    If Unstable, ACLS and prepare for ecmo

  • 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

  • Cold and Dead?Patients with severe accidental hypothermia and cardiac arrest may benefit from resuscitation even in cases of prolonged downtime and prolonged cpr

  • The Obvious:-Decapitation-Non-compressible chest-Ice in mouth and nose-DNR order

    The Unreliable:-rigor or livor mortis-fixed pupils-tissue deterioration

  • Rosens:Significant predictors of outcomeasphyxia, prehospital arrest, low or no BP, high BUN, need for intubation in ER

    Literature: Mt. Hood: only survivors had signs of life on scene, temps were above 20 degrees, K < 7Mair et al. 1994: K > 10, pH < 6.5, Others: fibrinogen 250mmol/L

  • Frostbite

  • Case:

    In minor ER

    63 M

  • PernioLocal, inflammatory, bluish-red lesions

    Caused by prolonged vasoconstriction

    Gentle drying and massaging.

  • Immersion Injury (Trench Foot)

  • Cold InjuryNon-Freezing

    PernioImmersion InjuryCold UrticariaFreezing


  • FrostnipReversible and superficial

    No tissue loss

    Pale and discomfort and tingling

  • Case:

    27 F Car broke down on a rural road.Decided to walk out

    While 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.

  • Frostbite

  • Classification

  • TreatmentRemove wet clothingRapid rewarming with warm water (40 degrees)Analgesia!!NSAIDs?Td

  • TreatmentThawing:40 degreesUntil part feels soft, erythema presentUsually requires 10-30 minutesActive motion by patient

  • TreatmentPost-thaw:ElevateSterile, bulky dressingAloe Vera?Blisters?TPA?Heparin?Abx?Hyperbaric O2?, Pentoxifylline?

  • TreatmentSurgery?


  • SummarySpectrum of freezing and non-freezing injuries

    Treat by rapid rewarming

    Aloe, ibuprofen, and Td (others are controversial)

  • Thanks to Kyle Mclaughlin for help with his experiences, cases, and knowledge.

    As opposed to therapeutic hypothermia

    Not too uncommon around these parts - In fact, Dr. McLaughlin has a few stories hell be able to share with us as we go along..

    Weather records in Canada: mount logan -77.5, snag, yukon -63, fort vermillion, ab -61.1, Calgary -45

    We only have an hour so Ill keep it brief wherever possible.

    There will be a handout (made by Kyle) that I will send out. Also, any further questions and Im happy to provide you with the references.

    I also have a short video from the USC series for anyone who is interested.

    Youll find a whole table in Rosens about this but just keep in mind the basics:

    Essentially: Extremes of age, intoxication/behavioural, and co-morbids

    Old people because: chronic disease (which interfere with heat production and conservation), medications, social isolation, older homes, Young because: larger SA to V ration, relatively smaller subcutaneous tissue layer, inefficient shiveringNeonates: no behavioural defense, Etoh/Behavioural: name says it. They lack the behavioural mechanism to leave the cold or bundle up.

    Decrease heat productionIncrease heat lossImpaired thermoregulationOther miscellaneous statesKyle, Id like you to give the history on this guy right up to the point where EMS get his initial temp.that will lead into the first question about classification and the subsequent questions about differential and expected symptoms at given temps. After that well give more info

    25 yo Ice climber at Johnston Canyon- ground level fall and submerged under ice this past Nov. unable to free self from under ice but able to find air pockets and under water caves to breath in. Made decision to leave one-way caves twice back under the ice. Partially submerged for 20-25 minutes. Breaks a small hole in ice and passerby's descend a rope from 5 meters up - patient flops on top of ice. EMS arrive and bystanders have covered patient in jackets. Patient altered and not shivering. EMS strip him down, place in bag and crack neonate warming pads. By the time he arrives in Banff- rectal temp 31, shivering, alert, GCS 15, in rapid A. Fib. Warmed to 37 over 5 hours with bear hugger and warm fluids. Still in A. Fib with rate 150-160 Asymptomatic. Cardioverted to normal sinus. Home after Psych has seen for expected PTSD.Key points: Management at scene- directing EMS to remove cold clothes and actively warm if not shivering.-arrhythmias: most will resolve with warming, expect any type, Osborne J waves are classic.This may help in terms of standardizing your lingo but also correlates with their clinical presentation

    Slide of the degrees celcius with corresponding clinical presentation:

    In more simplified terms:In the mild phase, the body is compensating for the heat loss by producing/conserving more heatIn the moderate phase, protective/compensatory measures begin to fail and clinical signs begin to developIn the Severe phase, the patient is grossly unstableIn the Profound phase, the patient is dead