Accidental Hypothermia by liaoqinmei

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									                                                6/4/2008




                           Accidental
                          Hypothermia
                         Gregory J. Moore, MD
                                FACEP




Accidental Hypothermia      Epidemiology

Unintentional drop
   in the “core”         Incidence
                                     Exposure
temperature below
       35° C.
                            Primary Secondary
                               Indoor Outdoor




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             Normal Physiology of
            Temperature Regulation
                                                                                                                         Radiation
                                                                          Evaporation                                    55-65%
                         Cold Exposure                                    Respiration
                                                                          20-30%
Blood temperature        Lateral Spinothalamic          Direct Reflex
                                Tract

                    Hypothalamic Nuclei

Shivering     Endocrinologic         Autonomic               Adaptive
                                      Nervous               Behavioral
                                       System               Responses
                                                                                        Conduction
                                                                                        Convection
                                                                                        15%




                                                                                    Core
                                                                         Stage   Temperature         Characteristics
                       Core
      Stage                                                              Moderate 32°C 89.6°F   Stupor; 25% decrease in
                    Temperature           Characteristics                                       oxygen consumption
                                                                         Zone
      Mild Zone     36°C 96.8 °F       Increase in metabolic rate,                31   87.8     Extinguished shivering
                                       tachycardia, CNS depression                              thermogenesis
                    35      95         Maximum shivering                         30      86     Atrial fibrillation and other
                                       thermogenesis                                            arrhythmias develop;
                                                                                                poikilothermia; pulse and
                    34      93.2       Amnesia, dysarthria, and poor
                                                                                                cardiac output 2/3 of normal;
                                       judgment develop; normal
                                       blood pressure; maximum                                  insulin ineffective
                                       respiratory stimulation                                  Progressive decrease in level
                                                                                 29      85.2
                                       Ataxia and apathy develop                                of consciousness, pulse and
                    33      91.4                                                                respiration; pupils dilate

                                                                                 28      82.4   Decreased ventricular
                                                                                                fibrillation threshold; 50%
                                                                                                decrease in oxygen
                                                                                                consumption and pulse




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            Core                                                    Core
Stage    Temperature                                    Stage    Temperature      Characteristics
                          Characteristics
Severe   27°C 80.6°F   Loss of reflexes and voluntary   Profound 19°C 66.2°F   Flat EEG
Zone                   motion                           Zone
         26   78.8     Major acid-base disturbance;              18   64.4     Asystole
                       no reflexes or response to
                       pain
         25   77                                                 15.2 59.2     Lowest infant accidental
                       Cerebral blood flow one-third                           hypothermia survival
                       of normal; cardiac output
                                                                 13.7 56.6     Lowest adult accidental
                       45% of normal; pulmonary
                                                                               hypothermia survival
                       edema may develop
         23   73.4                                                             Lowest therapeutic
                       No corneal or oculocephalic               9    48.2
                                                                               hypothermia survival
                       reflexes
         20   68
                       Lowest resumption of cardiac
                       electro-mechanical activity,;
                       pulse 20% of normal




     Impaired Thermoregulation                           Decreased Heat Production

                                                                 Age extremes
     Decreased                     Increased
        Heat                         Heat                        Inadequate fuel
     Production                      Loss
                                                                 Endocrinologic insufficiency

                                                                 Neuromuscular inefficiency




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Increased Heat Loss   Impaired Thermoregulation
                       Central
                         – traumatic, vascular, neoplastic,
 Iatrogenic               degenerative,
 Exposure               – congenital
                       Peripheral
 Dermatologic
                         – cord transection, neuropathies
 Acclimatization      Metabolic
                         – altered plasma osmolality
                       Pharmacologic
                         – therapeutic or toxic levels of agents




Prehospital
Hypothermic
   Life
  Support




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   Extrication Process                 „Core‟ Temperature
                                   Measurement Considerations
    Examination

    Insulation

    Monitoring                         Tympanic      Rectal
    Oxygenation                        Bladder    Esophageal
    Hydration

    Rewarming

    Gentle   Transport




Stabilization Assumptions                Key Decision

  Responsive  = perfusion            Active (exogenous) or
  Unresponsive = poikilothermia      Passive (spontaneous)
  Irritable myocardium                    Rewarming?
  Temperature gradient




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                                   Consider Active Rewarming:

                                       Cardiovascular   instability
                                       Below 32 ºC
                                       Age extremes

                                       CNS dysfunction

                                       NM inefficiency

                                       Endocrine inefficiency




Active External Rewarming


 Direct   cutaneous transfer of
  exogenous heat

 Truncal   +/-
            +/- extremities

 Considerations   and
  complications




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                                Arteriovenous Anastomoses
                                         Rewarming
                                  Immersion of hands, feet, forearms,
                                   and calves in 44-45OC water
                                  AVA’s open
                                  Warms venous subcutaneous blood
                                  Negative pressure rewarming is a
                                   permutation




                               Active Core Rewarming Options
         Active
         Core
                                      Inhalation
       Rewarming
                                      IV  fluids
Delivery of heat directly to          Irrigation

              core”
         the “core”                   Peritoneal lavage

                                      Thoracic cavity lavage

                                      Extracorporeal

                                      Diathermy




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 Airway Rewarming

 Heated   humidified oxygen
 Efficiency varies with
  conditions
 Oxygenation and ventilation
  issues
 Tracheal intubation




  Heated IV Fluids               Heated Irrigation


 40 - 42ºC
       42º                       Gastrointestinal

 Heat transfer limitations      Bladder

 Peripheral vs. central         Mediastinal

                                 Thoracic   cavity
 Heating options




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    Peritoneal Lavage

  Isotonic              40º
            dialysate at 40º to
      º
   45ºC
   45
  Infuse 2 L - retain 20 minutes

  Double – catheter; outflow
   suction
  Exchange rate 6L/HR

  ROR 1 - 3ºC/hr




Closed Thoracic Lavage

 Sterile            42º
         NS @ 40 - 42ºC in 3L
  bags
  Counter-
 Counter-current fluid infuser

                  2-
 Infuse anterior 2-3 ICS @ MCL

          5-
 Suction 5-6 ICS @PAL

       4-
 ROR 4- 8ºC/hr




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              ECR                         Prime Transfusion



                                              Blood     Oxygenator       Patient
   Cardiopulmonary                           Pump     Heat Exchanger

    bypass
   Arteriovenous
   Veno-venous
   Hemodialysis
                                                              Cannulae




 Criteria for Rewarming                   Hourly Rewarming Rates
         with CPB

Salvageable cardiac arrest
pH over 6.5                         Δo
Potassium below 10-12 mEq/L         C
Core temperature at least 10-12OC
Completely frozen extremities
Profound rhabdomyolysis




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                            Initiate CPR In Accidental
                               Hypothermia Unless:
                              Do- not-
                             Do-not-resuscitate   status is
                              documented and verified
Advanced Hypothermic         Obviously lethal injuries are
    Life-Support              present
                             Chest wall depression is
                              impossible
                             Any signs of life are present
                             Rescuers are endangered by
                              evacuation delays or altered
                              triage conditions




 Atrial Arrhythmias          Ventricular Arrhythmias

 Considered innocent          Prophylaxis unresolved
 Expect slow ventricular      Ectopy not predictive

  response                     Pharmacologic options

 Spontaneous conversion       Pacing

 Avoid meddling




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                                 Ominous Outcome Predictors

                                   Core T below 10-12OC
                                   Arterial pH below 6.5
                                   Serum potassium above 10
                                    mEq/L
                                   Fibrinogen below 50 mg%
                                   Intravascular thrombosis
                                   Asphyxia




       Prevention                         Summary


 Education                        Hypothermia   is a masquerader
 Preparation                      Individualize your approach
  – rest, nutrition, hydration     Transfer criteria
 Insulation
    "COLD”
  – "COLD”




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 “No one is dead until they
    are warm and dead”
unless they‟re already dead




                              Heat Emergencies
                                       Heat Cramps
   Environmental                       Heat Exhaustion
                                       Heat Stroke
   Emergencies
    Heat Emergencies

  Gregory J. Moore, MD
         FACEP




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                                                                                 6/4/2008




            Heat Cramps                            Heat Exhaustion
 Symptoms                                 Symptoms

  Severe pain, Nausea, Rapid pulse,         Weakness, Headache, Nausea,
  Moist skin, Normal body temperature       Anorexia, Abdominal cramps,
                                            Vertigo, Syncope, Rapid pulse, Cool
 Treatment
                                            skin, Normal body temperature
  Place in a cool environment     Drink    Treatment
  water or 1/2 strength electrolyte         Place in a cool environment, Sponge
  drink Rest for 12 hours                   with cool water, IV of .9 NS




             Heat Stroke                                Treatment
 Extreme    Medical Emergency             Establish and maintain airway with
 Recognition is critical!!!                high flow O2
 Symptoms                                 Cool the patient rapidly

   Loss of consciousness may be the        Establish IV of .9 normal saline

  first sign                               Monitor for seizures

   Headache, Delirium, Seizures            Thorazine may help with shivering

   Skin is hot and dry
   Temperature is >106F




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                                      6/4/2008




“Give me the splendid, silent sun
                    full- dazzling”
 With all his beams full-dazzling”




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