Cold Weather Emergencies

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Cold Weather Emergencies

• Victor Politi, M.D., FACP
• Medical Director -
• SVCMV-Physician Assistant Program

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Frostbite
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Definitions

• Primary VS Secondary
• Primary
• Normal thermoregulation
• Overwhelming cold exposure
• Secondary
• Abnormal thermogenesis
• Multiple causes

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Physiology Heat dissipation

• Radiation (55-65)
• Gradient between environement and exposed body
  area.
• Conduction (2-3)
• Direct contact with cold substance
• Convection (10-15)
• Wind
• Evaporation (20-35)

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Physiology

• Above 32?C
• Vasoconstriction
• Shivering
• Basal metabolic rate
• Below 32?C
• No shivering
• Below 24?C
• No basal metabolic rate

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Mild (gt 32?C)

• Increase metabolic rate
• Maximum shivering thermogenesis
• Amnesia / dysarthria / ataxia
• Loss of coordination
• Tachycardic, tachypneic
• Normal BP

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Moderate (28 32?C)

• Stupor
• No shivering
• Bradycardic / A.fib
• ? BP ? RR
• Pupils dilated (lt 30?C)

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Severe (lt28?C )

• Coma
• No corneal or oculocephalic reflexes
• ?? BP
• V.fib (Maximum risk 22?C)
• Apnea
• Asystole
• Areflexia / fixed pupils
• Flat EEG (19?C)

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Osborn (J) Wave

• Mr. John J. Osborn in the early 50s.
• When T?lt 33?C
• 25-30 of patients
• Positive-negative deflection

Osborn JJ Experimental hypothermia respiratory
and blood pH changes in relation to cardiac
function. Am J Physiol 1953 175389.
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Osborne (J) Wave

• Amplitude proportionnal to degree of hypothermia
• Usually V3-V6
• At junction of QRS and ST segment

Osborn JJ Experimental hypothermia respiratory
and blood pH changes in relation to cardiac
function. Am J Physiol 1953 175389.
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ECG in Hypothermia

• Muscle tremors artifacts
• Early changes
• Bradycardia
• T wave inversion
• Prolonged PR, QRS and QT intervals
• A.fib when T? lt 32?C
• V.fib when T? lt 28?C

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Rewarming methods Passive rewarming

• Endogenous heat production
• Shivering, metabolic rate, TSH, sympathetic,
• Involves decreasing heat loss
• Remove from cold environnement
• Remove wet clothes
• Provide blanket

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Rewarming methods Active external rewarming

• Heat to body surfaces
• Heating blankets (fluid filled)
• Air blankets
• Radiant warmers
• Immersion in hot bath
• Water bottles / Heating pads
• Less effective than internal rewarming if
  vasoconstricted

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Rewarming methods Active internal (core)
rewarming

• Warm iv fluids
• Warm, humid oxygen
• Peritoneal lavage
• Gastric / Esophageal lavage
• Bladder / Rectal lavage
• Pleural / Mediastinal lavage
• Microwaves (Diathermy)
• Extracorporeal circulatory rewarming

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Warm iv fluids

• SalineNot RL
• Long tubulure lost of heat
• Can use microwave for saline (No D5W)
• Annals of EM, 1984 and 1985
• 1L of NS to 39?C 2 minutes at high power.
• No microwave rewarming for PRBC
• Hemolysis
• Hemoglobinuria
• Transfusion reaction

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Warm, humidified O2

• 42?C-46?C
• Prevent heat loss
• Negligible heat gain
• Very important in management of hypothermic
  patient
• Up to 30 of heat production lost through airway.

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Gastric/Oesophageal/ Bladder/Rectal lavage

• Not shown to be better than external rewarming.
• Limited surface area
• Limited heat exchange
• Limited utility (!)
• Recommend as last resort when other modalities
  not available.

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Peritoneal lavage

• Fluid at 40-45?C
• Up to 12 L/h
• KCl free
• Hepatic rewarming
• Renal support when dialysate is used
• 2?C-4?C / h
• C.I.
• Abdominal trauma
• Acute abdomen
• Free intra-abdominal air

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Extracorporeal blood rewarming techniques

• Hemodialysis
• Arteriovenous rewarming
• Venovenous rewarming
• Cardiopulmonary bypass

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Extracorporeal blood rewarming

• Hemodialysis renal dysfunction
• AV depends on the pts BP
• CPB is the  Gold Standard .
• CPB improves long term survival and neurologic
  outcome.
• 15 of 32 long term survivors and none had
  neurologic deficits (7 years later).

B.H. Walpoth and al. Outcome of survivors of
accidental deep hypothermia and circulatory
arrest treated with extracorporeal blood warming,
N Engl J Med, 19973371500-5
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In The ED - Prethaw

• After stabilizing core temperature and addressing
  associated conditions -prepare to initiate rapid
  thawing
• Protect part
• Stabilize core temperature
• Hydration
• No friction massage

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In the ED - Thaw

• Rapid rewarming in 38-410 C circulating water
  until distal flush (thermometer monitoring)
• Requires 10-30 min with active motion of part
  without friction massage
• Parenteral analgesia

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In the ED - Postthaw

• Ibuprofen 400mg q 12h
• Tetanus prophylaxis
• Streptococcal prophylaxis for 48-72hr
• Elevation

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Sequelae

• Neuropathic
• pain
• phantom
• causalgia
• Tabes burning
• chronic

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Sequelae

• Thermal sensitivity
• heat
• cold
• Sensation
• hypesthesia
• dysesthesia
• paresthesia
• anesthesia

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Conclusion

• Hypothermia is rare but treatable
• Good outcome after prolonged arrests
• Include Hypothermia in your ? Dx
• Include T? as a 5th vital sign
• Call early to organize CPB if available if
  patient in cardiac arrest
• Prevention is still the best

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Other Causes of Hypothermia
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Questions ???