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Temperature-related
   Emergencies
  David A. Caro, MD
Temperature-related
            Emergencies
• Introduction
    Temperature Control/Physiology
    Mechanisms of Heat Dissi...
Temperature-related
            Emergencies
• Heat Illnesses
    Heat stress
    Heat exhaustion
    Heat stroke
Temperature-related
            Emergencies
• Cold Illnesses
    Frostbite
    Hypothermia
Introduction
      Heat Control Physiology
• Normal human temperature 96.8 to 100.4oF
  (36 -37.8oC)
  – Temperature can r...
Temperature Emergencies
• A rise in core temperature above the normal
  range (hyperthermia) or a decrease below
  the nor...
Heat Production



             Temperature   Ambient Heat


   Heat Loss
to environment
Skin Receptors



                 Hypothalamus



Core Receptors


                 Thermoregulation
Veins

Hypothalamus
               Sweat Glands



                Behavior
Hot


      Cold
Introduction
       Heat Dissipation Mechanisms
• Radiation - electromagnetic dissipation - 65%
• Evaporation - transfer o...
Radiation



AIR        EM Radiation




 The body at the higher temperature emits more energy than the one
 at the lower ...
Convection



         AIR MOVEMENT



  SKIN
Evaporation
• For every ml of water evaporated from the
  surface of the skin, 0.58 Kcal are removed
  from the body.
• In...
Temperature Measurement
•   Axillary - most inaccurate
•   TM - wide variability
•   Oral - affected by ventilation
•   Re...
Heat Illnesses
• Heat Stress
• Heat Exhaustion
• Heat Stroke
Heat Illness
• Heat Stress
     Heat Cramps
     Heat Tetany
     Heat Edema
     Heat Syncope
     Prickly Heat
Heat Exhaustion
• Syndrome of weakness, fatigue, headache,
  nausea, vomiting, vertigo, orthostasis, and
  impaired judgem...
Heat Stroke
• Thermoregulatory Failure
• Profound CNS dysfunction
• Classic vs. exertional
Heat Stroke
•   CNS dysfunction
•   CV dysfunction
•   Hepatic dysfunction
•   Renal failure
•   Hematologic complications
Heat Stroke - Differential
              Diagnosis
•   meningitis           • DTs
•   encephalitis         • typhoid fever...
Heat stroke treatment
• ABCs
• Cooling
  –   remove from heat; remove clothing
  –   spray water/fan
  –   ice packs/cooli...
Heat stroke treatment
• Benzos for seizures, shivering
• IV fluids
  – replace deficits
  – treat rhabdomyolysis
• Treat c...
Cold Illnesses
• Hypothermia
• Frostbite
Hypothermia
• 92-95oF - Mild
• 87-92oF - Moderate
• < 87oF - Severe
Frostbite
• Spectrum - similar to burns
  – Mild (analagous to 1o burn)
  – Moderate (2o burn)
  – Severe (3o burn to gang...
Treatment - Mild Hypothermia
• Remove wet clothing; Replace with dry
  clothing/blankets
• Ambient warming
• Warmed oral f...
Treatment - Moderate
             Hypothermia
•   Remove wet clothing; replace with dry
•   Monitor cardiac, respiratory s...
Treatment - Severe Hypothermia
•   All of the above
•   Careful movement; may induce V Fib
•   Intubate as needed
•   Warm...
Frostbite
• Damage done by crystallization within
  cells/interstitium/small vessels
• Reversible to a point
Frostbite
• Treatment
  – Begin rethawing only when it can be completed
  – Warm, wet heat (immersion) is the ideal; 104 –...
Review – Temp Emergencies
• Thermoregulation
• Heat loss/gain physiology
  – Radiation, convection, evaporation
• Temperat...
Review – Temp Emergencies
• Heat illnesses
  – Minor
  – Major (heat stroke)
• Cold illnesses
  – Minor
  – Major
Temperaturelecture
Temperaturelecture
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Transcript of "Temperaturelecture"

  1. 1. Temperature-related Emergencies David A. Caro, MD
  2. 2. Temperature-related Emergencies • Introduction Temperature Control/Physiology Mechanisms of Heat Dissipation Temperature Measurement
  3. 3. Temperature-related Emergencies • Heat Illnesses Heat stress Heat exhaustion Heat stroke
  4. 4. Temperature-related Emergencies • Cold Illnesses Frostbite Hypothermia
  5. 5. Introduction Heat Control Physiology • Normal human temperature 96.8 to 100.4oF (36 -37.8oC) – Temperature can reach 104oF during strenuous exercise • Preoptic Hypothalamus – responsible for temperature control via thermoregulation
  6. 6. Temperature Emergencies • A rise in core temperature above the normal range (hyperthermia) or a decrease below the normal range (hypothermia) is the consequence of an imbalance between heat production and heat loss.
  7. 7. Heat Production Temperature Ambient Heat Heat Loss to environment
  8. 8. Skin Receptors Hypothalamus Core Receptors Thermoregulation
  9. 9. Veins Hypothalamus Sweat Glands Behavior
  10. 10. Hot Cold
  11. 11. Introduction Heat Dissipation Mechanisms • Radiation - electromagnetic dissipation - 65% • Evaporation - transfer of heat to make liquid a gas - 25% • Convection - heat transferred to air and water in close proximity to skin - 8% • Conduction - direct heat transfer - 2%
  12. 12. Radiation AIR EM Radiation The body at the higher temperature emits more energy than the one at the lower temperature, and the net transfer of energy (heat) is down the temperature gradient.
  13. 13. Convection AIR MOVEMENT SKIN
  14. 14. Evaporation • For every ml of water evaporated from the surface of the skin, 0.58 Kcal are removed from the body. • Insensible - skin, respiratory – approximately 600 ml/day • Sensible - sweat – up to 3 liters/hr
  15. 15. Temperature Measurement • Axillary - most inaccurate • TM - wide variability • Oral - affected by ventilation • Rectal • Bladder, Esophageal, PA catheter - in ICU setting
  16. 16. Heat Illnesses • Heat Stress • Heat Exhaustion • Heat Stroke
  17. 17. Heat Illness • Heat Stress Heat Cramps Heat Tetany Heat Edema Heat Syncope Prickly Heat
  18. 18. Heat Exhaustion • Syndrome of weakness, fatigue, headache, nausea, vomiting, vertigo, orthostasis, and impaired judgement • NO major CNS symptoms (seizures, coma)
  19. 19. Heat Stroke • Thermoregulatory Failure • Profound CNS dysfunction • Classic vs. exertional
  20. 20. Heat Stroke • CNS dysfunction • CV dysfunction • Hepatic dysfunction • Renal failure • Hematologic complications
  21. 21. Heat Stroke - Differential Diagnosis • meningitis • DTs • encephalitis • typhoid fever • status seizures • hypothalamic • falciparum malaria hemorrhage • thyroid storm • medications
  22. 22. Heat stroke treatment • ABCs • Cooling – remove from heat; remove clothing – spray water/fan – ice packs/cooling blankets – lavage (NG, bladder, thoracic) – Dialysis/CP bypass
  23. 23. Heat stroke treatment • Benzos for seizures, shivering • IV fluids – replace deficits – treat rhabdomyolysis • Treat coagulopathy
  24. 24. Cold Illnesses • Hypothermia • Frostbite
  25. 25. Hypothermia • 92-95oF - Mild • 87-92oF - Moderate • < 87oF - Severe
  26. 26. Frostbite • Spectrum - similar to burns – Mild (analagous to 1o burn) – Moderate (2o burn) – Severe (3o burn to gangrene)
  27. 27. Treatment - Mild Hypothermia • Remove wet clothing; Replace with dry clothing/blankets • Ambient warming • Warmed oral fluids
  28. 28. Treatment - Moderate Hypothermia • Remove wet clothing; replace with dry • Monitor cardiac, respiratory status • Radiant/heat blanket warming • Warmed IV, oral fluids • Warmed, humidified oxygen • Warmed IV bags to groin, axillae; ? immerse
  29. 29. Treatment - Severe Hypothermia • All of the above • Careful movement; may induce V Fib • Intubate as needed • Warmed NG, Foley lavage • Warmed pleural/peritoneal lavage • Dialysis, Bypass
  30. 30. Frostbite • Damage done by crystallization within cells/interstitium/small vessels • Reversible to a point
  31. 31. Frostbite • Treatment – Begin rethawing only when it can be completed – Warm, wet heat (immersion) is the ideal; 104 – 110of – Be prepared to treat pain with narcotics
  32. 32. Review – Temp Emergencies • Thermoregulation • Heat loss/gain physiology – Radiation, convection, evaporation • Temperature measurement
  33. 33. Review – Temp Emergencies • Heat illnesses – Minor – Major (heat stroke) • Cold illnesses – Minor – Major
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