1. Temperature-related
Emergencies
David A. Caro, MD

2. Temperature-related
Emergencies
• Introduction
Temperature Control/Physiology
Mechanisms of Heat Dissipation
Temperature Measurement

3. Temperature-related
Emergencies
• Heat Illnesses
Heat stress
Heat exhaustion
Heat stroke

4. Temperature-related
Emergencies
• Cold Illnesses
Frostbite
Hypothermia

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. 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. Heat Production
Temperature Ambient Heat
Heat Loss
to environment

8. Skin Receptors
Hypothalamus
Core Receptors
Thermoregulation

11. Veins
Hypothalamus
Sweat Glands
Behavior

12. Hot
Cold

13. 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%

14. 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.

15. Convection
AIR MOVEMENT
SKIN

16. 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

17. Temperature Measurement
• Axillary - most inaccurate
• TM - wide variability
• Oral - affected by ventilation
• Rectal
• Bladder, Esophageal, PA catheter - in ICU
setting

18. Heat Illnesses
• Heat Stress
• Heat Exhaustion
• Heat Stroke

19. Heat Illness
• Heat Stress
Heat Cramps
Heat Tetany
Heat Edema
Heat Syncope
Prickly Heat

20. Heat Exhaustion
• Syndrome of weakness, fatigue, headache,
nausea, vomiting, vertigo, orthostasis, and
impaired judgement
• NO major CNS symptoms (seizures, coma)

21. Heat Stroke
• Thermoregulatory Failure
• Profound CNS dysfunction
• Classic vs. exertional

22. Heat Stroke
• CNS dysfunction
• CV dysfunction
• Hepatic dysfunction
• Renal failure
• Hematologic complications

23. Heat Stroke - Differential
Diagnosis
• meningitis • DTs
• encephalitis • typhoid fever
• status seizures • hypothalamic
• falciparum malaria hemorrhage
• thyroid storm
• medications

24. Heat stroke treatment
• ABCs
• Cooling
– remove from heat; remove clothing
– spray water/fan
– ice packs/cooling blankets
– lavage (NG, bladder, thoracic)
– Dialysis/CP bypass

25. Heat stroke treatment
• Benzos for seizures, shivering
• IV fluids
– replace deficits
– treat rhabdomyolysis
• Treat coagulopathy

26. Cold Illnesses
• Hypothermia
• Frostbite

27. Hypothermia
• 92-95oF - Mild
• 87-92oF - Moderate
• < 87oF - Severe

28. Frostbite
• Spectrum - similar to burns
– Mild (analagous to 1o burn)
– Moderate (2o burn)
– Severe (3o burn to gangrene)

29. Treatment - Mild Hypothermia
• Remove wet clothing; Replace with dry
clothing/blankets
• Ambient warming
• Warmed oral fluids

30. 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

31. 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

32. Frostbite
• Damage done by crystallization within
cells/interstitium/small vessels
• Reversible to a point

33. 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

34. Review – Temp Emergencies
• Thermoregulation
• Heat loss/gain physiology
– Radiation, convection, evaporation
• Temperature measurement

35. Review – Temp Emergencies
• Heat illnesses
– Minor
– Major (heat stroke)
• Cold illnesses
– Minor
– Major