The document discusses human thermoregulation and metabolism. It describes how the hypothalamus controls thermoregulation through peripheral thermoreceptors to maintain core body temperature within a narrow range. It outlines the mechanisms used to increase or decrease body temperature, such as vasoconstriction/vasodilation, shivering, and sweating. Disorders like hypothermia and hyperthermia are also examined, along with their causes, symptoms, and treatment approaches.

1. {
Metabolism and
Thermoregulation
ISHAK LEWI NDAUMANU
SURTI WULAN KHARISMA
YULIUS HERMANTO
FINI MEIRISA ALNAZ
M. RAZAK SUDARMAN
YUDI PURNAMA NUGRAHA
ANDREA NISTIANA
ERA YULIAN INEKA

2. Process of transfer and transformation of Heat Energy
To maintain balance between Heat Production & Heat Loss
Homeostasis requires stable temperature of 98.6°F  37 degree
Celsius
Thermoregulation

3.  Body temperature (BT)  maintained within a narrow
range, despite changes in environmental conditions,
physical activity and other influencing factors
 Core temperature  Normal core temperature 36.1-37.0 ºC
 Surface temperature of the skin and extremities can vary 
30°C - 40°C
Homeothermic

4.  Orally (0.3 to 0.5°C higher than
the surface temperature)
 Rectally (0.5 to 1°C higher than
the surface temperature)
 Axillary (arm-pit) (0.5 to 1°C
lower than the surface
temperature)
 Tympanic membrane (TM)
* Measures radiant heat
energy from the TM and
nearby ear canal
BT measurement

5. Human
Thermoregulation

6. Control Mechanism
 Hypothalamus
 Peripheral thermoreceptors
Thermoregulation
Thermosensitive neurons
in hypothalamus balance
heat production and
dissipation

7. Mechanisms of Heat Loss

8.  Activated by cold exposure
 Reflex vasoconstriction
 Stimulation of the hypothalamic nuclei
 Heat preservation mechanism
 Shivering
 Autonomic and endocrine responses
 Adaptive behaviors
Body Temperature Regulation

9. Thermoregulation of human body

10. Heat regulation in humans

11. nerves
Less heat generated
More water covers the
skin.
More evaporation
Skin arteries dilate
More blood to the
skin.
More radiation &
conduction of heat
Muscles of
skin arteriole
walls relax
Sweat
glands
increase
secretion
Muscles
reduce
activity
Core body
temperature
>37°C
Hypothalamus
Thermoreceptors
Increase Body Temperature

12. nerves
More heat
generated
Less water covers the
skin.
Less evaporation
Skin arteries
constrict
Less blood to the
skin.
Less radiation &
conduction of heat
Muscles of
skin arteriole
walls
constrict
Sweat
glands
decrease
secretion
Muscles
shivering
nerves
Core body
temperature
<37°C
Thermoreceptors Hypothalamus
Decrease Body Temperature

13. Increase Body Temperature Decrease Body Temperature
Vasoconstriction: Arterioles get
smaller to reduce blood going to
skin, keeping the core warm.
Shivering: Rapid contraction and
relaxing of skeletal muscles. Heat
produced by respiration.
Piloerection: Hairs on skin stand up
(trapping more air) and decreasing
heat loss.
Curling up: reduces heat loss,
decreases surface area.
Vasodilation: arterioles dilate
(widen) so more blood enters the
skin capillaries and heat is lost.
Sweating: Glands secrete sweat
which removes heat when water
evaporates.
Pilorelaxation: Hairs on skin flatten
(trapping less air) and increasing
heat loss.
Stretching Out: By opening up, the
body has a larger surface area.

14. Central
Trauma or Neoplastic lesions,
degenerative processes, congenital
Peripheral
Acute spinal cord transection (loss of
peripheral vasoconstriction)
Metabolic
DKA, uremia, hypoglycemia, sepsis,
pancreatitis
Medications
Narcotics (stops shivering response)
barbituarates, benzodiazepines, anti-
seizure meds, anti-psychotics and
sedative, NSAIDS
Impaired Thermoregulation

15. {
Hypothermia

16. Accidental Hypothermia
 Body’s core temperature unintentionally drops below 35ºC (95ºF)
Primary Hypothermia
 Due to environmental exposure, no underlying medical condition
causing disruption of temperature regulation.
Secondary Hypothermia
 Low body temperature resulting from a medical illness, e.g., trauma.

17. Decrease heat production
 Age extremes
 Inadequate stored fuel (hypoglycemia, malnutrition
 Endocrine or neuromuscular (low thyroid, etc)
Increased heat loss
 Exposure (including poor prep and acclimatization)
 Skin (burns, etc)
Impaired thermoregulation
Cold Water Submersion
Factors Predisposing to Hypothermia

18. Cold Disorders

19. Mild
(90º - 95ºF)
35C – 32C
catecholamine release= peripheral
vasoconstriction; increased ventilatory rate; cold
induced dieresis; confusion=faulty judgment,
amnesia; ataxia, apathy, shivering thermogenesis,
hyporeflexia.
Moderate
(80º - 90ºF)
32C – 28C
decreased metabolic rate= decreased oxygen
consumption, Inability to rewarm spontaneously,
enzyme suppression, sympathetic nervous
reduction, loss of shivering, hyporeflexia,
coagulopathies, decreased ventilation rate, stupor
Severe/Prof
ound
(< 80ºF)
<28C
metabolic acidosis= increased cardiac irritability,
ventricular fibrillation, severe hypotension,
decreased or absent ventilation, hyperkalemia,
coma.
Profound  asystole, mimic brain death, flat
EEG
Degrees of Hypothermia

20. Independently, penetrating trauma, GCS <8 or shock
(BP<90mmHg) were all predictive of patients arriving
hypothermic.

21. Pillars
 Hypothermia (<35C)
 Acidosis (<7.1)
 Coagulopathy (INR > 1.5)
“In the most severely injured casualties, when the lethal
triad are present, death is imminent”
 Bleeding patients with these findings have up to 90%
mortality rate.
Triad Of Death

22.  Driven by tissue injury and shock (hypoperfusion)
 Associated with increased mortality and worse outcomes
 Causes Protein C activation which leads to rapid
anticoagulation and fibrinolysis
 Clotting dysfunction begins at the moment of traumatic impact
 Physiological responses are initiated producing “acute
traumatic coagulopathy (ATC)
Acute Traumatic Coagulopathy

23.  Prevent malignant cardiac dysrhythmias!
 Gentle handling; horizontal position.
 Remove patient to a warm environment.
 Remove wet clothing and replace with dry warm blankets to
also cover head & neck.
 Initiate active gentle external rewarming
 Padded splint to frostbitten extremities to prevent additional
injuries to tissues.
Prehospital Pearls

24.  Passive  prevents further heat loss
 Noninvasive
 Remove wet/cold clothes
 Cover patient in warm environment out of wind
 Healthy patients with mild hypothermia
 Active
 Whenever there is cardiovascular instability (more
susceptible to VF)
 Temp <90ºF
 Age extremes (geriatric and very young)
 Neuro or endocrine insufficiency
Rewarming

25. Delivers heat directly to the core
 Heated/humidified inhalation
 Heated IV fluids (104-107.6)
 Padded warm packs to major pressure point areas(neck, axillary,
groin)
 Peritoneal lavage (hospital)
 GI/bladder irrigation (hospital)
 Extracorporeal rewarming (hospital)
 Dialysis(hospital)
Active Core Rewarming

27. Best wrap: foil padded space blanket

29. Advantages of warmed IV Fluids at normal body
temperature is the improved absorption of administered
medications (+/- 10% per degree F compared to cold IV
fluids)
Cold IV fluids may induce hypothermia in compromised
patients and those that are predisposed to hypothermia,
for example:
• further cooling of hypothermic patients
• cooling of traumatized patients (slowed metabolic
heat production)
• cooling of geriatric patients (poor circulation, slowed
metabolism) - diabetic patients
• cooling of pediatric patients (small body mass)
• cooling of burn victims (replacing plasma loss)
• Holds at a safe temperature indefinitely with out
overheating

31. Hypothermia protocol

32.  E.g : drawning in cold water
 Mammalian Diving Reflex :
 Apnea
 Bradycardia
 Vasoconstriction
 Shunting to inner core of body: pulmonary, coronary, and
cerebral circulation.
Cold Water Submersion

33.  Remove from water with full spinal precautions preferable.
 Gentle ABC’s of resuscitation asap (pts. respirations and
pulse rate may be difficult to detect; any doubt: start CPR)
 Move to warm environment asap. Forced warm air.
 Gently: remove wet or constricting clothing, dry off, active
rewarming: insulated warm packs to major pressure point
areas & wrap in blankets.
 Warm IV solutions and warm humidified O-2 if possible.
Treatment of cold water drowning/near drowning:

34. “Patient is not dead until rewarmed.”

35.  Most common freezing injury of tissues
 Occurs at temp below 32ºF
 Ice crystal formation damages cells
 Stasis progressing to microvascular thrombosis
Frostbite

36.  Contact with thermal conductors
 Wind-chill quickly freezes acral areas
 Immobility, constrictive clothing
 Atherosclerosis, nicotine, alcohol
Factors Predisposing to Frostbite

37.  Sensory deficits always present (light-touch, pain, temperature
perception)
 “chunk of wood” sensation and clumsiness
 “frostnip” transient numbness and tingling without tissue
destruction
Symptoms of Frostbite

38.  May be intensely painful (anticipate analgesics orders)
 Never use dry heat or allow tissues to refreeze
 Rubbing may be harmful
 Final demarcation may take 60-90 days
How should frozen tissues be
thawed?

39. Causes:
 hypothalamic lesions (infarction, hemorrhage, tumor, trauma, encephalitis)
 intoxication(anticholinergic and sympatho mimetic drugs, salicylates,
amphetamines, cocaine)
 acute spinal cord transection above T3-4
 delirium, catatonia
 malignant neuroleptic sy.(caused by skeletal muscle rigidity from treatment
with neuroleptic medications (e.g., antipsychotics, antidepressants,
antiemetics).
 malignant hyperhermia (rapid and massive skeletal muscle contraction
from exposure to anesthesia)
 dehydration, heat stroke, generaised tetanus
Central hyperthermia

40.  When blood flow is diverted to the skin, reduced perfusion of the
intestines and other viscera can result in ischemia, endotoxemia,
and oxidative stress
 Excessively high tissue temperatures (heat shock >41° C, 105.8° F)
can produce direct tissue injury
 Heat shock, ischemia, and systemic inflammatory responses can
result in cellular dysfunction, disseminated intravascular
coagulation, and multiorgan dysfunction syndrome
 Reduced cerebral blood flow, combined with abnormal local
metabolism and coagulopathy, can lead to dysfunction of the
central nervous system
Mechanisms in damage of tissue in
hypethermia

41. Minor intensity of heat illness - symptoms and
signs :
• Miliaria rubra (heat rash) - results from occlusion of eccrine
sweat gland ducts
• Heat syncope (fainting) - caused by temporary circulatory
insufficienc as a result of pooling of blood in the peripheral
veins
• Heat cramps (skeletal muscles cramps) - occur during and
after intense exercise and are believed to result from excessive
loss of sodium in sweat
Sympoms and signs of heat illness
(hyperthermia)

42. Serious heat illness – sympoms and signs
- Heat exhaustion - a mild to moderate illness characterized
by an inability to sustain cardiac output with moderate
(>38.5° C, 101° F) to high (>40° C, 104° F) body temperatures
(hot skin and dehydration)
- Heat injury - a moderate to severe illness characterized by organ
(e.g. liver, renal) and tissue (e.g. gut, muscle) injury with high
body temperatures, usually but not always greater than 40° C
(104° F)
- Heat stroke - a severe illness characterized by central nervous
system dysfunction with high body temperatures, usually but
not always greater than 40° C (104° F)

43. 1. Holcomb J et al. The Journal of Trauma, 2007
2. Firth D. et al. Acute Traumatic coagulopathy – 2012
3. Sayad M et al. Emergency medicine International,
2013
4. WMS Practice Guidelines for Hypothermia -
Wilderness and Environmental Medicine, 2015
5. Enviromental Emergencies, chapter 38, 2013
References

44. Thank You