Transcript Therapeutic Hypothermia - UCI Department of Emergency Medicine

Therapeutic
Hypothermia
Bryan Sloane
What is it?
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A lowering of the core body temperature
for medical benefits.
Normal Body Temperature = 37°C
Therapeutic hypothermia range = 32-34°C
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Bladder Temp.
Why use it?
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Neuroprotective effects
Down regulate the negative aspects of the
immune response following traumatic injury to
the CNS.
 Peripheral Tissue Preservation following
amputation
 Protective effects on the CNS following
hypoxia
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History of Therapeutic
Hypothermia
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In 1800’s Russia, patients in arrest would be
covered in snow with the hopes of a return of
spont. circulation.
Napoleon’s forces used it for the preservation of
amputated limbs as well as an anesthetic
In 1937 Fay cooled a pt. to 32° C to prevent
cancer cells from spreading
By 1959 it was being used for CNS injury as well
as in aneurysm repair.
Modern Uses
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The American Heart Association and European
Resuscitation Council have recommended
induced hypothermia in patients who have a
return of spontaneous circulation after an out of
hospital cardiac arrest.
This decision was based on two trials from 2002
which showed significant neurological protection
following anoxic brain injury
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275 pts. Hypothermia group had 55% favorable
outcome vs 39% in nonthermic (Holzer [Eur] and
Benard [Aus])
CNS injury
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Fig. 2. Spinal cord
injury: hematoma (H)
with shift and
compression of the
spinal cord (M; Dr.
Bodo Kress)
Damage can come
from inflammatory
responses,
hemorrhage, or
hypoxia
What is the immune response
and how does it hurt?
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Immune responses are triggered by injury and
involved leukocytes and chemical signals such
as chemokines and complement
Cytokines regulate the process by signaling the
release of other factors and recruiting different
leukocytes
Very regulated process, but dangerous in the
CNS because it is delayed compared to
peripheral tissue and due to the specialized cells
found only in the CNS
What does it do/hurt cont.
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The injury induced inflammation is though
to directly effect some of the
neuropathology and necrosis that exists
after CNS injury. (unique 2° necrosis)
Associated Cytokines may be neurotoxic
via induction of reactive oxygen species
Tumor Necrosis Factor-alpha is also
released. It is cytotoxic to some neuronal
cells and neuroprotective for others.
One more immuno slide……
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Nitric oxide mediated damage
Also protective and destructive, depending on
the timing
 Plays a role in the generation of VERY toxic
free radicals that destroy lipids through
peroxidation
 NO has been shown to contribute to cell
death after CNS injury.
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So where does hypothermia
come in?
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Mild hypothermia has been shown to
protect neurological tissue following injury.
Reduces metabolic rate in hypoxic injury
and has a huge effect in slowing the
immune response.
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It has been shown that it can reduce
leukocyte rolling and adhesion (key part in
immune response)
How can we be sure?
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Dimar, et al. 2000
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Study using rat models of
CNS injury
Used acute stenosis of the
Spinal Cord as well as
severe contusion
Directly applied a cooling
factor to the injured region
of the Cord
Showed that rats who were
treated with directly applied
hypothermia had a
significant increase in
recovery
Has it been used clinically?
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YES, for many things
1 famous prehospital
application
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Buffalo Bills tight end Kevin
Everett 2007
fracture dislocation of C3C4
No sensation below the
neck
COMPLETE RETURN OF
MOTOR FUNCTION
following induced
hypothermia!!!!
Sources
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Bernhard, Michael, Andre Gries, Paul Kremer,
and Bernd W. Bottiger. "Spinal Cord Injury (SCI)---Prehospital Managment." Resuscitation 66
(2005): 127-39.
Dimar, John, Christopher Shields, Yi P. Zhang,
Darlene A. Burke, George H. Raque, and Steven
D. Glassman. "The Role of Directly Applied
Hypothermia in Spinal Cord Injury." SPINE 25
(2000): 2294-302.
Alzaga, Ana G., Mario Cerdan, and Joseph
Varon. "Therapeutic Hypothermia."
Resuscitation 70 (2006): 369-80.
Sources Cont.
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Behtea, John R., and Dalton W. Dietrich.
"Targeting the host inflammatory response in
traumatic spinal cord injury." Current Opinion in
Neurology 15 (2002): 355-60.
Suprun, Christopher. "The Cold Truth about
Spinal Injury." Journal of Emergency Medical
Services 16 Nov. 2007.
Cappuccino, Andrew. "Moderate Hypothermia as
Treatment for Spinal Cord Injury."
ORTHOPEDICS 31 (2008): 243.