NUR 245 Exam 2 – Questions And Accurate Answers
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Terms in this set (295)
intracranial regulation components 3 essential components
-Brain tissue (78%)
-Blood (12%)
-CSF (10%)
ICP primary injury at the initial time of the injury
-impact of car accident
-blunt force trauma
results in
-displacement bruising or damage to any of the
components
ICP secondary injury resulting
-hypoxia, ischemia, hypotension, edema or increased
ICP
follows primary injury
-can occur several hours to days after
,intracranial pressure hydrostatic force measured in the brain CSF
compartment
factors of ICP changes in
-arterial pressure
-venous pressure
-intra-abdominal and intrathoracic pressure
-temperature
-blood gases (CO2 levels)
to increase or decrease these depends on brains
ability to adapt to change
Monroe-Kellie doctrine states: the 3 components must stay relatively close in the
closed skull
-if 1 increases the volume from another component
must decrease
will not happen in displaced skull fractures or
craniotomy
ICP ranges can measure in ventricles, subarachnoid space
subdural space, epidural space, or brain tissue using a
pressure transducer
Normal range- 5-15 mm Hg
increased ICP - pressure greater than 20 mm Hg
(MUST BE TREATED)
,Normal compensatory mechanisms -changes in CSF volume (due to absorption or
ICP production/ displacing CSF into the subarachnoid
space)
-changes in blood volume (through collapse of
cerebral veins/dural sinuses, vasoconstriction/dilation
or changes in venous return)
- changes in brain tissue volume (distention of dura or
compression of brain tissue)
- limited ability to compensate for changes, ICP rises
as volume increases and decompression occurs,
results in compression and ischemia
Cerebral blood flow (CBF) amount of blood passing through 100 g of brain tissue
a minute
-CBF is 50ml/ min passing through 100g of tissue
-brain requires constant supply of O2 and glucose
-uses 20% of body O2 and 25% of bodies glucose
Autoregulation of CBF brain regulates own blood flow; due to its metabolic
needs
-automatic adjustment in diameter of blood vessels
(Vasoconstricton or vasodilator) ALLOWS CEREBRAL
CIRCULATION
-ensures consistent CBF is provided for metabolic
needs
Only effective is MAP is 70- 150
below 70- CBF decreases; ischemia, syncope/blurred
vision occur
above 150- further vasoconstriction response is lost
, cerebral perfusion pressure (CPP) pressure needed to ensure blood flow to the brain
-equal to MAP minus ICP ( CPP= MAP- ICP)
normal- 60-100
-decrease in CPP causes autregulation to fail and CBF
to decrease
CPP less than 50= ischemia and neuronal death
CPP less than 30= ischemia and incompatible with life
(as we age weight size of 33 of neurons decreases)
-when cerebral vascular resistance is high, blood flow
to brain tissue is impaired (think high after load)
-Trascranial doppler monitors changes in cerebral
vascular resistance
-higher CPP may be needed for patients to prevent
tissue damage (stroke patient may need higher BP,
increased MAP/CPP)
Factors affecting CBF Co2, O2 and hydrogen concentration affect cerebral
blood vessel tone (regulates pressure)
increase in Co2/paCo2- relaxes smooth muscle,
dilates vessels, decreases cerebralvascular resistance
and increases CBF
-decrease in PaCo2- constricts vessels, increases
cerebral vascular resistance and decreases CBF
O2 tension less than 50- cerebral vascular dilation -
decreases cerebral vascular resistance, increases CBF
and increases O2 tension (causes lactic acid to
accumulate)
-lactic acid increases and hydrogen accumulates
(causes acidic environment)
-acidic environment- further dilates (may cause
autorgeulation to be lost)
calculations of cerebral perfusion CPP= MAp-ICP
pressure MAP= SBP+2 (DBP) divided by 3
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Match Blocks Charms NEW
Terms in this set (295)
intracranial regulation components 3 essential components
-Brain tissue (78%)
-Blood (12%)
-CSF (10%)
ICP primary injury at the initial time of the injury
-impact of car accident
-blunt force trauma
results in
-displacement bruising or damage to any of the
components
ICP secondary injury resulting
-hypoxia, ischemia, hypotension, edema or increased
ICP
follows primary injury
-can occur several hours to days after
,intracranial pressure hydrostatic force measured in the brain CSF
compartment
factors of ICP changes in
-arterial pressure
-venous pressure
-intra-abdominal and intrathoracic pressure
-temperature
-blood gases (CO2 levels)
to increase or decrease these depends on brains
ability to adapt to change
Monroe-Kellie doctrine states: the 3 components must stay relatively close in the
closed skull
-if 1 increases the volume from another component
must decrease
will not happen in displaced skull fractures or
craniotomy
ICP ranges can measure in ventricles, subarachnoid space
subdural space, epidural space, or brain tissue using a
pressure transducer
Normal range- 5-15 mm Hg
increased ICP - pressure greater than 20 mm Hg
(MUST BE TREATED)
,Normal compensatory mechanisms -changes in CSF volume (due to absorption or
ICP production/ displacing CSF into the subarachnoid
space)
-changes in blood volume (through collapse of
cerebral veins/dural sinuses, vasoconstriction/dilation
or changes in venous return)
- changes in brain tissue volume (distention of dura or
compression of brain tissue)
- limited ability to compensate for changes, ICP rises
as volume increases and decompression occurs,
results in compression and ischemia
Cerebral blood flow (CBF) amount of blood passing through 100 g of brain tissue
a minute
-CBF is 50ml/ min passing through 100g of tissue
-brain requires constant supply of O2 and glucose
-uses 20% of body O2 and 25% of bodies glucose
Autoregulation of CBF brain regulates own blood flow; due to its metabolic
needs
-automatic adjustment in diameter of blood vessels
(Vasoconstricton or vasodilator) ALLOWS CEREBRAL
CIRCULATION
-ensures consistent CBF is provided for metabolic
needs
Only effective is MAP is 70- 150
below 70- CBF decreases; ischemia, syncope/blurred
vision occur
above 150- further vasoconstriction response is lost
, cerebral perfusion pressure (CPP) pressure needed to ensure blood flow to the brain
-equal to MAP minus ICP ( CPP= MAP- ICP)
normal- 60-100
-decrease in CPP causes autregulation to fail and CBF
to decrease
CPP less than 50= ischemia and neuronal death
CPP less than 30= ischemia and incompatible with life
(as we age weight size of 33 of neurons decreases)
-when cerebral vascular resistance is high, blood flow
to brain tissue is impaired (think high after load)
-Trascranial doppler monitors changes in cerebral
vascular resistance
-higher CPP may be needed for patients to prevent
tissue damage (stroke patient may need higher BP,
increased MAP/CPP)
Factors affecting CBF Co2, O2 and hydrogen concentration affect cerebral
blood vessel tone (regulates pressure)
increase in Co2/paCo2- relaxes smooth muscle,
dilates vessels, decreases cerebralvascular resistance
and increases CBF
-decrease in PaCo2- constricts vessels, increases
cerebral vascular resistance and decreases CBF
O2 tension less than 50- cerebral vascular dilation -
decreases cerebral vascular resistance, increases CBF
and increases O2 tension (causes lactic acid to
accumulate)
-lactic acid increases and hydrogen accumulates
(causes acidic environment)
-acidic environment- further dilates (may cause
autorgeulation to be lost)
calculations of cerebral perfusion CPP= MAp-ICP
pressure MAP= SBP+2 (DBP) divided by 3
