Welliver Paper-Josh Flashcards
The composition of the Cranial vault contains what 3 components which together determine ICP? for extra credit what % soed each make up?
- Brain tissue (80%)
- Blood (12%)
- CSF (8%)
Brain is 80%
how much does it weigh in grams? and lbs? and % of tbw?
- 1300g
- 3 lbs
- 2%
Blood is 12%
it receives how much of CO? how much total flow mL/min
- 15-20% CO
- 750mL/min
CSF 8%
how many mL in cranium and spinal cord total? how many mL in cranium ar any given time?
- 150mL
- 75mL
Normal ICP is what?
<= 10 mmHg
CSF production is by the _____ in the ____ _____ and makes approx ____ mL/day?
- Choroid plexuses
- Lateral ventricles
- 400mL
The ______ allows bilateral communication of internal carotid and vertebral artery blood flow?
Circle of Willis
Tumor locations are generally described as ______ or ______
- supratentorial
- Infratentorial
what is the CSF flow through the Brain?
- Choroid plexus (in lateral ventricles)
- Foromen of Monro
- 3rd ventricle
- Aqueduct of Sylvius
- Fourth Ventricle
- Foramen of Magendi & Luschka
- Cistern Magna
- Subarachnoid space and Spinal Column
- absorbed via Vill of SA space
CBF:
what is the avg CBF
(mL/g/min)
50mL/100g/min
CBF:
what is the total CBF (mL/min)
750mL/min
CBF:
what is the range of CBF?
(mL/g/min)
10-300 mL/100g/min
CBF:
the gray matter (neuronal bodies) receives how much of the CBF?
80mL/g/min
CBF:
thus the white matter (axons) receive how much CBF?
20mL/g/min
CBF:
alteration in CBF may be detrimental by drawing blood away from _____ areas or beneficial by providing more blood, and hence O2 to _____ areas
- Ischemic
- Ischemic
CBF:
CBF occurs throough what?
Circle of Willis
CBF:
list 3 factors that can affect CBF?
- Luxury perfusion
- Steal Phenomenon
- Inverse steal or Robin hood phenomenon
Factors that Affect CBF:
which factor is when perfusion excess of metabolic needs?
Luxury Perfusion
(you have too much your living the dream.. I’m rick james bitch)
Factors that Affect CBF:
Luxury Perfusion may be beneficial in healthy brains but may cause ______ in brains which have ischemic areas
“Steal Phenomenon”
Factors that Affect CBF:
w/ luxury perfusion what is 2 examples in which it may occur?
- Tumor Metabolites that cause vasodiltion in surrounding tissues
- VAAs decrease CMRO2 and Increase CBF
Factors that Affect CBF:
is Steal phenomenon detrimental or beneficial
Detrimental (bad bad bad)
Factors that Affect CBF:
what phenomenon is blood is stolen from ischemic areas of the brain by causing vasodilation in healthy areas of the brain.
Steal Phenomenon
Factors that Affect CBF:
w/ Steal Phenomenon what are 2 things that can cause it
- Increased PaCO2
- VAAs
Factors that Affect CBF:
why is Steal Phenomenon so detrimental?
Ischemic Brain tissue, which has already maximally dilated vessels due to released vasodilator subnstances, loses luxury perfusion due to global shunting of blood flow
Factors that Affect CBF:
what is the inverse steal or Robin hood phenomenon
- Decreased pCO2 constrictes normal velles but not necessarily the ischemic areas d/t vasomotor paralysis. this is one rational for hyperventilating pt’s w. intracranial tumors associatd w/ increased ICP especially when administering VAAs whch cause Vasodilation
Circle of Willis:
what are the 5 (8 total) arteries of circle of willis?
- Anterior Cerebral Artery (2)
- Anterior Communicating Artery (1)
- Internal Carotid Atery (2)
- Posterior communicating Artery (2)
- Posterior cerebral artery (1)
Circle of Willis:
what 2 (3 total) arteries are connected to the circle of willis but not actually part of the circle of willis?
- Basilar artery (1)
- Vertebral artery (2)
Determinants of CBF:
PaCO2 has a ____ relationship
Linear relationship
Determinants of CBF:
PaCO2- a 1mmHg increase = what to CBF
- 1-2 mL/100g/min increase in CBF
Determinants of CBF:
PaO2- there is a profound increase in CBF anly at a PaO2 ______mmHg?
< 50 mmHg
Determinants of CBF:
CPP equation
CPP= MAP - ICP (or CVP)
Determinants of CBF:
what is normal CPP
100 mmHg
Determinants of CBF:
CPP < 50 mmHg means what to EEG
Slowing
Determinants of CBF:
A CPP= 25-40 mmHg does what to EEG
Flat EEG
Determinants of CBF:
CPP < 25 mmHg = what?
permanent brain damage
Determinants of CBF:
what is Autoregulation? include the range!
- The vasculature self regulates by vasoconstrction or vasodilation b/t a MAP of 60-160 mmHg
Determinants of CBF:
Autoregulation- if the MAP is less than 60 or greater then 160mmHg what needs to happen in order to maintain anstant CBF
additional Vasoconstriction or vasodilation is needed
Determinants of CBF:
once Autoregulation is out of range blood flow becomes solely dependent on ________ as the vasculature connot further constrict or dilate th maintain CBF.
Pressure
Determinants of CBF:
teh autoregulation curve is sifted to the _____ for pt’s w/ chronic HTN, therefore these pt’s require a higher MAP to Maintain CBF
right
Determinants of CBF:
all VAAs _____ CBF in a dose dependent manner!
Increase
Cerebral Metabolic Rate Oxygen Consumption (CMRO2)
CMRO2 is expressed as _____ of O2 consumed per ___ g of brain tissue per _____
mL
100g
min
Cerebral Metabolic Rate Oxygen Consumption (CMRO2)
what is normal CMRO2
3-3.8 mLO2/100g/min
Cerebral Metabolic Rate Oxygen Consumption (CMRO2)
what is the coupling effect w/ CMRO2 and CPP
- Coupling is the direct linear relationship.
- As CMRO2 increases or Decreases, CPP will also increase or decrease correspondingly
Cerebral Metabolic Rate Oxygen Consumption (CMRO2)
the direct linear relationship b/t CMRO2 and CBF can be modified and altered by what?
Anesthestics
Anesthestic management
Cerebral Metabolic Rate Oxygen Consumption (CMRO2)
ALL VAAs, BArbs, and Benzo do what to what to CMRO2
- Decrease
Cerebral Metabolic Rate Oxygen Consumption (CMRO2)
VAAs decrease CMRO2 while ____ CPP disrupting the relationship of CMRO2 to CPP
Increasing
What is the main energy source used by the brain?
Glucose
Glucose consuption by the brain averages wha?
- 5mg/100g/min
Determinants of CMRO2:
what are 3 main things that determine CMRO2
- Coupling
- Temp
- Sz activity
Determinants of CMRO2:
what does coupling do?
- As metabolic demands increase so does cerebral blood flow and vice versa
Determinants of CMRO2:
How does temp effect CMRO2
- For each 1C decrease in temp there is 7-8% decrease in CMRO2
Determinants of CMRO2:
temp: At 20C body temp an EEG is what?
flat showing no brain activity
Determinants of CMRO2:
what do seizures do to CMRO2
Increase it
ICP:
Normal ICP is what?
<=10mmHg
ICP:
temporary increase in ICP can occur during what events in the OR
- Coughing
- Valsalva
- HTN
ICP:
sustained Elevated ICP >15 mmHg ______ CPP and increases the rick of Cerebral ischemia, and severely increased ICP may lead to brainstem heriniation through the foramen magnum
Decreases
ICP:
Intracranial Tumors are space occupying lesions and depending on their size and location may ______intracranial pressure
Increase
ICP:
Preventing _____ in ICP is the main anesthestic Concern
Increases
ICP:
__________ decreases CBF by causing cerebral vascular vasoconstriction which decreases ICP
HYPERventilation
ICP:
thus decreasing CBV ____ ICP
Decreases
ICP:
_______ decreases Brain tissue water content therby decreasing ICP
Diuretics
ICP:
______ and ______ catheters allow CSF to drain which decreases ICP
Ventriculostomy and intrathecal
what are teh hallmark sigs of Cushings Reflex?
- HTN
- Bradycardia
Why do you get the HTN and Bradycardia w/ cushings reflex
- When CPP requirements exceed the arterial pressure hyppothalamic sympatheic reflex increases BP tp restroe CBF.
- The Increased BP stimulates the Carotid bodies which lowers the HR
what is Cushings Triad?
- HTN
- Bradycardia
- irregular respiration
Why does cushing triad occur?
- after the cushing reflex with worsening elevation in ICP for whch the reflex cannot adequatly compensate
- irregular respirations may ensue
- this becomes the triad
Cushings triad reflects sever increases in ICP and Severe Cerebral ischemia and Impending ______
herniation
Just a fact
It is estimated that __% of pts w/ elevated ICP display all 3 components of Cushiings triad
33%
Supratentorial Tumors occupy what area
midbrain and cerebral cortex
Infratentorial tumors occupy what areas?
- cerebellum and brainstem
Positioning risk:
Sitting
VAE
Positioning risk:
lateral oblique position
Brachial plexus injury
Positioning risk:
prone
- POVL
Positioning risk:
Supine
- head and neck rotation or extension
thats it for that I will make a separte one for the question on the paper!!!
