Lecture 7: Flashcards
What are the three components of the intracranial vault and their percentage of space:
- Cerebral spinal fluid (10-15%
- Brain (80-85%)
- Blood (5-10%)
List the route CSF takes from production to absorption:
- Produced in the lateral ventricles
- Flow through the interventricular foramina
- Third ventricle
- Cerebral aqueduct
- Fourth ventricle
- Foramina of Luschka
- Magendie
How much CSF is in the intracranial volume:
-10%
How much CSF is produced in a 24 hour period:
500 cc
How much CSF is there at any given time:
150 cc
What conditions increase CSF:
- Choroid Plexus Papilloma
- Hyperthermia
- Decreased serum osmolality
- Increased CSF osmolality
What conditions decrease CSF:
- Hypothermia
- Increased hydrostatic pressure
- Diamax
- Increased serum osmolality
- Decreased CSF osmolality
How much blood occupies the intracranial space:
-10% (60 - 80 CC)
(Circle of Willis) Carotid arteries provide circulation of blood to which part of the brain:
-anterior cerebral circulation
List the path of that provides circulation to the anterior cerebral part of the brain from the heart:
- Aorta
- common carotid arteries
- Bifurcates into external and internal carotid arteries
- Internal branch enters the base of the skull
- arterial supply of the eye via the ophthalmic artery
- Bifurcates into the anterior and middle cerebral arteries
T/F: arterial supply of the eye is via the ophthalmic artery off of the internal carotid arteries.
TRUE
The vertebral arteries provide blood circulation to which part of the brain?
-Posterior brain
Where does the vertebral arteries enter the posterior fossa:
-Foramen Magnum
The basilar artery is from the _____ artery and is just below the _____ arteries.
- vertebral
- pontine
The posterior inferior cerebellar artery and the spinal arteries are from which main artery.
-Vertebral artery
Is the basilar artery cephalad or caudad:
-cephalad
Is the posterior inferior cerebellar artery cephalad or caudad:
-caudad
The posterior cerebral artery is the terminal branch of the:
basilar artery
What artery communicates between the posterior cerebral artery and the internal carotid artery:
-posterior communicating artery
Where does the inferior and medial surfaces of the occipital and temporal lobes get their blood supply from:
Posterior cerebral arteries
Where does the medial side of the frantal and parietal lobes obtain their blood supply from:
-anterior cerebral artery
The left and right anterior cerebral arteries are connected by the:
-anterior cerebral arteries
Which cerebral artery is the largest:
-middle cerebral artery
The artery that runs along the lateral cerebral fissure is known as:
-middle cerebral artery
Which artery supplies the lateral surface of the cerebral hemisphere:
-middle cerebral artery
How does venous blood from the brain return:
-drains into the venous sinuses which lie between the layers of the dura mater and drain into the internal jugular vein.
What are FIVE main characteristics of the of the brains venous system:
- Sinuses are valveless
- Blood can flow back and forth
- Pressure within them is negative (AIR EMBOLISM)
- Little influence by the autonomic nervous system
- Chemically influenced
What does the blood brain barrier allow passage of:
- small molecules (H2O, O2, CO2)
- Lipophilic moecules (EtOH, heroin)
- Passive transport of glucose
- active transport of amino acids/NT precursors
What does the blood brain barrier prevent the passage of:
- Large molecules (dopamine)
- Charged (ionized) molecules
T/F: The left carotid artery arises from the aortic arch.
TRUE
T/F: The right carotid artery arises from the aortic arch.
FALSE (…arises from the right innominate artery.)
Does the BBB have many pores:
NO. It is the Paucity of pores that is responsible for what is termed the BBB.
How is water transported into the brain:
-Bulk Flow
What can disrupt the BBB:
- Sever HTM (???>160 mmHG)
- Tumors
- Trauma
- Stroke
- Infection
- High PaCO2
- Hypoxia
- sustained seizures
What tissue in the brain requires the most cerebral blood flow:
- Gray matter (Cortical)
- —–75-80mL/100g/min
What increases the cerebral metabolism and flow:
- stimulation
- arousal
- nociception
- mild hyperthermia
What decreases the cerebral metabolism and flow:
- sedative hypnotic agent
- hypothermia
Cerebral blood flow less than 30 mL/ 100gm/min means:
ischemia
Cerebral blood flow less than 20mL/100gm/min means:
-abnormal EEG and infarct
Cerbral blood flow less then 15mL/100gm/min means:
-irreversible damage
CBF is coupled to cerebral metabolic rate of oxygen by an uncharacterized mechanism thought to involve:
- K+
- H+
- Ca++
- adenosine
- prostaglandins
What will occur to CBF if CMRO2 decreases:
-CBF decreases
How do you factor CPP:
MAP - ICP = CPP
What is normal CPP:
70 - 100 mmHg
CBF is controlled by what factor:
- CPP
- PaCO2
- H+, HCO3
- PaO2
- Temperature
- Neurogenic
- Autoregulation
-
Cerebral blood flow will remain constant if MAP is between:
60 - 150 mmHg
What will cause a loss in CBF autoregulation:
- Hypoxia
- Acidosis
- Trauma
- Volatile anesthetics (less with forane)
What are the three compensation for intracranial pressure:
- CSF Regulation
- Cerebral Blood Flow-Auto Regulation
- Metabolic Auto Regulation
What is a potent CBF arterially:
-PaCO2
If PaCO2 changes by 3 mmHg approximately how much will CBF change in percent from baseline:
~9% (CBF changes by ~3% of baseline for each 1 mmHg change in PaCO2)
T/F: CBF changes 1-2 mL/100g/min per mmHg change in PaCO2.
True
Which has a slower response to CBF, H+ or PaCO2 and why:
- H+
- these ions take much longer due to entering the extra cellular fluid (ECF) slowly
T/F: pH has a(n) inverse relationship with cerebral blood flow (CBF).
TRUE
At what point does hypoxia take over and creates cerebral vasodilitation:
-PaO2 < 50 mmHg
What is the usual venous PaO2:
35 mmHg (reduction below 30 mmHg is necessary to increase CBF
Absence of effective blood flow results in loss of consciousness within:
10 - 15 seconds
How is 85-90% of glucose obtained in the brain:
-oxidative pathway
What will 8 degrees of Celsius do to the CMRO2 of the brain:
decrease by 1/2
Which cranial nerve(s) are linked to controlling CBF:
- X
- V
What neurotransmitters are vasoactive in the brain:
- Epi
- Norepi
- Dopamine
- Serotonin
Trendelenberg and anemia will cause a _________ increase in CBF.
increase
Age, increase viscosity, and PEEP will cause a _____ decrease in CBF.
Decrease
Generrally all CBF will be decreased with intravenous anesthetic agent except:
Ketamine
Will anesthetic agents cause an increase in cerebral blood flow:
Yes, but only in high doses.
(Low doses of anesthetic agents have show little effect.
Which anesthetic cause will most likely cause less cerebral vasodilatation Sevo, Des, Iso, or Halo.
Halo
T/F: Succinylcholine does NOT increase ICP.
FALSE
Alpha and beta agonist and antagonists have what effect on the CBF if the BBB is intact.
They have no effect.
What will vasodilators do to CBF:
INCREASE CBF
What is luxury perfusion syndrome:
- Increase in local accumulation of metabolic by products causes an increase in vasodilation in that area
- Vessels sstay maximally dilated or have increased flow
What is cerebral steal syndrome:
- In areas of focal ischemia with a resutling loss in autoregulation an increase in PaCO2 produces a resultant increase in CBF in the normal areas
- This takes blood away from the already ischemic areas since the vessels in this area cannot dilate
What is inverse steal or Robin Hood Syndrome:
- The arterioles in an area are maximally dilated
- They do not respond to a decrease in PaCO2 and will not constrict
- Cerebral blood flow will be increased in this area and stolen away elsewhere
Which classification system do most institutions use for brain tumor and describe the classification:
-World Health Organization
- Benign (least aggressive)-Grade I
- Malignant (most aggressive)-Grade IV
T/F: Suproteatorial Tumors are more common in adults.
TRUE
T/F: Infrteatorial Tumors are more common in pediatrics.
TRUE
List the places where the brain can herniate through:
- Cingulate gyrus
- Uncinate gyrus
- Level of the verebellar tonsils through the foramen magnum
- opening in the skull
What is vasogenic edema:
-breakdown in the blood brain barrier which allows protein to move into the extracellular tissue of the brain.
What is cytotoxic edema:
- result of neuronal damage
- Increases the amount of sodium and water in the brain cells, leading to increased brain cell volume
What is the treatment of choice for many intracranial aneurysms.
-Endovascular therapy
How long after can a stroke victim receive thrombosis or thrombectomy after the first S/S appear:
-up to 8 hours
______ often accompanies subarachnoid hemorrhage resulting in ischemia.
vasospasm
What type of therapy would most likely be used for vasospasms near the circle of willis.
-balloons
Intracranial hemorrhage may demonstrate what changes on an EKG:
- PVC
- ST-T
What type of medication would be used for cerebral vasospasms:
Verapamil
nimodipine
nicardipine
