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172 Cards in this Set
- Front
- Back
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what is the 3rd leading cause of death in the US
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CVAs
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What is the second most common vascular operation performed in the US
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carotid endarterectomy
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most strokes are caused by______
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cerebral ischemia
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Framingham study reported that the risk of a stroke was ___% 2 years after TIA and approximately_____% 12 years after a TIA had occurred?
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30% 2 years
55% 12 years |
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because of an increased risk for stroke following a TIA what surgical procedure is performed
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carotid endarterectomy (CEA)
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which carotid artery is incised and the plaque within the arterial lumen removed to improve cerebral blood flow
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internal carotid
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what theory of pathogenesis of cerebrovascular disease states that a thrombosis of carotid artery causes loss of blood flow and cerebral ischemia
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Flow reduction theory
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what theory o pathogenesis of cerebrovascular disease states that embolization of debris from atherosclerotic plaque causes intermittent and permanent cerebrovascular symptoms
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Embolic theory
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What theory of pathogenesis of cerebrovascular disease is considered the principal cause of TIAs and most strokes
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Embolic theory
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what medical problem could lead to an embolic stroke?
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A fib
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review circle of willis
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pg 993 patho book
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what equalizes blood pressure to the brain to provide alternate routes for cerebral perfusion in the event of cerebral arterial compromise
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Circle of Willis
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what % occlusion must be present to indicate the need for CEA
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>70% in asymptomatic
50-70% in symptomatic |
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atherosclerotic thickening of the ____of the internal carotid artery obstructs blood flow leading to the need for a CEA
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intima
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Location of what vein is important for the surgeon because it usually approximates the level of the carotid bifurcation
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Facial vein
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which common carotid artery branches straight off the aortic arch
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Left common carotid artery
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the internal common carotid artery branches off the right common carotid artery which originates where?
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brachiocephalic trunk
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prior to clamping during a CEA you may be asked to give what? and why?
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heparin, to prevent thrombus formation
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what is the goal ACT for a CEA procedure
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around 200
400=bypass patient |
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a distal stump pressure below what indicates a need for shunt placement
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<50-60
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why are distal stump pressures measured?
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to determine the driving pressure and ensure adequate collateral circulation
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CPP=
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MAP-ICP
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during a CEA procedure ICP is not usually increased therefore ____ plays the predominant role in determining CPP
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MAP...keep 20% of baseline
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MAP between ______ maintains constant CBF
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60-160
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normal CBF=
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50ml/100g/min
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decreased perfusion and ischemia can be reflected by ____
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changes in LOC
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what CO2 level should you maintain for a patient having a CEA.
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normocapnia 30-35
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the presence of what other disease process is well documented in the presence of carotid stenosis
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CAD
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2 highest risk factors preop for patients having carotid surgery
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smoking and hypertension 62%
followed by abnormal EKG, prior MI, angina, DM, hyperlipidemia |
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should you use Succs for CEA?
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no can increase ICP which will alter CPP
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what induction agents would you use for a patient having a CEA
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thiopental, propofol, or etomidate
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It is important to blunt what response related to DL, what meds would you give?
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sympathetic response,
lidocaine, esmolol, small dose of narcotics |
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the carotid sinus contains receptors that are sensitive to changes in
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pressure
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the carotid body is a CHEMORECEPTOR that responds to changes in what
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chemical compositions in the blood specifically the degree of oxygenation
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what increases myocardial oxygen demand the most
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tachycardia
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hypercapnia can lead to what?
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intracranial steal, which is a paradoxical decrease in blood flow to ischemic areas in response to vasodilator stimuli
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alpha 2 receptors are located primarily where?
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presynaptic nerve terminals
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Alpha 2 receptors creae a negative feedback loop that inhibits what
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further release of NE from the neuron
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postsynaptic Alpha 2 receptors in the CNS cause ____ and reduce _____
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sedation
sympathetic outflow which leads to vasodilation and decreased BP |
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what is an example of an alpha 2 agonist
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dexmedetomidine and clonidine
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what two drugs can decrease cerebral metabolism to 40% below normal values providing cerebral protection
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barbiturates and propofol
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hypothermia is associated with decreases in cerebral metabolic rates and O2 consumption. A decrease in care temp of 1 degree c decrease CMRO2 by what percent
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7%
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the carotid sinus has what type of receptors
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baroreceptors (stimulation causes hypotension in CEA)
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what can mimic cerebral ischemia seen on EEG
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hypothermia, hypocapnia, electrolyte disturbances, volatile anesthetics, and Hx of CVA
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SSEPS are preserved during what type of anesthetic technique
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TIVA
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SSEPs monitors measure the integrity of what portion of the spinal cord
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posterior, dorsal horn. Sensory. Post central gyrus of mid cerebral cortex.
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what continues to be the gold standard in identifying neurologic deficits related to carotid artery cross clamping
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EEG
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is there any monitor that is completely adequate in determining the need for a shunt in CEA surgery
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no
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a value of less that ____ the value prior to surgery when using a transcranial doppler is considered ischemic
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40%
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HTN post op CEA increases the risk for what complication
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hematoma...which could lead to difficult airway due to tracheal deviation
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what drugs are used to treat
Tachycardia hypotension HTN |
esmolol
neo nitro |
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what CN are assessed post op CEA
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7, 9, 10, 12
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what is the uncoupling effect of anesthetics
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increased CBF and decreased CMRO2
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what is the most optimal method of monitoring cerebral perfusion
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awake patient
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what is the most stimulating to the patient during a CEA procedure that would increase sympathetic discharge leading to hemodynamic instability
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DL
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what type of block may be done on a patient for CEA
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deep cervical plexus block, superficial cervical plexus block, or local skin infiltration
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what is the goal of regional anesthesia for CEA
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effectively block C2-C4
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When using a deep cervical plexus block what may lead to the patient feeling like they are having a hard time breathing
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ipsilateral phrenic nerve paralysis
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what is a horners syndrome and who is at risk?
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pts receiving a deep cervical plexus block...ptosis (dropping of eyelid) anhydrosis (decreased sweating) and miosis (constriction of pupil) on the ipsolateral side
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what are two major disadvantages to a superficial cervical block
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surgery may last longer than the block and you lack muscle relaxation
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is "brain protection" possible with regional anesthesia ?
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no
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the most cited disadvantage of of regional anesthesia is
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lack of patient cooperation
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by decreasing cerebral and cardiac metabolism the inhalation agents provide a degree of protection against ischemia, an effect called
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anesthetic preconditioning
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how should you manage the pts blood pressure throughout a CEA procedure
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high in the beginning to help promote collateral circulation, 20% of baseline in the middle, the low at the end to prevent hematoma formation
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IF adequate cerebral perfusion is compromised what symptoms will you see and what should you do
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dizziness, contralateral weakness, decreased mentation and loss of consciousness...shunt should be placed and may need a emergent airway
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what is the number one postop complication of carotid endarterectomy
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MI because pts already have CAD placing them at increased risk for MI
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if your patient is unable to smile symmetrically post op there could be damage to what CN
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7 facial
ipsalateral=nerve injury contralateral=CNA |
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what CN functions to control muscles of the facial expression, saliva secretion
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CN 7 Facial
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If damage to the recurrent laryngeal nerve how would it manifest
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inspiratory stridor
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if your patient has difficulty swallowing post op and ispilateral horners syndrome what CN may be damaged
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IX glossopharyngeal
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this CN functions include swallowing and pharyngeal muscles
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glossopharyngeal IX
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if your patient is having mild swallowing problems post of along with hoarseness, inadequate gag reflex, fatigued voice, vocal cord paralysis they could have damage to what CN
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X vegas
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what CN functions to control laryngeal muscle movement
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X vegas
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if your patient is showing signs of ipsalateral weakness in neck and shoulder with shrugging there could have been damage to what CN
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XI spinal accessory
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this CN functions to control shoulder muscles
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XI spinal accessory
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if you ask your patient to stick out there tongue and it droops to the ipsalateral side what CN may have been damaged
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XII hypoglossal
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What CN functions to innervate the tongue?
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XII hypoglossal
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what CN traverses the internal carotid artery
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XII hypoglossal
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is SBP greater that what is associated with an increased incidence of TIA stroke or MI
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>180
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damage to the carotid body could lead to blunting of what reflex? What should you supply
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chemoreceptor reflex, supply supplemental O2
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this results from increased blood flow to the brain as a result of loss of cerebral vascular autoregulation
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cerebral hyperperfusion syndrome
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what are the s&s of cerebral hyperperfusion syndrome
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headache, visual disturbances, altered LOC and seizures
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a loss of what wave on an EEG and what other things are seen that would be indicative of neurological dysfunction
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B wave, emergency of slow wave activity and decreased amplitude
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this assess the cortical electrical function
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EEG
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this assesses perfusion pressure in the operative carotid artery
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carotid stump pressure
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this assess blood flow velocity in the middler cerebral artery
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transcranial doppler
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this assesses the cerebral regional oxygen saturation
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cerebral oximetry
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This is an abnormal localized dilation of the intracranial arteries
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cerebral aneurysms
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rupture of what type of aneurysm is a leading cause of subarachnoid hemorrhage
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saccular
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what is the peak age for rupture of a cerebral aneurysm? Who is at higher risk, men or women?
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55-60 women 3:2
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more than how many patients with SAH die or develop significant lasting neurologic disabilities before they receive any treatment
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1/3
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approximately 50% of ruptured aneurysms will do what in 6 months
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rebleed
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SAH happens most commonly at the _______
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bifurcations of major arteries
anterior arteries of the circle of wills most common |
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what Hunt and Hess score would be given to a patient who is asymptomatic or minimal headache with slight nuchal rigidity
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grade 1
mortality rate 0-5% |
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what Hunt and Hess score would be given to a patient with moderate to severe headache, nuchal rigidity, no neurologic deficit, possible cranial nerve palsy
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grade 2
mortality rate 2-10% |
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what Hunt and Hess score would be given to a patient with drowsiness, confusion, or mild focal deficit
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Grade 3
mortality 10-15% |
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what Hunt and Hess score would be given to a patient with stupor, moderate to severe hemiparesis, possibly early decerebrate rigidity and vegetative disturbances
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Grade 4
mortality 60-70% |
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what Hunt and Hess score would be given to a patient with deep coma, decerebrate rigidity and moribund appearance
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grade 5
70-100% mortality |
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if a patient has another medical condition, such as HTN, DM, atherosclerosis, Pul. disease, or vasospasm how does this change there hunt and hess score?
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there grade will be one higher in the next less favorable category
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The world federation of neurosurgeons grade for SAH based on what
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GCS...grade III=GCS14-13 and is the start of motor deficits after this function and CGS rapidly decline
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the site of the bleeding aneurysm is best located by what
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CT scan
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Normal ICP
Normal CPP |
5-12
80-100 |
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In 85% of patients what is the presenting symptom of SAH
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"worst headache of my life"
transient loss of consciousness in 45% of pts. |
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Increased blood pressure is directly related to an _____ in transmural pressure which increases the likelihood of _____
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increase
bleeding |
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where do neurosurgeons like to keep blood pressure before clipping of the aneurysm
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120-150
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what are the most common ECG changes seen with a SAH
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t wave or ST segment changes...also can see U wave or prolongation of the QT interval
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this is the reactive narrowing of cerebral arteries after SAH
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vasospasm
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how do definitively diagnose a SAH
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lumbar puncture if blood in CSF = SAH
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New blood on a CT scan looks ____ only blood or thrombus looks _____
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white
grey |
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why is epsilon amino caproic acid given to patients with SAH
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prevents fibrinolysis
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what are the coils made out of ?
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platinum
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Why is keppra used more often than phenytoin in SAH
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does not cause enzyme induction and has a wider therapeutic margin no labs necessary for serum levels
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during the preop period do you want to sedate a patient with SAH
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yes, bed rest, sedation, analgesics recommend to minimize stress
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what if the first things that may lead to vasospasm
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direct trauma to the vessels
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what in platelets are spasmogenic
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serotonin
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what spasmogenic substances may be present in the subarachnoid blood
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oxyhemoglobin (effects mediated by free radicals)
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these are synthesized by platelets and brain tissue as a response to injury are are known to produce prolonged arterial constriction
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prostagandins
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successful treatment of vasospasm depends on maintaining _____
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CPP...expanding intravascular volume
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when doing hemodilution you want the HCT at what
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32%
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post aneurysm clipping what do you want the blood pressure to be?
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high, prevents viscus blood and ischemia, increases driving pressure
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what must be ascertained preoperatively
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baseline neurologic status
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if the pts hunt and hess score is I or II when is the best time for clipping?
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early 18-72 hours
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post op blood sugar should be < _____
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120
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Vasospasm is not seen until ____ hours after SAH and peaks ___ days after SAH and is rarely seen ____ week after SAH
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72hr
7 days 2 weeks |
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blood where can cause changes in the cerebral arteries to cause severe constriction
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basal cistern
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what are the s&s of cerebral vasospasm
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worsening headache, confusion, and HTN
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what medications are used to treat vasospasm
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ca+ channel blockers
nimodipine (po) and nicardipine (IV) |
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if a vasospasm is refractory to treatments with nimodipine an nicardipine what is done
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direct injection of papavrine in IR
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what is tripe H therapy and when it is done?
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Hypervolemia, hypertension, and hemodilution done after clipping
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3 most common post op complications following clipping
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hydrocephalus (evd drain)
rebleeding vasospasm |
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brian edema and swelling results from irritation of _______. How is it treated?
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parenchyma
steroid(decadron, may cause perianal burning) and/or mannitol (osmotic diuretic that crosses BBB) |
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when should you give mannitol?
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after the dura is open to prevent fluctuations in ICP
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The goal during induction of anesthesia for aneurysm surgery is to reduce the risk of aneurysm rupture by minimizing the _____
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transmural pressure
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it is very important during anesthesia for a SAH to have absolute avoidance of
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acute hypertension
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what do you want your MAP to be at the time of clipping
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70-80
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what drugs are given to blunt the sympathetic response to DL
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thiopental or prop for induction,
fentanyl or sufentanil for opiod and IV lidocaine |
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what is required for mayfield pin placement?
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additional opiod, thiopental or propofol, can give nipride to decrease BP
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what should not be included in any Local anesthetic for a SAH case
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epinephrine because could lead to significant increase in BP
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why is it important to prevent drastic drops in ICP in a pt with SAH
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the pressure may be tamponading a bleed
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where should the Aline be zeroed if trying to maintain CPP
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base of the skull
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hyperventilation should be limited to
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28-32 mmHG
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what medication is used for induced hypotension
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nipride (sodium nitroprusside)
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what is appropriate body temp for a patient undergoing surgery for SAH?
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32 degrees C
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what are side effects of sodium nitroprusside
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cyanide and thiocyanate toxicity (tx with sodium thiosulfate or sodium nitrate)
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why is trimethaphan not used for inducted hypotension
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causes histamine release that can lead to vasospasm
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what other disease can occur in patients with a SAH
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SIADH and DI and Cerebral salt wasting
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cerebral salt wasting causes release of ______ and cause hyponatremia
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natriuretic peptide
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what are the s&s of cerebral salt wasting
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hyponatremia, volume contraction, high urine sodium concentration
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where is ADH synthesized
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supraoptic nuclei of the hypothalamus (some in the paraventricular nuclei)
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where is ADH stored
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posterior pituitary
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ADH is released when osmoreceptors sense extracelluar increases in osmolarity the result is ....
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H2O reabsorption and less H20 excreted
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if your patient is volume overloaded with hypovolemia what may the have
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SIADH
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if your patient is having large volumes of dilute urine and is hypenatremic what may they be suffering from
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DI
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mild hypothermia=
profound hypothermia= |
34
20 |
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what is a very serious complication of hypothermia
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coagulopathy
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congenital intracerebral networks in which arteries flow directly into veins.
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arteriovenous malformations
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where are most arteriovenous malformations found
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supratentorial
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the plexus of abnormal arterial to venous connections in the avm
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nidus
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major vascular supply to the avm, usually pial in orgin
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arterial feeder
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high flow low resistance shunt in the nidus capable of recruiting vessels
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collateral vessels
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most common initial presentation of AVM
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spontaneous hemorrhage
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AVMs are graded using what system
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spetzler and martin
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what is a common post op complication of AVMs
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normal perfusion breakthrough syndrome
*edema, hemorrhage in surrounding tissues, hyperemia |
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Peds AVMs usually involve enlargement of
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vein of Galen
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what artery covers all of the eloquent areas of the brain
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middle cerebral artery
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what do you give to reverse heparin
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protamine
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where is the pituitary gland located. what is it connected to?
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sella turica connected to the hypothalamus by the pituitary stalk
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the hypophysis is also known as the
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pituitary gland
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the anterior pituitary gland is also known as the
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adenohypophysis
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the posterior pituitary gland is also known as the
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neurohypophysis
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what are the two hormones secreted by the posterior pituitary
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ADH (vasopressin) and oxytocin
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when is DI normally seen and what is the treatment
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within the first 12 hours postop
treat with DDAVP or vasopressin |
