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61 Cards in this Set
- Front
- Back
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What is the #1 non-cardiac vascular sx?
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CEA
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What is a bruit?
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An audible narrowing of the lumen due to turbulent flow
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Why can you not revascularize a 100% occluded stenosis?
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Because the blood distal to the occlusion will coagulate when flow is restored it will cause an emboli.
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Pts with what % of stenosis have a increased morbidity to CVA if sx intervention performed?
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Those <75% compared to those of >75%
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Symptomatic patients will present to OR for sx when lesions are what %?
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>70% Ipsilateral
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Asymptomatic pt’s will present for sx when lesions are what %?
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>60%
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What are the most common tests performed to determine stenosis of carotid lesions?
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Carotid Dopplers
Cerebral Angiography |
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What is the disadvantage to Doppler studies?
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Not as accurate
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What is the visual symptom called that is classic for stenosis of the carotid artery?
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Amaurosis Fugax seen in ipsilateral occlusions, which is an indirect specific test for occlusion.Described as a brown curtain being pulled over the eye
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Which tests evaluate perfusion to the eye as a test for occlusive disease?
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Opthalmodynanometry
Oculo-pneumo-plethysmography Orbital directional dopppler ultrasound |
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At age 65 why does the prevalence of stroke equalize in males and females?
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The loss of estrogen protection after menopause
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Why does prevalence increase in males again after age 75?
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Because females live longer and the men that are left are in worse health
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A patient with a past hx of stroke with resolved residual effects c/o of weakness in the previously affected limb. You know that what may have occurred?
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This may resolve within a few days because that s/s of residual effects may re-occur after anesthesia.
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What are the 3 mechanisms by which cerebral ischemia is produced?
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Stenosis/Total occlusion
Embolization Steal syndrome |
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Steal syndrome usually diverts blood away from the brain to where?
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To the arm
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What are 3 categories of symptomatic carotid stenotic patients?
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TIA-s/s last <24hrs resolving w/o deficit
RINDS-s/s >24hrs-3 wks and resolve w/o deficits CVA-s/s > 24hrs and usually contain permanent deficits |
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What is the risk in post operative period for post CEA?
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Hemorrhage because the vessels in the head are not used to the increased pressure in the head
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What is the morbidity related to the procedure?
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Neuro-CVA
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What is the mortality associated with the procedure?
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Cardiac-perioperative MI. Leading cause of mortality (40-60%)
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Where do most intraoperative strokes arise from?
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Emboli
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What is the controversy surrounding CEA sx?
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When to operate
Allow 4-6 wks to stabilize vs. <24 hrs to reverse the events and preserve neurons |
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What is the chance of perioperative MI with hx of heart disease?
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4x>
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What is the significance of obtaining Radionuclide Angiography testing?
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A Dipyridamole-Thallium Scan will show an uptake of thallium slowly in tissues with low flow
*****Reversible ischemia will clue you in to a pts potential for heart disease Should always be done on increased grade stenosis for Carotid and/or CABG pts |
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The key to the Goldman Risk index is?
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The greater the # the worse the prognosis
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What is the risk of perioperative MI < 3 mths old?
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4-37%
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After 6 mths what is the risk of perioperative MI?
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5-6%
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Why would you perform a consecutive CEA/CABG procedure?
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Because the outcomes may be increased in:
Pts with carotid stenosis > 75% LM disease Unstable angina However the morbidity is increased |
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Where does the problem occur for neuro events in a pt undergoing CABG with stenotic carotid lesions?
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Decreased Perfusion during non pulsatile flow- reason why the CEA should be done 1st
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CPP should remain where for sx?
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80-90 torr
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MAP should remain where for sx?
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80-100 torr
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ICP should remain where for sx?
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0-15 torr
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Describe coupling?
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The relationship of O2 delivery to consumption
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What is normal cerebral flow rate?
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750cc/min
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What is normal CMRO2?
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3.5 ml/100gm tissue/min
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What are other key factors in Neuronal survival?
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Supraphysiological PaO2
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Where does the blood flow to the circle of Willis come from?
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80% ICA -ACOM
20% Vertebral arteries -PCOM |
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Describe the effects of a decreasing CPP?
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<50 torr = EEG slowing
25-50%= flat EEG <25 irreversible brain damage- unless sufficient brain protection-hypothermia |
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What autoregulation parameters are needed for adequate perfusion?
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CPP-80-90
MAP- 60-160 ICP-<30 (>30 compromises CBF and CPP) PaO2->50 torr (<50 profound decrease in CBF) PaCO2 20-80 -<20torr shifts Oxyhgb curve to the left -CBF changes 1-2 ml/100gm/min ~ per 1 torr change in PaCO2 |
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What occurs with MAP >150-160 torr?
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Disruption of BBB---> Cerebral edema
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What is the sequencing of clamping of the carotid bifurcations?
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Internal/External/Common
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Why?
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Because the most important structures are fed by the ICA- disruption of plaque to these areas is minimized by clamping the ICA 1st.
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What are the organ systems targeted for concern with CEA?
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Heart and Neuro
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What regional technique may be utilized in CEA?
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Cervical Plexus Block
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When is “only local at the sx field” anesthetic technique best utilized for CEA?
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Short sx time
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What determines the need for CVP/PA monitoring?
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Fluid status by LV functioning
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Where should they be placed?
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Opposite side
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Where are stump pressures measured?
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Distal the clamp in the ICA
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Where should the pressure be for stump pressures?
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>60 torr to maintain adequate perfusion pressures
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Where should ideal fluid status be?
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Euvolemia to slightly hypovolemic
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When should STP be used for burst suppression in CEA cases?
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When the EEG is lost that indicates stroke evolving
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How much CO goes to the head?
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20%
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What significance does this have?
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A narrowed vessels has less- may need to increase BP during clamping but remember that MI is #1 mortality
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What are the Carotid Sinuses?
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Baroreceptors reacting to stretch receptors for BP control located above the bifurcation
Afferent limb is CN IX (Sine is 9) |
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What are the Carotid Bodies?
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Chemoreceptors reacting to changes in O2 and CO2 levels also located in the bifurcation
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What occurs post operatively to these receptors?
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Either don’t work well or work too well (most likely will not work too well)
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What is the reflex called and describe it when the Carotid sinus is manipulated during sx?
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The Herring Brewer reflex-HOTN/Brady
The sinus is stimulated and sends a signal via the Herring branch of the glossopharyngeal n. and the efferent limb is CN X |
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What is the tx of this reaction?
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Stop stimulation (inform the sx)
Inject the site with LA |
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BP swings occur for what reason during sx?
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Loss of function of the receptors or may be stimulating the receptors
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What drugs should always be primed and ready in a CEA?
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NEO/Nipride/ or NTG
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Postoperative complications of CEA include?
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CVA-hemorrhage
Hyper-perfusion Syndrome-long term loss of autoregulation results in hyperperfusion and the brain can't constrict leading to lethargy and confusion HTN-Loss of baroreceptor regulation, regain of control may take days HOTN-may be volume or MI Loss of Carotid Body function- hypoxic drive blunted leading to increased PaCO2 Resp Insufficiency-Differential: Sx hematoma/RLN/Tension Pneumo-dissection LOC-CVA/Intimal flap-especially w/stump |
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Sx is ok for Asymptomatic pts when what benefit is met?
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The benefits outweigh the risk of stroke
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