Anesthesia Principles: CEA Flashcards

Internal carotid artery
Terms Definitions
What accounts for 80% of CVA's?
Ischemic Cerebral vascular disease
What is the most common site of atheroscelrosis in the brain?
Proximal Internal Carotid Artery
What is the treatment goal for the patient undergoing a CEA?
To reduce the risk of recurrent stroke
What artery branches off of the Brachiocephalic artery?
Right common carotid artery
Where does the Left common carotid artery branch from?
Directly from the Aorta
What do the common carotids bifurcate into?
The internal and external carotid arteries
What does the internal carotid artery branch into and supply?
*Branches into the middle and anterior cerebral arteries
*Supplies the ocular globe via the opthalmic artery, and the cerebral hemispheres.
What does the external carotid artery supply?
The neck, face, scalp, oral, nasal cavities and meningies.
What three nerves run in close proximity to the neck vessels?
Hypoglossal nerve(IX)
Recurrent Laryngeal Nerve (branch of vagus)
Vagus nerve (X)
What does the carotid sinus contain?
Contains baroreceptors or stretch receptors and carotid bodies.
Where are the carotid sinuses located?
Above the carotid bifurcation
What happens when the carotid sinus is manipulated?
Afferent impulses are sent to the vasomotor center via the glossopharyngeal nerve.
What is the efferent response to carotid sinus stimulation?
Vagal in nature causing bradycardia and possibly hypotension
What two manifestations are responsible for carotid stenosis?
Thrombus or Embolus
What is the term that describes monocular blindness?
Amaurosis Fagux
What is the definition for a Transient Ischemic Attack (TIA)?
A neurologic event that resolves in less than 24 hours.  Major strokes are preceded by TIA's
What is the definition of a stroke?
A neurologic deficit lasting >24 hours. 
What s/s would be present with a large embolus passing into the Middle Cerebral Artery?
*Contralateral deficits that affect the face and upper extremity.
What are the s/s of a large emboli traveling into the Anterior Cerebral Artery?
*Effects the contralateral legs producing loss of motor and sensory function.
How is asymptomatic carotid stenosis usually detected?
As an incidental finding.  A bruit can be auscultated in the neck.
What are indications for getting a CEA?
*Lesions greater than 70% with TIAs
*Severe ipsilateral carotid stenosis with mild stroke
*30-70% occlusion with ipsilateral symptoms
 
How long should a CEA be delayed after a CVA?
Why?
*4-6 weeks
*Because of a 20 fold increase in the risk of intraoperative cerebral ischemia
Is surgery performed on lesions that are 100%?
*No, if collateral flow wasn't present around the 100% occlusion the patient would be dead.
What nerves are at risk of injury when the carotid sheath is opened to expose the carotid artery (4)?
*The Phrenic Nerve
*The Vagus Nerve
*Hypogolssal Nerve
*Recurrent Laryngeal Nerve
How many units of heparin are typically needed to maintain an ACT>300?
 
5,000-10,000 units
When will heparinization be needed?
Following complete exposure of the common, internal and external carotid
How are all three arteries (common, internal and external carotid) clamped and why?
*Sequentially to minimize distal embolization
What is the onset of heparin?
3 minutes
What is the half life of heparin?
90 minutes
How is the carotid dissected during the CEA procedure?
*From the common carotid to the ICA distal to the area of plaque.
How is the plaque freed from the artery?
*It is endarectomized and feed from the artery 
How is the arteriotomy closed or repaired?
*With a prosthetic patch and flow is restored.
What is a medication and a diagnostic procedure that may or may not be performed at the end of a CEA?
*Use of protamine sulfate
*Angiogram
Why is a shunt sometimes utilized during a CEA?
*To minimize cerebral ischemia by reestablishing flow to the ipsilateral cerebral hemisphere during cross clamping.
What pressure is measured and what parameters determine use of a shunt?
*Stump pressures
*<60mmHg indicates the need for a shunt
What does a stump pressure <60 indicate?
What is the false positive rate of a stump pressure?
*Inadequate retrograde flow from the Circle of Willis.
*30%
List complications of a shunt
*Surgical field obstruction
*Air entrainment, embolism
*Create an intimal flap that can promote thrombus formation
*Plaque dislodgement during placement
*Blood loss from dislodgement
What along with a through H&P should be considered Preop?
*Lab studies
*Cardiac clearance with complete history of past or present illness (MI, CHF, Angina, Valvular disorder, previous surgeries or interventions)
*Cerebral blood flow studies
*Vital signs with BP in both arms
*Respiratory function
*Blood Type & Screen
*Renal Function
What is the greatest cause of surgical mortality in a CEA?
*1-4% related to Myocardial Infarction
What is the greatest cause of surgical Morbidity in a CEA?
*Intraoperative neurological event (Stroke)
What are some other common co-existing diseases in the patient undergoing a CEA?
*HTN
*Generalized Arteriosclerosis
*CAD
*DM
*Past Hx of CEA
*Smoking
What should be evaluated preop if this is the second CEA procedure? Why?
*Vocal cord function may be evaluated to r/o Superior Laryngeal Nerve injury or paralysis
What need to be thoroughly documented Preop in the patient undergoing a CEA.
*Neurological Exam with residual effects of past CVAs
Where should the arterial line be placed in the pt undergoing a CEA?
*In the contralateral radial artery
What are some things to consider when setting up the room for a CEA?
*Arterial line set up 
*Pressure line available for Stump pressure monitoring
*Standard monitors- 5 lead EKG
*Prepare for patient to possibly be turned away from anesthetist losing access to head and ipsilateral arm
*Possible intraop EEG, TCD, SSEP
*NO EKG leads under neck or head due to possible intra op angiogram
What are two acceptable anesthetic techniques for a CEA?
*Cervical plexus blockade (superficial and deep)
*general anesthesia
Which anesthetic option (general or regional) is the most commonly utilized option?
*General
List some advantages in using a GETA technique during a CEA
*Airway control
*Cerebral protection
*decreased patient movement
*length of procedure not a factor
*What are some disadvantages with using GETA for a CEA?
*More hemodynamic fluctuations
*Inability to assess neurologic function throughout procedure
List advantages of using cervical plexus blockade for a CEA
 
*Provision of better hemodynamic stability
*An awake patient available for immediate neurologic evaluation potentially decreasing the need for unnecessary intraoperative shunting
What is the best neurologic monitor of the patient undergoing a CEA?
*an awake patient
What are some disadvantages of using regional anesthesia for the patient undergoing a CEA?
*Technical difficulty of managing the airway of an ischemic event did occur
*Requires a quick surgeon comfortable with this technique
*Unable to provide cerebral protection
*Inability to control PaCO2/ABGs
*It requires a cooperative patient and a normal coagulation profile
What are complications of regional anesthesia in the cervical region used for a CEA?
*Horner's Syndrome d/t stellate ganglion being affected
What are s/s of Horner's Syndrome?
Ipsilateral ptosis, miosis, anhydrosis, squeaky voice
Where should blood pressure be kept intraop during a CEA?
*BP should be kept in the patient's high normal range in order to maintain cerebral perfusion (Ischemic areas may have lost autoregulation)
How much fentanyl should be used during CEA?
*5-7mcg/kg front loaded in order to avoid sedation upon emergence
What are some pharmacological agents that should be used with caution during a CEA?
*Ketamine should be avoided
*STP and propofol due to cardiac depression 
*Desflurane d/t subsequent tachycardia associated with its use
 
For a CEA induction should be.................
*Slow and smooth allowing for endotracheal intubation without wide swings in MAP
What should absolutely be avoided while artery is clamped? Why?
*Hypotension
*Some suggest increase in MAP 20% prior to and during clamping of common carotid
What should absolutely avoided after artery repair in a CEA? What can occur if this happens?
*Hypertension
*Cerebral Hyperperfusion Syndrome (like a stroke when BP gets high)
Where should fluids generally be kept during a CEA?
*5-7mL/kg
What is a normal EBL for CEA?
50-150mL
What are modifications that anesthesia can control that lower CMRO2?
*Normocarbia (PaCO2 35-45)
*Normothermia
Why should hypothermia be avoided during a CEA and surgery in general?
*Due to the leftward shift it causes in the oxyhemoglobin dissociation curve (makes it harder for oxygen to dissociate from hemoglobin), post op shivering, and coagulopathy
What should you do if bradycardia ensues d/t surgical stretching of the baroreceptors?
*Tell the surgeon
*Try to let the response extinguish itself
*Can localize with 1% lidocaine on field
*Treat if symptomatic
*Can give a small amount of robinol to increase HR
Emergence from CEA should be...............
*Slow, smooth and devoid of wide swings in MAP
*Avoid coughing and bucking on OET
*Can give lidocaine to attenuate laryngeal reflexes
*Fully reverse NDMR
What should be checked after emergence from a CEA PRIOR to leaving the OR?
*Quick neuro check of bilateral muscle strength and tongue movement before leaving the OR!
What medication should be ready for use during and after emergence of a CEA? 
What medication should be used with caution?
*Antihypertensive medications should be ready 
*Use analgesics carefully to avoid hypoventilation
What is the most common cause of M&M postop in the CEA pt?
*Myocardial Infarction
What is the second most common cause of M&M postop in the CEA patient?
*Stroke
List some causes of respiratory depression post op in the CEA patient
*Narcotics
*Hematomoa
*Malfunctioning carotid bodies, less sensitive
What are the most common life threatening complications that can occur post op in the CEA pt?
*Acute Carotid Occlusion
*Hemorrhage
What does carotid hemorrhage present like?
What should be done?
*Wound enlargement, upper airway obstruction, and tracheal deviation
*Immediate control of airway 
*Returned to OR for angiography and possible reexploration.  
What are the manifestations of carotid occlusion?
Neurological status changes
What are some causes of hemodynamic instability in the post op CEA patient?
*Loss of normal baroreceptor function
*Hypervolemia
*Pain
*Hypoxemia and hypercarbia leading to increased intracranial pressure
What is the goal for maintenance of MAP post op in the CEA pt?
*At low normal range for the patient
When should the baroreceptors normally reset themselves post CEA?
*Within 12-24 hours
What is an alternative method of intervention for carotid stenosis other than CEA?
*Carotid Stenting
What is the patient population that is considered for Carotid Stenting?
The very high risk patients
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