• The common carotids
- External carotid artery
- Internal carotid artery
• Carotid circulation
supplies 80 to 90% of
cerebral blood supply
• Vertebral circulation
supplies 10 to 20% of
cerebral blood supply
• Continued blood supply
to the brain will depend
entirely on adequate
collateral blood flow
through the circle of
Willis if no shunt is used
• Bilateral carotid disease
have a higherriskof
perioperative stroke after
• Hypoglossal nerve
• Vagus Nerve
• Recurrent Laryngeal Nerve
• Mandibular Branch of
• Important to document
• Atherosclerotic plaque tends to
develop at the bifurcation of
ICA and ECA
• Problem of embolization >
occlusion or insufficiency
• Clinical presentation: Varies by site of stenosis and
• Isolated cervical Bruit in asymptomatic pts - high risk of
• Part of a generalized vascular disease
• Amaurosis Fugax ( Transient Mono ocular blindness ) -
• Transient Ischemic Event (TIA) - Sudden onset of focal
neurologic deficit which resolves within 24 hours
• Reversible Ischemic Neurologic Deficit (RIND)
Neurologic dysfunction greater than 24 hours but less
than 2 weeks
• Important to differentiate between carotid disease and
posterior vertebro-basilar artery disease
• Advanced age
• Hypercoagulable states
• Most common Non invasive test - carotid duplex
• Positive tests are followed by confirmatory
Treatment options :
• Medical management
• Carotid endarterectomy
• Percutaneous transluminal Carotid angioplasty &
Indications for surgery :
• TIAs with angiographic evidence of stenosis
• RIND with >70% stenosis or ulcerated plaque with
or without stenosis
• An unstable neurological status that persists
• Individualized - assessment of stroke risk weighing
medical management versus risk of perioperative
stroke, death, or cardiac event
• Large multicenter trials - comparing medical versus
surgical management ( anti-platelet therapy versus
• Patients with a minimum of 50% to 70% stenosis are
candidates with ipsilateral disease and acceptable
• The greater the degree of stenosis, the greater the
difference in outcome statistics compared to medical
• Prophylactic intervention
to prevent cerebral
infarction and relieve
symptoms of carotid
• This involves occluding
the common,external, and
internal carotid arteries,
isolating the diseased
segment, opening the
vessel wall, and removing
• The vessel is then closed.
• If the remaining intima is
too thin, the vessel is
• Use of a shunt during the
period of carotid cross
clamping depends on
whether evidence of
cerebral ischemia becomes
apparent with cross
clamping of the carotid
• Allows hemispheric cerebral
blood flow (CBF) to be
maintained during cross
• Especially advantageous when
the endarterectomy is expected
to be complex and require a
Technical problems - plaque or
air embolism, kinking of the
shunt, shunt occlusion on the
side of the vessel wall, and
injury to the distal internal
does not guarantee adequate
CBF nor prevent
• Avoidance of surgical incision,
• Minimal anesthetic requirements,
• Avoidance of cranial nerve injury and wound infections,
• Shorter duration of induced carotid occlusion by the
balloon catheter than with surgical clamping of the
• Lower hospital costs for shorter hospital and intensive
care unit (ICU) stays.
Clinical trials comparing CEA with angioplasty have been
• Study results - angioplasty & carotid endarterectomy
equally effective in preventing stroke.
Other manifestations of generalized arteriosclerosis -
• Coronary artery disease,
• Hypertension, and
• Renal disease renal dysfunction (end - organ
Medical conditions associated with
• Diabetes mellitus, and
• Pulmonary disease secondary to cigarette smoking
The patient's Neurologic Status and airway will need to be
• 30% to 50% of patients undergoing carotid
endarterectomy (CEA) have coronary artery disease.
• Patients should be specifically asked whether they
have angina, or have had a myocardial infarction (MI)
or congestive heart failure.
• Based on the Cardiac Risk Stratification for noncardiac
surgical procedures by the AHA/American College of
Cardiology Task force on assessment of therapeutic
cardiovascular procedures, CEA is classified as an
IntermediateRiskprocedure with a reported cardiac
riskgenerally less than 5%.
• Hypertension is present in 55% to 80% of patients with
carotid artery disease, and its presence would alter
intraoperative blood pressure management.
• A range of acceptable blood pressures, where the
patient is free of symptoms of both cardiac and
cerebral ischemia should be determined
• To provide acceptable range of perfusion pressures
during anaesthesia & surgery.
• Normal autoregulation will be lost in blood vessels in the
• Raising the blood pressure excessively to improve
cerebral perfusion may exacerbate myocardial
• Lowering the blood pressure to reduce the work of the
heart may compromise cerebral perfusion,
exacerbating cerebral ischemia.
• Aspirin should be continued throughout the perioperative
• Continuing of other agents must be balanced against the risk
• Clopidogrel - stopped 1-5 days before surgery depending on
presence, type & type of coronary stenting.
• Preferable to medically optimize the patient with Uncontrolled
Hypertension Or Untreated Metabolic Disease, or if possible,
delay surgery in the patient with a recent MI
• Presence of crescendo transient ischemia attacks (TIAs) may
not allow the delay.
• For ease of ventilation and intubation.
• If it is difficult to establish ventilation pt. may become
hypercarbic during induction adverse effects on regional
cerebral blood flow (CBF).
• Range of motion of the patient's neck that is tolerated -
• # Management of intraoperative ventilation should be
aimed at maintaining the patient's normal arterial
carbon dioxide level.
• One of the anesthetic goals for CEA under GA is to
have a patient who promptly emerges from anesthesia
and is able to cooperate with a basic neurologic
• Reassuring preoperative visit
• Benzodiazepine (e.g., diazepam 5 mg orally, 1 hour
preoperatively or midazolam 1 to 2 mg intravenously)
will provide anxiolysis and minimal respiratory
• Protecting brain and heart from ischemic injury
• Maintaining hemodynamic stability
• Ablate stimulatory(pain) and stress response to
• Awake, cooperative patient at end of procedure
allowing clear neurologic evaluation
• Electrocardiogram (ECG) leads II and V5
• Noninvasive blood pressure monitor
• Pulse oximetry
• End-tidal capnometry
• Esophageal temperature
• An intraarterial catheter should be used to monitor the
patient's blood pressure closely.
• CEA is not an operation in which large fluid shifts are
• A pulmonary artery catheter/CVP/TEE should not be
required in the patient with normal left ventricular
• i.v access - one well-secured and well-running,
medium-bore, intravenous catheter because major
• Adequate cerebral perfusion
• Helps to decide when to place the shunt during carotid
• No monitoring modality is as effective as watching an
• If the patient receives general anesthesia :
Electroencephalograph (EEG) - often
Somatosensory Evoked Potentials
Internal Carotid Stump Pressure, And
Jugular Venous Oxygen Saturation
• Intraoperative EEG monitoring is the most common
choice for CEA
• Continuous, non-invasive, inexpensive and provides
direct feedback within seconds after carotid clamping that
the brain is adequately perfused and oxygenated.
• Increasing levels of ischemia lead to a decrease in
recorded electrical activity
• Its sensitivity in detecting perioperative stroke is limited -
most strokes occur following surgery and are likely
related to thromboembolic phenomena.
• Rapid changes in anesthetic depth may also complicate
• This is particularly relevant where barbiturates or propofol
• Deep brain structures are not monitored by EEG.
• In patients with preexisting or fluctuating neurologic
deficits - false negative.
• EEG may not be an ischemia-specific monitor -
changes that occur with hypothermia,
hypocarbia, hypoxemia, and deep anesthesia mimic
electroencephalographic signs of ischemia
# EEG changes secondary to anesthetics or hypothermia
are more likely to be bilateral, whereas hemispheric
ischemia is more likely to affect the electrical activity of
only one side of the brain.
• Measures ipsilateral middle cerebral artery blood flow
• Detect and quantify embolic signals, which almost
always arise during dissection and/or angioplasty.
• Disadvantage - technically demanding.
• Reflects the presence of intact sensory pathways from
a stimulated peripheral nerve to the cortex where
electrical activity is monitored.
• Distortion of certain waveforms is associated with
• May be used when ischemia cannot be detected during
barbiturate anesthesia ( isoelectric EEG )
• Relative advantage over the EEG in patients with prior
Cerebral oximetry /NearInfrared Spectroscopy (NIRS) :
• Noninvasive, continuous, and easy to use.
• A relative decrease of 20% or greater in regional cerebral
oxygen saturation (rSO₂) suggested cerebral ischemia.
• Low positive predictive value and low specificity.
• If used exclusively - unnecessary shunting and lead to over-
shunting of patients.
Internal carotid stump pressure :
• Pressure in the portion of the internal carotid artery
cephalad to the carotid cross-clamp
• Used to determine whether cerebral blood flow (CBF)
during cross clamping was adequate to avoid neuronal
• Reflects pressure transmitted through collateral vessels.
• Anesthetic agents can alter carotid stump pressure without
changing regional CBF
General anesthesia :
Regional anaesthesia :
• A still patient
• A quiet operative field,
• Early control of the airway and
• Ability to “protect” the brain
• Inability to perform repeated
• Therefore, patients receiving
general anesthesia should have
their CBF or function monitored
•Patient remains awake
allowing for repeated
•Loss of patient cooperation.
•Alteration of mental status with
cerebral ischemia , Seizures
•Cannot provide brain
• Patients present hypertensive despite having taken
their morning antihypertensive and antianginal
• Most prone to hypotension after the induction of
• Propofol / etomidate may be used for induction.
• During the induction and intubation sequence, the
patient's blood pressure is kept in normal range by the
use of vasopressors - phenylephrine and vasodilators -
nitroglycerin or sodium nitroprusside.
• Phenylephrine - α agonist, has no direct effect on the
cerebral vasculature; cerebral perfusion is increased by
an elevation in the CPP.
• It increases blood pressure, cerebral perfusion
pressure, stump pressure, and regional cerebral blood
• Trachea may be sprayed with 100 mg lidocaine to
minimize stimulation by the endotracheal tube during
• LMA ↓ hypertensive & tachycardic episodes
• Sudden onset bradycardia & hypotension may be
caused by baroreceptor reflexes with surgical irritation
of carotid sinus.
- surgeons may infiltrate the carotid
bifurcation with 1% lidocaine to attenuate this
- this may result in more postoperative
• Maintenance of a “light” anesthetic appears to have
several advantages over deep anesthesia.
• It allows ischemic patterns on the EEG to be
• Facilitates maintenance of the patient's blood pressure.
• Light anesthetic, compared to a deep anesthetic using
phenylephrine to maintain blood pressure, results in a
lower incidence of perioperative myocardial infarction
• Any anesthetic regimen is suitable if it provides
hemodynamic stability, does not exacerbate cerebral
ischemia, and allows for a prompt emergence from
anesthesia at the conclusion of surgery
• Hypercapnia dilates cerebral blood vessels
increases cerebral blood flow.
• In CEA, may be detrimental if it dilates vessels in
normal areas of the brain while vessels in ischemic
brain areas that are already maximally dilated cannot
respond “steal phenomenon”
• Hypocarbia vasoconstriction worsens cerebral
• ‘ maintenance of NORMOCARBIA’
• Moderate hyperglycemia may worsen ischemic brain
• Hypothermia can depress neuronal activity sufficiently
to decrease cellular oxygen requirements below the
minimum levels normally required for continued cell
• In theory, hypothermia represents the most effective
method of cerebral protection.
• Almost all commonly used anesthetic agents reduce
cerebral metabolism, thereby decreasing the brain's
requirements for oxygen.
• Desflurane & Sevoflurane compared to Isoflurane allow
for faster emergence & recovery
• Volatile anaesthetics may provide preconditioning &
neuronal protection by inducing nitric oxide synthase.
- offer a degree of brain protection during
periods of regional ischemia.
- Thiopental decreases cerebral metabolic
oxygen requirements to about 50% of baseline.
- These maximally achievable reductions in
oxygen requirements correspond to a silent EEG.
• Etomidate and Propofol decrease brain electrical
activity and decrease cellular oxygen requirements.
• Etomidate preserves cardiovascular stability and
beneficial in a patient population whose cardiac
reserves are often limited.
• Propofol allows rapid awakening of pt & neurological
assessment at the end of surgery.
• Cerebral autoregulation is impaired by sevoflurane but
preserved under propofol-remifentanil anesthesia
• Propofol-remifentanil lower incidence of MI
• A sensory blockade is required in the C2 to C4
• This can be accomplished with either deepor
• In performing the blocks, care must be taken not to
excessively palpate the neck, because part of the
plaque in the carotid artery may dislodge and embolize.
• Performed by
infiltrating along with
middle third of the
posterior border of
muscle with local
Deep cervical plexus blocks
• Performed with three
injections along a line
(C6) to the mastoid
• Alternatively, a single
injection of local
anesthetic can be made
on the line between the
mastoid process and
Chassaignac's tubercle at
the level of C4 with the
needle directed medially
• Superficial cervical plexus block may be combined with
- reduces postop opioid requirements
- reduces PaCO₂
- increases patient satisfaction with analgesia
• Deep cervical plexus block
- does not increase the patients comfort
during procedure compared to superficial cervical
- increases complications from block
- rate of conversion to GA is more ( 2% vs.
• α₂ agonists may be used for sedation
• Dexmedetomidine reduces ischemic damage after
transient and permanent ischemia .
• Dexmedetomidine has been shown to reduce arousal
and decrease CBF
• Clonidine @ 1µg/kg/hr suppresses the
hyperadrenergic response to CEA
• GA + superficial cervical plexus block + clonidine =
• Choice of anesthetic technique should take into
account the preference of the surgeon and the
experience and expertise of the anesthesiologist.
• Hyperperfusion syndrome - headache & hypertension
• Results from blood flow to the brain that is greatly in
excess of its metabolic needs following CEA.
• May not occur until several days after surgery
• present with severe ipsilateral headache and can
progress to develop signs of increased cerebral
excitability or frank seizures.
• Transcranial Doppler - role in predicting which patients
will develop this syndrome.
• Steroids may be used in the treatment of
• Hypertension is more common than hypotension after
• Poorly controlled preoperative hypertension.
• Acute tachycardia and hypertension may precipitate
acute myocardial ischemia and failure
• It may lead to cerebral edema and/or hemorrhage
• Post-CEA hypertension is significantly associated with
adverse events like stroke or death
• Exclude and/or treat other causes of hypertension such
as bladder distention, pain, hypoxemia, and
• Lower the pressures to preop values most often with
labetalol in 5-mg increments
• In patients with reactive airways disease / bradycardia -
• Usually, the hypertensive episode has its peak 2 to 3
• Postoperative hypotension is less common.
• Causes : residual effects of anesthesia drugs,
overzealous treatment of hypertension, baroreceptor
resetting after increase in the flow
• 12-lead ECG should be obtained in the recovery room
in hemodynamically unstable patients because
significant hypertension or hypotension can be caused
• Postoperative respiratory insufficiency may be caused
by recurrent laryngeal nerve or hypoglossal nerve
injury, a massive hematoma, or deficient carotid body
• small hematomas - venous oozing
- treatment : gentle digital
compression / reversing residual heparin with
• Expanding hematoma - tracheal compression
- immediate evacuation
• More common with patch angioplasty
• Unilateral loss of carotid body - not very significant
• Bilateral loss of carotid body - loss of hypoxic drive
• Supplemental oxygen to be given routinely
• Drugs causing resp. depression should be avoided.
• The patient who awakens with a major new neurologic
deficit or who develops a suspected stroke in the
immediate postoperative period represents a surgical
• Inadequate collateral flow, carotid thrombosis may
cause postoperative stroke
• Prompt surgical reexploration can produce significant
• If the deficit - focal and minor, it is most commonly due
• Noninvasive assessment of internal carotid flow and
anticoagulation after exclusion of a hemorrhagic brain
lesion is the indicated treatment
• For patients undergoing neck exploration for a wound
hematoma following CEA - tracheostomy /
cricothyroidotomy tray should be available.
• Management of a difficult airway
• Esmolol - control of hyperdynamic cardiovascular
responses during awake intubation
• Difficulty in managing airway - wound is opened &
drained externally tracheal intubation before GA is
EMERGENCY CAROTIDENDARTERECTOMY :
• Patient may have full stomach -- aspiration prophylaxis
• Anesthetic technique is similar.