Carotid Surgery by murplelake77

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									Carotid Surgery
Anesthetic considerations
 Sam Hemans MD DDS
   Charles Smith MD
       3 August 2004
Objectives
•   Pathophysiology of carotid dz
•   Strategy for anesthetic evaluation
•   Perioperative management
•   Complications
•   New therapies in the field
Epidemiology

• 1.2m strokes or tia’s each yr in the US
• >150,000 deaths each yr
• 3rd leading cause of death
• CEA introduced in 1954 as a preventive
 measure for occlusive dz.
Indications

• >70% in symptomatic patients
• 50- 69% in symptomatic patients with low
  risk
• >60% in asymptomatic patients with
  favourable surgical risks
Physiologic considerations
•   Carotid dz is due to atheroslerosis
•   Most common site is the bifurcation of vessels
•   Ischemia is often due embolic phenomenon
•   During ischemia collateral flow critical
•   Principal pathways : Circle of Willis,extracranial
    anastomotic channels,leptomeningeal
    communications
Preoperative evaluation
• CEA has an inherent risk of perioperative stroke and cvs
    events
•   25% strokes associated with CEA occur intra-op
•   33% mostly embolic; some hemodynamic in origin
•   Recent data from the NASCET reports a 6.5% rate of
    stroke and death
•   1.1% rate of death, 0.9% disabling stroke,4.5%
    disabling stroke
•   Increased risk for stroke is most strongly associated with
    an active neurologic process prior to surgical
    intervention
Preoperative evaluation
•   Other risk factors for poor neurologic outcome
•   Hemispheric vrs retinal tia’s
•   Left sided procedure
•   Ipsilateral ischemic lesion on ct
•   Contralateral carotid occlusion
•   Impaired consciousness
•   Poor collaterals
•   An irregular or ulcerated plaque
•   Cea with CABG
Pre-op
• Medical complications occur 10% of time
• Hypertension: incidence of neurologic deficit related pre-op
    uncontrolled HTN
•   Multicenter study , diastolic>110 predictor of adverse events
•   Reasonable recc is delay elective surgery for diastolics>110
•   A less firm recc is to delay elective sx for sys >180
•   Carotid dz is a manifestaton of systemic dz: Good cardiac hx,
    previuos mi,angina,exs tolerance,chf,arrhythmias,ekg,cxr
    routine.Echo and stress test may be indicated as well.
•   Diabetes, may have increased cardiac related death but data seems
    to indicate that CEA can be performed safely in these patients
•   Renal Insufficiency, have a overall increased risk for stroke, death
    and cardiac morbidity
  Monitoring
Awake          Likely the gold standard for neurologic
patient        monitoring.However, there is absence of prospective data
               that will compel one to choose this method of neurologic
               monitoring
EEG            Neurologic changes may correlate with EEG. However,
               there is a fairly high rate of false positives for
               discriminating ischemia with the EEG
SSEP           Probably not any better than the EEG, but more complex.
               May be a better indicator of subcortical ischemia
Stump          Poor sensitivity/specificity
Press
TCD            TCD may be beneficial for assessing hemodynamic
               ischemia,shunt function,embolic
               phenomenon,hyperperfusion syndrome
Oximetry       High false positive rate
JvO2           Sensitivity,specificity and intervention thresholds not
               determined
Monitoring

• Std ASA monitors
• Continuous lead II , V5
• Arterial line routine
• PA cath and TEE may be considered in
 patients with symptomatic dz or recent mi
Anesthetic Management
• No compelling advantage has been demonstrated with
    either regional or general anesthesia
•   Technique should optimize perfusion to the
    brain,minimize myocardial stress and allow rapid
    recovery
•   Choice is often strongly influenced by the surgeon’s
    preference and the anesthesiologist familiarity with a
    specific technique
•   Recent study, sevo and des provided quicker extubation
    times and recovery profiles after CEA c/w iso with no
    significant peri-op differnces in CI and ST segment
    analysis
•   Propofol and narcotics may be associated with
    hypotension
Regional technique
• A regional technique for CEA necessitates
  the correct combination of patient,
  surgeon and anesthesiologist
• CEA requires block of C2- C4.
• Superficial cervical block, deep cervical,
  epidural and straight local or a
  combination of these have been utilized
  successfully
Regional technique
• Tangkanakul et al performed a meta – analysis
    of studies evaluating the efficacy and safety of
    regional anesthesia
•   The non-randomized study suggested that the
    use of regional was associated with approx 50%
    reductions in the odds of stroke, death, mi,
    pulmonary complications and length of hosp
    stay.
•   There was far too little data to either confirm or
    refute the study.
Modalities of Cerebral Protection
Surgical- placement of a shunt during x-clamp
Physiologic: Mild hypothermia 33-34C
                 Rx hyperglycemia
                 Hypertension
                 Hemodilution
                 Maintenance of normocarbia

Anesthetic:Barbiturates, no evidence for permanent focal deficits
                 volatile anesthetics, iso and sevo associated with lower critical bf
                 c/w halothane and enflurane
                 Etomidate shown to worsen outcome in animal models,thio
                 shown to improve ischemic injury
                 Propofol , animal studies have produced mixed results
Post- op
• The objective is a smooth     • Bleeding
    and prompt emergence        • Cranial Nerve injury, occurs in
                                    10% of patients
    with optimal systemic and   •   The most commonly injured
    cerebral hemodynamics,          nerves are,hypoglossal
    additional problems as          nerve,vagus, recurrent
                                    laryngeal,accessory nerve.
    follows:
                                •   Unilateral damage usually no
•   Hypertension                    immediate sx or intervention
•   Hypotension                 •   Bilateral damage could result
                                    in upper airway obstruction
•   Myocardial Infarction       •   Beware of patients with pre-
•   Stroke, usually embolic         existing neck surgery
CEA and CABG
One of the more difficult decision matrices
  regards the patient who presents with simultaneous dz of
   the carotid and the coronary vessels
Best available evidence – doubling of risk of death or
   stroke if performed as a single
  anesthetic as opposed to a staged procedure
In a staged procedure risk is related to which procedure is
   performed first: If CEA is performed first the risk of mi
   increases; if CABG is performed first the risk of stroke
   increases
Timing of CEA after Stroke
• Presently there is insufficient data to
  establish any guidelines
• In the 1980’s CEA patients typically stayed
  in the ICU for1-2days then floor 3-5days
• Recent data has shown that 24hr ICU IS
  sufficient since most perioperative strokes
  following CEA occurred within 24hrs after
  the surgery
Summary
• Indications, symptomatic         • Post op concerns, usually
  patients if stenosis>70% and       due to htn
  for selected patients if the
  lesion is 50- 69%                • Whichever anesthetic
• Pre-op concerns, uncotrolled       method is chosen, it is
  htn                                imperative that CBF be
• Anesthetic technique no            optimized, with min
  demonstrated advantage of          cardiac stress especially
  regional vrs general               during x-clamping.
• Cerebral Monitoring,             • The risk of ischemia may
  neurologic status in the awake
  patient, and the EEG may be        be decreased by
  considered close to the gold       maintaining normal to
  standard                           high perfusion pressure
New Therapies
• Carotid stenting and               • SAPPHIRE (Stenting and
  Angioplasty, the procedure           Angioplasty with Protection at
  involves the placement of a          High-Risk for Endarterectomy)
  saline filled balloon,pre-loaded   • First randomized trial to
  with a stent under                   evaluate the safety and
  angiographic guidance and            efficacy of carotid artery
  applying 15atm for 3mins,            stenting with emboli
  anesthetic technique is              prevention in high surgical risk
  sedation                             patients.
• Drawbacks, profound                • High risk criteria included,
  bradycardia, high incidence of       prior cea, neck surgery,
  strokes from the angiography         radiation to the neck, occlusion
  alone.                               of the contralateral carotids,
                                       chf and other confounding
                                       medical problems
conclusion

• Study actually a randomized trial   • SAPPHIRE study
  which compared cea with stenting    • Showed that in high risk patients
  and angioplasty                        CAS was a superior to CEA and
• Enrollment terminated after 723        that emboli prevention was also
  patients were enrolled, 416            improved in the CAS group of
  registry and 307 randomized, as        patients.
  interim analysis showed a marked
  benefit in favour of stenting.
  Success defined as <30% residual
  stenosis
• 30 day periprocedural combined
  stroke/mi/death rate which was
  the study endpoint was 5.8% in
  the stent group but 12.6% in the
  surgical group

								
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