By Dr. Mohamed Dorgham, MD Lecturer of Anesthesia, Critical Care medicine and Pain Therapy Carotid...

By Dr. Mohamed Dorgham, MD Lecturer of Anesthesia, Critical Care medicine and Pain Therapy

Carotid End ArterectomyCarotid End Arterectomy

Anatomy Anatomy

PathophysiologyPathophysiology

Atheroscelero-sis

Carotid Artery Occlusive Dis-

ease

Stroke TIA Amaurosis Fugax

Asympto-matic Bruit

Embolization

Hypoperfusion

StrokeStroke is the 3rd leading

cause of Death

andlong term disability

in USA

Perioperative Stroke

Carotid Stenosis

> 50%

Asymptomatic Carotid

Bruit1.0%

3.6%

IndicationsIndications

North American SymptomaticCEA Trial

North American SymptomaticCEA Trial European Carotid Surgery TrialEuropean Carotid Surgery Trial

1992

Definitive results for symptomatic patients with high grade stenosis

> 70%

SurgicalMedical0%5%

10%15%20%25%30%

2 years Stroke Rate

2 years Stroke Rate

Surgi

cal

Med

ical

0.00%5.00%

10.00%15.00%20.00%

Long Term Stroke Rate

Long Term Stroke Rate

9% # 26%9% # 26% 2.8% # 16.8%2.8% # 16.8%

70-99%70-99%

CA Surgery Asymptomatic Narrowing Operation Versus ASA

CA Surgery Asymptomatic Narrowing Operation Versus ASA

Mayo Asymptomatic CEA StudyMayo Asymptomatic CEA Study

5 Randomized trials evaluated CEA in Asymptomatic Pts

European Asymptomatic CA Surgery TrialCAS ~70%

European Asymptomatic CA Surgery TrialCAS ~70%

Asymptomatic CA (60%) Atherosclerosis Study

Asymptomatic CA (60%) Atherosclerosis Study

Depatment of veteransCEA + Aspirin Versus Asprin alone

>or= 50%

Depatment of veteransCEA + Aspirin Versus Asprin alone

>or= 50%

Largest Trial

CEA is not indicated 50-90% stenosis

Increased no. of MI & TIA

In Surgical Group

No difference in the incidenceOf Stroke & Death

5 yrs risk of Ipsilateral StrokeCEA+ASA: 5.1%

ASA alone: 11.0%

CEA+ASA: 6.4%ASA alone: 11.8%

Perioperative Morbidity and Mortality rates

Perioperative Morbidity and Mortality rates

Sympt

omati

c CAS

Asym

ptom

atic C

AS0

1

2

3

4

5

6

StrokeMortality

Systematic review of 51 studies ( from 1980- 1995) reported the results below

Systematic review of 51 studies ( from 1980- 1995) reported the results below

5.6%5.6%

1.6%1.6%1.3%1.3%

3.8%3.8%

Preoperative EvaluataionPreoperative Evaluataion

Cor-rectable

CAD28%

Severe ValvularDisease

Severe ValvularDisease Decompensated

CHF

DecompensatedCHF

Recent MIRecent MIUnstable AnginaUnstable Angina

Systemic Atherosclerosis

CAD Leading cause of

Early & Late Mortalities

Evaluation of Myocardial Function

Evaluation of Myocardial Function

Trials established that CEA prevents Stroke in selected patients

Perioperative medical TTT is standard for all CEAsFurther tests would have little potential to alter TTT

Percutaneous angioplasty + Stenting may be an alternative in high risk ptsCEA Remains the Gold Standard

1

2

3

No reduction in short term mortality with prophylactic revascularizationLow overall rates of cardiac M & M

It would be unlikely that further specialized tests would cancel the procedure

It would be unlikely that further specialized tests would cancel the procedure

4

Severe CAD (Unstable)+

Severe Carotid Artery Occlusive disease(Symptomatic)

Combined CEA +

Coronary revascularization

Role of Carotid Angioplasty + StentingBefore Staged CABG

Still unproven

Ablation of Stress re-sponses

Heart Protection

Brain Protection

Goals

Anesthetic management

Awake patient during or at the end of surgeryFor neurological examination

HR & BP control

Ablation of Surgical pain

Regional Versus General Anesthesia

No large scale prospective randomized trials evaluated the difference in Neurologic & Cardiac outcomes with Regional versus General Anesthesia

Most reports indicate no difference in perioperative mortality rates on basis of anesthetic technique

Rate of conversion from RA to GA 2-6%Decision to use one technique is based on:• Surgeon’s & Anesthetist’s experience

• Patient pereference

General Versus Regional Anesthesia

No clinical neurological assessment

Less BP stability

1. Inability to use pharmacological cerebral protection2. Inadequate access to airway 3. Near toxic level of LA4. Phrenic nerve paresis5. Claustrophobia6. Increased catechoamine level

1. Continuous neurological assessment2. Greater stability of BP.3. Reduced need for shunting4. Avoidance of expensive monitoring & Reduced hospital costs5. High patients preference (92%)

Advantages

Disadvantages

Disadvantages

1. Difficult vascular anatomy• Short neck• High carotid bifurcation

2. Control of respiration3. Brain protective measures4. Avoids excessive neck palpitations

Advantages

Commonly used Induction agentsCommonly used maintenance anestheticsShort to Intermediate acting NDMRStable hemodynamicsAwake patient at the end of procedure

General Anaesthesia

Sufentanil: 0.5-1.0 mcg/kg for sedation slow speech or delayed response to questionsThiopental / Etomidate / PropofolO2 50% + Low dose (< 0.5 MAC) inhaled AnestheticVecuroniumCombined Remifentanil + Propofol infusion

IsofluraneLow Critical rCBF

Less EEG changes during CA clamping

SevofluraneSame Critical rCBFRapid Emergence

Stress of Laryngoscopy &Intubation

EsmololUsed liberally

during induction

High normal BPInduced HTN

Hemodynamic Fluctuation

IV volume depletion

EsmololNitroglycerine

Nitroprusside

Light anesthesiaPhenylephrine

EphedrineVasopressors

IV fluids 5ml/KgTitration of Anesthetics

Immediate TTT

Anesthetic Problems

Phenylephrine 50-100 mcg

Surgical manipulations of carotid sinus

Infiltration of Carotid Biforcation

Barorecep-tors activa-

tion

Hypotention & Bradycar-

dia

Intra&

Postop-ertive

Hyperten-sion

Anesthetic Problems

CO2 management

Poor Collaterals

Poor Collaterals

ChronicHypo

perfusion

ChronicHypo

perfusionVasomotorParalysis

VasomotorParalysis

Hypercarbia

Hypocarbia

SteelPhenomenon

Inverse steelPhenomenon

Relation between hypercarbia & cerebral ischemia is unproven

NormocapniaOr

Mild Hypocapnia

Little clinical evidence of Inverse steelPaCO2 23 mmHg increases risk of ischemia

Vasoplegia significantly improve after CEA

Anesthetic Problems

Blood Sugarmanagement

Hyperglycemia increases ischemic injury

Blood glucose > 200mg% Increase incidence of

Stroke / TIA / MI / Death

Maintain blood sugar < 200 mg%

Avoid dangerousHypoglycemia

Anesthetic Problems

Emergence

NeurologicalDeficits

Hypertension&

Tachycardia

Myocardial Ischemia

Discuss with SurgeonAngioplastyReoperation

Aggressive pharmacological

TTT

Propofol # IsofluraneControl BP

Propofol # IsofluraneDecreased pharmacological intervention during emer-

gence

Propofol > IsofluraneDecreased incidence of My-

ocardial ischemia during emergence

All patients with myocardial ischemia on emergence had

SBP>200mmHg

Regional Anesthesia

Blocking C2 to C4 dermatomesSuperficial & Deep Cervical Plexus block

1. Requires Patient cooperation Constant communication Gentle handling of tissues2. Supplemental infiltration of LA by surgeon especially at the lower border and ramus of mandible3. Sedation must be kept to minimum

1.Assess conscious / speech / contralateral hand grip2.Clamp test 2-3 mins in awake pt indicates the need of shunt placement3. BP augmentation with phenylephrine if neurologic deficit

During Clamp Test After shunt placement

Monitoring

Prevent IO Strokes

Identify need of shunting

Identify benefit from BP augmentation

GoalsStump Pressure

It’s the back pressure from the contralateral CA & verte-

brobasilar system

EasyInexpensive

Continously available

Critical Stump pressure is Un-known

<50mmHg is associated with hypoperfusion

Monitoring

Prevent IO Strokes



Goals Regional cerebral Blood Flow

Iv or CA injection of Radioac-tive Xenon

Detectors placed over the ipsi-lateral cortex supplied by

MCA

Before – During – AfterCA clamping

Provided the relationship be-tween

Critical rCBF (ml/100gm/min) & EEG

Isoflurane: 10 Enflurane:15

Sevofluran: 10 Halothane: 20

Limitations:Expenses & Expertise

Monitoring

Prevent IO Strokes



Goals Electroencephalogram

Incidence of ischemic changes: 7.5-20%Contralateral CA stenosis: 50%

Ischemic changes:CA clamping HypotensionShunt malfunction Cerebral emboli

Limitations: Subcortical & small cortical infarctsFalse negative results Affected by: BP Temperature Anesthetic depth False +ve results perioperative strokes occur PO

Monitoring

Prevent IO Strokes



Goals SSEP

Based on the response of sensory cortex “supplied by

MCA” to peripheral sensory nerve

stimulation

Decreased CBF: Decrease amplitudeIncrease latency or both

CBF<12ml/100gm/min:Abolished response

Limitations:Affected by: BP Hypothermia AnestheticsFalse –ve resultsValidity not definitively established

Monitoring

Prevent IO Strokes



Goals Transcranial Doppler

Continuous measurement of mean blood flow velocity:

Detects microemblic events in MCA

Shunt function

Need of early CA clamping

Detects early asymptomatic CA occlusion

Hyperperfusion syndrome

Limitations:High rate of technical failureImproved outcome not yet reported

Monitoring

Prevent IO Strokes



Goals Cerebral Oxygenation

Jugular BulbVenous monitoring

Cerebral Oximeter

Global cerebral O2 Metabolism: Arterial – Jugular venous O2 content

SjvO2

Global cerebral O2 Metabolism: Arterial – Jugular venous O2 content

SjvO2

Continuous regional cerebral SO2 Through Scalp

Limitations:Wide Pt to Pt variability

Lack of clinical threshold

Continuous regional cerebral SO2 Through Scalp

Limitations:Wide Pt to Pt variability

Lack of clinical threshold

Postoperative Considerations

1. Neurological Complications

ThromboembolicMajor mechanism

Hemodynamic21%

Hypoperfusion Hyperperfusion

Syndrome of abrupt increased blood flow + Loss of autoregulation in surigically reperfused brain

Headache SeizuresFocal neurological signs Brain edemaIntracerebral hage 1-5 days PO (0.4-2.0%)

Risk Factors•Post operative HTN•Preop. severe CA stenosis•Recent contralateral CEA


2. Post operative Hypotension

Occurs as frequent as HTNOccurs as frequent as HTN

Carotid sinus hypersensitivity and reactivationMore common after regional anesthesiaCarotid sinus hypersensitivity and reactivationMore common after regional anesthesia

Myocardial ischemia & Cerebral ischemiaMyocardial ischemia & Cerebral ischemia

COP: Normal or elevated SVR: reducedCOP: Normal or elevated SVR: reduced

Judicious fluids + VasopressorsJudicious fluids + Vasopressors

Resolves within 12-24 hrsResolves within 12-24 hrs


3. Cranial & Cervical nerve dysfunction

Recurrent Laryngeal

Nerve

Superior Laryngeal

Nerve

Hypoglossal Nerve

MarginalMandibular

Nerve


4. Carotid Body Denervation

Unilateral Bilateral

Due to Surgical manipulationDue to Surgical manipulation

Impaired ventilatory response to mild hypoxemia

Impaired ventilatory response to mild hypoxemia

Loss of normal ventilatory responsesLoss of normal ventilatory responses

Loss of normal arterial pressure Responses to acute hypoxia

Loss of normal arterial pressure Responses to acute hypoxia

Increased resting PaCO2Increased resting PaCO2

Central chemoreceptors are the primary sensors for maintaining ventilationSerious respiratory depression in response to opioid administration


5. Wound Hematoma

North American Symptomatic CEA Trial: 5.5%Most of cases due to venous oozing

North American Symptomatic CEA Trial: 5.5%Most of cases due to venous oozing

External CompressionAggressive BP control

Immediate evacuation

Endovascular InterventionEndovascular InterventionManagement of carotid artery stenosis

By percutaneous interventionFemoral or CCA

Management of carotid artery stenosis By percutaneous intervention

Femoral or CCA

Angioplasty Stenting

GA with short acting drugs

GA with short acting drugs

Sedation With MACSedation

With MAC

Heparin ........> ACT= 250-300 secHeparin ........> ACT= 250-300 sec

Protective devices against embolizationProtective devices against embolization

AnticholinergicsAnticholinergics Intolerance to antiplateletsIntolerance to antiplatelets

Aortic arch diseaseAortic arch disease

CA torsiousityCA torsiousity

Calcification / Heavy thrombus burden / Unstable plaque Calcification / Heavy thrombus burden / Unstable plaque

Considerations Considerations Contraindications Contraindications

1.Manifestations: of CAD (Asymptomatic bruit ...> Stroke)2.Indications: Symptomatic Pt. +/- High grade stenosis3.Further evaluation of myocardial function4.Combined versus Staged operation5.Goals of anesthetic management 6.Regional versus GA7.Anesthetic problems8.Postoperative considerations9.Endovascular intervention

Summary

By Dr. Mohamed Dorgham, MD Lecturer of Anesthesia, Critical Care medicine and Pain Therapy Carotid...

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Transcript of By Dr. Mohamed Dorgham, MD Lecturer of Anesthesia, Critical Care medicine and Pain Therapy Carotid...