PowerPoint Presentation

Anesthesia for Carotid Endarterectomy: Risks, Benefits, Alternatives

Julie Pearson CRNA, PhDNCANA Annual MeetingNovember 2016

Review the risks, benefits, and alternatives of anesthesia for the patient undergoing carotid endarterectomy.

Consider the advantages/disadvantages of local, regional and general anesthesia for the patient undergoing carotid endarterectomy.

Assess the advancements in anesthetic agents and monitoring modalities utilized for the patient undergoing carotid endarterectomy.

Objectives

Severe (> 70% occlusion) asymptomatic carotid stenosis 0 - 3.1% in the general population.

Moderate (50-70% occlusion)

causes up to 10% of all ischemic strokes.

Carotid Artery StenosisStroke. 2010 October ; 41(10 Suppl): S31S34. doi:10.1161/STROKEAHA.110.595330.

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Blood flow cut off to an area of the brain.

Brain cell death

Symptoms and consequenceLocation and extent of damage

80 % preventable

TreatableSTROKENational Stroke AssociationNorth Carolina Stroke Association

Leading cause of neuro disability and 4th leading cause of death in US.2 million of 3 million stroke survivors in US have some degree of permanent disability.Annual cost to treat stroke and sequelae is $40 billion. 4

Leading cause of death and disability in NC.

Third leading cause of death in the state.

Stroke Belt

Stroke Buckle

North Carolina Stroke FactsNational Stroke Association; American Heart Association, N.C. Heart Disease and Stroke Prevention Branch, N.C. Department of Health & Human Services.

In 2007, less than 20% of NC adults knew S/S of stroke. Stroke Belt- region in southern part of the country where death from stroke significantly higher than rest of US.Stroke Buckle- coastal NC, SC & Georgia- death rate from stroke twice as high as national average 5

HYPERTENISON

Diabetes

Lipid levels

SmokingMedical Management

Carotid endarterectomy (CEA) -introduced as a treatment to prevent stroke in the early 1950s. Decreases stroke risk as much as 55%.100,000/yr in US

Carotid stenting (CAS) was introduced as a treatment to prevent stroke in 1994.

NASCET & ECSTCEA better results than medical management for symptomatic patients with high-grade carotid stenosis.

Carotid Endarterectomy (CEA)

80-90% of cerebral blood supply via r & l internal carotid arteries.10-20 % from vertebral arteries. Blood flow is 20 % of cardiac output.8

When carotid artery stenosis reaches 70 % becomes significant enout to resut in TIAA or stroke, if collateral blood flow inadequate. 9

Intermediate risk procedure

Mortality 0.5%

MorbidityStrokeMyocardial InfarctionNerve injurySurgical site infection

Carotid EndarterectomyACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery

The majority of patients with extracranial carotid occlusive disease have sufficient cerebral collateral circulation to permit clamping ofthe carotid artery during reconstruction.' However, even in the most experienced hands, there is a low percentage ofperioperative strokes associated with these procedures, some of which may result from ischemic injury during a period of carotid clamping in circumstances when collateral circulation is insufficient. Other causes include embolism of atherosclerotic debris or thrombus at the time of surgery and early thrombosis ofthe endarterectomized segment. 10

History and physicalAttention to cardiovascular historyHigh incidence of coronary artery diseaseAssess Risk factorsAge, Sedentary lifestyle, Family historyCo-morbiditiesHypertension, Hyperlipidemia, Tobacco use, Diabetes, Insulin resistance, Metabolic syndrome, Homocysteine levels, Nutrition, Weight, Alcohol consumption

Preoperative Evaluation

Hypertension

Antiplatelet Medications

Smoking Cessation

StatinsOptimization

Maintain cerebral perfusion (pressure and oxygenation)Minimize hemodynamic (cerebral and cardiac) fluctuationsMaintain cerebral blood flow during cross clampAllow for postoperative neurologic examination Anesthesia Management

Autoregulation lost in ischemic areasPerfusion is pressure dependent

Blood pressure- high-normal, minimize fluctuation

Carbon Dioxide levels- maintain normal levelsHypercapniaAssists blood flow in ischemic areasIn normal areas, diverts flow from ischemic areas

Glucose levelsHyperglycemia worsens ischemiaAttention to details

General Anaesthesia vs Local Anaesthesia for Carotid Surgery (GALA) GALA trial

General vs regional

PreferenceSurgeon PatientAnesthetist

ConsiderationsMonitoringOperating conditionsNeuroprotectionHemodynamicsChoice of anesthetic

Regional Anesthesia

Advantages

Evaluation of cerebral functionLess hemodynamic fluctuation Decreases need for shuntDecreased length of stayDisadvantages

Requires patient cooperationRequires regional anesthesia skill Challenge to convert to general Absence of cerebral protection

The disadvantages of this method include the technical difficulty of adequate regional anesthesia, the minimal sedation that can be permitted the patient, and the relative unsuitability of this technique in uncooperative patients and in those with anticipated problems of exposure posed by high carotid lesions or a short stout neck17

Cervical plexus block

Supplemented, as needed, with local infiltration

SedationRegional anesthesia

Regional anesthesia techniquesUltrasound guidance

MedicationsLocal anesthesiaSedationAdvancements in Regional Anesthesia

General Anesthesia

Advantages

Decreases CMRO2Redistributes blood flow to potential area of ischemiaPatient comfortManagement of oxygenation and ventilationDisadvantages

Inability to directly evaluate cerebral function requiring additional monitoringMore hemodynamic fluctuation Increased need for shuntIncreased length of stay

Monitoring techniques

Pharmacologic agentsInductionCerebral protectionMaintenanceEmergence Advancements in General Anesthesia

routine, selective, noneAwake patient- evidence of cerebral ischemia

General anesthesia- AllBilateral diseaseCerebral perfusion indicators

RisksThromboembolismAir embolismIntimal dissectionClottingObstruction of the surgical field

Shunt

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Level of Consciousness- most sensitiveElectroencephalography (EEG)Somatosensory Evoked Potentials (SSEP)Cerebral OximetryStump pressureTranscranial DopplerMonitoring Cerebral Perfusion

guide to selective shunting and as an indication of adequate shunt function

Sample policy:The technologist will have communicated to the surgeon a need to be notified 30 minutes before CLAMP so they are able to page the Neurologist/Electroencephalgrapher for the clamping event. Clamp time is logged and annotated with B/P, HR and temperature readings. Ischemic changes will most commonly appear within 20 sec to 1-min post clamp. These are seen as a drop off of the fast activity on the ipsilateral side and replaced with slow frequencies. Any lateralized changes are reported to the surgeon. That physician will decide if the placement of a shunt is needed. If the clamping is uneventful with no changes then monitoring is continued as before until the unclamping.Electroencephalography (EEG)Whittemore, A. D., Kauffman, J. L., Kohler, T. R., & Mannick, J. A. (1983). Routine electroencephalographic (EEG) monitoring during carotid endarterectomy. Annals of Surgery, 197(6), 707713.

During the past 10 years, the authors have used a variety ofapproaches to carotid reconstruction, as summarized in Table 1. The results achieved with general or regional anesthesia and routine shunting were not significantly different from those obtained in this series with general anesthesia, EEG monitoring, and selective shunting. However, the latter method is easily employed, presents no added risk, and has been shown to correlate well with studies of cerebral blood flow. Whether used with selective or routine shunting, EEG monitoring provides assurance ofadequate cerebral blood flow and aids in the demonstration of adequate shunt function.

H. The technologist will have communicated to the surgeon a need to be notified 30 minutes before CLAMP so they are able to page the Neurologist/Electroencephalgrapher for the clamping event. I. Clamp time is logged and annotated with B/P, HR and temperature readings. Ischemic changes will most commonly appear within 20 sec to 1-min post clamp. These are seen as a drop off of the fast activity on the ipsilateral side and replaced with slow frequencies. J. Any lateralized changes are reported to the surgeon. That physician will decide if the placement of a shunt is needed. K. If the clamping is uneventful with no changes then monitoring is continued as before until the unclamping. 24

Somatosensory Evoked Potentials (SSEP)

patients who have had a stroke before their carotid endarterectomy may have baseline evoked potential waveforms that are asymmetrical. However, SSEP monitoring during surgery is still feasible.25

Cerebral Oximetry

Pressure distal to carotid clamp

Represents pressure transmitted from the contralateral side via the Circle of Willis

Wide range 25-77 mmHg (40-60 mmHg)Cerebral ischemia rarely occurs at stump pressure above 60 mm Hg Stump pressure

https://www.bing.com/images/search?q=stump+pressure+during+carotid+endarterectomy&view=detailv2&&id=EEDA79DF6273348796D1B76B1F59BD7911E112F6&selectedIndex=42&ccid=jgfV8DRB&simid=608036837661738169&thid=OIP.M8e07d5f03441b7d253877c3a604c6abbo0&ajaxhist=0

Carotid artery back pressure at the time of clamping has correlated variably with the development of postoperative strokes.'4"5 Hertzer et al.9 found a decreased stroke rate in patients who were shunted for back pressures of less than 50 mmHg. Moore et al.'6 have found that 25 mmHg is the minimal acceptable back pressure in patients without a previous neurologic deficit. However, Baker et al.7 have noted ischemic EEG changes in patients with back pressures as high as 75 to 100 mmHg. Carotid stump pressure is a function of collateral circulation derived from the circle ofWillis, but it may not necessarily reflect distal segmental or cortical perfusion.9 27

Transcranial Doppler

ComplicationsHypertension/HypotensionBradycardiaHyperperfusion SyndromeMyocardial InfarctionStroke- 5.5%Bleeding/Hematoma/Airway obstructionCranial Nerve InjuryCarotid body damagePostoperative Considerations

Appropriate preoperative assessment and optimization

Appropriate case selection

Preference and experience of surgical and anesthesia team

Attention to and management of postoperative complications

Influencing Outcomes

Angioplasty and Stenting alternatives to Carotid Endarterectomy

Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE)

Stenting vs Endarterectomy for Treatment of Carotid Artery Stenosis (CREST)

Alternatives to Carotid Endarterectomy

General anaesthesia versus local anaesthesia for carotid surgery (GALA): a multicenter, randomized controlled trial The Lancet, Volume 372, Issue 9656, 2132-2142.

Heart Disease and Stroke Statistics2016 Update. Circulation. 2015; originally published December 16, 2015.

Stenting versus Endarterectomy for Treatment of Carotid-Artery Stenosis (Original Article, N Engl J Med 2010:363;11-23).

Select References

Comments or Questions

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