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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