Anesthesia for Surgery of the Carotid Artery

• Presented by R2 林至芃• 2000.6.22

Indications for CEA

• Really helpful?!• Symptomatic patients ( CAS >70%+ TIA,

RIND, mild stroke within 6 months)

Preoperative Considerations

• Risk factors for peri-op complication:angiographic characters, Age >75.symptom status, severe HTN, before CABG, ICA thrombus, Hx of angina

• PAOD! => carotid duplex?• Coexistent CAD! => major cause of M/M

Preoperative Considerations

• Internal CAS => impaired cerebrovascular reactivity + reduced ability to dilate intracerebral arterioles when CPP decline

• TCD for MCA blood flow velocity:a. predict cerebral ischemic riskb. identify asymptomatic patient

Preoperative Considerations• Pre-op BP control, but how long?!• Poorly controlled HTN :labile intra and

post-op BP!• BP reduction: gradually!! and stable!• Diabetic patient: avoid hyperglycemia

Intraoperative Considerations

• Goal:Risk factors modification for myocardial and cerebral ischemia.Maintain adequate CPP without stressing the heart!.Continual adjustment of CV parametersPrompt intervention

Cerebral Monitoring

• No consensus!• Xenon blood flow, TCD, cerebral oximetry,

SEP, EEG, continual NE under RA• processed EEG: not so sensitive!• TCD: D/D hemodynamic and embolic event

air or particulate emboli?• Cerebral oximetry: to be determined!

Cerebral protection

• Carotid shunt: not guarantee! emboli?• BP control: as pre-op level, or higher

potential myocardial risks=> TEE? Holter?• BP fluctuation => deactivation (clamping)

and re-activation (after declamping) of carotid sinus baroreceptor!=> local?! => increased intra and post-op hypertension

Ventilatory management• Normocapnia!!• Inverse steal?!

Hyperventilation=>redistribute blood from intact cerebrovascular reactivity to CO2 to impaired area? Decreased cerebral blood flow?

• Hypercapnia=> intracerebral steal

Temperature management

• Normothermia!!• JAMA 1997

Choice of anesthesia

• predict cerebral ischemia after ICA clamping!

• lower incidence of post-op hemodynamic liability?

• shorter post-op hospital stay? • Rate of adverse cardiac outcome?• Success of RA for CEA: gentle surgeon’s

hands

Choice of anesthesia

• RA: superficial; deep cervical plexus block• RA not ideal for: long OP time, difficult

vascular anatomy, short neck.• Even RA, anesthesiologist should be ready!• Most anesthetic induction agents : no

difference!(thiopental, etomidate)• Isoflurane!

Hemodynamic Stability• Enhanced with moderate dose of narcotics

avoid dose compromise rapid emergenceRemifentanyl!!

• Beta-blocker:minimise surges in HR and BPperi-op beta blockade=> beneficial effect on cardiac outcome

• atropine for reflex bradycardia• IVF+phylnephrine for hypotension

Minimally invasive carotid artery surgery

• Percutaneous angioplasty and stenting.• Sedation for cannulation, patient awake

during balloon inflation• anti-cholinergics to attenuate baroreceptor

response during balloon inflation or stenting• hemodynamic control.

Postoperative neurologic dysfunction

• 1/2~2/3 surgical etiology (ischemia during carotid clamping, postop thomboembolism)

• most common: emboli! • 20% stroke => intraop hemodynamic origin

Post-op hyperperfusion syndrome

• Abrupt increase in blood flow with loss of autoregulation in surgically reperfused brain

• P’t with severe HTN• Headache, signs of transient ischemia,

seizure, cerebral edema, ICH• MCA blood flow =>pressure dependent• meticulous BP control!

Post-op BP liability

• After CEA, carotid sinus sense sudden increase in BP => trigger baroreceptor mediated systemic hypotension!

• Anesthetise carotid sinus nerve, surgically induced carotid sinus nerve paresis.

Cranial nerve and carotid body dysfunction

• Recurrent laryngeal nerve dysfunction 5-6%

• Bilateral CEA=> loss of carotid body function => increase resting PaCO2

• unilateral CEA => impaired ventilatory response to mild hypoxemia.

Airway and ventilation problems

• Upper airway obstruction after CEA: rare but potentially fetal!!

• Hematoma!! • Tissue edema ,more common, secondary to

venous and lymphatic congestion => edematous supraglottic mucosal fold => not responding to steroid! => difficult intubation and mask ventilation!!

Airway and ventilation problems

• Phrenic nerve paresis (60-70%) after cervical plexus block (RA)

• little clinical consequence except mild increased PaCO2

• COPD!! Pre-existing contralateral diaphragmatic dysfunction!!

Thanks for your attention