Anesthesia for Surgery of the Carotid Artery Presented by R2 林至芃

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 risk b. 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 parameters Prompt 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 CO 2 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 emergence Remifentanyl!! Beta-blocker: minimise surges in HR and BP peri-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