Anesthesia for Carotid Surgery R1 胡念 之

Patient Profile Name: 陳阿檜 Sex: female Age: 49y/o Admission date: 93/12/03 C.C: Paroxysmal right side limbs shaking followed by right-sided transient weakness since 4 weeks ago

Present Illness This 59 y/o female has a history of H/T and DM under regular medication for several years. Baseline BP: 140/80 mmHg She had TIA in 92/06 and recovered completely.

4 weeks ago, she started to had paroxysmal right-sided shaking limbs followed by right-sided transient weakness, dysarthria and dysphagia which would recover in a few seconds were noted Admitted to NTUH on 12/03.

Image Study: pre-op Long segmental general narrowing & diminished flow are noted at the distal right ICA. Diffuse narrowing with poor perfusion is noted at the bilateral ACAs and MCAs, more severe at the right side.

Diagnosis & Treatment Moyamoya disease with PC-AC and PC- MC collateral; bilateral ICA narrowing Scheduled EC-IC bypass (L’t STA and MCA branch anastomosis) on 12-08

Fentanyl 4 ml Pentothol 250 mg Esmeron 40 mg Isoflurane IVF: Normal saline

MAP: 60 +/- mmHg

12/09 post-op D1 MAP 100 +/- mmHg

Image Study: post-op Anastomosis between left superficial temporal artery and left MCA posterior frontal branch as compared with prior ECA study.

Anesthesia of carotid surgery Preoperative Concerns Anesthetic Technique Cerebral Monitoring and protection Postoperative Concerns

Pre-operative evaluation and management Central nervous system: Pre-operative neurological deficits Cardiovascular system: 1. CAD is present in about 20±40% of patients undergoing CEA 2. silent CAD: most influenced factor of long- term prognosis 3. CEA: intermediate cardiac risk procedure Best Pract Res Clin Anaesthesiol (14) 2000

BP control: avoid BP control: avoid hypotension CPP = MAP - ICP Continued: β-blocker / calcium channel blocker ( heart protection) Discontinued: ACEI (lead to hypotension in combination with anesthesia agents)

Peri-op Anaesthesia Care Goal: the protection of cerebral function prevent cerebral ischemia minimize risk for myocardial infarct Anesthetic Modalities Blood pressure

Anesthetics management General anesthesia (Balanced anesthesia) Barbiturate: Pentothol (most common), Etomidate, Propofol Barbiturate: Pentothol (most common), Etomidate, Propofol Opioid Opioid Muscle relaxant: no direct effect Muscle relaxant: no direct effect Volatile agent: Isoflurane (greatest brain protection) Volatile agent: Isoflurane (greatest brain protection) Regional anesthesia: cervical plexus block

Regional Anesthesia the need for benzodiazepines and/or opioids to make the patient comfortable airway management lack of the possibility to achieve cerebral protection

Blood Pressure During ischemia, autoregulation is impaired and CBF become exquisitely dependent on perfusion pressure. Increasing perfusion should open collateral vessels, effecting an increase in flow to the area of ischemia. Maintain normal to high mean arterial pressure in most situations(10% to 20% above normal)

Approximately 1/3 of perioperative strokes are hemodynamic in nature No demonstrable advantage of a specific general anesthetic technique

Cerebral monitoring no single method to achieve the goal ASA standard monitors A-line: close observation of the haemodynamic parameters EEG: manage burst suppression transcranial Doppler ultrasound (TCD): detect a significant decrease of velocity in the MCA during cross-clamping of the ICA (the velocities decreased) detecting embolization during and after CEA (sharp spikes) Awake Patient

Cerebral Protection HypothermiaNormocapnia Avoid hyperglycemia Normal to high mean arterial pressure Hemodilution

Hypothermia Mild hypothermia (33-34ºC) has benefit upon cerebral ischemia But, many patients may suffer from shivering in the recovery phase if mild hypothermia is employed Consequent increase in myocardial oxygen consumption Routine employment of mild hypothermia is not recommended Endovascular cooling and rewarming devices. Hyperthermia should be avoided.

Normocapnia Available data do not support reduction of PaCO 2 as a routine intervention to reduce cerebral injury Normocapnia seems to be most appropriate during CEA in most situations. ASA Refresher Courses (29) 2001 ASA Annu Rev (54)

Post-op period Goal: smooth and prompt emergence optimal systemic and cerebral hemodynamics optimal systemic and cerebral hemodynamics Post-op hyperperfusion syndrome Hypertension Myocardial Infarction Cranial Nerve Injury

Postoperative Hyperperfusion Syndrome Abrupt increase in blood flow Loss of autoregulation in surgically reperfused brain High risk: high grade carotid artery stenosis severe hypertension after CEA Finding: headache, signs of transient cerebral ischemia, seizures, brain edema and even intracerebral hemorrhage Normotension should be maintained in patients at risk for the hyperperfusion state

Post-op Hypertension Worsen neurologic outcome Exacerbating the hyperperfusion syndrome Resultant intracerebral hemorrhage. β-blocker, Trandate, and Nitrates

What about our patient? Induction and maintenance agents Mean arterial blood pressure Peri-op: 60 +/- mmHg Peri-op: 60 +/- mmHg Post-op: 100 +/- mmHg Post-op: 100 +/- mmHg BT: 35 → 36 ℃ eTCO 2 : 30 +/-

Thanks for Your Attention Have a nice day