Anesthesia for Carotid Surgery

1. Anesthesia for Carotid Surgery R1胡念 之

2. 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

3. 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. 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.

5. 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.

6. 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

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

8. MAP: 60 +/- mmHg

10. 12/09 post-op D1 MAP 100 +/- mmHg

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

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

13. 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

14. 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)

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

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

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

18. 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)

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

20. 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

21. Cerebral Protection • Hypothermia • Normocapnia • Avoid hyperglycemia • Normal to high mean arterial pressure • Hemodilution

22. 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.

23. Normocapnia • Available data do not support reduction of PaCO2 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)

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

25. 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

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

27. What about our patient? • Induction and maintenance agents • Mean arterial blood pressure Peri-op: 60 +/- mmHg Post-op: 100 +/- mmHg • BT: 35 → 36℃ • eTCO2: 30 +/-

28. Thanks for Your Attention Have a nice day