Book reading

1. Book reading 報告日期:2012-02-23 指導醫師: 藺瑞安 醫師 指導老師:戴溫然 老師 報告者: 黃淑宜、李如萍 Chapter 30 CENTRAL NERVOUS SYSTEM DISEASE

2. Neuroanatomy Neurophysiology Intracranial pressure Intracranial pressure-volume relationship Cerebral protection Preoperative assessment Anesthesia for neurosurgery Clinical cases Table of contents

3. Neuroanatomy

5. Neuroanatomy • Blood brain barrier disruption • Hypertension • Trauma • Infection • Hypoxemia • Sever hypercapnia • Tumors • Seizure

6. Neurophysiology • Cerebral Blood Flow • Effects of CBF • Cerebral Metabolic Rate • Cerebral Perfusion Pressure and Autoregulation. • Effects of PaCO2 and PaO2 on CBF • Effects of anesthetics

7. Cerebral Blood Flow • Cerebral Blood Flow= 15% Cardiac output • CBF: 50 ml/100g/min • CPP =MAP-ICP (or CVP)

8. Cerebral Metabolic Rate Body Temperature 37℃ ↓ 1℃→ CMRO2↓7 %

9. Cerebral perfusion and Autoregulation Autoregulation OK  CPP: 50~150mmHg Autoregulation(-) Trauma；neurosurgery Hypertension shifts the auto regulatory curve  Right

10. Effects of PaCO2 and PaO2 on CBF PaO2 PaCO2 CPP ICP Autoregulation 50-150mmHg

11. Effects of CBF CMRO2 CPP=MAP-ICP (or CVP) PaCO2: 於 PaCO2 :20~80mmHg 範圍內, ↑1mmHg, CBF ↑ 1-2 ml/100g/min PaO2

12. Effects of anesthetics Thiopental ＆ Propofol : CBF ↓ CMRO2 ↓ Ketamine:CMRO2 ↑; CBF ＆ ICP ↑ N2O:CBF ↑ may be CMRO2 ↑ Opioids : CBF ↓ CMRO2 ↓

13. Intracranial Pressure-Volume Relationship

14. IICP ICP=5-15mmHg IICP • Positionalheadache • Nausea +Vomiting • Hypertension + Bradycardia • Conscious change • Altered patterns of breathing • Papilledema

15. 1.Cerebrospinal fluid ↓ Ventricular drainage Lumbar drainage Lasix 2.Cerebral blood volume↓ IV anesthetic HyperventilationPaCO2 ＜30mmHg Avoid hypotension＆ hypertension 3.Increase venous outflow Elevate head Avoid constriction at the neck. Avoid PEEP Avoid airway pressure↑ 4.Cerebral edema ↓ Mannitol ;Craniectomy Resection space Occupying lesions Prevent ischemia Methods to decrease ICP

16. Effect of anesthetic on ICP Intravenous anesthetic: CMRO2↓CBF ↓ICP ↓ Avoid Etomidate (epilepsy history) Opioids: PaCO2↑ Neuromuscular blocking drugs(-) Volatile anesthetic :CBF ↑ CBV ↑ ICP↑ Dose-dependent increase

17. Cerebral protection Cerebral protection • Barbiturates • Hypothermia

18. Pre-op Neurologic evaluation IICP? Vasospasm? EKG HHH therapy if vasospasm Calcium channel blockers. Induction Avoid ↑SBP. Maintain CPP Avoid ischemia Intracranial Aneurysms HHH: Hypertension, Hypervolemia, Hemodilution

19. Maintenance Opioid plus propofol or volatile anesthetic Mannitol (0.25-1 g/kg IV) Normal or ↑systemic blood pressure Postoperative Normal to ↑ systemic blood pressure. Early awakening Neurologic assessment HHH therapy Intracranial Aneurysms HHH: Hypertension ,Hypervolemia Hemodilution

20. Preoperative Assessment • Altered level of consciousness • Headaches • Motor or sensory deficits • IICP? • Cranial nerve abnormalities • Compression of the optic chiasm focal deficits or visual impairment • Seizures • Steroid/Diuretic/Anti-convulsion drug…etc. • CT/MRI for mass lesion. Mid-line shift?

21. Monitoring • Standard monitors,ex:EKG,NIBP,SpO2 • A-Line, CVP(not routinely used) • Capnography, GAS • NMT (peripheral nerve stimulator) • Foley catheter • ICP or EVD monitor

22. Positioning- Supratentorial tumorsIntracranial vascular lesions →Supine

23. Positioning-Sitting (I)Posterior fossa or Infratentorial tumors • Posterior cervical spine and the posterior fossa operation. • Decreased blood in the operative field. • Provider have a superior accesses to the airway and improved ventilation.

24. Venous Air Embolism (I) • Increased risk for venous air embolism • Significant elevation of the head • The operative site above the level of the heart • The venous sinuses in the cut edge of bone • or dura may not collapse when transected.

25. Venous Air Embolism (II) • ETCO2↓、SpO2↓、PaCO2↑ • Arterial hypoxemia、Cardiovascular collapse • Transesophageal echocardiography • Central venous catheter

26. Induction of Anesthesia • The Goal of induction • Avoid Hyper/Hypotension • As close as possible to and certainly within • 10% of average awake values • Avoid Cough • Avoid ICP↑or MAP↓→CBF↓ • Avoid use of PEEP • PaCO2:Keep 30 and 35 mmHg

27. Common clinical cases • Intracranial Aneurysms • Intracranial Masses • Arteriorvenous Malformation (AVM) • Carotid Stenosis

28. Intracranial Masses • Pre-op • IICP? Avoid sedatives and opioids • CT/MRI • Anxiolytics • Monitors • Supratentorial masses • Standard ASA monitors, A-line, Foley catheter • Infratentorial masses • depend on positioning • Induction+Maintenance • Avoid increasing ICP • Deep anesthesia • Skeletal muscle paralysis • Nitrous oxide (X) • Mannitol (0.25-1g/kg IV)

29. Arteriorvenous Malformation (AVM) • Pre-op • Is similar to that for aneurysms. • Intra-op • ↓Blood loss • A-line, IV • Hyperventilation • Mannitol • Resection • Embolization • Stereotactic Radiosurgery • (gamma knife).

30. Carotid Stenosis-Carotid Endarterectomy (CEA) • Pre-op • Neurologic examination is indicated to look for preoperative deficits. • Screen for associated CAD. • Anxiolytics may be useful. • Induction+ Maintenance • Avoid increases in mean arterial pressure • Maintain adequate CPP (baseline to 20% above) • during carotid clamping • Nitrous oxide.(X)

31. 謝謝聆聽 !!

32. QUESTIONS OF THE DAY • 1. What is cerebral autoregulation? Under what circumstances is it altered? What is the impact of intravenous (IV) or inhaled anesthetics on cerebral autoregulation? • 2. What are the effects of changes in PaCO 2 or PaO 2 on cerebral blood flow? • 3. What are the effects of IV or inhaled anesthetics on cerebral blood flow? • 4. What are the manifestations of venous air embolism in a patient undergoing craniotomy under general anesthesia? What is the appropriate management? • 5. During craniotomy for tumor resection, the surgeon notes “brain swelling” in the operative field. What are the initial steps in management? • 6. A patient with subarachnoid hemorrhage (SAH) pre-sents for intracranial aneurysm clipping. What complications of SAH may develop in the perioperative period?