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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. Neuroanatomy Neurophysiology Intracranial pressure Intracranial pressure-volume relationship Cerebral protection Preoperative assessment Anesthesia for neurosurgery

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Book reading

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


Table of contents

Neuroanatomy

Neurophysiology

Intracranial pressure

Intracranial pressure-volume relationship

Cerebral protection

Preoperative assessment

Anesthesia for neurosurgery

Clinical cases

Table of contents



Neuroanatomy1
Neuroanatomy

  • Blood brain barrier disruption

  • Hypertension

  • Trauma

  • Infection

  • Hypoxemia

  • Sever hypercapnia

  • Tumors

  • Seizure


Neurophysiology
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


Cerebral blood flow
Cerebral Blood Flow

  • Cerebral Blood Flow= 15% Cardiac output

  • CBF: 50 ml/100g/min

  • CPP =MAP-ICP (or CVP)


Cerebral metabolic rate
Cerebral Metabolic Rate

Body Temperature 37℃

↓ 1℃→ CMRO2↓7 %


Cerebral perfusion and autoregulation
Cerebral perfusion and Autoregulation

Autoregulation OK  CPP: 50~150mmHg

Autoregulation(-) Trauma;neurosurgery

Hypertension shifts the auto regulatory curve

 Right


Effects of paco 2 and pao 2 on cbf
Effects of PaCO2 and PaO2 on CBF

PaO2

PaCO2

CPP

ICP

Autoregulation

50-150mmHg


Effects of cbf
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


Effects of anesthetics
Effects of anesthetics

Thiopental & Propofol : CBF ↓ CMRO2 ↓

Ketamine:CMRO2 ↑; CBF & ICP ↑

N2O:CBF ↑ may be CMRO2 ↑

Opioids : CBF ↓ CMRO2 ↓



IICP

ICP=5-15mmHg

IICP

  • Positionalheadache

  • Nausea +Vomiting

  • Hypertension + Bradycardia

  • Conscious change

  • Altered patterns of breathing

  • Papilledema


Methods to decrease icp

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


Effect of anesthetic on icp
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


Cerebral protection
Cerebral protection

Cerebral protection

  • Barbiturates

  • Hypothermia


Intracranial aneurysms

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


Intracranial aneurysms1

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


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?


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


Positioning-

Supratentorial tumorsIntracranial vascular lesions

→Supine


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.


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.


Venous Air Embolism (II)

  • ETCO2↓、SpO2↓、PaCO2↑

  • Arterial hypoxemia、Cardiovascular collapse

  • Transesophageal echocardiography

  • Central venous catheter


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


Common clinical cases

  • Intracranial Aneurysms

  • Intracranial Masses

  • Arteriorvenous Malformation (AVM)

  • Carotid Stenosis


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)


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).


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)



Questions of the day
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?


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