Supratentorial tumors :Anesthetic Considerations and Awake Craniotomy

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Supratentorial tumors Anesthetic Considerations
and Awake Craniotomy

• Moderator Dr.Hemanshu
• Presenter Priyanka,Neeraj

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.co
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Incidence

• 85 primary
• 60 primary and supratentorial
• Gliomas 35
• Meningiomas 15
• Pituitary adenomas 8

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Neoplasms

• ? PRIMARY
• 1)Brain parenchyma
• 2)Intraventricular
• 3)Extraaxial
• METASTATIC

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Perioperative care
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• CBF (MAP-ICP) / CVR
• increasing ICP is often associated with cerebral
  vasodilatation or incresing MAP to maintain CBF ,
  making assessment a relatively complex process.

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Secondary insults to already injured brain

• Intracranial
• Increased intracranial pressure
• Epilepsy
• Vasospasm
• Herniation falx, tentorium, foramen magnum,
• craniotomy
• Midline shift tearing of cerebral vessels

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• Systemic
• Hypercapnia/hypoxemia
• Hypo-/hypertension
• 
  
• Hypo-/hyperglycemia
• 
  
• Low cardiac output
• 
  
• Hypo-osmolality

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Problems

• Local and generalized pressure
• Small and slowly expanding ?minimal neurologic
  dysfunction
• Increase in size ?central area of hemorrhagic
  necrotic tissue ?expands rapidly ???ICP
• Massive hemorrhage, seizures and air embolism in
  head elevated or sitting position

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Goals of anesthesia

• 1)Global maintenance of cerebral homeostasis by
• normovolemia and normotension
• normoglycemia
• mild hyperoxia and hypocapnia
• mild hyperosmolality and hypothermia

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• 2) Minimization of need for surgical retraction
  by using chemical brain retraction.
• 3) Maximize therapeutic modalities that
  ?intracranial volume.
• 4) Provision of early neurosurgical awakening

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Reducing ICP , Brain Bulk , and Tension

• GOAL to promote adequate oxygen and nutrient
  supply by maintaining adequate CPP ,oxygenation
  and glucose supply .
• CLINICAL STRATEGY
• To diagnose and treat the underlying causes
• Avoid exacerbating factors
• Reduce ICP

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Osmotic agents

• Mannitol
• 20(1098 mOsm/L) mol wt 182

? blood osmolality antisludge effect -
ICP effect within 4 -5 min, lasts 3-4 hrs,dose
0.5-2g/kg. No change in CBF and ?ICP by 27 at
25 min. (autoregulation intact) and ?CBF by 5
and ? in ICP 18 at 25 min (impaired
autoregulation).
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• Transient, early and delayed effects
• Delayed effects
• - ?BV ? ?CO and BP ? autoregulatory ?in CBV
• - ?hematocrit
• - rebound ?in ICP
• - generation of increased intracellular
  osmolarity via idiogenic osmoles

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Hypertonic saline

• Has been shown to decrease ICP in animal and
  human studies.
• Various conc and doses have been used 3, 7.5,
  23.4 all show ?ICP and ?CPP.
• No deleterious diuresis and undesired
  hypovolemia.
• Useful in pts refractory to mannitol.

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Loop diuretics

• ICP reduction is small and less effective.
• Isosmotic reduction of the extracellular space
  ?ICP without ? CBV and osmolality.
• In patients with impaired cardiac reserve
• Mechanism
• Systemic diuresis.
• ?cerebral edema by improving cellular water
  transport.
• Dose 0.5-1 mg/kg iv alone or 0.15 -0.3 mg/kg
  with mannitol

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Steroids Dexamethasone

• ? peritumoral vasogenic edema
• effect may take 12-36 hrs
• Mechanism
• 1)repair of abnormal BBB
• 2)prevention of lysosomal activity
• 3)enhanced cerebral electrolyte transport
• 4) promotion of water and electrolyte secretion
• 5) Inhibition of Phospholipase A2 activity

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Hyperventilation

• Cerebral vasoconstriction ? ?CBF
• ?1 mm Hg PaCO2 ? 1-2 ml /100 gm/min ?CBF
• Duration of effectiveness ? 4-6 hrs
• Impaired responsiveness ?ischemia
  ,tumors,infection etc
• Target PaCO2 30 -35 mm Hg

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Fluids

• Restricted fluid intake ? traditional approach
• Can cause hypovolemia, hypotension , ?renal
  perfusion, electrolyte and acid base
  disturbances.
• Glucose free isoosmolar solution
• Hourly maintenance fluids and replacement of
  losses .
• Hematocrit 25 -30

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PEEP

• ?ICP by ? mean intrathoracic pressure , impairing
  cerebral venous outflow and cardiac output .
• used cautiously and with monitoring
• 10 cm H2O or less have been used without
  significant rise in ICP or ?CPP.

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• Position - Head up 15-30, neutral rotation.
• Head elevation reduces head rotation associated
  increase in ICP in intracranial tumour patients.
• CJA 2000 ,(47) ,415-420

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• Hypothermia.
• CBV decreasing drugs ? barbiturates
  ,BZD,etomidate and propofol .
• CSF drainage.
• Decompressive craniectomy.
• Vasoconstrictive cascade.( ?MAP ??CPP ,?CBVand
  ?ICP)

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Premedication

• Lethargic patients ? no premed.
• alert and anxious ?anxiolytic
• sedation and analgesics in the OR
• goal
• 1) avoid hypoxia , hypercapnia and partial
  airway obstruction ? ?ICP
• 2) avoid stress and hypertension .
• continue steroids , anticonvulsants
  ,antihypertensives and other cardiac medications
  .
• H2 blockers and prokinetics

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Monitoring

• Routine monitoring NIBP,ECG, SpO2,etCO2
• Close hemodynamic monitoring
• CVP and ABP
• NMB monitoring
• blood glucose
• electrolyte
• osmolality
• cerebral monitoring

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Induction and Intubation

• Preoxygenation and voluntary hyperventilation
• Fentanyl (1-2µg/kg)or alfentanil , sufentanil or
  remifentanil
• Propofol (1.25-2.5 mg/kg) or Thiopentone (3-6
  mg/kg)
• NDMR /DMR
• Controlled ventilation( PaCO2 30-35)
• Position ? pterional ,frontal and parasaggital
  approach.

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• Control of ICP on induction
• narcotic
• NDMR
• hyperventilation ,ensure high saturation
• blunt the stress of intubation
• deepen anesthetic, narcotic, thiopentone,
  lidocaine, ß blocker (short acting)
• prompt intubation

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Maintenance

• Goal control of brain tension via control of
  CBF and CMR (chemical brain retractor concept )
• mild hyperosmolality
• iv anesthetic , adequate depth
• mild hypervent. Mild hyperoxygenation
• mild controlled hypertension
• normolemia , no vasodilators
• head up position, no venous compression .
• No PEEP, no ventilator fight.
• Avoidance of brain retractors.

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• Fentanyl 1-2 µg/kg/hr, alfentanil 5-10 µg/kg/hr,
  remifentanil 0.2-0.5 µg/kg/hr, sufentanil 0.1-0.3
  g/kg/hr.
• Volatile 0.5-1 isoflurane.
• Controllability, predictability and early
  awakening.
• ?CBF, ICP, brain bulk minimized by moderate
  hyperventilation and concentration lt1 MAC.

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• A randomized, prospective study of patients
  subjected to craniotomy in propofol fentanyl,
  isoflurane fentanyl or sevoflurane fentanyl
  anesthesia
• Anesthesiology 2003, 98(2)

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• Propofol requirement is decreased in patients
  with large supratentorial tumours.
• Anesthesiology 1999,90(6),1571-6
• Cerebral blood volume and blood flow responses to
  hyperventilation in brain tumours during
  isoflurane or propofol anesthesia.
• Anesth Analg 2002, 94,664-667.

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• In brain tumors , infusion of propofol with
  fentanyl or remifentanil has shown to ? ICP more
  effectively than either isoflurane or sevoflurane
  
• however the risk of cerebral hypoperfusion has
  been questioned with propofol (?CBF/CMR ratio)
• if severe intracranial hypertension persists
  despite hyperventilation and other maneuvers, and
  the brain is tight a total intravenous technique
  is preferred.

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Emergence

• Routine craniotomy extubated at the end of
  surgery .
• permits assessment of results of surgery and
  provide a baseline for continuing postop
  neurologic follow up .

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Preconditions for Early Emergence

• Systemic homeostasis
• 1) normovolemia ,normothermia
• 2)normotension(MAP80 mmHg)
• 3)Mild hypocapnia (PaCO235 mmHg)
• 4)Normoglycemia
• 5)Mild hyperosmolality
• 6) Hematocrit approx. 30

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• Brain homeostasis
• normal CMR,CBF and ICP .
• antiepileptic prophylaxis
• adequate head up position
• lumbar or external ventricular CSF drainage

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Early vs Delayed Awakening

• Early awakening
• Advantages
• 1)Earlier neurologic examination and
  reintervention if necessary
• 2)Earlier indication of furthur investigation
• 3)Less stress response
• Disadvantages
• 1) ?risk of hypoxemia and hypercapnia
• 2) Monitoring in ICU

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• Delayed awakening
• Advantages
• 1)Less risk of hypoxemia or hypercapnia
• 2)Better respiratory and hemodynamic control
• 3)Earlier transfer to ICU
• Disadvantages
• 1)Less neurologic monitoring
• 2)Larger hemodynamic changes
• 3)More catecholamine release .

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