supratentorial tumors anesthetic considerations and awake craniotomy n.
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Supratentorial tumors :Anesthetic Considerations and Awake Craniotomy. Moderator: Dr.Hemanshu Presenter: Priyanka,Neeraj . www.anaesthesia.co.in anaesthesia.co.in@gmail.com. Incidence . 85% primary 60% primary and supratentorial Gliomas 35% Meningiomas 15% Pituitary adenomas 8%.

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supratentorial tumors anesthetic considerations and awake craniotomy

Supratentorial tumors :Anesthetic Considerations and Awake Craniotomy

Moderator: Dr.Hemanshu

Presenter: Priyanka,Neeraj

www.anaesthesia.co.inanaesthesia.co.in@gmail.com

incidence
Incidence
  • 85% primary
  • 60% primary and supratentorial
  • Gliomas 35%
  • Meningiomas 15%
  • Pituitary adenomas 8%
neoplasms
Neoplasms

● PRIMARY

1)Brain parenchyma

2)Intraventricular

3)Extraaxial

  • METASTATIC
slide5
CBF = (MAP-ICP) / CVR
  • increasing ICP is often associated with cerebral vasodilatation or incresing MAP to maintain CBF , making assessment a relatively complex process.
secondary insults to already injured brain
Secondary insults to already injured brain:

Intracranial

  • Increased intracranial pressure
  • Epilepsy
  • Vasospasm
  • Herniation: falx, tentorium, foramen magnum,

craniotomy

  • Midline shift: tearing of cerebral vessels
slide7
Systemic

Hypercapnia/hypoxemia

Hypo-/hypertension

Hypo-/hyperglycemia

Low cardiac output

Hypo-osmolality

problems
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
goals of anesthesia
Goals of anesthesia

1)Global maintenance of cerebral homeostasis by

  • normovolemia and normotension
  • normoglycemia
  • mild hyperoxia and hypocapnia
  • mild hyperosmolality and hypothermia
slide10
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

reducing icp brain bulk and tension
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

osmotic agents
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).

slide13
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”

hypertonic saline
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.
loop diuretics
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

steroids dexamethasone
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

hyperventilation
Hyperventilation :
  • Cerebral vasoconstriction  ↓CBF
  • Δ1 mm Hg PaCO2  1-2 ml /100 gm/min ΔCBF
  • Duration of effectiveness  4-6 hrs
  • Impaired responsiveness ischemia ,tumors,infection etc
  • Target PaCO2 30 -35 mm Hg
fluids
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%
slide20
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.
slide21
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

slide22
Hypothermia.
  • CBV decreasing drugs  barbiturates ,BZD,etomidate and propofol .
  • CSF drainage.
  • Decompressive craniectomy.
  • Vasoconstrictive cascade.( ↑MAP ↑CPP ,↓CBVand ↓ICP)
premedication
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

monitoring
Monitoring :
  • Routine monitoring : NIBP,ECG, SpO2,etCO2
  • Close hemodynamic monitoring
  • CVP and ABP
  • NMB monitoring
  • blood glucose
  • electrolyte
  • osmolality
  • cerebral monitoring
induction and intubation
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.

slide26
Control of ICP on induction:
  • narcotic
  • NDMR
  • hyperventilation ,ensure high saturation
  • blunt the stress of intubation
  • deepen anesthetic, narcotic, thiopentone, lidocaine, β blocker (short acting)
  • prompt intubation
maintenance
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.
slide28
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 <1 MAC.
slide29
A randomized, prospective study of patients subjected to craniotomy in propofol fentanyl, isoflurane fentanyl or sevoflurane fentanyl anesthesia

Anesthesiology 2003, 98(2)

slide30
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.

slide31
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.
emergence
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 .

preconditions for early emergence
Preconditions for Early Emergence :
  • Systemic homeostasis :

1) normovolemia ,normothermia

2)normotension(MAP=80 mmHg)

3)Mild hypocapnia (PaCO2=35 mmHg)

4)Normoglycemia

5)Mild hyperosmolality

6) Hematocrit approx. 30%

slide34
Brain homeostasis :

normal CMR,CBF and ICP .

antiepileptic prophylaxis

adequate head up position

lumbar or external ventricular CSF drainage

early vs delayed awakening
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

slide37
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 .

www.anaesthesia.co.inanaesthesia.co.in@gmail.com