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 [email protected] 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

[email protected]


Incidence
Incidence Craniotomy

  • 85% primary

  • 60% primary and supratentorial

  • Gliomas 35%

  • Meningiomas 15%

  • Pituitary adenomas 8%


Neoplasms
Neoplasms Craniotomy

● PRIMARY

1)Brain parenchyma

2)Intraventricular

3)Extraaxial

  • METASTATIC



  • CBF = (MAP-ICP) / CVR Craniotomy

  • 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: Craniotomy

Intracranial

  • Increased intracranial pressure

  • Epilepsy

  • Vasospasm

  • Herniation: falx, tentorium, foramen magnum,

    craniotomy

  • Midline shift: tearing of cerebral vessels


  • Systemic Craniotomy

    Hypercapnia/hypoxemia

    Hypo-/hypertension

    Hypo-/hyperglycemia

    Low cardiac output

    Hypo-osmolality


Problems
Problems Craniotomy

  • 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 Craniotomy

1)Global maintenance of cerebral homeostasis by

  • normovolemia and normotension

  • normoglycemia

  • mild hyperoxia and hypocapnia

  • mild hyperosmolality and hypothermia


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 chemical brain retraction.

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: chemical brain retraction.

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).


  • Transient, early and delayed effects chemical brain retraction.

  • 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 chemical brain retraction.

  • 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: chemical brain retraction.

  • 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 chemical brain retraction.

  • ↓ 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 : chemical brain retraction.

  • 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 chemical brain retraction.

  • 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%


PEEP: chemical brain retraction.

  • ↑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.



  • Hypothermia. chemical brain retraction.

  • CBV decreasing drugs  barbiturates ,BZD,etomidate and propofol .

  • CSF drainage.

  • Decompressive craniectomy.

  • Vasoconstrictive cascade.( ↑MAP ↑CPP ,↓CBVand ↓ICP)


Premedication
Premedication : chemical brain retraction.

  • 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 : chemical brain retraction.

  • 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 : chemical brain retraction.

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.


Control of ICP on induction: chemical brain retraction.

  • narcotic

  • NDMR

  • hyperventilation ,ensure high saturation

  • blunt the stress of intubation

  • deepen anesthetic, narcotic, thiopentone, lidocaine, β blocker (short acting)

  • prompt intubation


Maintenance
Maintenance : chemical brain retraction.

  • 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.


  • 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.




  • 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 : remifentanil has shown to ↓ ICP more effectively than either isoflurane or sevoflurane

  • 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 : remifentanil has shown to ↓ ICP more effectively than either isoflurane or sevoflurane

  • 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%


  • Brain homeostasis remifentanil has shown to ↓ ICP more effectively than either isoflurane or sevoflurane :

    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 : remifentanil has shown to ↓ ICP more effectively than either isoflurane or sevoflurane

  • 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


  • Delayed awakening remifentanil has shown to ↓ ICP more effectively than either isoflurane or sevoflurane :

    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 .

[email protected]


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