Anesthesia for Supratentorial Tumors

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Anesthesia for Supratentorial Tumors

• Pekka O. Talke, MD
• Department of Anesthesia and
• Neurosurgery, Cottrell
• Chief of Neuroanesthesia
• University of California, San Francisco

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Title

• 35.000 brain tumors/yr
• 85 primary
• 60 primary and supratentorial
• 15 mets (1/6 of tumors)

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General Considerations

• Surgical exposure (retraction)
• Intracranial pressure (ICP)
• Secondary insult to brain
• Hemorrhage, seizures, air emboli
• Rapid emergence
• Stress response

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ICP

• Tissue, blood, CSF
• Intracranial-Volume relationship
• Effects of anesthetics on ICP
• Tumor mass and edema (steroids)

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Anesthetics

• Intravenous anesthetics (not ketamine) are
  cerebral vasoconstrictors
• Reduce CMR
• CO2 reactivity intact

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Anesthetics cont.

• Volatile anesthetics are cerebral vasodilators
• Increase ICP
• Reduce CMR
• CO2 reactivity intact

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Anesthetics cont.

• Nitrous oxide increases CMR and ICP
• Can be controlled by hypocapnia
• Opioids reduce CMR
• CO2 reactivity intact
• Nitroglycerine, nitroprusside, hydralazine are
  cerebral vasodilators

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Reduction of ICP

• Intravenous anesthetics
• Hyperventilation (30-35 mmHg)
• Mannitol (0.5-1.0 gm/kg, 320 mOsm/kg),
  (hypernatremia, hypokalemia, hypovolemia)
  hypertonic saline
• Lasix
• CSF drainage
• Hypoxia, hypovolemia
• Head position (venous drainage)
• Increase MAP

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Preop Plan

• Vascular access
• Fluid therapy
• Anesthetics
• Ventilation
• Monitoring
• Neuromonitoring

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Preop

• Sedationhypercapnia, hypoxia, obstruction
• Stress increased CMR, CBF
• Analgesia/sedation midas 0.5.-2.0 mg/fentanyl
  (25- 100 ug)
• Steroids
• Anticonvulsants (relaxants, loading SLOW)

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Preop cont.

• Two large Ivs
• A-line (CPP, ABG, glucose, osm)
• Asleep? To avoid stress

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Monitoring

• BP, HR, CVP?
• Pulse ox
• ERTCo2
• Temperature (hypothermia?)
• Urine
• Relaxometry (hemiplegia, dilantin, tegretol)
• Glucose, Hg, Hct

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Monitoring cont.

• EEG
• SSEP
• ICP?
• Motor mapping

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Induction

• Avoid hypoxia, hypercarbia, stress response
• Propofol/pentothal/hyperventilate
• Opioids/relaxants
• Head position (venous obstruction)
• More drugs for intubation/pinning

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Maintenance

• Control CMR, CBF
• Good depth of anesthesia
• Adequate CPP

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Maintenance cont.

• Volatile (lt1 MAC)/intravenous anesthetics/N2O
• Mild hyperventilation
• Aim for speedy emergence (CT scan)

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Increased ICP

• Hyperventilate
• Venous drainage
• Relaxation
• Change to IV anesthesia
• Delete N2O
• Diuretics

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Fluids

• Not hypoosmolar
• Colloids (bleeding)
• Mannitol (320 mOsm/g)

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Emergence

• Attenuate stress response (autoregulation
  impaired/labetalol)
• Avoid hypercarbia, hypoxia (opioids)
• Avoid coughing
• Slow awakening (CT)
• Seizure, edema, hematoma, pheumocephalus, vessel
  occlusion, ischemia, metabolic

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Title

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Title

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Title

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Intracranial

• Increased intracranial pressure
• Midline shift tearing of the cerebral vessels
• Herniation falx, transtentorial, trans-foramen
• Magnum, transcraniotomy
• Epilepsy
• Vasospasm

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Systemic

• Hypercapnia
• Hypoxemia
• Hypotension or hypertension
• Hypoosmolality or hyperosmolality
• Hypoglycemia
• Hyperglycemia
• Shivering or pyrexia
• Low cardiac output

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Prevention

• No overhydration
• Sedation, analgesia, anxiolysis
• No noxious stimulus applied without sedation and
  Local Anesthesia
• Head-up position, no compression of the jugular
  veins, head straight
• Osmotic agents mannitol, hypertonic saline

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Prevention cont.

• Beta-blockers or clonidine or lidocaine
• Steroids, if a tumor is present
• Adequate hemodynamics MAP, CVP, PCWP, HR
• Adequate ventilation Paco2gt100 mm Hg, Paco2 35
  mm Hg
• Intrathoracic pressure as low as possible
• Hyperventilation on demand before induction
• Use of intravenous anesthetic agents for
  induction and maintenance in case of tensed brain

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Treatment

• CSF drainage if ventricular or lumbar catheter in
  situ
• Osmotic agents
• Hyperventilation
• Augmentation of anesthesia with intravenous
  anesthetic agents propofol, thiopentone,
  etomidate
• Muscle relaxant
• Venous drainage head up no PEEP, reduction of
  inspiratory time
• Mild controlled hypertension if autoregulation
  present

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History

• Seizure
• Increased intracranial pressure (ICP) headache,
  nausea, vomiting, blurred vision
• Decreased level of consciousness, somnolence
• Focal neurologic signs hemiparesis, sensory
  deficits, cranial nerve deficits, and so on
• Paraneoplastic syndromes including presence of
  thrombosis

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Physical Evaluation

• Mental status
• Papilledema (increased ICP)
• Signs of Cushings response hypertensive
  bradycardia
• Pupil size, speech deficit, Glasgow coma score,
  focal signs
• Medication
• Steroids
• Antiepileptic drugs

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Technical Examination (CT or MRI Scan)

• Size and location of the tumor silent or
  eloquent area, near a major vessel, and so on
• Intracranial mass effect midline shift,
  decreased size of the ventricles, temporal lobe
  hernia
• Intracranial mass effect hydrocephalus,
  cerebrospinal fluid space around brainstem
• Others edema, brainstem involvement,
  pneumocephalus (recraniotomy)

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Evaluation of Hydration Status

• Duration of bed rest
• Fluid intake
• Diuretics
• Inappropriate secretion of antidiuretic hormone

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Induction

• Adequate anxiolysis in the anesthetic room
• Adequate fluid loading (5 to 7 ml/kg of NaCl
  0.9)
• ECG leads in place capnometer, pulse oximeter,
  and noninvasive blood pressure monitors
• Insertion of intravenous and arterial lines under
  local anesthesia
• Fentanyl 1 to 2 ?g/kg or alfentanil, sufentanil,
  or remifentanil

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Induction cont.

• Preoxygenation and voluntary hyperventilation
• Propofol 1.25 to 2.5 mg/kg or thiopentone 3 to 6
  mg/kg for induction
• Nondepolarizing muscle relaxant vecuronium,
  rocuronium, or other controlled ventilation at
  Paco2 of 35 mm Hg
• Propofol 50 to 150 ?g /kg/min or isoflurance 0.5
  to 1.5 (or sevoflurane of desflurane) for
  maintenance and fentanyl (or alfentanil,
  sufentanil, or remifentanil) 1 to 2 ?g/kg or
  alfentanil, sufentanil, or remifentanil

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Induction cont.

• Lignocaine 1.5 mg/kg
• Intubation
• Local anesthesia and intravenous fentanyl 2 ?g/kg
  for skull-pin head-holder placement and skin
  incision adequate head-up positioning no
  compression of the jugular veins
• Mannitol 0.5 to 0.75 g/kg
• Insertion of a lumbar drain
• Possibly N2O when the dura is open and brain is
  slack
• Normovolemia with the use of NaCl 0.9 or starch
  6no Ringers lactate

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ICP Control

• Mild hyperosmolality (use NaCl 0.9 304 mOsm/kg
• as baseline infusion give mannitol 1319
  mOsm/kg
• 0.5 to 0.75 g/kg or hypertonic saline 7.5 2533
  mOsm/kg 3 to 5 ml/kg before bone flap removal)
• Intravenous anesthetic agent (propofol), adequate
  depth of anesthesia
• Mild hyperventilation, mild hyperoxygenation

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ICP Control cont.

• Mild controlled hypertension MAP maintained
  around 100 mm Hg in order to decrease CBV and ICP
• Normovolemia no vasodilators
• Mild hyperoxia
• Together with
• Adequate head-up positioning
• Free venous drainage no compression of the
  jugular veins
• No PEEP, no ventilator fight (myorelaxants)
• Lumbar drainage
• Avoidance of brain retractors

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Awakening

• Neurosurgical awakening should maintain
• Stable arterial blood pressure and thus cerebral
  blood flow and intracranial pressure
• Stable oxygenation and carbon dioxide tension
• Stable CMRO2
• Normothermia

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Awakening cont.

• Neurosurgical awakening should avoid
• Coughing
• Tracheal suctioning
• Airway overpressure during extubation
• Patient-ventilator dyssynchrony

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Awakening cont.

• Neurosurgical awakening should provide
• Optimal conditions for neurologic examination