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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.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

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  1. Supratentorial tumors :Anesthetic Considerations and Awake Craniotomy Moderator: Dr.Hemanshu Presenter: Priyanka,Neeraj www.anaesthesia.co.inanaesthesia.co.in@gmail.com

  2. Incidence • 85% primary • 60% primary and supratentorial • Gliomas 35% • Meningiomas 15% • Pituitary adenomas 8%

  3. Neoplasms ● PRIMARY 1)Brain parenchyma 2)Intraventricular 3)Extraaxial • METASTATIC

  4. Perioperative care

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

  6. Secondary insults to already injured brain: Intracranial • Increased intracranial pressure • Epilepsy • Vasospasm • Herniation: falx, tentorium, foramen magnum, craniotomy • Midline shift: tearing of cerebral vessels

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

  8. 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

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

  10. 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

  11. 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

  12. 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).

  13. 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”

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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%

  19. 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.

  20. 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

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

  22. 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

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

  24. 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.

  25. 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

  26. 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.

  27. 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.

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

  29. 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.

  30. 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.

  31. 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 .

  32. 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%

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

  34. 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

  35. 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

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