Anesthesia for Supratentorial Tumors

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

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

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

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

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

6. Anesthetics cont. • Volatile anesthetics are cerebral vasodilators • Increase ICP • Reduce CMR • CO2 reactivity intact

7. 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

8. 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

9. Preop Plan • Vascular access • Fluid therapy • Anesthetics • Ventilation • Monitoring • Neuromonitoring

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

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

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

13. Monitoring cont. • EEG • SSEP • ICP? • Motor mapping

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

15. Maintenance • Control CMR, CBF • Good depth of anesthesia • Adequate CPP

16. Maintenance cont. • Volatile (<1 MAC)/intravenous anesthetics/N2O • Mild hyperventilation • Aim for speedy emergence (CT scan)

17. Increased ICP • Hyperventilate • Venous drainage • Relaxation • Change to IV anesthesia • Delete N2O • Diuretics

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

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

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

25. 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

26. Prevention cont. • Beta-blockers or clonidine or lidocaine • Steroids, if a tumor is present • Adequate hemodynamics: MAP, CVP, PCWP, HR • Adequate ventilation: Paco2>100 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

27. 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

28. 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

29. Physical Evaluation • Mental status • Papilledema (increased ICP) • Signs of Cushing’s response: hypertensive bradycardia • Pupil size, speech deficit, Glasgow coma score, focal signs • Medication • Steroids • Antiepileptic drugs

30. 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)

31. Evaluation of Hydration Status • Duration of bed rest • Fluid intake • Diuretics • Inappropriate secretion of antidiuretic hormone

32. 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

33. 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

34. 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 6%—no Ringer’s lactate

35. 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

36. 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

37. 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

38. Awakening cont. • Neurosurgical awakening should avoid: • Coughing • Tracheal suctioning • Airway overpressure during extubation • Patient-ventilator dyssynchrony

39. Awakening cont. • Neurosurgical awakening should provide: • Optimal conditions for neurologic examination