The Child with Brain Tumor: Important Anesthetic Concepts

1. The Child with Brain Tumor:Important Anesthetic Concepts Hany El-Zahaby, MD Ain Shams University

2. Aim “Highlight the current neuro-physiological concepts and how to apply it to best of the anesthetic practice for the child with brain tumor.”

3. Brain tumors The second most common solid tumor in childhood. • Posterior fossa tumor • Supratentorial tumor • Suprasellar tumor

4. Translocation of CSFto the distensible spinal subarachnoid space • Translocation of blood to scalp veins.

5. Intracranial Compliance • The infant with open fontanels and cranial sutures would have a more compliant intracranial space especially with gradual increase in volume. • Full-term neonates ICP is 2-6 mmHg with increasing head circumference as the first clinical sign of increased ICP. • Infants presenting with signs and symptoms of intracranial hypertension have fairly advanced pathology.

6. Classic signs of high ICP as papilledema, pupillary dilatation, hypertension, bradycardia may be absent. • Headache, irritability & morning vomiting. • ↓ level of consciousness & abnormal responses to painful stimuli.

7. Monitoring Intraventricular catheters Subarachnoid bolts/screws

8. Epidural monitor Fiberoptic ICP monitor

10. Herniation Syndromes 1- Defect of calvarium. 2- Interhemisphericfalx: Internal capsule-posterior cerebral A.-blindness. 3- Trans-tentorialherniation: 3rd CN & brain stem compression leading to pupillary dilatation, hemiplegia & loss of consciousness “The uncal syndrome”. 4- Cerebellarherniation: Brain stem compression & obstruction of CSF circulation leading cardiorespiratory failure.

11. Cerebral Blood Volume and Cerebral Blood Flow CPP = MAP – ICP Penlucida Penumbra Maintaining COP & CPP is of utmost importance

12. CerebrovascularAutoregulation • Myogenic control of arteriolar resistance enables brain perfusion to remain stable despite moderate changes in MAP & ICP. • It is lost in acidosis, vessels supplying tumors, cerebral edema. • Abrupt ↑BP →hemorrhage/cerebral edema. • Worsening cerebral ischemia with moderate hyperventilation in children with compromised cerebral perfusion. Cerebral autoregulation range in neonate is 20-60 mmHg

13. Posterior fossa(infra-tentorial) tumor (50%) • Medulloblastoma, cerebellarastrocytoma, brain stem gliomas • CSF flow obstruction increasing ICP • Cranial nerve affection-ataxia • Arrhythmias-respiratory affection (late) • Bradycardia-hypertension-acute blood loss may complicate the procedure.

14. Supra-tentorial tumors (25-30%) • Astrocytomas, oligodendrogliomas, ependymomas, and glioblastomas. • Focal deficits, seizures. • UMNL → avoid succinylcholine. • Anticonvulsants. • Somatosensory evoked potential needs no Ms. relaxation.

15. Supra-sellartumors (15-20%) • Craniopharyngioma, optic gliomas, pituitary adenomas, hypothalamic tumors. • Hypothyroidism/steroid therapy/diabetes insipidus. • Nocturnal enuresis → serum electrolytes and osmolality. • Trans-sphenoidal approach.

16. History • General • Respiratory • Cardiovascular • GIT • Endocrinal • Hematologic • Allergies Specific • Seizures • Headache, Lethargy • Vomiting, enuresis, anorexia • Swallowing incoordination • Visual/hearing impairment • Motor disability/abnormal movement • Medications

17. Examination • Level of consciousness • Motor/sensory function • Reflexes • Cranial nerves • ICP • Pupillary size/reflex • Gag reflex/aspiration pneumonia • Muscle atrophy (receptor up-regulation)

18. Investigations • Routine + S. osmolality. • On individual basis: ABG, CXR, ECG. • Neuro-radiological studies. • Preoperative discussions: neurosurgeon, neurophysiologists & parents.

19. Premedication/Monitoring • Transport in head-up position. • Sedation only in OR. • Routine monitoring. • Nerve stimulator on a limb with normal neurologic function. • Arterial catheter: Referingthe transducer to external auditarymeatus to estimate CPP.

20. CVP • ↑ICP → no head-down → Femoral vein. • If no ↑ICP → subclavian vein is a reasonable choice. • Peripherally inserted central lines. • Wide-bore long saphenous vein catheter. “Early removal of all lines especially the arterial line”.

21. Induction • Uncooperative child with intracranial tumor and moderately decreased intracranial compliance who is agitated, resistant to parental separation child with no IV?? • IV-IV-IV • Thiopental/propofol • Sevoflurane • Fentanyl 2-3 µ/kg • Atracurium/cisatracurium/rocuronium

22. Airway Management and Intubation Aim: Effective and smooth airway management avoids increase ICP, hypoxemia, hypercarbia, and coughing. • Oral for supine/nasal for prone. • Securing ETT – folded gauze. • Check bilateral air entry with head flexion & after final positioning. • Open OGT. • Pad the eyes. • Access to ETT/connections/vascular catheter sites.

23. Prone position • Avoid abdominal compression. • Venous congestion of face, tongue, and neck . • Decreased lung compliance. • Avoid extreme flexion of head: • brainstem compression. • cervical cord ischemia. • endobronchial intubation.

24. Local infiltration: 0.25% bupivacaine with 1 : 200,000 epinephrine 1 ml/kg. • LA: equal volumes of bupivacaine 0.5% and epinephrine 1:100,000 (1mg/100ml saline)

25. Anesthetics that decrease ICP and CMRO2 and maintain CPP are desirable.

26. “The choice of anesthetic agents for maintenance of anesthesia has been shown not to affect the outcome of neurosurgical procedures.” “Todd MM, Warner DS, Sokoll MD, et al. A prospective, comparative trial of three anesthetics for elective supratentorial craniotomy. Anesthesiology 1993;78:1005– 20.”

27. Blood and Fluid Management • Early transfusion avoids severe anemia & hypoperfusion. • Doubling oncotic pressure has less effect on preventing brain edema than 1 meq/L increase in serum sodium. • Cerebral edema through disrupted BBB is worsened by excessive administration of hypotonic IV fluids. • Normal saline/Ringer’s solution (308 mOsm/L) is preferred than LR (285mOsm/L).

28. No glucose-containing solution is used even for extended surgeries except in: • Diabetic child. • Severely debilitated child. • Child on TPN. • When given, no more than the maintenance. • Normovolemia should be maintained throughout the procedure.

29. Temperature control • Maintaining normal temperature is the goal despite beneficial effect of mild hypothermia on CMRO2. • Forced hot air warming mattresses is the most effective mean.

30. VAE • Occurs when there is pressure gradient between the operative site and the heart especially with low CVP. • Flood with saline, bone wax, Trendelenburg position, fluid bolus, PEEP and aspirate air through a central venous catheter.

31. Emergence • PONV: Opioids and blood in the CSF versusdexamethazone and granisetrone. • No residual muscle paralysis is accepted on extubation. • Full awakening before extubation. • Neurological assessment in OR.

32. “The child with brain tumor is expected to leave OR at least as neurologically as before operation”. • In unconscious child postoperatively, ICP should be monitored, ventilation continued and immediate CT-scan should be done.

33. Postoperative • Regular paracetamol & small doses of opioids. • Intraoperativefentanyl usually covers the early postoperative period. • Diabetes incipidus may need vasopressin (1-10 mU/kg/hr). • CT and MRI are often performed 1 or 2 days after craniotomy.

34. Neuro-protection Goals: Avoid cerebral edema Avoid cerebral hypoxia Avoid cerebral hypo-perfusion Avoid cerebral hyper-metabolism Avoid neuronal membrane damage

36. Take-home messages • Maintain • Normo-volemia. • Normo-osmolality. • Normo-thermia. • Normo-ventilation. • Normal CPP.

37. Thank You 2012