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Neurosurgery and ICU. Wilson Ho July 2009. Neuro-physiology ICP monitoring Severe head injury Brain tumor Hemorrhagic stroke hyponatremia. Neuro - physiology. Monroe - Kellie Principle. Skull is a rigid box Brain 80% Blood 10% CSF 10%
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Neurosurgery and ICU Wilson Ho July 2009
Neuro-physiology • ICP monitoring • Severe head injury • Brain tumor • Hemorrhagic stroke • hyponatremia
Monroe - Kellie Principle • Skull is a rigid box • Brain 80% • Blood 10% • CSF 10% • Expansion of one component is at the expense of the other components
Monroe-Kellie Principle Volume-Pressure Curve Normal ICP ~ 4 –15mmHg
Auto-regulation • The brain’s ability to change the diameter of its blood vessels automatically over a range of normal BP to maintain a constant cerebral blood flow (CBF) in response to its metabolic needs. • The Brain can effectively auto-regulate its hemodynamics when BP is 60-170mmHg & ICP <30 mmHg • CBF is Normally 750 ml/min
Auto-regulation curve CBF Slope not zero 10 50 140 mmHg CPP Critical closing P. Cerebral Perfusion Pressure = MAP - ICP
Auto-regulation compromised Systemic factors • MAP < 50 mmHg • poor perfusion – ischemia • MAP > 170 mmHg • Arteries unable to constrict – hyperaemia – increase ICP Local factors • Head Injuries • Tumors • vascular lesions • increases metabolic activities • Prolonged ICP > 30 mmHg
Cerebral Perfusion Pressure • CPP = MAP – ICP • MAP = DBP + 1/3 (SBP – DBP) • 60-150mmHg range. CPP should be maintained > 65 mm Hg for adequate blood supply to brain
ICP monitoring • Indications • Suspected raised intracranial pressure • Unable to monitor clinically • CSF retention • Post op condition
ICP monitoring • Intraventricular • Monitoring • Therapeutic • Parenchymal • Easy installation • Subdural / epidural • Inaccurate • Rarely used
ICP Catheter problems Ensure all connections are tight No leakage of CSF Regular changes of scalp dressing Minimize manipulations Early removal • Infection • Over - drainage • Blockage • Disconnection • Bleeding • Inaccuracy • Pull out accidentally Keep drainage bag at proper level Empty bag regularly Poor wave-form Unavoidable Avoid kinking of tubings Inform immediately Double check with water column Re-calibrate Inaccurate when no CSF around catheter Can be dangerous Especially for confused patients
Management of raised ICP • Blocked ? • Need re-calibration ? • Sedated enough ? • Proper ventilation ? • Trend of ICP ? • Other parameters & physical signs • CT brain
To lower ICP • Level of bed • Sedation / paralysis • Controlled hyperventilation • Osmotic diuresis – Mannitol / Glycerol • Maintain adequate systemic BP • Let out CSF from EVD • Surgery • Removal of mass lesion • Decompressive craniectomy
General Principles • To prevent “secondary insults” to the brain • Primary insult • Damage sustained during impact
Severe Head Injury GCS (3-8) SECONDARY BRAIN DAMAGE • Cerebral Swelling • Medical / Surgical means • Herniation • Removal of hematoma and contusion • Cerebral ischemia • Maintain adequate perfusion and oxygenation • Infection • CSF leak, open brain trauma • Convulsion • Anti-convulsants
Patients needing ICU care • Close monitoring • Multi-system trauma • Depressed conscious level • Likely to deteriorate • Post operative patient • Potential candidates for organ donation
Pathology • Cerebral Contusion • Lobes and poles against skull bone • Intracranial hematoma • Epidural hematoma • Subdural hematoma • Skull fracture • Vault – open / close • Skull base • Diffuse axonal injury
General Principle • Small contusion / hematoma can be absorbed • Cerebral swelling peak around day 7 - 10 • Remove lesions with mass effect • Monitor & maintain CPP • Prevent Seizure • Prevent hyperthermia
Within 1st hour After 6 hours
Basal skull fracture • Clinical suspicion • Confirmed by CT scan • CSF fistula • NO nasal gastric tube
Brain tumor • Primary • Glioma • Secondary – more common • Lung / colon / breast / kidney • Supra-tentorial / Infra-tentorial compartment
Post operative ICU care • Elective resection • Rarely emergency resection • Large raw area for large tumors • Prevent STRUGGLING / HYPERTENSION • Steroid • Anticonvulsant
Posterior fossa tumor • Cerebellar metastatic tumor • Nerve sheath tumor • Brainstem tumor
Respiratory problem / Aspiration problem • Check gag reflex / consult speech therapist
Pituitary Tumor • Functional • Acromegaly / Cushing disease • Nonfunctional • Visual symptoms / Mass effect • Transphenoidal removal • Microscopic / Endoscopic approach
Post operative monitoring • Visual acuity, visual field • Residual tumor hemorrhage • Optic nerve / chiasm injury • CSF leakage • Excessive urine output • Usually temporary