Raised Intracranial Pressure

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Introduction:

Uncontrolled sustained or rapid rises in intracranial pressure eventually lead to brainstem herniation and ischaemia resulting in cardio-respiratory collapse and brain death.  It is a one of the major resuscitative issues to address in acute care.  Slower increases allow more adaptation and less dramatic changes in function.

Pathology

Any increase in brain tissue, CSF volume or blood volume (qv Monroe-Kelly Doctrine)

  • Brain e.g. oedema, tumour, abscess
  • CSF  e.g. hydrocephalus, benign intracranial hypertension
  • Blood e.g. Intracranial bleeding

See also Surgical Sieve and Causes of Acute Presentations

See Also

Clinical Features (usually in order)

  • Headache (worse with lying recumbent, morning headache, worse stooping, coughing, straining)  q.v. Low-Pressure Headache (worse standing)
  • Vomiting
  • Altered Mental State
  • Lateralising neuological signs
  • Pupillary inequality (if bilateral herniation both pupils fixed and dilated
  • Cushing’s reflex (^BP, v HR) – cerebral ischaemic reflex to increase BP and improve perfusion stimulating a compensatory baroreceptor reflex to decrease HR)
  • Respiratory Arrest

Management

  • Identify and treat cause

if GCS < 8

  • Elevate head > 30 degrees
  • Prevent hypoventilation / Controlled mechanical ventilation (high CO2 causes vasodilatation)
  • Maintain MAP 50-70mmHg above ICP (CPP = MAP-ICP)
  • Osmotherapy (to induce fluid shifts out of brain compartment)
  • Surgical decompression (of space occupying lesion or hydrocephalus)

Controversies

  • Hemi-craniectomy for cerebral oedema or intracerebral bleeding
  • Does ICP monitoring change patient outcomes?
  • Jugular bulb oximetry as measure of cerebral metabolic activity (disbanded)

*CPP = Cerebral Perfusion Pressure, MAP = Mean Arterial Pressure, ICP = Intracranial Pressure)

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