Raised Intracranial Pressure

Question 1

What is the normal ICP?

Answer 1

• Between 7-15 mmHg in adults in the supine position

Question 2

What is the Cerebral Perfusion Pressure?

Answer 2

• CPP is the net pressure gradient causing cerebral blood flow to the brain
• CPP = MAP - ICP

Question 3

What are the Causes of Raised Intracranial Pressure?

Answer 3

• Idiopathic Intracranial Hypertension
• Traumatic Head Injuries
• Infection - Meningitis
• Tumours
• Hydrocephalus

Question 4

What are the features of Raised Intracranial Pressure?

Answer 4

• Headache
• Vomiting
• Reduced Level of Consciousness
• Papilloedema
• Cushing’s triad = widening pulse pressure, bradycardia, irregular breathing

Question 5

What investigations and monitoring is required for Raised ICP?

Answer 5

• Neuroimaging = CT/ MRI
• Invasive ICP monitoring = catheter placed into the lateral ventricles of the brain to monitor the pressure
• collect CSF samples and drain small amounts of CSF to reduce the pressure

Question 6

What is the Management for Raised ICP?

Answer 6

• Investigate and treat the underlying cause
• Head Elevation to 30 degrees
• IV mannitol = osmotic diuretic
• Controlled hyperventilation = aim to reduce pCo2, vasoconstriction of the cerebral arteries, reduced ICP, rapid temporary lowering of ICP. This leads to a rapid temporary lowering of ICP, caution is needed as may reduce blood flow to the ischaemic parts of the brain
• Removal of CSF = drain from intraventricular monitor, repeated lumbar puncture, ventriculoperitoneal shunt (hydrocephalus)