Raised ICP Flashcards
What is intracranial pressure?
The pressure within the skull and is the sum of pressure from brain tissue, blood volume and CSF
What is the Monroe-Kellie hypothesis?
Because the skull is a closed, non expandable compartment, an increase in one of the constituents of ICP is compensated for by a decrease in one of the other constituents
According to the Monroe-Kellie, what happens when ICP is increased?
Reduction in CSF production
Reduction of cerebral blood flow
Eventually herniation of brain tissue
What is the normal range of ICP?
5-15mmHg
What is cerebral perfusion pressure?
The net pressure gradient that supports cerebral blood flow
What is the equation for CPP?
CPP = MAP - ICP
According to the relationship between CPP and ICP, what happens when ICP increases?
Any increase in ICP will reduce the amount of blood flowing into the brain
What are causes of raised ICP?
Hydrocephalus
Head injury
Cerebral oedema
- Vasogenic: tumour, trauma, ischemia, infection
- Cytotoxic: hypoxia, hypercapnia, encephalopathy
- Interstitial: obstructive hydrocephalus
Dural sinus thrombosis
Metabolic: hypoxia and hypercapnia
SOL: tumours, abscess, haematoma
Idiopathic intracranial hypertension
What is the presentation of raised ICP?
Headache - worse in the morning, wakes patient from sleep, worse lying down, bending and coughing
Drowsiness
Nausea, vomiting
Malaise
Focal neurological symptoms
Visual - peripheral field loss, reduced acuity, pupil constriction then dilation, swollen disc (papilloedema)
Cushing’s response
What is Cushing’s response?
A physiological response to try and maintain CPP and prevent cerebral ischaemia
Hypertension, bradycardia, irregular breathing
Increase in MAP will try and improve the gradient for cerebral blood flow that was reduced by increase ICP
What investigations are done in raised ICP?
Bloods: FBC, U&Es, LFT, glucose, coagulation, culture, ABG
CT head
LP is no signs of SOL and deemed safe to do so (aim is to measure opening pressure)
What is the acute management of raised ICP?
ABCDE
Elevate head 30-40 degrees
What is the management of raised ICP that aims to reduce ICP?
Mannitol
Hypertonic saline
Intubate and hyperventilate (reduces PCO2, cause cerebral vasoconstriction and reduce ICP)
What is the management of raised ICP that aims to prevent cerebral oedema?
Dexamethasone
What is the surgical intervention for raised ICP?
Burr-hole
Craniotomy
Removal of SOL