L18 ICP Flashcards
What is normal ICP
5-15 mmHg
Some causes of increased ICP
tumours swelling increased vascular volume increased CSF volume bacterial meningitis
What happens when ICP is more than MABP
no cerebral blood flow
death
What is most common cause of death following stroke
cerebral oedema
What is BBB made up of
endothelial cells, tight junctions, basement membrane, astrocytes, pericytes
What happens when BBB is compromised
albumin is let in and water follows which = swelling
What is vasogenic oedema
increase in fluid around cells
What is cytotoxic oedema
accumulation of intracellular fluid (increase in cell size)
Which type of oedema (vasogenic or cytotoxic) occurs first and which will increase ICP
cytotoxic occurs first
vasogenic will increase ICP
What occurs as a result of cytotoxic oedema
cell energy failure –> loss of ATP –> decreased Na+/K+ pump activity –> Na+ accumulates within cell –> uncontrolled water entry –> irreversible cell injury or death
What is the Monroe-Kellie doctrine
If one component in skull increases, another one must decrease to maintain ICP
What will increased ICP cause
decreased brain oxygenation ischaemia hypercapnia decreased LOC dilated pupils bradycardia herniation loss of autoregulation hypoxia + lactic acidosis = increased vasodilation
What happens when ICP = systolic arterial pressure
blood flow will cease
death
What are the 4 compensatory mechanisms to reduce ICP
- Increased CSF reabsorption and decreased production
- venous vasoconstriction
- arterial vasoconstriction (ischaemia)
- arterial vasodilation (in attempt to reperfuse tissue but leads to increase ICP further)
Three types of herniaton
subfalcine
uncal
tonsillar
