Pathophysiology of Elevated ICP

Question 1

What GCS score is a severe TBI

Answer 1

8 or lower

Question 2

Secondary brain injury

Answer 2

Occurs after initial trauma
From neuron hypoxia/ishcemia
There are no inherent energy stores in neural tissue, so there is a cell energy supply/utilization mismatch
Get cell death

Question 3

Cerebral blood flow (CBF) =

Answer 3

MAP - ICP

Question 4

Monro-Kellie Doctrine

Answer 4

The cranial cavity is a rigid box and cannot expand
3 compartments: parenchyma, vasculature, and CSF space
If there is an increase in 1, it has to occur at the expense of the other 2 compartments

Question 5

2 main methods of ICP monitoring

Answer 5

Intraparenchymal (wires into brain)

Ventriculostomy (tube into the ventricle)

Question 6

What is normal ICP

Answer 6

Under 20-25 mmHg

Question 7

3 ways you can reduce ICP by affecting the parenchyma

Answer 7

Sedation
Temperature control
Osmotherapy

Question 8

How does sedation and temperature control reduce ICP?

Answer 8

Brain has flow-metabolic coupling

If you can reduce the metabolism of the brain, then you get less blood flow (and less ICP)

Question 9

2 substances you can give for osmotherapy to reduce ICP

Answer 9

Mannitol (only use once - for crisis control)

Hypertonic saline

Question 10

How can you increase venous return to decrease ICP

Answer 10

Raise the head of the bed! To 30 deg

Question 11

Does hypercapnia cause vasodilation or vasoconstriction? How does this change ICP?

Answer 11

Vasodilation

Increase ICP

Question 12

Decompressive craniotomy

Answer 12

Remove the skull to allow the brain to swell
For diffuse edema
Specific regulations in who gets this

Question 13

What happens to the range of autoregulation after TBI

Answer 13

Gets narrowed

BP management is very important in these patients