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Flashcards in Cerebral perfusion & ICP Deck (30)
1

How much of the CO does the brain receive?

15%

2

What is the normal cerebral blood flow?

55 to 60 ml/100g

3

At what blood flow will ischaemia be observed?

20ml/100g

4

At what blood flow will permanent brain damage occur?

10ml/100g

5

What if the effective blood pressure gradient across the brain?

Cerebral perfusion pressure (CPP)

6

What is the equation which define CPP?

CPP = MAP -ICP

7

Which an increased ICP what will happen to CPP?

Decrease

8

What factors regulate cerebral blood flow?

CPP
Arterial O2 & CO2

9

What is cerebral autoregulation?

The ability to maintain blood flow to the brain over a wide range of CPP (50-150mmHg)

10

If CPP is low, what will happen to arterioles?

Dilate in order to maintain blood flow

11

If CPP is high, what will happen to arterioles?

Constrict

12

What does CO2 do to blood flow?

Cause dilation of vessels do increases

13

What is a subacute to chronic cause of intracrainal hypertension?

Cerebral oedema

14

What is the BBB composed of?

Astrocyte foot processes
Endothelial tight junctions

15

What does the BB prevent?

Prevents toxic materials from reaching brain

16

What substances are able to cross the BBB?

Lipid soluble substances

17

According to what doctrine is the skull a rigid structure which contains 3 substances?

Monro-Kelly Doctrine

18

What 3 substances does the skull contain which contribute to volume?

Brain tissue
Blood
CSF

19

When there is a new intracranial mass, a compensatory change in volume has to occur which results in____

Decrease in venous blood OR CSF

20

What is change in compliance?

Change in volume observed for a given change in pressure (dV/dP)

21

What is elastance?

Change in pressure observed for a given change in volume (dP/dV)

22

What are the compensatory homeostatic mechanisms the brain compensates for increased ICP?

Veins collapse & squeeze blood out
CSF is displaced from ventricular system to subarachnoid space

23

At the critical volume, following compensatory homeostatic control, a small change in volume will produce____

large change in pressure

24

What are the different Lundberg waves =?

ABC waves

25

What is the Cushings Reflex?

Bradycardia
Hypertension
Irregular breathing
(vasopressor response)

26

If there is an increase in ICP what will happen to CBF?

Decrease - activation of sympathetic system

27

What does sympathetic innervation do to CVS?

Vasoconstricts - hypertension
Tachycardia

28

Why is bradycardia observed in Cushings reflex?

Mechanical distortion of brainstem - respiratory centre crushed.
Aortic baroreceptors stimulate vagus nerve

29

What is the management for increased ICP?

Raise bed - increase Venous return
Mannitol or hypertonic saline
Hyperventilation: decrease CBF
Surgical decompression

30

What is the average weight of human brain?

1400g