Cerebrovascular Perfusion

Question 1

What do:
CPP
ICP 
MAP 
stand for?

Answer 1

Cerebral perfusion pressure
Intracranial pressure
Mean atrial blood pressure

Question 2

What is the normal value for ICP?

Answer 2

<15 mmHg

Question 3

What affects CPP?

Answer 3

MAP-ICP

It is normally a function of cerebral blood flow rather than cerebral blood pressure however the flow is influence by both blood pressure and vascular resistance.

Question 4

How much of the body blood and oxygen are received by the brain?

Answer 4

The brain receives 15% of the body CO and consumes 20% of the total body oxygen consumption

Question 5

If blood supply to the brain is stopped what are the affects?

Answer 5

Person unconscious within 10 seconds and dead within 4-6 minutes

Question 6

What is the normal CPP that is required to perfuse the brain?

Answer 6

60-80 mmHg

Question 7

What can the brain do to maintain the ICP?

Answer 7

Reduce venous blood held in the brain by up to 75ml or decrease CSF held in the brain by up to 75ml

Question 8

What other factors affect the CPP?

Answer 8

PCO2 and PO2

Question 9

What influence does PCO2 have on cerebral blood flow?

Answer 9

Hypercapnia - cerebral vasodilation

Hypocapnia- cerebral and carotid vasoconstriction

Question 10

What influence does PO2 have on cerebral blood flow?

Answer 10

Hypoxia- cerebral vasodilation

Question 11

What occurs as part of the death spiral?

Answer 11

Cranial Insult 
Tissue oedema 
Compression of arteries 
Increased ICP
Decrease Cerebral blood flow 
Decrease oxygen to the brain 
Oedema around necrotic tissue 
Increased ICP around brain steam and respiratory centre
CO2 accumulates leads to vasodilation 
Increased ICP dues to increased blood volume
Death