Exam 3: 10/4 Lecture 2

Question 1

What is CRMO

Answer 1

Cerebral metabolic rate. It looks at the metabolism of the neurons, glial cells, and all support tissues in the brain.

Question 2

What is the relationship between metabolic rate and blood flow

Answer 2

Proportionate. As metabolic rate increases blood flow increases to provide nutrients needed to support the work being done

Question 3

Normal ICP

Answer 3

10-12 mm/Hg

Question 4

How is Cerebral perfusion pressure calculated

Answer 4

MAP - ICP

Question 5

What is CSF pressure going to limit

Answer 5

Perfusion. The higher the CSF the harder it is to get blood flow into the closed space in the brain.

Question 6

With high CO2 levels, the CO2 combines with water to form what

Answer 6

Bicarb and protons

Question 7

What happens as a result of an increased metabolic rate

Answer 7

O2 levels drop, CO2 rises, acids rise. This drives blood flow into the brain.

Question 8

How does temperature affect

Answer 8

For every 1 degree Celsius drop in tissue temperature the Oxygen demand drops by 6-7%

Question 9

How does CO2, specifically PaCO2 affect brain blood flow

Answer 9

1mm/Hg PaCO2 change will result in 2-4% change in cerebral blood flow

Question 10

What factor is responsible for the changes in brain blood flow seen with changes in PaCO2 levels

Answer 10

Concentration of protons in CSF. Protons in CSF are driving increased brain blood flow.
*CO2 is directly related to protons. But protons are driving this change.

Question 11

How can we manipulate CO2 to lower ICP

Answer 11

Hyperventilating a patient will cause patient to blow off more CO2. This is useful to lower ICP but is a temporary fix (about 6 hours long)

Question 12

Why is hyperventilating seen as a temporary fix

Answer 12

The bicarb buffering system of the CSF will eventually even out the proton concentration.
*it will catch up and correct this imbalance over a 6 hour timeframe.