Calculate the cerebral perfusion pressure of a patient who has an arterial blood pressure of 120/80 mm Hg and an intracranial pressure of 15 mm Hg

A. 185 mm Hg
B. 85 mm Hg
C. 78 mm Hg
D. 68 mm Hg

ANS: C
A. Incorrect response: See explanation C.
B. Incorrect response: See explanation C.
C. Correct response: The formula for calculating the cerebral perfusion pressure is as follows:
mean arterial pressure – intracranial pressure = cerebral perfusion pressure
STEP 1: Determine the mean arterial pressure (MAP).

= 280 mm Hg/3
= 93 mm Hg
STEP 2: Calculate the cerebral perfusion pressure (CPP).

CPP = MAP – ICP
= 93 mm Hg – 15 mm Hg
= 78 mm Hg?
The normal ICP ranges from 5 to 15 mm Hg.
The normal CPP ranges from 70 to 100 mm Hg. (The text gives a normal range for the CPP as 60 to 70 mm Hg.)
D. Incorrect response: See explanation C.?