Calculate the cerebral perfusion pressure of a patient who has an ...

[amal]

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

Question 2

How should the therapist evaluate cerebral blood flow in a patient who is being mechanically ventilated for traumatic brain injury?
 
  A. by measuring the intracranial pressure
  B. by evaluating the cerebral perfusion pressure
  C. by assessing central venous pressure
  D. by determining the mean arterial pressure

[SVictor]

Answer to Question 1

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.

Answer to Question 2

ANS: B
A. Incorrect response: See explanation B.
B. Correct response: In addition to correcting hypoxemia, the therapist needs to implement an effective ventilatory strategy to enable the optimization of cerebral blood flow, usually measured as cerebral perfusion pressure.
C. Incorrect response: See explanation B.
D. Incorrect response: See explanation B.