Certified Registered Nurse Anesthetist (CRNA) Practice Exam

In the assessment of CPP, what formula is used?

1. MABP - ICP

2. MABP + ICP

3. MABP x ICP

4. MAP + CVP

The correct answer is: MABP - ICP

The correct formula for assessing Cerebral Perfusion Pressure (CPP) is derived from the difference between Mean Arterial Blood Pressure (MABP) and Intracranial Pressure (ICP). This is because CPP is a crucial indicator of the blood flow to the brain, and it is essential to ensure that the brain receives adequate perfusion for optimal function. MABP represents the average pressure in a person’s arteries during one cardiac cycle, while ICP refers to the pressure inside the skull. By subtracting ICP from the MABP, you assess the net pressure gradient that drives blood flow to the brain. This net pressure is vital, as too low a CPP can lead to inadequate cerebral blood flow and resultant neurological damage, while too high a CPP can indicate potential cerebral edema or hemorrhage. The other options do not represent the established method for calculating CPP. Adding ICP to MABP does not provide a meaningful measure of cerebral perfusion, as it combines two different pressure variables without yielding a clinically relevant outcome. Multiplying MABP by ICP or using CVP (central venous pressure) with MABP also does not correlate to the flow dynamics essential for understanding cerebral perfusion. This reinforces the importance of using the difference between M