Short Answer 
The relationship between mean arterial pressure (MAP), intracranial pressure (ICP), and cerebral perfusion pressure (CPP) can be understood by defining key terms, calculating CPP using the formula CPP = MAP – ICP, and interpreting the results. For example, with MAP at 65 mm Hg and ICP at 22 mm Hg, the CPP is 43 mm Hg, which is low and indicates a risk of inadequate blood flow to the brain, anticipated to result in widening pulse pressure.
Step 1: Understand the Key Definitions
Familiarize yourself with the important terms related to brain blood flow:
- Mean Arterial Pressure (MAP): This is the average arterial pressure throughout one cardiac cycle, indicating overall blood flow to the organs.
- Intracranial Pressure (ICP): The pressure within the skull from brain tissue and cerebrospinal fluid.
- Cerebral Perfusion Pressure (CPP): This represents the pressure that drives oxygen delivery to the brain and is calculated using the formula: CPP = MAP – ICP.
Step 2: Calculate the CPP Value
Apply the given values to find the CPP:
- Given:
MAP = 65 mm Hg
ICP = 22 mm Hg - Use the formula:
CPP = 65 – 22 = 43 mm Hg
This value indicates the effectiveness of blood supply to the brain.
Step 3: Interpret the CPP and Anticipate Findings
Evaluate the significance of the CPP value and its implications:
- A normal CPP range is between 60 to 80 mm Hg. A CPP of 43 mm Hg is low, suggesting inadequate blood flow to the brain.
- This low CPP can lead to risks like brain ischemia, and one expected physiological response is *widening pulse pressure*, where the body adjusts blood pressure parameters to maintain cerebral perfusion.
Hence, the anticipated finding based on this analysis is *widening pulse pressure*. The answer is clear: D. Widening pulse pressure.