Mean arterial pressure from CO and TPR
A drug doubles total peripheral resistance, and cardiac output falls by 25%. By what factor does mean arterial pressure change?
Answer B: explanation for every choice
A
This accounts for the fall in cardiac output but ignores the resistance change.
B
Correct. MAP ≈ CO × TPR = 0.75 × 2 = 1.5.
C
This adds the percentage changes (+100% − 25%) instead of multiplying.
D
This ignores the fall in cardiac output.
TakeawayMAP ≈ CO × TPR. Multiply the factors.
Equation usedCardiac output and blood pressure
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