Pathyophysiology question

[Freedom42]

I'm studying for a test using an old sample exam. What is the correct answer to this question?

A wide pulse pressure may indicate that a person has

A) high stroke volume and low compliance of large arteries

B) low stroke volume and low compiliance of large arteries

C) high stroke volume and high compliance of large arteries

D) low stroke volume and high compliance of large arteries

I know that BP is determined by cardiac output and peripheral vascular resistance; an increase in either one will elevate systolic BP. So I eliminate choices B and D regarding low stroke volume.

The question, then, is the compliance high or low? An artery that has low compliance would be stiff, leading to an elevated BP and therefore a wide pulse pressure. Choice A: Am I right?

Thanks for your help. First exam of the semester -- I've got the jitters.

[Corey Narry, MSN, RN, NP]

I think you picked the right answer but this is kind of a tricky question. Pulse pressure widening are seen in the elderly more commonly. This is due to an increase in systolic blood pressure due to stiffening of the large arteries and decreased diastolic blood pressure due to a reduced elastic recoil or reservoir capacity in the aorta. This is also seen in aortic reugurgitation where the LV would need a higher force to eject against an incompetent aortic valve causing a rise in systolic pressure and a decrease in diastolic pressure as less blood are able to remain in the aorta at diastole due to regurgitation. In younger individuals, a wide pulse pressure is most common after physical exertion when the heart compensates with a higher stroke volume.

[Freedom42]

Thanks, Juan. After waking up repeatedly overnight and thinking about the question, I've decided the key word is "may." Oy!

Now, here's the converse:

A narrow pulse pressure probably indicates that a person has

A) high stroke volume and high peripheral vascular resistance

B) low stroke volume and low peripheral vascular resistance

C) high stroke volume and low peripheral vascular resistance

D) low stroke volume and high peripheral vascular resistance

Going with my "may" strategy, "probably" is my keyword here. This patient probably does not have a high stroke volume, eliminating options A and C. Theoretically, couldn't the patient have a low stroke volume with high PVR (e.g., compensated hypovolemia?). Still, if the patient is hemorrhaging, he's got a low stroke volume and low PVR. I'm going with B. Thoughts, anyone?

[Corey Narry, MSN, RN, NP]

I think the answer is actually D. Narrow pulse pressure is seen in early hypovolemia where there is insufficient circulating volume (low stroke volume) leading to a lower systolic pressure and the autonomic nervous system responds by peripheral vasoconstriction, hence a high PVR, to augment the diastolic pressure. As the opposite of Aortic Regurgitation, it is also seen in Aortic Stenosis.

[BCRNA]

Wide pulse pressure is a hallmark of hypovolemia. Decreased blood volume causes a much lower diastolic pressure. If the patient is compensating with an adequate stroke volume then you have a wide pulse pressure. The elderly can have wide pulse pressure from loss of vascular compliance. In my experience a wide pulse pressure can be used to guide clinical decisions. Narrow pulse pressure doesn't imply any disease process, though can be used to identify malfunctioning equipment. A really narrow pulse pressure is not physiologically possible (means no perfusion pressure).

[Freedom42]

Thank you both! BCRNA, do I interpret your answer to be B?

[Corey Narry, MSN, RN, NP]

Pulse Pressure Variation (PPV) can be used to guide volume resuscitation in mechanically ventilated patients. High PPV can indicate low intravascular volume status.