Lower limb vascular resistance with post-ductcal coarc

[username456789]

Sorry for posting all these dumb random questions I come across in QBanks (is there a thread for this kind of thing already?)

Anyway, I just did a random 48q Kaplan QBank block and got two compensated postductal coarctation questions. Both answers involved evaluating the vascular resistance of the lower body.

In one question, it was stated that FLOW is the same above and below, and that vascular resistance in the upper limbs would be increased vs. normal, and that lower limb vascular resistance would be "NORMAL."

Eight questions later the explanation to another answer stated that in a coarctation, vascular resistance should be increased vs. normal in the upper limb (so far so good, that's consistent with their previous answer), and that lower limb vascular resistance would be DECREASED vs. normal (via autoregulation/myogenic response).

I'm having a brain fart here, so maybe they're somehow both right, but from what I can tell both situations were more or less the same (stable patient, postductal coarctation, explain the hemodynamics) but with different answers.

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[MilkmanAl]

I would expect lower limb resistance to stay normal, if they're assuming that the blood flow is normal.

 

[username456789]

I would expect lower limb resistance to stay normal, if they're assuming that the blood flow is normal.

Yeah and the explanation for the first one was that as long as the kidneys and the R-A-A system is working fine, resistance would remain "normal." But I'm pretty sure the second question had essentially the same scenario, with no reason to assume the body could not adapt hemodynamically/hormonally.

 

[turkeyjerky]

it seems logical to me that vascular resistance would be increased in the upper body and decreased in the lower body.

 

[vicinihil]

Because you're getting LOWER blood flow to your kidneys and triggering the RAA what's causing the lower body to not have HIGHER resistance since you have SYSTEMIC hypertension and angiotension II is causing OVERALL vasoconstriction and not just selective one part of the body?

 

[username456789]

Because you're getting LOWER blood flow to your kidneys and triggering the RAA what's causing the lower body to not have HIGHER resistance since you have SYSTEMIC hypertension and angiotension II is causing OVERALL vasoconstriction and not just selective one part of the body?

I believe part of the explanation was that with the upper circulation there's initially an increased flow that washes away metabolic vasodilators from tissues, leading to more vasoconstriction? And thus keeping the flow in check? It wasn't making a ton of sense at the time and I don't have the time to even go back over it all to see if it makes sense physiologically, but I definitely see where you're coming from with your question . . .

 

[vicinihil]

ok so maybe it's like this....

We all agree that the upper limbs would experience hypertension due to increase flow and vasoconstriction by angiotension.

The lower limbs would have normal to decrease pressure because:

MAP = CO * Resistance

perhaps it's not necessarily the resistance being low (maybe that's a component, i don't know) but to me it makes sense that there will be less flow (CO) to it thereby either keeping MAP normal or lower (by increasing resistance to compensate for the decrease in CO).

That makes sense to me. I don't know if that did to anyone else or am I confused haha.

 

[go lakers]

I remember this question!
...It annoyed me

 

[WDeagle]

Yea i remember being irritated by this question. It doesnt help that Kaplan Qbank has terrible explanations. If i had to do it over again i would avoid kaplan.

 

[username456789]

Yea i remember being irritated by this question. It doesnt help that Kaplan Qbank has terrible explanations. If i had to do it over again i would avoid kaplan.

Is it against forum rules to post screenshots of both questions/explanations? I'm guessing it might be, but I'm too lazy to type out the entire question, answer choices, and explanation for both questions.

I'm hoping it's allowed, though, so you guys can check and make sure I'm not crazy.

Edit: I assume that if it's not illegal per SDN, it likely is "against the rules" per Kaplan.

 

[MilkmanAl]

Yeah, don't go posting exact questions and/or answer choice sets in any way. Even posting more than "this question had to do with x and had this answer" has gotten some people in trouble.

 

[vicinihil]

oh no you artificially bump my Qbank average by 1/2000 questions ahhh the horror or lying to myself! haha

Anyone come to a consensus regarding the answer?

 

[MilkmanAl]

I didn't say it made sense, just that it has happened.