Conflicting concepts..

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Conflicting concepts..

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7 Posts

RayBerg
Forum Senior

Topics: 32
Posts: 150

05/27/07 - 11:09 AM

Hey guys,
I've come across some conflicting concepts hope someone can clarify it for me.

Goljan says - in inc salt intake --> vasoconstriction --> inc fluid return to heart --> Inc diastolic BP

But, when discussing Hi Output Heart Failure, he says - endotoxic shock --> vasodilatation --> dec resistance --> Inc return to R heart

So, is there an increase in return to R heart in vasodilation AND vasoconstriction? I was under the understanding that only vasoconstriction increases return to the heart. Please explain....

Thanks

arlete
Intern in 2009!!!!!
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Topics: 30
Posts: 2,227

05/27/07 - 03:59 PM

Vasodilation decreases return to heart.

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RayBerg
Forum Senior

Topics: 32
Posts: 150

05/27/07 - 09:29 PM

Thanks arlete.

For those who listen to Goljan. Did he make a mistake then??

me007
Forum Guru

Topics: 72
Posts: 803

05/27/07 - 10:18 PM

no, he did not.
there is increased return of blood to the heart and increased cardiac output in septic shock.
and vasodiation.

RayBerg
Forum Senior

Topics: 32
Posts: 150

05/28/07 - 12:37 AM

So you're saying that the increase in contractility (CO) overcomes the decreased return that one would have otherwise because of vasodilation and that's how we get an increased return.

Am I understanding you correctly? Thanks for the response guys..

RayBerg
Forum Senior

Topics: 32
Posts: 150

05/28/07 - 11:31 AM

me007 wrote:
no, he did not.
there is increased return of blood to the heart and increased cardiac output in septic shock.
and vasodiation.

the following is an explanation by meg:

Anemia :arrow: local tissue hypoxia :arrow: local vasodilators released like Adenosine :arrow: vasodilation of arterioles :arrow: more blood to capillaries, venules, veins to right heart :arrow: more into pulmonary to left heart :arrow: all this to increase preload and hence cardiac output.

She, too, insinuates that vasodilation inc blood flow to the heart which causes increase in pre-load. Please clarify..

drduck
Forum Guru

Topics: 82
Posts: 529

05/28/07 - 11:49 AM

hey one thing is clear....vasodil....causes decrease venous return to the right side of the heart....
now it depends on whether there is hypoxia or not...
if hypoxia present....there is pulmonary vasoconstriction and it no longer behaves like a venous pool(reservior) and pours the same amount of blood that it has recieved from rt. ventricle to the left atrium...
thats why it is a must to give venodilators in case of CHF....so that the extra blood reaching the rt side of heart stays in the pulmonary pool and less reaches to the left side and less is the work for the heart....

about the septic shock....man, its real difficult to undrstand it so easily....there are so many things going on side by side...
at first there is severe vasoconstr. followed by sustained peripheral vasodilatation....
it doesnt include pulmonary circulation....which suppliments the loss of blood from the systemic circulation that has occoured due to the massive peripheral pooling of blood.

and mind u...in septic shock there is production of CARDIODEPRESSANTS....that still causes further damage....really difficult thing to manage...

Edited by drduck on 05/29/07 - 03:03 AM

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