Can Diuretics Reduce Afterload? How?

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Can Diuretics Reduce Afterload? How?

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prep4usmleee
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Topics: 1
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06/02/08 - 12:37 PM

#1

I'm confused by the diagram on p. 250 of my 2007 First Aid, which indicates that diuretics help reduce afterload (which contributes to their usefulness in treating heart failure).

It's very clear to me how diuretics reduce preload, simply by reducing the amount of intravascular blood. And I understand how this reduced preload is helpful for patients with CHF.

And of course it would be *nice* if diuretics also reduced afterload, because that, too, would help reduce cardiac demand. But to my mind, afterload is mediated principally by arteriolar constriction, which if anything should INCREASE in the setting of reduced intravascular volume.

Amy I right, or am I confused? Could someone tell me whether (and how!) diuretics reduce afterload?

Thanks!

-Josh

arlete
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06/02/08 - 12:58 PM

#2

Hi, prep...

I can't tell you how, but I am sure furosemide acts in the pulmonary vascular bed way before its diuretic action, which makes it so useful for pulmonary edema. nod

nod

That's all I have to say about it. confused

confused

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Ig F
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06/03/08 - 06:40 AM

#3

anyone?never heard of diuretics reducing afterload........can some one plz explain if that occurs????

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shazbaz
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06/12/08 - 04:16 PM

#4

Dont diuretics reduce blood pressure...and blood pressure is a measure of after load and so diuretics would decrease after load

P4a99
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06/12/08 - 11:50 PM

#5

shazbaz wrote:
Dont diuretics reduce blood pressure...and blood pressure is a measure of after load and so diuretics would decrease after load

I thought the same too.

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arlete
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06/13/08 - 07:09 AM

#6

Diuretics reduce blood pressure BECAUSE they reduce preload. Blood pressure is a measure of cardiac output (which depends on preload and heart rate) and peripheral vascular resistance, not only afterload. Beta blockers, for example, decrease blood pressure through HR, and they actually increase PVR.

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P4a99
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06/13/08 - 10:17 AM

#7

But eventually wouldnt afterload decrease too?

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arlete
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06/13/08 - 04:19 PM

#8

I just read that diuretics cause blood vessels to dilate, too, so they reduce pre and afterload. nod

nod

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giomed20
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06/19/08 - 07:52 AM

#9

action of Furosemide on pulmonary edema is the second way of this vessels. nobady knows how it works, smiling face

smiling face

but it is only real fact

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