Mannitol in CHF, why not?

DayDreamin ER CRNP · Sep 25, 2010

What kind of drug is mannitol? Mannitol is a form of ......?

And that ______ goes to the brain so it would be a good diuretic for lowering ______.

________ is the most commonly used drug for CHF. Yes, it is considered a diuretic but it really treats _______ by keeping the body from absorbing _______.

think about the effects of mannitol on the body vs. a loop diuretic.

m

MEDICJOHN · Sep 25, 2010

I get all that, I just can't wrap my head around WHY it would exacerbate pulmonary edema. I know its a form of sugar and I know lasix works be inhibiting Na resorbption. I dont get why sugar would pull water INTO alveoli

DayDreamin ER CRNP · Sep 25, 2010

My guess is that is has something to do with permeability and metabolism of those cells.

I'm totally beat but I feel like the answer is in my brain somewhere I just can't drag it out. I swear I KNOW this answer.

MEDICJOHN · Sep 25, 2010

lol, thank you for your time, none the less, if you think of it...let me know....i obsess over things sometimes when, REALLY, it doesn't matter...only that I KNOW not to give it at the wrong time.

DayDreamin ER CRNP · Sep 25, 2010

My clinical teacher is a cardiac god (in his mind anyway). I'll ask him next week if you can wait that long.

I swear I know this answer. ::brainfart::

MEDICJOHN · Sep 25, 2010

I can wait, thats fine....nothing pressing. I'm impressed I could fill in your above blanks without looking..(pat on back to me)

suanna · Sep 25, 2010

Mannitol pulls fluid volume into the vascular space- sounds great if you are pulling it out of the lungs into the vascular space, but what about all the fluid it pulls out of the other 3rd space tissue- arms, legs... Once that fluid is in the blood stream the osmotic pressure is going to equalize and what you have done is equal to giving a liter or two (depending on the pts overall avail fluid, and the manny dose) of fluid bolus. You don't have to be a cardiac god to understand why a CHF patient wouldn't want to have a sudden increase in thier vascular fluid voulme of a liter+. Pulling in peripheral edema dosen't help if it ends up drowning the heart and backing up into the lungs- Swollen ankles is much less of a problem.

DayDreamin ER CRNP · Sep 25, 2010

I can wait, thats fine....nothing pressing. I'm impressed I could fill in your above blanks without looking..(pat on back to me)

:yeah: :yeah:

See? We ARE gettin there!

I think that is an excellent question by the way. It really made me think at least.

m

MEDICJOHN · Sep 26, 2010

Ok, that makes sense now, (even though I'm not a "cardiac god") I didn't really need the insult...only an explanation. I got both it seems..but thats ok...I understand now. thanks for the explanation.

suanna · Oct 3, 2010

Ok, that makes sense now, (even though I'm not a "cardiac god") I didn't really need the insult...only an explanation. I got both it seems..but thats ok...I understand now. thanks for the explanation.

No insult was intended- I know there are people in this forum that know WAY more than I do and can go into acute detail about the angiotension/renin cycle and the relative effects on loop dieuretics on barroreceptors and BLA BLA BLA... I'm sure there are reasons why concentrated albumin (a coloidal voume plasma expander) is more or less dangerous than Heta starch, or mannitol or whatever. My intention was to say you can get too involved in the details if fluid physiology when the the simplest explanation is often the clearest. I certainly didn't think my post was insulting to you.

nursingstudent1212 · Feb 13, 2012

Can someone please explain why we don't used mannitol in CHF. Yes, I know it's not indicated, but I can't understand why it is contraindicated. If it "pulls water" out, why would it not be a good thing?
Confused!
John

Within the kidneys is the juxtaglomerular apparatus that is sensitive to changes in pressure and volume (perfusion). When there is a decrease in either one it will activate the RAAS, which we all know results in the secretion of aldosterone, which increases sodium and water and subsequently increases preload. Activation of the RAAS also results in systemic vasoconstriction, which increases afterload. The increases in preload and afterload can be very detrimental to an already weakened heart (heart failure). Mannitol can result in hypoperfusion to the kidneys thereby causing the juxtaglomerular apparatus to activate the RAAS. Ergo mannitol is contraindicated in CHF patients.