Ascites, and third spacing

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Specializes in Paramedic 15 years, RN now.

Is ascites, seen in Liver failure the same thing as third spacing seen in the abdomen of CHF?

I dont think you could drain the belly of a CHF edema but i know you can drain the former.

I think ascites is not really third spacing because its in the peritoneal cavity itself. right?

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Specializes in Tele, ICU, ED, Nurse Instructor,.

I believe you are correct. Ascites can be assessed by percussion of the abdomen. Third spacing can be assessed by the skin weaping. It reminds me of anasarca in which includes the liver and other important parts of the body systems.

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Specializes in Critical Care, Education.

As an educator, I am overjoyed at your question. It's obvious that you are trying to create your own meaningful "mental model" of fluid balance & related problems. This is real learning. You're on the right track.

There are basically 2 causes of ascites: transudate & exudate. Transudate is caused by increased pressure in the portal vein (portal hypertension) - causing the fluid to passively 'leak' through the vessel walls. On the other hand, exudates are the result of fluid that is actively secreted due to inflammation or malignancy. A quick differentiation is made by analyzing protein levels. Transudate has low protein (protein molecules are too big to leak out of the vessel), but exudate will have near normal protein. The vast majority of ascites is due to hepatic disease.

Third spacing - is essentially transudate that is generalized to other areas of the body. Basically, there is a 'fluid overload' situation due to some underlying cause - too much iv fluid, massive tissue injury, cardiac failure -- that overwhelms the ability of the kidneys to get rid of it. Diseased renal function (due to kidney disease, poor renal circulation, ARF, etc) will make the process happen even faster. The overload causes intravascular pressure to increase until it begins to 'leak' out of the vessels into surrounding tissue. But in this case, the leaks are not focused to one area (like portal hypertension) so edema is noted in other areas of the body especially those with a lot of soft tissue (expansion space) that are affected by gravity such as pre-tibial, sacral, etc.

Clear as Mud??

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Specializes in Urgent Care NP, Emergency Nursing, Camp Nursing.
As an educator, I am overjoyed at your question. It's obvious that you are trying to create your own meaningful "mental model" of fluid balance & related problems. This is real learning. You're on the right track.

There are basically 2 causes of ascites: transudate & exudate. Transudate is caused by increased pressure in the portal vein (portal hypertension) - causing the fluid to passively 'leak' through the vessel walls. On the other hand, exudates are the result of fluid that is actively secreted due to inflammation or malignancy. A quick differentiation is made by analyzing protein levels. Transudate has low protein (protein molecules are too big to leak out of the vessel), but exudate will have near normal protein. The vast majority of ascites is due to hepatic disease.

Third spacing - is essentially transudate that is generalized to other areas of the body. Basically, there is a 'fluid overload' situation due to some underlying cause - too much iv fluid, massive tissue injury, cardiac failure -- that overwhelms the ability of the kidneys to get rid of it. Diseased renal function (due to kidney disease, poor renal circulation, ARF, etc) will make the process happen even faster. The overload causes intravascular pressure to increase until it begins to 'leak' out of the vessels into surrounding tissue. But in this case, the leaks are not focused to one area (like portal hypertension) so edema is noted in other areas of the body especially those with a lot of soft tissue (expansion space) that are affected by gravity such as pre-tibial, sacral, etc.

Clear as Mud??

So, Ascites is but one manifestation of thirdspacing, as was my understanding, or is it something different? And, as follow-up to your explanation, does the decision on whether or not to remove fluid from the abdomen depend on if it is transudate or exudate?

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Specializes in Paramedic 15 years, RN now.

In short, I think I am on the right track, in that, hepatic ascites is not really 'THIRD" spacing at all, it s more like "second" spacing if there was such a thing. In my mind...1st space = in the vessels, 2nd space = outside the vessels, 3rd space = in between, in the tissue. So, since the peritoneum CAN be drained, that would mean the fluid is actually IN a space, that space being a, sort of, SECOND space.

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Specializes in Urgent Care NP, Emergency Nursing, Camp Nursing.

My understanding is that the First/Second spaces are in the vasculature (cardiovascular and lymphatic) and intracellular spaces, where fluid is supposed to be. The "third" space is all the other places in the body that fluid can accumulate, but shouldn't, hence pedal edema, scrotal edema, sacral edema, ascites, and periorbital edema.

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Specializes in Nursing Education.

Agreed. Ascites is definitely a type of third-spacing. (I just double-checked in my Med-Surg book, too :rolleyes:)

You're pretty close with you're understanding of spacing, but not quite there yet. Here's a good way to think about it:

1st spacing: Includes all fluid that is where it is supposed to be...this includes fluid inside cells, and inside the blood vessels.

2nd spacing: Refers to abnormal fluid accumulating in interstitial spaces. This fluid is NOT in the cells, and NOT in the blood vessels. But (and here is the important thing about 2nd spacing) it is still 'in contact' with those areas so that the fluid could easily move back into the 1st spacing areas should the variables of hydrostatic pressure, diffusion, and osmosis change to make that happen.

3rd spacing: This is trapped fluid. Basically, this fluid is in a place in the body where it is difficult or impossible for it to move back into the cells or blood vessels without medical intervention. The peritoneal cavity is one of those locations in the body, making ascites a type of 3rd spacing.

Does that make sense to you?

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Specializes in Paramedic 15 years, RN now.

Yes, makes sense. I just really over analyze stuff, as a rule.

Though I understand the concept perfectly, my mind wants to put fluid that CAN BE ASPIRATED into another category alltogether. Which, clearly, that is not the case. I just have to accept that peritoneal fluid is the same as edema, essentially.

thanks for all the fascinating input

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ascites is 3rd spacing because it is in the peritoneal cavity and shouldn't be.

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Ascitic fluid from liver failure/portal hypertension is exactly the same as fluid from heart failure, and for the same reason-- portal hypertension. If the heart can't efficiently pump the blood that comes to it, what happens? It backs up. You see jugular venous distension (JVD) because the right heart / central venous pressures (CVP) are high. The other veins downstream, like the portal veins, have elevated pressure too. Same things happens then as happens to them when they have to force their way through a sold, cirrhotic liver: high pressure, and they leak. Ascites.

And by definition, first and second spaces are the intravascular and intracellular spaces. The third space is the interstitial or intraperitoneal space-- edema is third-spacing, ascites is third-spacing, pleural effusions are third-spacing ... The fluid, whatever its composition, is not available for circulation or cellular use.

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

This thread is a couple of years old but has great information.

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