Third spacing

Yes, it can. It may be useful for you to open you A&P book and review the capillary dynamics. However, I'll give the short and sweet version. Blood is comprised of many different components. However, proteins are the main concern in this case of liver failure and low protein. With the liver compromised, proteins levels will drop. So, what are the roles of proteins in fluid balance? Well, proteins have a lot of "osmotic pull" or some say "oncotic pull" or "osmotic pressure" or "oncotic pressure." What does that mean? It means that proteins are large have the ability pull a lot of fluid. Water goes from high to low concentrations of solutes. Where there is high concentrations of proteins, there will be a lot of water. In the case of a normal patient, there is lots of proteins in the blood and therefore, the blood primarily consists of water. Now, in the case of the liver failure pt. Liver failure =====> less protein synthesis =====> hypoalbumenia. Can you guess what happens where there is hypoalbumenia? Fluid will shift. Where? A third space. Well, what's a third space? A location where fluid doesn't normally collect or is unavailable to the body for normal processes. Can't be intracellular or extracellular. Then where? Well, we have to two main cavities where is could go. The peritoneal cavity or the pleural cavity. In the case of liver failure, ascites, is within the peritoneal cavity. As far as portal HTN contributing to 3rd spacing more so than low protein. I'm not sure. I believe portal HTN is a structural issue which can lead to capillary damage and protein leaking into a 3rd space. What happens if proteins leak? Can you guess? Similar to above, fluid/water will follow. Hope this helps.

Many thanks for that, it helps alot

Excellent post Floridatrail2006 :) Thank you

Wow thanks for that post floridatrail!! New grad here and this is great info for anyone!!

Thanks for the compliment. :)

So what you're saying is the main cause of ascites "3rd spacing" is decreased oncotic/osmotic pressure in the vessels aka hypoalbuminemia?

I wonder does portal HTN cause ascites as much as decreased oncotic pressure?

Ascites in liver failure has two causes-- first, the low oncotic pressure causes fluid leaking, although you don't see it as much in the other places you see it in other patients with low serum proteins.

The major reason is the portal hypertension. Of course, hypoproteinaceous blood is gonna leak even more easily than normal -> ascites. But the major cause is mechanical, from the pressure.