Help with Fluid and Electrolytes

Students Student Assist

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Hi -

I'm hoping someone can explain this because I am tying myself in knots trying to figure it out. So, I'm studying for our finals next week, and going over fluids and electrolytes. I'm trying to figure out how to recognize if FVE is relative or actual, and how would you know anyway?

Here's my thinking - please correct me!!!

FVE is basically over-hydration. I assume caused by drinking too much, correct? I'm not understanding how having too much Na+ intake can lead to hypertonic FVE....surely too much sodium would cause dehydration, would pull water out of the ICF into the ECF...? How is that FVE - or does that mean that there is now too much fluid in the EC space compared to the IC space? In other words, to be in homeostasis, the balance of the fluid in the intra and extra cellular spaces must remain within a certain balance, and now one has shifted so that is considered FVE?

I guess I understand WHERE the fluid is not right for the body, but why is that considered FVE...?? Especially when we throw in the opposite, hypotonic FVE which would cause too much fluid in the IC space??

Please help!!

Triddin

380 Posts

Fluid volume excess is too much fluid in the circulatory system. Hypertonic is too much sodium/electrolytes which pull h2o from the cells to the blood stream. You can also have isotonic. There are several reasons a person can have a fluid volume excess. Over hydration is one reason. You definitely don't want to give too many boluses. I have also seen a case or two of water intoxication. With water intoxication, it isn't the fluid volume excess that is the problem as much as the dilution of the sodium in the blood stream. Depending on the solution and how many boluses you give, you could have a hypertonic, hyper volume fluid volume excess.

You need to look at other factors as well. Kidney damage and hormonal imbalances also can result in FVE. If the kidneys aren't working, they can't filter out fluids and it builds up in the body. SIADH, Cushing and hyperaldosteronism result in too much ADH/aldosterone which causes the body to retain fluids as well.

If your Blood Na (from increased sodium intake is absorbed into the blood/ Too many NaCl boluses, fleet enema etc) is higher than that in the cells, it will pull fluid from the cells into the blood stream. This will make the cells dehydrated but since you have an increased fluid volume in the circulatory system (fluid overload).

Hopefully this helps? Generally when we talk about hypo,hyper and isotonic, we refer to it in relativity to the blood streams osmolarity. Keep that in mind and you should be able to figure out which way the water will move

hayhayrome

7 Posts

Okay so fluid volume excess can be bad because if you have too much fluid in your circulatory system there is a higher pressure--high pressure=hypertension=damage. Think if you fill a balloon with too much water it will pop! Or if 2 people are trying to walk through a doorway compared to 6 people there is way more resistance! So the body tries to compensate and shifts the fluid into the tissue=edema, or it can shift fluid into the lungs which you see a lot in questions about elderly people and pneumonia. Of course fluid volume excess rarely happens to a healthy person, unless there is already an issue in the body, ex. kidney failure, heart failure, old age.

Thank you!!

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