Fluid & Electrolytes...

kahumai, RN · Feb 20, 2005

There's a book called "Fluids & Electrolytes Made Incredibly Easy."

I heard it's ~wonderful~....maybe that would help you? This stuff isn't easy, but if you don't learn it now, count on MANY wrong answers on upcoming tests & possible clinical mistakes. Do your best; Good Luck! :)

checkers · Feb 20, 2005

There was a thread about this not too long ago, that really helped me. I hope this link works....

https://allnurses.com/forums/showthread.php?t=92701&highlight=fluid+electrolyte

Fraggle · Feb 20, 2005

Hi everyone, I am having a hard time understanding the Fluid and Electrolyte balance. Does anyone know why a particular IV is given to someone...ie, why a hypertonic solution is used instead of a hypotonic solution....etc... I really want to understand this stuff, but it is driving me crazy. Thanks.

That book is very good, I have it. For electrolytes, just memorize the ranges and what body part they act upon (like Ca+ and muscles). Even though you get the range on the lab sheet, you still have to know them by heart for tests. Plus, knowing what they act upon makes things easier.

Also, when ever you give a Hypertonic, you are pulling water from cells into the blood. When you give a Hypotonic, you are pushing water from the blood into the cells.

So, if a person is hypovolemic, you want to give them Hyper. But not too much, or the cells would "dry out." What if someone has fluid overload? Well, you're definitely not going to give them a Hypertonic, then.

purplekath · Feb 21, 2005

Basically, the fluid inside the cell wants to have the same amount of "stuff" (electrolytes etc) in it as the fluid outside the cell. The semi-permeable plasma membrane left to it's own devices will make this "equal over time" by letting solutes flow in and out so that things are equal on both sides of the membrane. In other words, solutes will flow naturally via diffusion to where there is more water and less solutes, in much the same way as the smell from a perfume bottle will eventually reach every corner of the room it is in. In the same way, water will flow to places where there is less water. This evens things out so that things are eventually equal on both sides.

Of course this is quite simplistic, as there are all sorts of protein channels, pumps etc that will move things around using energy in different directions, but for now, just imagine that you're dealing only with this principle of diffusion/osmosis.

Hypertonic solution is one that contains MORE solutes (particles of electrolytes) than the fluid inside the cell. Therefore, the water inside the cell will be drawn towards a hypertonic solution. So you would administer a hypertonic solution to a pt that has too much fluid inside their cells....because the solution will literally draw water OUT of cells. Hypotonic solution works the opposite way -- it will draw water INTO cells. Isotonic solution does neither - it contains the same concentration of water and solutes as cells contain, so there is no nett movement...you're just administering fluids and nothing more.

OK - where does this fit with your patient? If your patient is suffering from an extracellular dehydration (not enough water outside the cells), then you would give a hypertonic solution to draw fluid from the cells and into the extracellular fluid where you need more water. If the dehydration is intracellular, then you want water to travel INTO the cells, so a hypotonic solution would be best. Different conditions will lead to different kinds of dehydration. If someone is just randomly losing fluid - for example in a big bleed, then you simply need to replace the fluid. So you would administer an isotonic solution.

Hope that helps!

Rivs · Feb 22, 2005

Thanks alot for the great explanations and sites...... :)