A hemodynamics question

jnette, ASN, EMT-I · Mar 6, 2004

We're just getting into the basics of fluid replacement IV therapy. One thing I'm having difficulty understanding is the dynamic of hypervolemia treatment. Since hypervolemia is an excess in isotonic fluid, then would you introduce any IV fluid at all before diuresing? I've heard two different schools of thought. One: do not give a fluid at all; 2: give a hypertonic solution which would take fluid off the tissues. Which is correct and could you give me your rationale? Would you believe this is my spring break, it's a beautiful day, I live across the street from a south Florida beach and I'm worrying about this stuff?
Thanks.

The idea is to restrict fluids and sodium. While hypertonic solutions will pull the fluid from tissue, it will, however be moved to the intervascular space. Which is what you don't want as it will lead to pulmonary congestion and pulmonary edema... and CHF.

As far as the concern of hypervolemia being an excess of isotonic fluid... osmolality is usually not affected since fluid and solutes are gained in equal proportion.

Hope I've got it right... if not, we'll both soon learn something !

wonderbee, BSN, RN · Mar 6, 2004

A big thank you to you jnette! This question has been bugging me for the past two days.

jnette, ASN, EMT-I · Mar 6, 2004

A big thank you to you jnette! This question has been bugging me for the past two days.

You're more than welcome !

Now go and enjoy your Spring Break !!! Go hit the beach ! woohooooooooo !!!

Lucky You ! :)

duckboy20 · Mar 6, 2004

I would say no ivf, push diuretics and watch for electrolyte abnormalities. That is just me, probably not the right thing but oh well.

malenurse1 · Mar 6, 2004

We're just getting into the basics of fluid replacement IV therapy. One thing I'm having difficulty understanding is the dynamic of hypervolemia treatment. Since hypervolemia is an excess in isotonic fluid, then would you introduce any IV fluid at all before diuresing? I've heard two different schools of thought. One: do not give a fluid at all; 2: give a hypertonic solution which would take fluid off the tissues. Which is correct and could you give me your rationale? Would you believe this is my spring break, it's a beautiful day, I live across the street from a south Florida beach and I'm worrying about this stuff?
Thanks.

This is so cool, we just went over this in pathophys this week! With fluid volume excess you already have edema so you want to move the fluid from the interstitial space to the intravascular space in order for diruretics to be effective. Remember, you want the kidneys to do their job before resorting to artificial means of diuresis. Your patient is likely going to be hypernatrimic, so the IV fluid of choice would be D5W. You want to give potassium sparing diuretics to protect from the associated hypokalemia.

I hope this is right or I'm gonna fail next weeks pathophys test on fluid volume and electrolytes!

For what its worth...take your books to the beach! :balloons:

jnette, ASN, EMT-I · Mar 6, 2004

This is so cool, we just went over this in pathophys this week! With fluid volume excess you already have edema so you want to move the fluid from the interstitial space to the intravascular space in order for diruretics to be effective. Remember, you want the kidneys to do their job before resorting to artificial means of diuresis. Your patient is likely going to be hypernatrimic, so the IV fluid of choice would be D5W. You want to give potassium sparing diuretics to protect from the associated hypokalemia.
I hope this is right or I'm gonna fail next weeks pathophys test on fluid volume and electrolytes!
For what its worth...take your books to the beach! :balloons:

:chuckle Now we're back to square one ! Her original question.. to give fluids or not? :rotfl:

Guess it would depend on the severity of the condition, just what you're trying to accomplish and in what amount of time. Speaking from a strictly dialysis background, I know that we don't want the excess fluid ANYWHERE... tissues OR vasulature... as obviously our patients have no means of getting rid of it.

But what malenurse says makes sense, too... (for patients who have kidneys, at least)...you might want to promote diureses initially with a non saline solution. Hmmmmmmm... now I'M going to have to dig out the books and research this again, too ! :rolleyes:

Unless some wise, seasoned nurse pops in here to help out !!!

jnette, ASN, EMT-I · Mar 6, 2004

:chuckle Now we're back to square one ! Her original question.. to give fluids or not? :rotfl:
Guess it would depend on the severity of the condition, just what you're trying to accomplish and in what amount of time. Speaking from a strictly dialysis background, I know that we don't want the excess fluid ANYWHERE... tissues OR vasulature... as obviously our patients have no means of getting rid of it.
But what malenurse says makes sense, too... (for patients who have kidneys, at least)...you might want to promote diureses initially with a non saline solution. Hmmmmmmm... now I'M going to have to dig out the books and research this again, too !
Unless some wise, seasoned nurse pops in here to help out !!!

OK... just went over all this again in some of my books, and the consensus is as I originally stated... first and foremost sodium restriction. FVE intervention basically consists of sodium and fluid restriction, and if symptomatic, administration of K+ sparing diuretics.

D5W, however, is isotonic as well, and while it assists in reducing hypernatremia, it is primarily used for tx. of fluid loss and dehydration.. ergo, should be used with caution in pts. with renal or cardiac disease due to risk of fluid overload. So kind of a viscious cycle there.

I would suggest simply the sodium and fluid restrictions, and IF paranteral fluids are being administered, to monitor these closely.

wonderbee, BSN, RN · Mar 6, 2004

This is so cool, we just went over this in pathophys this week! With fluid volume excess you already have edema so you want to move the fluid from the interstitial space to the intravascular space in order for diruretics to be effective. Remember, you want the kidneys to do their job before resorting to artificial means of diuresis. Your patient is likely going to be hypernatrimic, so the IV fluid of choice would be D5W. You want to give potassium sparing diuretics to protect from the associated hypokalemia.
I hope this is right or I'm gonna fail next weeks pathophys test on fluid volume and electrolytes!
For what its worth...take your books to the beach! :balloons:

Well... hmm. Me thinks its time to really talk this thing out. The patient is hypervolemic which is an isotonic situation. Hypernatremia would indicate a hypertonic situation in the ECF which is not the same as hypervolemia. Please correct me if I'm wrong because this is new stuff to me. So if you put D5W (isotonic) fluid in the intravascular space, then you have no fluid shift and the situation remains the same except you have introduced more fluid and worsened the condition. If you introduce hypotonic solution, then the cells will hemolyze and you essentially drown your patient. If you use hypertonic, all fluids will go into the intravascular space which will decrease cardiac output and you have CHF. On the other hand, if you get the fluid into the vasculature and off the tissues and diurese simultaneously, then that might get us to where we want to go? Now I'm assuming (bad thing) that in hypervolemia, you're going to have degrees. When it reaches the point of pulmonary edema, the ABC's will tell us priority number one is to get the fluid off the lungs so maybe the hypertonic solution, at that point, might be the right thing to do. However, before it gets to that point, perhaps just restricting the fluids and using a loop diuretic might do the job. Any more thoughts? This is really important and interesting stuff.

duckboy20 · Mar 6, 2004

RNKittyCat. on a lot of that you are right, on one thing you said you are wrong to a point. If you give a hypertonic solution, that will work to pull fluids into the vascular space. Depending on the status of your patient, that will work to increase their cardiac output ie starlings law. Past a point however the heart will be unable to keep up which will lead to the CHF. Your patient could be hypervolemic due to third spacing but have a normal blood pressure and no symptoms whatsoever of CHF or intravascular excess, maybe not, maybe they are having symptoms. I think the real treatment depends on that patient, and that particular condition they are in. There are a variety of ways to treat. The body's main mechanism for treating high blood pressure which could be a result of hypervolemia is to increase its diuresis. If the kidneys cannot keep up, probably want to give them a boost. Just my thoughts.

jnette, ASN, EMT-I · Mar 6, 2004

On the other hand, if you get the fluid into the vasculature and off the tissues and diurese simultaneously, then that might get us to where we want to go?
Now I'm assuming (bad thing) that in hypervolemia, you're going to have degrees. When it reaches the point of pulmonary edema, the ABC's will tell us priority number one is to get the fluid off the lungs so maybe the hypertonic solution, at that point, might be the right thing to do. However, before it gets to that point, perhaps just restricting the fluids and using a loop diuretic might do the job. Any more thoughts? This is really important and interesting stuff.

You got it... prevention is key.

IF hypertonics are needed at any point ( and I believe diuretics would be used before going that route) remember that hypertonics lead to the associated complications of hypernatremia ( equals more fluid gains) and hypokalemmia.

But SODIUM is the real culprit in hypervolemia ! The sodium salt itself (sodium chloride) is what causes fluid retention. Get rid of the sodium, (low salt or no salt diet) and you've kicked butt.

In other words, you're only restricting fluids because the body's sodium content will continue to hoard those fluids... not want to give it up. It's not really the fluid that's the bad guy here, but the sodium because the sodium keeps those fluids in the body rather than excreting them.

Many/most fluids also contain sodium...so adding fluids will also increase the sodium content. Thaty's why you go with sodium AND fluid restrictions.

Does that help? :chuckle

jnette, ASN, EMT-I · Mar 6, 2004

Then, too, know that if you only pull the fluids off the tissues and into the vasular compartment, that will continue the cycle...will lead right back to too much fluid in the vasculature, force it back out into the tissues, as well as congest the lungs and heart.

Verrrrrrrrrrrrry tricky business... which mandates fine tuning.

Thoroughly confused now? :stone