Fluid status

Antikigirl, ASN, RN · Jan 12, 2005

Lasix stimulates kidneys to produce more urine, as a result it reduces the amount of free water in the body. Along with increase in urine volume, Lasix causes loss of Sodium and Potassium in the urine.

Why would this benifit..because WATER FOLLOWS SODIUM!!!!! Open the flood gates as you will for sodium to go out...the body will take that fluid too! It tends to effect the cardiopulmonary systems hard..and thusly takes the excess fluids off that system to take the load off the heart!

But don't get caught up in the cardiac and forget the pulmonary system! The heart cares less really..it pumps due to demand..now the lungs on the other hand...oh yes it cares big, and can't work at all with excess fluids making O2 and CO2 transfers, let alone acid reduction (remember the first line of acidosis...blow it out or puffing...lungs can't 'puff' if they are full of fluid..putting it simply!).

Lasix tends to do this better than HCTZ for some reason, and since I didn't master in pharmacology or cardiology I am not sure as to the exact reason it does this...all I need to know is that it does..but watch the patients K levels (and sodium too..but that normally is comp by normal diets..so watch your low sodium patients!).

With lasix..if someone has a small output..watch the BP, dizziness, input/output, any odd cardiac or pulmonary effects, any changes in alertness, and muscles contractions (since sodium and potassium are the source of contraction..lack of such will go wrong in muscle...fine being first..larger motor skills next!). But other than that...40 mg q day of lasix is not too much (20 mg is a typical low dose done for most!)...I don't even get too scared till the doc calls for 80 or more per day...(not that I don't worry at 40...just not as much!).

If a patient still had small output look carefully at the lungs (any congestion?), whether they really have good input, and of course never deny the possiblity of UTI!

Any other pearls of wisdom?

stn2003, RN · Jan 12, 2005

i'm assuming this man has chf.

when a person with chf becomes hypervolemic- fluid overload in the vascular space- the heart cannot sufficiently pump the excess fluid and the extra fluid backs up from the heart into the lungs, causing the wheezing and all sorts of other probs.

administering Lasix, Bumex, etc. will reduce the volume of blood in the vascular space, hopefully to the point where the heart can sufficiently pump it all through the body, and then there would be no extra fluid to backup into the lungs.

you did not mention that this man had any edema to indicate fluid overload in the third space, but it is possible to be hypovolemic and have fluid overload in the interstitial space. this is not a so much a heart pumping problem as it is a lack of protein (albumin). Proper amounts of albumin maintain the osmotic-oncotic pressure that keeps fluid in the vascular space, and keeps it from shifting to the interstitial spaces. In a situation like this, the MD may order a hypervolemic solution to help pull the fluid back into the vascular space, and additives of albumin to maintain the oncotic-osmotic pressure to keep the fluid in the vascular space. And of course, once the fluid is in the vascular space then the kidneys can excrete it and output should increase.

hope this makes sense : )

btw, i'm still a student, so if I'm wrong someone please correct me : P

leslie :-D · Jan 12, 2005

i don't think you can be hypervolemic in the soft tissues, even if that's where everything is seeping into. hyper/hypovolemia i thought, referred to the vasculature only.

and to maintain oncotic pressure they normally give albumin to bring the colloids back into the vessels, pulling the fluid in with it.

the human body has a sequence of mechanisms to compensate for ailments gone awry.

but i agree, it's a delicate balancing act giving lasix to someone with wet lungs but appears hypovolemic otherwise.

leslie

UCDSICURN · Jan 12, 2005

Let's back up and look at the whole clinical picture. We need to look at more information than just urine output to make a clinical judgement on a patient's volume status, particularly intravascular volume. Blood pressure, I&O's, cardiac history if any, echocardiogram reports if any, current clinical picture, chest films, BNP studies if done, and kidney function to just name a few. Taking all of this into consideration the physician felt it necessary to diurese the patient rather than fluid challenge him/her.

My question is, how exactly does Lasix work to remove excess fluid from lung lets say?

If a patient has a cardiac history such as congestive failure, we know that the blood is inadequately pumped in the systemic circuit. We also know that they usually have poor ejection fractions. This being their baseline, we put them in the hospital and we tend to get a little overzealous with the fluid and worsen their failure. With the heart not pumping the blood forward as well as it should, there is a backup in the pulmonary circuit. By administering Lasix you decrease the intravascular volume which decreases the stretch on the heart and allows it to pump more effectively and decreasing pulmonary circuit congestion, which indirectly "removes" fluid from the lung.

Also, can't a person be hypovolemic AND fluid overloaded? Meaning, they have third spacing but are essentially hypovolemic with low urine output? Along these lines...if a patient has low urine output but is slightly overloaded in lungs/periphery, why doesn't that overloaded fluid go back into the vascular space and filter through the kidneys? Why do the kidneys act all dumb and say, "oh gee, not fluid for us guys today."

Generally speaking hypo/hypervolemia and fluid overload is in reference to the intravascular compartment. You're either normal hypo or hypervolemic. You can be very fluid positive yet be intravascularly depleted. A good read for you on this would be to read up on the Systemic Inflammatory Response Syndrome. It pretty much covers everything from sepsis to trauma and the massive 3rd spacing associated with it. Go to an ICU and ask to see a patient in full blown septic shock. They'll blown up like a balloon with fluid...eyes swollen shut, scleral edema, etc etc. As bad as they look, it is absolutely necessary to maintain end organ perfusion and prevent multisystem organ failure associated with hypoperfusive states.

As far as fluid getting back into the blood stream or intravascular compartment this has to do a lot with osmolarity or oncotic pull. Another good read. By giving a patient Lasix and causing them to dirurese you increase serum osmolarity and you're able to "pull" fluid back into the intravascular space.

Hope this helps.

D.C.

begalli · Jan 12, 2005

I also wonder what this patient's kidney status is? I wonder what his creatinine was?

begalli · Jan 12, 2005

As far as fluid getting back into the blood stream or intravascular compartment this has to do a lot with osmolarity or oncotic pull. Another good read. By giving a patient Lasix and causing them to dirurese you increase serum osmolarity and you're able to "pull" fluid back into the intravascular space.

Osmolarity being more proteins (or albumin) in the vasculature to do the pulling.

Great post!

zacarias, ASN, RN · Jan 13, 2005

. Go to an ICU and ask to see a patient in full blown septic shock. They'll blown up like a balloon with fluid...eyes swollen shut, scleral edema, etc etc. As bad as they look, it is absolutely necessary to maintain end organ perfusion and prevent multisystem organ failure associated with hypoperfusive states.
D.C.

Thanks all for your great responses!! I guess I was really tired when I wrote that. But what DC mentions above is what I'm talking about. Treating the massively third-spaced patient with major hypovolemia is tricky.

Also, what did you mean DC when you said Lasix increases serum osmolarity? I would think it would decrease it, getting rid of sodium and all.

I think the research also states that it now realized that it is not good to "challenge" kidneys by giving them diuretics (unless of course they are fluid overloaded). I'll have to research that one some more.

Thanks again fellow nurses!

whitebunny · Oct 30, 2009

mark~~~~~~~~~~~