Understanding (UF) Ultrafiltration Goals Formula

I just finished the third day of my Hemodialysis or Nephrology nurse training and our lesson was all about (UF) Ultrafiltration Goals Computation. Of course, what can you expect with anything that involves computations or in short Math? Tricky, indeed! As what every nurse would say, we took up nursing to avoid all those, however, it seems like the opposite. So, after a million times of mistakes which honestly, I rarely got a correct answer during our (UF) Ultrafiltration Goals Computation  exercise, I managed to create some tips from the wrong answers I got that eventually helped me aced the post test. Though it wasn’t perfect but 2 mistakes is not bad at all, anyway, you get points from the solution.haha  Below is the (UF) Ultrafiltration Goals Formula according from my own understanding.

Let’s have an overview first. As a note, this formula is from the Global Nephrology Training Centers (where I am enrolled as trainee) and may not be applicable in most places, countries or centers.

(UF) Ultrafiltration

(UF) Ultrafiltration can be simply defined as fluid removal, therefore when we talk about (UF) Ultrafiltration Goals, it is the amount of excess fluid we aim to get or filter from the dialysis patients. We use the (UF) Ultrafiltration Goals formula below:

UFgoal = UFnet + medications + blood + NSS (flushing) + backwash (BW)

(UF) Ultrafiltration Net

UFnet, on the other hand, is the difference of the patient’s pre-weight and dry weight. We use the (UF) Ultrafiltration Net formula below:

UFnet = pre-weight – dry weight (DW)

Pre-weight is self-explanatory. Dry weight, on the other hand, (basing from our knowledge that the kidneys of dialysis patients are unable to remove the excess fluid) is their normal weight when they are not fluid overloaded.

Now getting to the details…

(UF) Ultrafiltration Goals

Let’s get back to the formula.

UFgoal = UFnet + medications + blood + NSS (flushing) + backwash (BW)

Now that we know what UFnet is; we move on the rest of the fluids incorporated during the treatment: medications, blood, NSS (flushing) and backwash (BW) that are needed as well to fully compute our total UFgoal.

The unit of measurement for UFgoal is expressed in liters (L) so everything will be in small quantities, if not, it might be in milliliters (mL) which needs to be converted to “L”.

Medications and Blood

In a given problem, medications are easy to spot. The only tricky part is, we tend to forget to convert them because usually or always, they are expressed in (mL). The same goes with blood, this time, what you should take note is to the number of bags is given to the patient.

NSS (flushing)

NSS (flushing) is given for heparin-free dialysis, bleeding patients or those having allergic reactions with heparin. This is the trickiest part because it is not literally stated in the problem or question, unlike medications and blood, but only supporting details or ideas. “Temporary loss of leg” “epistaxis” are examples of supporting details that does not directly tell you that patient is bleeding but give you an idea that patient is having such episodes.

Flushing is given 50 mL per 15 min. The whole duration of dialysis is 4 hours, if you to try to do computations:
UF goal formula, NSS flushing for dialysis

Backwash (BW)

Backwash (BW) means clean (a filter) by reversing the flow of fluid through it. It simply serves as an allowance for the fluids used to clean the filter after use. However, not all facilities add BW to the UFgoal. This formula / computation is exclusively used by the Global Nephrology Training Centers (where I am enrolled as trainee) and also varies in some places. In Mindanao, we add .5L for Hepa(-) while .8L for Hepa(+) while in other branches, it’s .3L.

So the formula would now look like:

UF Goal formula

Let’s answer this easy sample question:

Sample Question

Mr. Winston Smith, aged 32, was admitted to an out-patient dialysis facility for a treatment. He weighs 55.8 kg, manifests DOB, and a grade 2 edema on the both feet. His dry weight is 53.4 kg. As the NOD assigned to Mr. Smith, what is the UF goal for this patient? In the instance that Mr. Smith asks to increase the computed goal will you agree?

Pre-weight = 55.8kg
Dry-weight = 53.4kg
Medications = not given
Blood = not given
BW = .5 for Hepa (-) since patient is not stated as positive


UFnet is in kg that is also equivalent in L.
UFnet is in kg that is also equivalent in L. Also, this is for Trainees enrolled in Global Nephrology Training Centers. You can skip the BW part if your centers don’t add it.

I’ll get back with another post for more sample questions.