I came across an exceptional article many years ago. This guide assists me for supplementing PN when it is being compounded by our pharmacy. It is old but is is good!
There is sometimes a feeling that one should be restrained when increasing or decreasing electrolytes in PN. “A potassium below 3, should I increase the potassium in the PN from 32 mEq/liter to 40 mEq/liter.” The years have taught me that increasing by much more than that is necessary to make a difference in serum potassium levels.
One should always assess if there are reasons for low serum lab values. Medications, drains. urinary output, other IVF could be affecting lab values. I have generally found that if a patient is requiring IV supplementation of potassium, magnesium or calcium for several days, it is acceptable and often times necessary to increase the amount in the PN bag to make a real difference in serum levels.
For potassium levels below 2.9, increasing potassium to 80 mEq/liter is recommended. If potassium levels are elevated, then take it all out and change the chloride/acetate balance if needed.
Sodium levels are largely dependent on dehydration or fluid overload. Often times, sodium will still need to be supplemented despite being in a state of dilution, especially if levels fall below 130.
How and When to Supplement
I will reference an article that I have used as reference over the years. This article and flowsheets gave me the confidence to increase and decrease electrolyte amounts more aggressively, which, in my opinion, has improved patient outcomes and normalize serum levels more quickly.
An example of this:
Na levels 130-134; if dilutional; continue with 35 mEq/liter, if not dilutional; increase to 70mEq per liter. The next day, if Na still low and dilutional; increase to 50 mEq/liter. If not dilutional and still low; increase to 100 mEq/liter.
As a young and inexperienced RD, I would have never ventured to increase Na to this amount. This article has given me the tools to evaluate patients thoroughly and provide better doses of electrolytes. Over the years, I have looked for more updated recommendations, but this article is so wonderful in its specific guidelines.
Below is the link to this article from “Nutrition in Critical Practice”
https://aspenjournals.onlinelibrary.wiley.com/doi/abs/10.1177/088453360001500208#:~:text=Techniques%20and%20Procedures%3A%20Guidelines%20for%20Managing%20Electrolytes%20in%20Total%20Parenteral%20Nutrition%20Solutions
https://doi.org/10.1177/088453360001500208
If you are a Dietitian who works in critical care, I would recommend becoming a member of ASPEN. Access to “Nutrition in Clinical Practice” and best practice guidelines provided by ASPEN are beyond helpful and educational.
(This article is under copy right and I do not think I can publish it or part of it without permission. I have requested to be able to use part of it to show how helpful it is for everyday practice. Hopefully in the coming weeks I will be able to share this with you. )
I hope this is helpful!