Iv mag or k+ which do I hang first?

Specialties Emergency

Updated:   Published

Recently I had a patient that needed both iv k and iv mag. The patient had one patent iv site. I hung the potassium 1 st because it would take the less time. Then get the mag started. When handing off my patient the RN told me that the mag should go first because it is what the k will stick to. I had not heard this before and am unable to find any information on this. Has anyone else?

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Well, while I'm not sure I agree with the other RN's verbiage, she is correct that hypomagnesemia can make hypokalemia refractory to treatment, so hanging the mag first would be the correct action, as far as I know.

Just out of curiosity, what order did the MD write for them in?

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Specializes in MPH Student Fall/14, Emergency, Research.

According to Lexicomp, these are compatible, and there are no warnings against infusing concomitantly - is there any reason you couldn't run them together?

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I wondered that too, but it's pretty common practice to run things in one at a time on stable patients because if they have an adverse reaction, you can be pretty certain which medication they're reacting to. Also, in this case, I'd want to correct the hypomagnesemia prior to administering the K+, since as I mentioned above, the low K+ may be refractory to treatment in the presence of hypomagnesemia.

But, I'd be curious to hear the OP's rationale as well.

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Specializes in Critical Care.

Ideally, you give mag first, although it's not critical to do so. Magnesium modulates the transport of potassium into cells. Low magnesium = decreased potassium uptake which results in more of the potassium you gave being excreted.

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Mmmm, sort of...intracellular Mg2+ modulates the transport of K+ *OUT* of cells by blocking secretion of K+, so if there is a deficiency of intracellular Mg2+, then more K+ is secreted by the distal renal tubule. Only about 2% of the total Mg2+ in the body is in the plasma. The rest is in bones and cells. It takes 3-4 hours for the Mg2+ in kidney and heart cells to exchange with the Mg2+ in plasma, meaning that you should give the mag first so it has time to start moving into the cells so that it is more likely to be effective in blocking potassium excretion.

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Specializes in Trauma/ED.

Isn't this an ED Nursing thread? Start another line and run them both if you are worried about running them together. Save me from this ICU'ish intracellular speak :-)

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Specializes in Critical Care.
~*Stargazer*~ said:
Mmmm, sort of...intracellular Mg2+ modulates the transport of K+ *OUT* of cells by blocking secretion of K+, so if there is a deficiency of intracellular Mg2+, then more K+ is secreted by the distal renal tubule. Only about 2% of the total Mg2+ in the body is in the plasma. The rest is in bones and cells. It takes 3-4 hours for the Mg2+ in kidney and heart cells to exchange with the Mg2+ in plasma, meaning that you should give the mag first so it has time to start moving into the cells so that it is more likely to be effective in blocking potassium excretion.

We don't infuse potassium into the cells, we infuse it into the serum and then depend on good net uptake to improve potassium levels, it's sort of like cells are scooping up potassium with a bowl, except those with low magnesium are scooping them up with a colander. Cells with low potassium are leaking the potassium they are receiving right back out, which decreases the net uptake and secretion.

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MunoRN said:
We don't infuse potassium into the cells, we infuse it into the serum and then depend on good net uptake to improve potassium levels, it's sort of like cells are scooping up potassium with a bowl, except those with low magnesium are scooping them up with a colander. Cells with low potassium are leaking the potassium they are receiving right back out, which decreases the net uptake and secretion.

There is no inhibition of potassium uptake. Potassium is flowing into the cells just fine. The problem is that magnesium blocks potassium secretion back OUT of the cell, and with low intracellular mag levels, potassium is allowed to freely exit the cell. So, potassium uptake is not affected, and secretion is increased.

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Larry77 said:
Isn't this an ED Nursing thread? Start another line and run them both if you are worried about running them together. Save me from this ICU'ish intracellular speak ?

An ED nurse can't have an understanding of fluid and electrolyte balance? Sheesh!

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Specializes in Medical-Surgical/Float Pool/Stepdown.

To respond to Larry777

I have never worked in a ED but why wouldn't you want to do it right for the patient the first time...fast isn't always the best...just like placing every IV start in the AC for a patient being admitted!!!

I have tremendous respect for ED nurses but this comment just seems...frankly...not well thought out...maybe more time to think was needed! :facepalm:

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Quote
To respond to Larry777 I have never worked in a ED but why wouldn't you want to do it right for the patient the first time...fast isn't always the best...just like placing every IV start in the AC for a patient being admitted! I have tremendous respect for ED nurses but this comment just seems...frankly...not well thought out...maybe more time to think was needed! :facepalm:

Thank you you for your response to that ?

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