This doesn't make sense to me....

[MattiesMama]

I'm working on my care plan and I have a pt who is on Digoxin and Lasix for A-Fib and CHF...his serum potassium is low, yet he is on a LOW potassium diet

I'm reading in my book that Lasix causes potassium loss, and that low potassium can actually cause cardiac dysrhythmias. On top of that, he has stage III renal failure, so wouldn't that put him at increased risk for digitalis toxicity? What would be the reasoning behind those meds in combination, and the low potassium diet on top of it?

I just want to get some others opinions before I bring it up to my drill sargeant-I mean, clinical teacher

[PvNurse2009]

Your patient is on a low potassium diet because he is in chronic renal failure. True, lasix is a potassium losing diuretic and dig toxicity is increased when potassium is low, but things are a little different in this patient. In chronic renal failure, there is an accumulation of potassium in the blood due to the kidneys' inability to excrete it. If his potassium level is low, the dr may write an order for KCl to raise this level temporarily, but that is why he is on this medication and a low potassium diet. Hope this helps. Just a hint of advice, my past clinical instructor was the drill sergeant type and every clinical day we went thru 21 questions about our patient's diseases and how they interconnect. It may be helpful if you review the patho of your patient's conditions and know important facts about the medications that they are taking before clinicals. Also, be thinking of nursing diagnoses and interventions. It really helps when you have these kinds of instructors. I know they seem impossible, but they are a blessing in disguise believe me!!!!!

[MattiesMama]

Thanks so much! That was kind of along the lines of what I was thinking but I couldn't quite put it together...

One question though-is the goal of a low potassium diet to keep his ka within the "normal" range, or is it beneficial for someone with renal failure to have it be a little lower than normal?

[PvNurse2009]

The goal of the diet is to keep the potassium levels somewhat within normal range, but mostly to keep it from elevating into dangerous levels. You cant totally eliminate the potassium from the diet, but you don't want to add to an already ongoing problem. (being CRF) I hope i explained this in a way you can understand

[DolceVita, ADN, BSN, RN]

Darn it -- I just love this website! I don't think I will get through NS without it.

[kgh31386, BSN, MSN, RN]

Very well explained, but...out of curiosity, how low was the potassium level? Oh and a side note, Renal Failure can come from CHF(it's a snowball effect). It's all a balancing act with this patient.

[NurseKitten, MSN, RN]

It is NOT beneficial for the K+ to be slightly below the 3.5 mEq/L point. The three electrolytes governing the heart's action potential (therefore it's ability to generate impulses from the SA) are sodium, calcium and POTASSIUM.

K+'s too high, you begin to see ectopy and general irritability. As it advances, the heart has a difficult time repolarizing itself (go back to your A&P textbook and look at a ventricular action potential - stage 3) so you can end up with a profound bradycardia. Lowest I ever saw was 32 bpm, with t-waves so tall you could have skiied down them!

K+'s too low, and you can paradoxically see much of the same thing.

With that caveat, you said he was stage III CRF - don't remember the exact numbers, but he's not close to dialysis. Recalculate his GFR for yourself. If you don't know how to do it, PM me, and I'll give you the formula. It's an old one, and has fallen out of favor, but it's still good for a quick "down and dirty" idea of what you're dealing with. Stage III out of V, and he's already on a low K+ diet? Either something else is going on, or the CRF's progressed.

Good luck. :)

[MattiesMama]

GFR was 22 and his Ka was 3.1....

A GFR that low probobly means he is more advanced than stage III, no?

His HR was extremely irregular, but it was elevated...like an average of 90bpm and this is a 92 year old pt.

He also had low sodium and low calcium from what I can remember...but they are putting him on sodium restriction now too because he's retaining so much fluid

[Daytonite, BSN, RN]

gfr diminishes as people age. that doesn't mean there is renal failure or renal insufficiency. this website gives a thorough explanation of the pathophysiology of chf, but it takes patience to read and understand all the concepts behind it: http://cvphysiology.com/index.html - cardiovascular physiology concepts. then, check out http://www.cvpharmacology.com/index.html - cardiovascular pharmacology concepts

[MattiesMama]

That is a great website Dayonite...wish I had known about it last week when I was doing my case study on him, lol!

So since Lasix is a loop diuretic it would make sense that both his Ka+ and his Na+ would low since Lasix inhibits reabsorbtion...but why the low calcium? And if he is on such a powerful diuretic, why is he swollen up like the pilsbury doughboy and having oliguria? Would that point to progressing kidney failure, heart failure, or both?

[Daytonite, BSN, RN]

calcium needs too be replaced daily. see calcium.doc and sodium.doc.

[NurseKitten, MSN, RN]

If he's retaining that much fluid, look at his albumin, as well. He could be third-spacing all his fluid.

Look here: http://emedicine.medscape.com/article/238798-overview

It's a good general article on CRF - may help you understand some of the pathophys of the many causes.

A GFR of 22 is Stage 4. Dialysis is indicated at 15, although at 92 y/o, yes, technically, I suppose you COULD, but it's really a point if you SHOULD.

Hopefully, everyone has realistic expectations.

Bless you for being concerned and caring. :)