Monday, April 22, 2013

Dialyzing the highest potassium

So last week I asked how you would dialyze the patient in the following scenario:
You have been called on a Sunday night for emergent dialysis in a patient with hyperkalemia. The patient is a MWF dialysis patient and had a normal dialysis session on Friday. Her ECG on admission is absolutely terrifying and her potassium is 9.9 (hemolyzed). The blood sugar on admission was 965. When you arrive, with K-machine in tow, the patient has been on an insulin drip for an hour and the potassium is down to 5.2
I have received 54 responces and the results have been pretty stable from the beginning. By far the favorite option was to pack up the dialysis machine and head back home. No dialysis for you

I don't see any signifigant trends based on background of the provider:

The raw data is available for perusal here. And you can keep voting here.

That is not how I voted. I voted for 2 hours on a 2K bath. My feeling was that the ECG showed dramatic cardiac toxicity and though the emergency seemed to be over, with a repeat potassium of 5.2, I had no guarantee the insulin drip would continue through the night. If it was stopped, intracellular potassium could diffuse back out of the cells. But what really pushed me was the fact that he is scheduled to receive dialysis in just a handful of hours anyways. If I just push that schedule up and dialyze him tonight I provide an extra margin of safety for his potassium and improve my sleep hygiene. No nightmares of lost IV access for the insulin drip.

Because I viewed this emergency dialysis as just pushing forward the scheduled dialysis I went with the standard 2K dialysis bath.

Now for the best part of any blog post, belittling people who don't agree with me. The above paragraph takes care of no dialysis.
  • Zero K bath. Too great a risk of hypokalemia. We presume that he does not have excess total body potassium, merely maldistribution of intracellular potassium. Zero K baths are dangerous. Who can forget the classic scene in Grey Anatomy where Izzie is fired for ordering a zero K bath, putting a patient in shock, so that the poor dialysis patient misses her transplant. (I love that show, they even let surgical residents write dialysis orders.)
  • One K bath. See above. Though the concern about the toxicity of low potassium baths seems to be overblown.
  • Two K bath. Perfect.
  • Three K bath. Should work just fine.
  • Four K bath. What's the point, at the current potassium of 5.2, two hours on a 4 K bath will remove a trivial amount of potassium and is functionally identical to no dialysis at all.
Defend your sorry choice in the comments below.

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