Written by Megan Hilbert
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Irregularities in potassium (both hyper- and hypo-) increased the likelihood of in-hospital cardiac arrest (IHCA), but only hyperkalemia was associated with worse post-resuscitation outcomes.
Problems with your patient’s K+ are not OK
This was a registry-based, matched, case-control study done in Denmark. The index time was defined as the time of cardiac arrest, with the exposure being a blood potassium level within 24 hours of the index time. The investigators completed analysis with potassium both as a continuous and categorical variable (with severe hypokalemia defined as < 2.5 and severe hyperkalemia > 6.5). They then completed four step-wise models of each group (continuous vs. categorical) where they controlled for a number of other factors including: comorbidities, number of blood samplings, creatinine, arterial pH, bicarb, chloride, and cardiac arrest characteristics.
The most pertinent finding is that severe hyperkalemia was associated with a 2.03 (95%CI 1.28-3.23) and severe hypokalemia with a 2.65 (95%CI 1.61-4.39) increased odds of IHCA compared with normokalemia. The predicted probability of ROSC decreased with increased severity of hyperkalemia (but not hypokalemia) and was associated with decreased 30 day and one-year survival. The good thing about this study is that it was registry-based and likely representative of the general population.
A limitation is that, while they controlled for many variables, confounders are likely still present––cardiac arrest doesn’t usually occur in a vacuum. Also, because blood gas values were not included in this data set, potassium trends couldn’t be documented, so we are missing data that could demonstrate that rapid changes to potassium levels increase likelihood of IHCA as well.
How does this change my practice?
I tend to ignore potassium abnormalities (except marked hyperkalemia) in my patients in the ED, but I will continue to be vigilant to the presence of hypokalemia and initiate repletion particularly in patients that I plan to admit.
Source
Potassium Levels and In-Hospital Cardiac Arrest: A Matched Case-Control Study. Crit Care Med. 2025 Jul 1;53(7):e1426-e1436. doi: 10.1097/CCM.0000000000006713. Epub 2025 May 19. PMID: 40387484
Hi, I was confused by this: “I don’t tend to ignore potassium abnormalities (except marked hyperkalemia) in my patients…” could you clarify?
My bad…post is corrected now.
Thanks that makes more sense, but I’m still curious, do you not not pay much attention to hypokalemia?
I think what Megan was saying is that historically, she has not paid as much attention to hypokalemia, but she will now. I kind of messed up the edit.