In this episode, I’ll discuss the effects of calcium during treatment of hyperkalemia.
Using calcium in patients with severe hyperkalemia is recognized as the most critical first step of treatment.
Textbooks and tertiary referenceswidely quote that the purpose of giving IV calcium in severe hyperkalemia is to stabilize the cardiac membrane.
However a group of researchers using a canine cell model of hyperkalemia have reached a different conclusion about the effects of calcium. First published as a research forum abstract in 2010 by Annals of Emergency Medicine, the research was just published in full in Critical Care Medicine in 2024, which was when I first became aware of it.
In the researcher’s hyperkalemia model, treatment with calcium restored conduction velocity, resulting in narrowing of the QRS and normalization of the electrocardiogram, but did not restore action potential duration.
Resting membrane potential was significantly elevated by hyperkalemia but it was not restored with calcium treatment. This finding suggests that a mechanism is at work that is unrelated to cardiac membrane stabilization.
In addition, the researchers found that the effects of calcium treatment were attenuated during L-type calcium channel blockade. This finding suggests a mechanism related to calcium-dependent conduction rather that sodium-dependent conduction.
The authors conclude:
These data suggest that Ca2+ treatment for hyperkalemia restores conduction through Ca2+-dependent propagation, rather than restoration of membrane potential or “membrane stabilization.” Our findings provide a mechanistic rationale for Ca2+ treatment when hyperkalemia produces abnormalities of conduction (i.e., QRS prolongation).
It is unusual for animal studies to result in changes to clinical practice in humans. However this research might help persuade clinicians who currently focus on potassium levels as the primary decision point for when to give calcium to recognize the importance of using calcium to treat ECG changes at any potassium level for a patient with severe hyperkalemia.
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