Hyperkalemia-induced cardiac arrest requires which treatment in addition to cardiopulmonary resuscitation?

• A. Adenosine
• B. Sodium bicarbonate
• C. Magnesium sulfate
• D. Calcium chloride

Answer: (D)

Hyperkalemia in the setting of cardiac arrest demands immediate stabilization of the heart's electrical activity. The key move is to protect the myocardium from the dangerous effects of high potassium while you work to lower potassium levels. Calcium achieves this by increasing the threshold potential of cardiac myocytes, making them less excitable and less prone to dangerous conduction abnormalities. This membrane stabilization buys time and helps CPR be more effective as you pursue definitive potassium-lowering measures.

Calcium chloride is the rapid-acting option used to provide this membrane stabilization in the hyperkalemic arrest scenario. It does not lower potassium itself, but it bluntly guards the heart against the immediate toxic effects of hyperkalemia, allowing time for therapies like insulin with glucose, bicarbonate if acidosis is present, beta-agonists, or dialysis to shift or remove potassium.

Adenosine, while useful for certain tachyarrhythmias, does not address the underlying potassium toxicity and can complicate the arrhythmia. Sodium bicarbonate can help with acidosis-accelerated potassium shift, but it is not the primary membrane-stabilizing step needed during arrest. Magnesium sulfate is indicated for other rhythm disturbances (like torsades de pointes or certain toxicities) and is not a targeted treatment for hyperkalemia-induced arrest.