In this QuikCrit, we break down when calcium actually helps in hyperkalemia, and when it doesn’t.

Starting with a crashing patient and a wide QRS, we walk through the cardiac action potential, why hyperkalemia slows conduction, and how calcium stabilizes the myocardium without lowering potassium.

We cover:

• Why Vₘ follows potassium (Vₘ ≈ Eₖ)
• How calcium raises threshold potential and restores conduction
• ECG changes in hyperkalemia
• Calcium chloride vs gluconate
• The role of calcium in PEA arrest
• Why giving calcium blindly may not help, and may cause harm

Bottom line:

Calcium isn’t a routine arrest drug, it’s targeted therapy for hyperkalemia