Hyperkalemia: The Daily PANCE Blueprint
A patient with severe hyperkalemia develops progressive ECG changes. Which sequence best reflects the typical progression of cardiotoxicity as potassium rises?
A. Delta waves → Narrow QRS → Flat T
B. Tall T → PR prolong → No P → Sine
C. Short PR → Wide QRS → ST ↑
D. Tall T → Q waves → Long QT
Answer and topic summary
The answer is Tall peaked T waves → PR prolongation → Loss of P waves → Sine wave pattern
Hyperkalemia causes predictable ECG changes due to its effects on myocardial conduction. Elevated extracellular potassium reduces the resting membrane potential and slows conduction through the myocardium, producing a stepwise progression of ECG abnormalities as serum potassium rises.
Typical progression:
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Tall, peaked (“tented”) T waves – earliest and most classic finding due to accelerated repolarization.
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PR interval prolongation – slowed atrial conduction.
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Loss of P waves – atrial paralysis occurs as potassium rises further.
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QRS widening progressing to a sine wave pattern – ventricular conduction deteriorates and may rapidly progress to ventricular fibrillation or asystole.
Clinical pearl:
The appearance of a sine wave pattern is a pre-arrest ECG finding and requires immediate treatment with IV calcium to stabilize the cardiac membrane, followed by therapies that shift potassium intracellularly (e.g., insulin + glucose, beta-agonists) and remove potassium (e.g., diuretics, dialysis).
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Smarty PANCE Content Blueprint Review:
Covered under ⇒ PANCE Blueprint Renal System ⇒ ⇒
Also covered as part of the Emergency Medicine EOR and General Surgery PAEA EOR topic list
