NCLEX-RNPhysiological AdaptationMedium
The nurse reviews telemetry on a client with a serum potassium level of 6.8 mEq/L. Which ECG change is the priority finding requiring immediate intervention?
- AProlonged QT interval
- BPeaked T waves with widened QRS
- CFlattened T waves
- DProminent U waves
Show answer & explanationAnswer & explanation
Correct answer: B. Peaked T waves with widened QRS
Severe hyperkalemia causes peaked T waves progressing to a widened QRS complex, indicating impending ventricular fibrillation or asystole and requiring immediate treatment (calcium gluconate, insulin/glucose).
Why the other options are wrong
- A. Prolonged QT is more associated with hypocalcemia or hypomagnesemia.
- C. Flattened T waves are associated with hypokalemia, not hyperkalemia.
- D. U waves are a classic sign of hypokalemia.
Hyperkalemia ECG Changes
Progressive ECG changes correlate with severity of hyperkalemia, from peaked T waves to widened QRS to sine wave pattern.
- Peaked T waves are the earliest sign
- Widened QRS indicates worsening toxicity
- Sine wave pattern precedes cardiac arrest
- Calcium gluconate stabilizes the cardiac membrane
Memory trick: Tall Tents, Wide Tents, then Silence (K+ kills the heart's rhythm)