A 58-year-old male with type 2 diabetes and chronic kidney disease (eGFR 22 mL/min) presents to the emergency department with acute dyspnea and palpitations. His serum potassium is 7.2 mEq/L. The ECG shows the pattern marked **A** in the diagram — tall, peaked, narrow-based T waves in the precordial leads, with flattened P waves and prolonged PR interval. Which of the following interventions should be administered FIRST to address the immediate life-threatening cardiac effects of this electrolyte abnormality?
A. Regular insulin 10 units IV with 50 mL of 50% dextrose
B. Intravenous calcium gluconate 10% 10 mL over 2–3 minutes
C. Nebulized albuterol 10–20 mg
D. Hemodialysis via temporary femoral catheter
Explanation
Why intravenous calcium gluconate 10% 10 mL over 2–3 minutes is right
The pattern marked A represents hyperkalemia with ECG changes (peaked T waves, P wave flattening, PR prolongation, QRS widening) indicating severe potassium elevation (K+ >6.5 mEq/L). Calcium gluconate is the FIRST-LINE emergency intervention because it provides immediate cardiac membrane stabilization by restoring the resting membrane potential gradient, thereby reducing the risk of malignant arrhythmias and cardiac arrest. The ECG improves within minutes, though potassium levels do not change. This must be given before any measure to lower potassium, as it buys time and prevents sudden cardiac collapse. Per Harrison's and ESC guidelines, calcium is the initial agent of choice when ECG changes are present.
Why each distractor is wrong
Regular insulin 10 units IV with 50% dextrose: While this is essential for transcellular K+ shift and lowers serum potassium by 0.5–1.2 mEq/L over 30 minutes, it does NOT stabilize the cardiac membrane acutely. It must be given AFTER calcium in the presence of ECG changes to prevent arrhythmia during the lag time before potassium enters cells.
Nebulized albuterol 10–20 mg: This also shifts K+ intracellularly (by ~0.5–1.0 mEq/L) but is slower and less reliable than insulin. It is an adjunctive agent, not first-line, and does not address the immediate cardiac electrical instability.
Hemodialysis via temporary femoral catheter: Although hemodialysis is definitive for potassium removal (25–50 mEq/hr) and is indicated in this patient with CKD, it takes time to establish vascular access and initiate. In the presence of severe ECG changes, immediate cardiac stabilization with calcium must precede dialysis setup.
High-YieldNEET PG
In hyperkalemia with ECG changes (peaked T, flat P, wide QRS), give IV calcium FIRST to stabilize the heart; insulin + dextrose and albuterol come next to shift K+ into cells; dialysis is definitive but not first-line.
2023 ESC Guidelines on AKI; Harrison's Principles of Internal Medicine 21e
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