A 55-year-old male with a history of hypertension and diabetes is found unresponsive. His blood glucose is 45 mg/dL. After administering intravenous dextrose, he regains consciousness but is confused. His serum potassium is 6.8 mEq/L, and ECG shows peaked T waves. What is the most urgent initial step to stabilize his cardiac membrane?
✓ Correct Answer: Option B
The patient has severe hyperkalemia with ECG changes (peaked T waves), indicating cardiac instability. Intravenous calcium gluconate is the most urgent intervention to stabilize the cardiac membrane and prevent life-threatening arrhythmias, acting directly on the myocardial excitability.