A 68-year-old woman on lisinopril and spironolactone for heart failure develops serum K+ of 6.4 mEq/L. ECG shows peaked T waves. After IV calcium gluconate is given, the next immediate priority to shift potassium intracellularly is:
- A IV sodium bicarbonate only
- B IV insulin (10 units) plus 50 mL of 50% dextrose ✓
- C Oral sodium polystyrene sulfonate (Kayexalate)
- D IV furosemide
Explanation
Management of hyperkalemia with ECG changes (peaked T-waves) requires: first, membrane stabilization with IV calcium gluconate (already given, protects cardiac membrane immediately). Second, temporizing measures to shift K+ intracellularly: insulin-dextrose is the most reliable and rapidly effective method (onset 15–30 min, reduces K+ by 0.5–1.5 mEq/L). Insulin activates the Na/K-ATPase pump; dextrose prevents hypoglycemia. Salbutamol (nebulized beta-2 agonist) is an additive temporizing measure. Sodium polystyrene sulfonate is an elimination strategy with slow onset (hours), not an immediate shift agent. Bicarbonate has unreliable effect in non-acidemic patients.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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