A 60-year-old patient with end-stage renal disease misses two hemodialysis sessions and presents with generalized weakness. Serum potassium is 7.4 mmol/L. The ECG shows peaked T waves, prolonged PR interval, and QRS widening. What is the immediate first drug to administer?

Answer and explanation

Correct answer: C. Intravenous calcium gluconate 10% (10 mL over 2-3 minutes) for cardiac membrane stabilization

  1. Step 1: Recognize severe hyperkalemia with cardiac conduction abnormalities and imminent risk of ventricular fibrillation.
  2. Step 2: Intravenous calcium (calcium gluconate or calcium chloride) directly antagonizes the membrane excitability effects of hyperkalemia and stabilizes cardiac myocyte membranes within 1-3 minutes.
  3. Step 3: Insulin and beta-2 agonists shift potassium intracellularly but take 15-30 minutes to act and do not stabilize cardiac membranes.
Answer
Intravenous calcium gluconate 10% (10 mL over 2-3 minutes).
Why not the others: 'Intravenous regular insulin 10 units with 50 mL of 50% dextrose' is the second step to shift potassium intracellularly, not the first membrane stabilizer; 'Nebulized salbutamol 10-20 mg' provides intracellular shifting with delayed onset; 'Oral sodium zirconium cyclosilicate (Lokelma)' eliminates potassium via the GI tract over several hours.

Practise more Internal Medicine and Therapeutics.

Free questions with an explanation for every one, and full timed Oman Medical Specialty Board Examination (OMSB) mock tests.

All Internal Medicine and Therapeutics questionsTake a mock test

More Internal Medicine and Therapeutics questions