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Septic shock — USMLE Step 2 CK MCQ

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ModerateEmergency MedicineSeptic shockUSMLE Step 2 CK

A 78-year-old woman with chronic kidney disease takes digoxin for heart failure. She develops nausea, confusion, and yellow-tinted vision after several days of poor oral intake. Pulse is 34/min and blood pressure is 78/46 mm Hg. ECG shows high-grade atrioventricular block with frequent ventricular ectopy. Potassium is 6.2 mEq/L and serum digoxin concentration is markedly elevated. Which treatment is most appropriate?

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Correct answer: D — Administer digoxin-specific immune antibody fragments

This patient has life-threatening chronic digoxin toxicity caused by reduced renal clearance, with gastrointestinal and visual symptoms, hyperkalemia, hemodynamic instability, high-grade atrioventricular block, and ventricular ectopy. Digoxin-specific immune Fab binds free digoxin and is the definitive antidote; severe dysrhythmia, shock, and significant hyperkalemia are indications for prompt treatment while a poison center or clinical toxicologist is consulted. Standard airway and circulatory support continue simultaneously. Atropine or temporary pacing may be needed while the antidote takes effect, but pacing can provoke dysrhythmias and does not neutralize the toxin. Digoxin has a large volume of distribution and is poorly removed by hemodialysis. Hyperkalemia generally improves as toxicity is reversed, so potassium replacement would be dangerous. Giving more digoxin worsens sodium-potassium ATPase inhibition. Intravenous calcium is not a digoxin antidote and must not replace immune Fab in a patient with these life-threatening manifestations.

Reference: American Heart Association. 2025 Guidelines for CPR and ECC: Adult and Pediatric Special Circumstances of Resuscitation—Cardiac Glycoside Poisoning. https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/adult-and-pediatric-special-circumstances-of-resuscitation