During CPR, a patient in ventricular fibrillation (VF) has received 3 defibrillation shocks and 4 minutes of high-quality CPR. Which drug should now be administered?

• A Lignocaine 1.5 mg/kg IV as first-line antiarrhythmic
• B Magnesium sulphate 2 g IV for all VF cases
• C Amiodarone 300 mg IV bolus (after the 3rd failed shock); epinephrine 1 mg IV every 3–5 minutes throughout CPR ✓
• D Atropine 1 mg IV to prevent bradycardia post-shock

Explanation

Current AHA/ERC ACLS guidelines for refractory VF (failing first 3 defibrillation attempts): Epinephrine 1 mg IV every 3–5 minutes (given as soon as IV access established, from the 3rd shock cycle). Amiodarone 300 mg IV bolus after the 3rd shock (a second dose of 150 mg can be given for refractory VF). Lidocaine (1–1.5 mg/kg) is the alternative if amiodarone is unavailable. Magnesium sulphate 2 g is specific for torsades de pointes, not routine VF. Atropine was removed from ACLS VF/pulseless VT algorithm. Continuous high-quality CPR with minimised interruptions remains paramount.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.