During in-hospital cardiac arrest with ventricular fibrillation (VF), the FIRST shock is delivered at 360 J (monophasic) or 150–200 J (biphasic). After 2 minutes of CPR following the first shock, VF persists. Epinephrine 1 mg IV has been given. The second antiarrhythmic drug considered after amiodarone failure in refractory VF is:

• A Procainamide 30 mg/min
• B Magnesium sulphate 2 g IV (only for torsades de pointes)
• C Lignocaine (lidocaine) 1–1.5 mg/kg IV ✓
• D Adenosine 6 mg IV

Explanation

AHA 2020 ACLS guidelines: for shock-refractory VF/pulseless VT, amiodarone 300 mg IV bolus is the first-line antiarrhythmic. If VF/VT persists, lignocaine (lidocaine) 1–1.5 mg/kg IV is the acceptable alternative, particularly when amiodarone is unavailable or in digitalised patients prone to amiodarone-induced digoxin toxicity. Magnesium 2 g IV is specifically indicated for torsades de pointes (polymorphic VT with prolonged QT) but is not a first/second-line agent for refractory VF. Adenosine treats supraventricular tachycardia, not VF. Procainamide is an IV antiarrhythmic for stable VT, not refractory VF during CPR.

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

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Written and medically reviewed by the StethoPrep medical team.