What is the next dose of Amiodarone (amiodarone) for a patient in refractory ventricular fibrillation who has already received an initial dose of 300mg?

Next Dose of Amiodarone for Refractory Ventricular Fibrillation

The next dose of amiodarone for a patient in refractory ventricular fibrillation who has already received an initial dose of 300mg should be 150mg IV/IO. 1

Dosing Protocol for Refractory VF

The American Heart Association guidelines provide a clear protocol for amiodarone administration in refractory ventricular fibrillation:

1. Initial dose: 300 mg IV/IO
2. Follow-up dose: 150 mg IV/IO 1

This follow-up dose should be administered as an IV/IO bolus when the patient remains in ventricular fibrillation despite the initial interventions (defibrillation, CPR, vasopressors, and initial amiodarone dose).

Administration Considerations

When administering the 150 mg follow-up dose:

• Administer as an IV/IO bolus
• For breakthrough episodes of VF, the 150 mg should be mixed in 100 mL of D5W and infused over 10 minutes to minimize the risk of hypotension 2
• Use a volumetric infusion pump for accurate delivery
• Preferably administer through a central venous catheter with an in-line filter 3
• Monitor for hypotension, which is the most common adverse effect during administration 2

Post-Resuscitation Considerations

If return of spontaneous circulation (ROSC) is achieved:

• Continue with a maintenance infusion of 1 mg/minute for 6 hours
• Follow with 0.5 mg/minute for the next 18 hours 3, 2
• Total dose should not exceed 2100 mg in the first 24 hours due to increased risk of hypotension 2

Important Clinical Considerations

• Amiodarone has been shown to increase short-term survival to hospital admission compared to placebo or lidocaine in patients with refractory VF 1, 4
• Monitor for and be prepared to treat adverse effects:
  • Hypotension (most common - 26% of patients) 5
  • Bradycardia
  • AV block

Alternative Options

If amiodarone is unavailable or contraindicated:

• Lidocaine may be considered as an alternative at a dose of 1-1.5 mg/kg IV, with additional doses of 0.5-0.75 mg/kg every 5-10 minutes to a maximum of 3 mg/kg 1
• However, amiodarone has been shown to be superior to lidocaine for shock-resistant ventricular fibrillation, with 22.8% vs 12.0% survival to hospital admission 4

Remember that while antiarrhythmic medications may help terminate the arrhythmia, high-quality CPR, timely defibrillation, and addressing any underlying causes remain the cornerstones of management for refractory ventricular fibrillation.