Amiodarone is a medication used in emergency cardiovascular care, particularly within Advanced Cardiovascular Life Support (ACLS) protocols. It functions as an antiarrhythmic drug, helping to restore and maintain a normal heart rhythm during life-threatening cardiac events. The information provided in this article is for educational purposes only and should not be considered a substitute for professional medical advice or training. ACLS protocols and medication administration are exclusively for trained medical professionals.
Understanding Amiodarone’s Role in ACLS
Amiodarone is used in ACLS for life-threatening arrhythmias, specifically pulseless ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT). It is also considered for stable wide-complex ventricular tachycardia (VT). Amiodarone is often used when initial interventions, such as defibrillation, cardiopulmonary resuscitation (CPR), and vasopressors like epinephrine, have not been successful.
Amiodarone works by affecting multiple cardiac cell actions. It is a Class III antiarrhythmic drug, primarily blocking potassium ion channels involved in the heart’s repolarization phase. This action prolongs the cardiac action potential and effective refractory period, stabilizing the heart’s electrical activity and preventing disorganized signals.
Additionally, amiodarone affects sodium and calcium channels and has properties similar to beta-blockers. These combined effects slow the heart rate, prolong conduction through the heart’s electrical pathways, and reduce cardiac muscle cell excitability. Its combined effects make it valuable for controlling abnormal heart rhythms in emergencies.
Amiodarone Dosing in ACLS Scenarios
For adult patients experiencing pulseless ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), the initial recommended dose is 300 mg. This dose is administered as an intravenous (IV) or intraosseous (IO) bolus. This first dose is typically given after initial defibrillation attempts, CPR, and vasopressor administration have not resulted in a stable rhythm.
If pulseless VF or pVT persists or recurs after the initial 300 mg dose, a second dose of 150 mg may be considered. This subsequent dose is also given as an IV or IO bolus, and further stabilizes the cardiac rhythm.
For patients with stable wide-complex tachycardia (VT) who have a pulse, the initial dose is 150 mg, infused intravenously over 10 minutes. This slower infusion helps manage the patient’s condition while they still have a perfusing rhythm.
In an emergency setting, the maximum cumulative intravenous dose should not exceed 2.2 grams within a 24-hour period. Exceeding this limit is associated with an increased risk of significant hypotension. These dosages are for acute emergency situations and require continuous medical supervision.
Key Considerations for Amiodarone Administration
Amiodarone can be given via intravenous (IV) or intraosseous (IO) routes. While it can be given as a rapid IV push in pulseless cardiac arrest, for other scenarios, it is often diluted. For infusions, amiodarone is typically mixed with D5W (dextrose 5% in water).
Potential acute side effects include hypotension and bradycardia. Rapid infusion, especially in patients with a pulse, can lead to a drop in blood pressure. Due to its chemical properties, amiodarone can cause phlebitis, so administering it through a central venous line is often preferred when possible.
Certain situations require caution or may contraindicate amiodarone use, such as known hypersensitivity to the drug or iodine. It is also contraindicated in patients with severe sinus node dysfunction or second- or third-degree heart block if a pacemaker is not in place. During and after administration, continuous monitoring of the patient’s heart rhythm via ECG, blood pressure, and heart rate is important. Continuous monitoring helps assess the drug’s effects and manage adverse reactions.
Post-Resuscitation Amiodarone Management
After return of spontaneous circulation (ROSC), if ongoing rhythm control is needed, amiodarone management often transitions from bolus doses to a continuous intravenous infusion. This maintenance infusion helps sustain the antiarrhythmic effect and prevent recurrence of life-threatening arrhythmias. A common regimen involves an initial infusion rate of 1 mg per minute for the first six hours.
Following this initial period, the infusion rate is typically reduced to 0.5 mg per minute for the subsequent 18 hours. This allows for a total dose of approximately 1000 mg over the first 24 hours of infusion therapy. The duration of this continuous infusion can vary, but it may be continued for several days as needed to stabilize the patient’s rhythm.
Once stable, patients may transition to oral amiodarone for long-term management. This conversion typically occurs after intravenous administration, with oral dosing adjusted based on IV therapy duration. The goal is to maintain cardiac stability while minimizing potential side effects associated with prolonged use.