What are the contraindications to using amiodarone (antiarrhythmic medication) in cardiac arrest?

Contraindications to Amiodarone in Cardiac Arrest

Amiodarone is contraindicated in cardiac arrest patients with known hypersensitivity to any components of amiodarone (including iodine), cardiogenic shock, marked sinus bradycardia, and second- or third-degree AV block unless a functioning pacemaker is available. 1

Absolute Contraindications

Amiodarone should not be administered in cardiac arrest situations when the following conditions are present:

1. Known hypersensitivity to amiodarone components:

   • Hypersensitivity to iodine
   • Previous hypersensitivity reactions including rash, angioedema, cutaneous/mucosal hemorrhage, fever, arthralgias, eosinophilia, urticaria, thrombotic thrombocytopenic purpura, or severe periarteritis 1

2. Cardiogenic shock 1

   • While this may seem paradoxical in cardiac arrest (which is essentially a form of cardiogenic shock), this contraindication applies to situations where amiodarone might be considered for use after ROSC or in peri-arrest situations

3. Conduction disorders (when no pacemaker is available):

   • Marked sinus bradycardia
   • Second-degree AV block
   • Third-degree AV block 1

4. Heart transplant patients 2

   • Amiodarone is specifically contraindicated in patients who have undergone heart transplantation

Clinical Context in Cardiac Arrest

It's important to understand that amiodarone is primarily indicated for shock-refractory ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) during cardiac arrest. According to the 2018 AHA guidelines:

• Amiodarone should be considered for VF or pVT that persists or recurs after ≥1 shocks 2
• It is administered after CPR, defibrillation attempts, and vasopressor therapy have been initiated 2
• The recommended dose is 300 mg IV/IO, which may be followed by one dose of 150 mg IV/IO 2

Important Considerations and Potential Adverse Effects

When administering amiodarone during cardiac arrest, be aware of these potential complications:

1. Hypotension:

   • The polysorbate-containing formulation can cause hypotension due to the vasoactive solvent 2
   • The captisol-containing formulation has fewer vasoactive effects 2
   • Consider administering a vasoconstrictor before amiodarone to prevent hypotension 2

2. Bradycardia and heart block:

   • May occur particularly after ROSC 1
   • Monitor closely if ROSC is achieved

3. QT prolongation and torsades de pointes:

   • Should not be used in combination with other drugs that prolong QT interval without expert consultation 2

4. Phlebitis:

   • Can occur with peripheral administration 3

Practical Application in Cardiac Arrest

In the context of cardiac arrest management:

1. Timing of administration:

   • Administer after unsuccessful defibrillation attempts and CPR
   • Do not delay CPR or defibrillation to establish vascular access for amiodarone administration 2

2. Alternative medications:

   • If amiodarone is contraindicated or unavailable, lidocaine may be considered as an alternative 2
   • The 2018 AHA guidelines state that either amiodarone or lidocaine may be considered for shock-refractory VF/pVT 2

3. Efficacy considerations:

   • While amiodarone may improve rates of ROSC and survival to hospital admission, it has not been demonstrated to increase long-term survival or survival with good neurological outcome 2, 4
   • The ROC-ALPS trial showed no significant difference in survival to hospital discharge between amiodarone, lidocaine, and placebo 5

Special Populations

For pediatric patients with cardiac arrest, similar contraindications apply, with dosing adjusted based on weight (5 mg/kg rapid bolus, maximum 300 mg) 2.

Remember that establishing vascular access for amiodarone administration should never compromise the performance of high-quality CPR or timely defibrillation, which are the interventions most strongly associated with improved survival in cardiac arrest 2.