Antiarrhythmics: Lidocaine & Amiodarone
For patients in V-Fib or pulseless V-Tach, administration of an antiarrhythmic should be given approximately 2 minutes (or 5 CPR cycles) after our first dose of Epinephrine. The person running the code has two choices: Lidocaine & Amiodarone.
The use of these two antiarrhythmics is today’s Pass ACLS topic.
For Cardiac Arrest
Lidocaine
Studies comparing the effectiveness of Amiodarone and Lidocaine have shown little overall difference on a cardiac arrest patient’s survival to discharge. So, we can administer 1 to 1.5 mg/kg of Lidocaine IV push as our first antiarrhythmic approximately two minutes after epi for cardiac arrest patients in V-Fib or pulseless V-Tach.
Depending on how your crash cart or drug boxes are stocked, it might be necessary to use more than one prefilled syringe to administer the desired dose of 1 to 1.5 mg/kg. A common prefilled is 10 mg/ml and comes in a 5 ml syringe for 50 mg total. To administer 1 mg/kg to a 220 pound (100 Kg) patient would require two prefilled syringes while to deliver 1.5 mg/kg would require three.
If the patient’s rhythm doesn’t change, a second dose of 0.5 to 0.75 mg/kg of Lidocaine may be given in 5-10 minutes. Don’t let the math trick you, this is just half the initial dose. For that 220 pound patient that we gave 150 mg to 5 minutes ago, a second dose of 75 mg would be 0.75 mg/kg. Lidocaine has a maximum dose of 3 mg/kg and we generally max out a medication before trying something different, so a Lidocaine regimen may be 1.5 mg/kg followed by two 0.75 mg/kg doses at 5 minute intervals.
Amiodarone
If, instead of Lidocaine, you choose to administer Amiodarone, the dose doesn’t require any calculations; for adults in cardiac arrest with a shockable rhythm refractory to defibrillation, it’s simply 300 mg given IV push. If the V-Fib or pulseless V-Tach persists, a second dose of 150 mg may be given in 3-5 minutes. Amiodarone needs to be diluted in D5W prior to use and should only be given through a filter to prevent the accidental introduction of an emboli.
Because Amiodarone is a repeat in 3-5 minute medication, it fits well within our alternating 2 minute CPR cycles and code flow.
Post Cardiac Arrest
If our patient has return of spontaneous circulation (ROSC), a drip of the antiarrhythmic medication that converted them is sometimes started if the patient continues to have ventricular ectopy on the ECG after we’ve ensured appropriate oxygenation.
If Lidocaine converted the patient and is indicated by ventricular ectopy on the monitor, the Lidocaine drip rate is 1-4 mg/min.
If Amiodarone converted the patient, a drip should be started at 1 mg/min and run over 6 hours.
Do not “automatically” start an antiarrhythmic drip after ROSC for prophylaxis.
Wide Complex Tachycardia
Amiodarone & Lidocaine may also be used for stable, wide complex tachycardias in order to prevent a cardiac arrest. When used to treat stable V-Tach with a pulse, Amiodarone is given as a drip. The dose is 150 mg infused over 10 minutes. If administration of Amiodarone stops the V-Tach, a maintenance infusion should be started at 1 mg per minute run over 6 hours. If V-Tach returns, an additional dose of 150 mg over 10 minutes may be administered.
ACLS doesn’t provide specific dosing for Lidocaine when used to treat patients with stable, wide-complex tachycardias. For many, the dosing will be the same as when used for pulseless patients: 1-1.5 mg/kg slow IV push followed by 0.5-0.75 mg/kg in 5-10 minutes if the V-Tach persists. If Lidocaine stops the V-Tach, a maintenance drip can be run at 1-4 mg/min. Follow your local protocols or institution’s SOPs when administering Lidocaine in your workplace and only if it’s within your scope of practice.
Patients in V-Tach with a pulse rarely remain stable for long. These patients must be closely monitored and may benefit from having defib pads in place should emergent cardioversion or defibrillation be needed.
