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Epi and Antiarrhythmics in Medica Cardiac Arrest

Question# 851

In the context of a pulseful VT that becomes a witnessed VSA that remains in VT or VF is it beneficial to consider administering Lido/Amio prior to Epi after initial cardiac arrest management has been performed. Current AHA guidelines give mixed info suggesting Epi always first but that fast administration of Lido/Amio is beneficial for dysrhythmic related cardiac arrest.

Answer:

As per the ALS PCS, antiarrhythmics (amiodarone & lidocaine) are indicated for shockable rhythms (ventricular fibrillation & ventricular tachycardia) in a cardiac arrest. As long as other priorities are being met (CPR, early defibrillation, and epinephrine) there is no need to wait to administer antiarrhythmics.

For a patient who is successfully shocked out of VF/VT, but for whom arrest with VF/VT recurs, antiarrhythmics are indicated (if not already given), and can be given immediately after the shock. These rhythms are bad and recurrence can be controlled with these medications. There is no requirement to wait or to be in shock refractory (x3 defibrillations) to administer amiodarone/lidocaine. Additionally, "The primary objective of antiarrhythmic drug therapy is to facilitate successful defibrillation and to reduce the risk of recurrent arrhythmias, [especially when given early on]. In concert with shock delivery, antiarrhythmics can facilitate the restoration and maintenance of a spontaneous perfusing rhythm." (https://www.ahajournals.org/doi/10.1161/CIR.0000000000000613)

If the patient has been successfully defibrillated, whether that be with a ROSC or less desirably into another rhythm such as PEA or asystole, there is no need to give antiarrhythmics as it would be contraindicated and the risks would outweigh the benefits. For example, administering a full dose amiodarone to someone with a pulse would be more harmful and could cause bradycardia and hypotension. If you recall, "Following the initial pulse check, subsequent pulse checks are indicated when a rhythm interpretation reveals a non-shockable rhythm (PEA or Asystole), or there are signs of life present" (Companion Document p. 28). The other risk is focusing on antiarrhythmics instead of early defibrillation and good quality CPR. These are the key principles when assessing risk/benefit. Remember, it’s all about the “why”, as opposed to protocolizing for all scenarios.

"While [antiarrhythmics] have theoretical benefits in selected situations, no medication has been shown to improve long-term survival in humans after cardiac arrest. Priorities are defibrillation, oxygenation and ventilation together with external cardiac compression." (https://litfl.com/anti-arrhythmic-drugs-and-cardiac-arrest/) This is especially true when the paramedic witnesses a cardiac arrest. It would be reasonable to wait until the second analysis analysis (to see if the shock worked) to administer epinephrine/antiarrhythmics while focusing on effective CPR and early defibrillation, as it is possible these priorities convert the patient. The vast majority of the time if someone has a witnessed VF/VT arrest, and it is recognized and shocked quickly, they will convert.

The risk of administering epinephrine immediately after a witnessed VF/VT that is defibrillated is that the patient may now have a pulse. Epinephrine in a patient with a pulse carries a high risk of dysrhythmia, hypertension, and myocardial oxygen demand at a time of deficit. If the initial rhythm is PEA or asystole, epinephrine should be given as soon as possible, as the evidence supports this.

In summary, for cardiac arrest, antiarrhythmics are used for VF/VT that is unresponsive to shock delivery, CPR, and vasopressors (epinephrine). As per the ACLS algorithm, epinephrine is administered first during a cardiac arrest as it helps to increase the heart rate and blood pressure which then improves blood flow to the organs. This boost can enhance the chances of a ROSC and restore a stable heart. On the other hand, antiarrhythmics are used to treat and prevent abnormal heart rhythms. Remember, as per the Companion Document, "If the timing were to fall such that epinephrine and an antiarrhythmic were to be administered within the same CPR cycle, proceed, ensuring to provide a saline flush between the two medications." (p. 28) This is perfectly acceptable practice as well to ensure both medications are administered promptly!

References

Companion Document (p. 28)
ALS PCS Medical Cardiac Arrest Medical Directive

https://litfl.com/anti-arrhythmic-drugs-and-cardiac-arrest/
https://www.ahajournals.org/doi/10.1161/CIR.0000000000000613
ACLS Guidelines

Published

22 October 2024

ALSPCS Version

5.3

Views

47

Please reference the MOST RECENT ALS PCS for updates and changes to these directives.