Timing of the first epinephrine dose in patients with shockable rhythm cardiac arrest

Popular usage of epinephrine is in cardiac arrest (CA) is early---often after the first shock in VF/pulseless VT arrest. What is widely ignored, however, is that this does not comport with guidelines. For CA with initial shockable rhythm ACLS guidelines call for epinephrine only after the second shock. European guidelines delay epinephrine until after the third shock. This issue was addressed for patients with in hospital onset of shockable CA in a BMJ study:

Setting Analysis of data from the Get With The Guidelines-Resuscitation registry, which includes data from more than 300 hospitals in the United States.

Participants Adults in hospital who experienced cardiac arrest with an initial shockable rhythm, including patients who had a first defibrillation within two minutes of the cardiac arrest and who remained in a shockable rhythm after defibrillation.

Intervention Epinephrine given within two minutes after the first defibrillation.

Main outcome measures Survival to hospital discharge. Secondary outcomes included return of spontaneous circulation and survival to hospital discharge with a good functional outcome. A propensity score was calculated for the receipt of epinephrine within two minutes after the first defibrillation, based on multiple characteristics of patients, events, and hospitals. Patients who received epinephrine at either zero, one, or two minutes after the first defibrillation were then matched on the propensity score with patients who were “at risk” of receiving epinephrine within the same minute but who did not receive it.

Results 2978patients were matched on the propensity score, and the groups were well balanced. 1510 (51%) patients received epinephrine within two minutes after the first defibrillation, which is contrary to current American Heart Association guidelines. Epinephrine given within the first two minutes after the first defibrillation was associated with decreased odds of survival in the propensity score matched analysis (odds ratio 0.70, 95% confidence interval 0.59 to 0.82; P less than 0.001). Early epinephrine administration was also associated with a decreased odds of return of spontaneous circulation (0.71, 0.60 to 0.83; P less than 0.001) and good functional outcome (0.69, 0.58 to 0.83; P less than 0.001).

Conclusion Half of patients with a persistent shockable rhythm received epinephrine within two minutes after the first defibrillation, contrary to current American Heart Association guidelines. The receipt of epinephrine within two minutes after the first defibrillation was associated with decreased odds of survival to hospital discharge as well as decreased odds of return of spontaneous circulation and survival to hospital discharge with a good functional outcome.

This makes perfect sense. After all, for all you know, the first shock may have resulted in ROSC and you may have no way of knowing that until after the next two minutes of compressions. In such a case a push of epi is the last thing the patient needs! So, although this study may be practice changing for some it shouldn't be because it merely reinforces the existing guidelines.

This is in contrast to non shockable CA in which the guidelines call for epinephrine as soon as possible following identification of PEA or asystole.