In this episode, I’ll discuss an article about timing of amiodarone for out-of-hospital, shock-refractory cardiac arrest.
A group of authors has hypothesized that the lack of clinically significant difference between amioadrone and lidocaine for out-of-hospital shock-refractory cardiac arrest is due to delayed timing of the administration of study medications. To evaluate this hypothesis, the authors published in Academic Emergency Medicine a secondary analysis of a 10-site, 55 EMS agency double-blind randomized controlled Amiodarone, Lidocaine, or Placebo in out-of-hospital cardiac arrest(OHCA) Study.
Patients were included if they had initial shockable rhythms and received the study drugs of amiodarone, lidocaine, or placebo before achieving the return of spontaneous circulation. Samples were stratified by early (defined as less than 8 minutes) and late administration groups (defined as 8 or more minutes). The authors then compared outcomes for amiodarone and lidocaine compared to placebo and adjusted for potential confounders.
Just over 2800 patients from the original study met inclusion criteria. About one-third of the patients were in the early administration group and two-thirds in the late administration group. In the early group, patients who received amiodarone has statistically signficantly higher rates of survival to hospital admission, survival to discharge, and functional survival when compared to placebo. Adjusted odds ratios were between 1.55 and 1.76 for these metrics in favor of amiodarone.
Patients in the early lidocaine group had no difference compared to placebo. In the late administration group there was no difference compared to placebo for either amiodarone or lidocaine.
The authors concluded:
The early administration of amiodarone, particularly within 8 minutes, is associated with greater survival to admission, survival to discharge, and functional survival compared to placebo in patients with an initial shockable rhythm.
It should be noted that this was a secondary analysis of an existing study and therefore should be hypothesis generating, not necessarily practice-changing, and it is unknown whether inpatients who experience shock-refractory in-hospital cardiac arrest would gain the same benefits as patients in this study. However in the case of in-hospital shock refractory arrest, it should be possible for a well-organized code team to have the amiodarone administered within 8 minutes as this is consistent with timing in ACLS algorithms.
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