Point | Counterpoint – IV Beats IO Epinephrine for OHCA

March 11, 2020

Written by Clay Smith

Spoon Feed
For out-of-hospital cardiac arrest (OHCA), administration of epinephrine IV vs IO was associated with improved return of spontaneous circulation (ROSC), survival to discharge, and survival with favorable neurological outcome.

Why does this matter?
The 2018 ACLS update says either IV or IO epinephrine may be given. In fact, it treats them as interchangeable options, listing it as “IV/IO access” throughout the algorithm. But are they equal?

Epi IV beat IO
This was a retrospective study of 35,733 OHCA patients in the ROC arrest registry from 2011-2015. Of these, 27,758 (77.7%) had epinephrine given IV, and 7,975 (22.3%) via IO. There were some differences in the IV and IO groups. For example, more patients who got IV epi had bystander-witnessed arrest and shockable rhythm. However, when statistically adjusted for these and other known confounders, three key outcomes were better for epinephrine when given IV vs IO: ROSC, aOR 1.37 (95%CI 1.28 to 1.46); survival to discharge, aOR 1.47 (95%CI 1.26-1.71); and survival with favorable neurological outcome, aOR 1.85 (95%CI 1.53-2.24). They also performed propensity score matching, with 5,684 per group. These were well matched except, of course, for vascular access – IV or IO – and results were similar. Specifically, the aOR of survival with favorable neurological outcome was 1.83 (95%CI 1.45 to 2.33) for the IV cohort vs IO. Improvement was also seen in all three outcomes with IV vs IO administration for both shockable and non-shockable rhythms. A word of caution – statistical adjustment and even propensity matching cannot account for all confounders. Only a RCT can truly answer this. But this association is interesting. At this point, it seems wise to use an IV first-line if you can get one.

Another Spoonful
REBEL EM has an outstanding post on a reanalysis of the PRIMED trial, with >13,000 patients.

Source
Intravenous versus intraosseous adrenaline administration in out-of-hospital cardiac arrest: A retrospective cohort study. Resuscitation. 2020 Jan 23. pii: S0300-9572(20)30030-7. doi: 10.1016/j.resuscitation.2020.01.009. [Epub ahead of print]

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