Written by Alex Clark
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This retrospective observational analysis showed an association with more favorable neurologic outcomes, survival to hospital discharge, and ROSC upon ED arrival, in an IV-first approach compared to humeral IO in out-of-hospital cardiac arrests.
IO, IO, it’s off to work I go…
Current guidelines recommend intravenous (IV) access as first-line during out-of-hospital cardiac arrest (OHCA). While intraosseous (IO) access is classically reserved for failed IV attempts, recent data suggest increased use during OHCA despite growing concerns for worse outcomes. This observational study conducted using the British Columbia Cardiac Arrest Registry investigated a strategy of IV vs. humeral-IO as the first-attempted intra-arrest vascular route of access by ALS-trained paramedics in OHCA.
The authors reviewed 2,112 total cases of which IV was the first attempted vascular access method in the majority (n = 1,575). A large number of OHCA cases were excluded (n = 32,675). The primary outcome was favorable neurologic outcome at hospital discharge, defined as a cerebral performance category (CPC) of 1 or 2. Secondary outcomes included survival to hospital discharge, return of spontaneous circulation (ROSC; palpable pulse of any duration), and ROSC at time of ED arrival.
The IV-first approach was associated with improved favorable neurologic outcomes at discharge (AOR 1.7, 95%CI 1.1-2.7), survival at hospital discharge (AOR 1.5, 95%CI 1.0-2.3), and ROSC at ED arrival (AOR 1.3, 95%CI 1.1-1.6). The IV group had successful placement in 93% of cases as compared to 98% in the IO cohort. Times to successful vascular access and epinephrine administration were similar. Interestingly, although sensitivity analyses performed in shockable rhythms supported the IV-first approach, there were no significant associations with outcomes in non-shockable rhythms. The authors hypothesize that lipophilic medications such as amiodarone or lidocaine may get trapped within the medullary cavity during IO administration compared to more hydrophilic meds like epinephrine.
How will this change my practice?
While there are several limitations including its retrospective nature, high number of exclusions, and external validity, the growing number of papers that suggest inferiority of the IO is provocative. The potential physiologic explanation for improved outcomes in IV access particularly in OHCA has my attention, and I will emphasize this with our pre-hospital providers. I look forward to the impending IV vs. IO RCT permutations.
Editor’s note: The recent VICTOR RCT found no difference in IV vs IO for OHCA and outweighs this retrospective study. Although this observational data suggesting superiority of IV is interesting, it’s likely not true. However, VICTOR certainly didn’t find IO was superior to IV. So, what should we do? An IV-first approach for OHCA seems reasonable. But VICTOR informs us that a very rapid pivot to IO, in failed IV access, is probably just as good. ~Clay Smith
Source
The association of intravenous vs. humeral-intraosseous vascular access with patient outcomes in adult out-of-hospital cardiac arrests. Resuscitation. 2024 Sep;202:110360. doi: 10.1016/j.resuscitation.2024.110360. Epub 2024 Aug 16. PMID: 39154890.
