Journal Club: Intraosseous vs. Intravenous Access During Out of Hospital Cardiac Arrest

Cardiac arrest is one of the most feared clinical situations both in and out of the hospital. When a patient suffers cardiac arrest, it is of the utmost importance to get access into the veins so that medications can be injected to try to help the heart start beating again.

There are two main ways to get access to the venous system: (1) placing a catheter directly into the vein (IV catheter), and (2) placing a catheter into the bone marrow space. The latter is called an intraosseous (IO) catheter. During cardiac arrest, placing IV can be challenging, especially with CPR ongoing and no blood circulating. Placing an IO catheter is quick and easy. The question is which is better in cardiac arrest? Enter this study published in the New England Journal of Medicine.

It was a randomized trial in which 1479 patients were randomized to get either IO or IV catheters during out of hospital cardiac arrest. The primary outcome was sustained return of spontaneous circulation (ROSC). Secondary outcomes were survival at 30 days and survival at 30 days with a favorable neurologic outcome.

The study found that, not surprisingly, more people had successful vascular access with IO catheters (92% vs. 80%). Yet, that did not translate into better outcomes: 30% of those randomized to get IO had sustained ROSC compared to 29% of those randomized to get IV catheters. This finding was not statistically significant.

Further, at 30 days, 12% of the IO group vs 10% of the IV group were alive, and this was not statistically significant, either. Moreover, a favorable neurologic outcome at 30 days occurred in 9% of the IO patients, and 8% in the IV patients, also not statistically significant. Therefore, placing IO catheters did not lead to better outcomes, despite the fact that more of the IO patients had successful vascular access.

This was a surprising finding. I would have thought that those patients who received IO catheters would have had ROSC faster and then have better outcomes. This study, however, did not bear that out.

There was one interesting finding that I noted: both groups had 15 minutes to the first dose of epinephrine. That, to me, seems like a long time. So, maybe this was the reason why the outcomes were not different? Perhaps getting an IO and then epinephrine more quickly can better affect outcomes?

That is for another study, I guess.

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