IO needles are always said to be able to deliver any drug, and with the same speed and onset as their IV cousins – also in critical patients. Most of use don’t really trust that fully, I think. The ones who trust the IO route are the ones that have been forced to rely on them – like military medical services. Especially front line services like the British MERT. So, to document the IO’s usefulness, they made a trial to convince us.
The British MERT service is one of the most intense pre-hospital services out there – delivering medical care to the front-line in Afghanistan. Due to the extent of damages, but also their young age and fitness level, these are some of the worst casualties who’re still alive when medical services reach them. In addition to their bled-out state, the environment makes for a very high stress work situation. Not the perfect setting for IV-cannulas. So IO needle have become their friend.
Their trial is not that strong, but very pragmatic: it was observational, as IV/IO randomisation wouldn’t really be possible. Basically, it’s more a proof of concept study. They made their outcome first pass intubation success as well as best laryngoscopic view. Kind of strange outcome measures, but they are probably not bad for registering drug onset times in a critical environment.
They don’t really have any good group to compare them to locally, so they compare them to data from other HEMS trials, like the recent London HEMS trial. The MERT probably being more intense than any civilian HEMS, that would be a more than fair comparison.
They included 34 patients with humerus, sternal and tibial insertion using the EZ-IO in humerus and tibia, FAST-1 in sternum. So they have a good spread on the most used IO insertion devices and insertion sites. ISS of 25, mostly blast injuries.
A counter argument to their intubation success is that these are young, fit males. They have a low incidence of intubation failure. Civilian services intubate all sorts of age, face and body compositions. I still find the 97% first pass success as a quite good measure of IO drugs working quickly, and working at the time of intubation.
They did not document the time from drug bolus to start of intubation, but we can only assume they used the standard 30-45 sec wait. In this high stress situation, they probably didn’t wait longer than absolutely necessary. And to be pragmatic, probably the best documentation you’ll get. Writing down drug and intubation times in these settings are not feasible. One way to do it would be to document times from the obiquitous helmet cams/GoPro’s. Maybe next time.
Of interest, also note that one patient was intubated ONLY on Suxamethonium 100mg due to profound hypovolaemic shock.
Not final evidence, but for the time being, this 34 patient observational study is the best documentation of IO drugs working well and with comparable onset times to IV in critical trauma patients. There are other studies that have found IO and IV onset times comparable, but mostly animal studies and some experimental patient studies. Here’s a document of real world application.
Full text here.