Intraosseous Versus Intravenous Vascular Access During Out-of- Hospital Cardiac Arrest – A Randomized Controlled Trial

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Also posted over at Rogue Medic (now at EMS Blogs).

For treatment of medical cardiac arrest patients, which is better – IO (IntraOsseous) or IV (IntraVenous) access for medication administration?

Since no medications have ever been demonstrated to improve survival from cardiac arrest (only chest compressions and defibrillation have), the most important consideration will be what method results in the least interruption of compressions and the least interference with defibrillation.

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All patients eligible for inclusion in this study had their first attempt at vascular access randomized to one of 3 locations: proximal tibial intraosseous, proximal humeral intraosseous, or peripheral intravenous. The proximal tibial insertion site was located medial to the tibial tuberosity, or just below the patella along the flat aspect of the tibia. The proximal humerus insertion site was defined as the greater tubercle of the anterior humeral head 1 cm proximal to the surgical neck of the humerus. Peripheral intravenous catheter placement could occur at any accessible peripheral vein but preferably at the antecubital fossa; the external jugular vein was not an option provided for catheterization.^[1]

Proximal tibial access points.

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Proximal humeral access point.
Images credit.

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Does this hurt? No. The patients are unresponsive and pulseless (dead), but even live patients and EMS personnel (who have tried this on themselves) report very little pain.

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Overall success took into account a failure to maintain initial vascular access during the course of resuscitation, which included needle dislodgement or the inability to successfully administer medications or fluid at any time during the resuscitation.^[1]

Those would interfere with the one claimed benefit – ability to deliver medication.

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There was no difference in time to success for either of the intraosseous routes compared with the peripheral intravenous route.^[1]

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Click on images to make them larger.

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The time to success is interesting. The times for the humeral site are similar to the tibial IO and the IV for placement and first drug administration – at least at the low end of the IQRs (InterQuartile Ranges). The problem is that the upper end of the IQRs is much longer than for the other methods. This is in part due to the low number of patients, which is partially explained by the 13 protocol violations – all in favor of the tibial IO site. The lack of familiarity of paramedics probably also contributes, resulting in much longer times for some of the paramedics.

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Finally, there were 13 protocol violations that favored the tibial intraosseous route, which may have been an indicator of bias among paramedics for that route and therefore could have resulted in confounding of the study results.^[1]

It may be that this group of paramedics was much more comfortable with the tibial IO, than with the humeral IO and this led to a greater likelihood of coming up with excuses for protocol violations. This may also have led to the performance differences. I have seen similar differences with the introduction of a new type of IV catheter to some services. There can be a lot of conscious and unconscious resistance to the new method, but after some familiarity develops, things tend to return to normal.

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In the literature, intraosseous needle insertions have been linked to local wound infections, osteomyelitis, fat emboli, and compartment syndrome.^18-20 During this study, there was no mechanism in place for EMS or hospital personnel to report complications in the use of the intraosseous device.^[1]

That would be good to know, but this was not one of the goals of the study.

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The average weight of patients in the humeral intraosseous group was greater than that of individuals in either of the other 2 arms of the study. This increased weight may have been associated with a difficulty in obtaining or maintaining vascular access.^[1]

Weight can be a problem for any method of IV/IO access, so this is a very important limitation.

Weight – mean (SD)

Overall – 97.3 kg (2.7)

Humeral IO – 103.9 kg (6.5)

IV – 97.7 kg (3.8)

Tibial IO – 91.5 kg (3.9)

An average weight of 228.6 pounds (103.9 kg) in the humeral IO group, but only 201.3 pounds (91.5 kg) in the tibial IO group? 27.3 pounds difference (13.8% difference).

That strongly suggests a problem.

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The proximal humerus can also prove tenuous during cardiac arrest because it is centered near the upper torso, where resuscitation efforts are occurring, including airway management, ongoing chest compressions, and rescuer interchange. The constant activity creates a tremendous amount of movement and further increases the risk of unintentional needle dislodgement, which was verified during the debriefing session after each out-of-hospital cardiac arrest, with paramedics frequently citing entanglement of the humeral intraosseous line, leading to dislodgement.^[1]

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The peripheral intravenous site is the most commonly used vascular access by all health care providers, yet it proved successful in less than 50% of cases in this study.^[1]

No matter how bad the success of the humeral IO was, the IV success was even worse – less than 50% first attempt success.

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Do IOs improve outcomes?

IOs may make it less likely that compressions will be interrupted, but we cannot tell from this study.

IOs may make it more likely that potentially harmful medications will be given.

The most interesting numbers I saw were the total fluid infused – twice as much in the IV group as in either IO group. No explanation is given, other than the possible slower flow rate for an IO. This may help to prevent fluid overload for those patients not in need of having an IV line accidentally left wide open.

There is no evidence that IOs, IVs, tubes, or medications improve survival to discharge with a working brain.

ACLS drug therapy during CPR is often associated with increased rates of ROSC and hospital admission but not increased rates of long-term survival with good neurologic outcome.^[2]

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Will this make the Three Stooges Pit Crew concept less of a comedy of errors to implement?

Probably not, but we can hope that the AHA does the right thing and eliminates all of the treatments that don’t work – ventilation, intubation, IV access, IO access, epinephrine, amiodarone, lidocaine, atropine – wait, they actually did remove atropine, so there is hope.

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Footnotes:

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^[1] Intraosseous Versus Intravenous Vascular Access During Out-of-Hospital Cardiac Arrest: A Randomized Controlled Trial.
Reades R, Studnek JR, Vandeventer S, Garrett J.
Ann Emerg Med. 2011 Dec;58(6):509-16.
PMID: 21856044 [PubMed - in process]

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^[2] Medications for Arrest Rhythms
Part 8: Adult Advanced Cardiovascular Life Support
2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
Part 8.2: Management of Cardiac Arrest
Free Full Text Article with links to Free Full Text PDF download

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