In this episode, I’ll discuss the intraosseous route in critically ill adults.
When a critically ill adult patient needs IV access, but it cannot be obtained, the intraosseous route of administration is a potentially life-saving alternative. The IO route has been well established for use in pediatrics and over the past 10 or so years has been increasingly recognized as an option in adults. The starting point for more widespread adoption in adults was likely the inclusion in the 2005 ACLS guidelines of IO use, and the 2015 update increased the prominence of the IO recommendation when IV access is not available.
Previous ACLS guidelines had recommended endotracheal administration of some medications during resuscitation if IV access could not be obtained. However endotracheal bioavailability is not as complete or reliable as IO and has therefore fallen out of favor in the guidelines.
The main advantage to the IO route over an attempt at a central line when peripheral access cannot be obtained is that IO access rapidly allows for the administration of virtually any medication, large amounts of fluid, and blood draws in a few seconds compared to the much longer time period for central access to be attempted.
Another advantage of the IO route is that, unlike veins that can collapse in shock or hypovolemia, the IO is not collapsible. There are 3 insertion points that are considered safe and easy to access: the proximal tibia, the distal tibia, and the proximal humerus.
If a patient is conscious while an IO is being placed, some clinicians prefer to administer lidocaine before starting any other medications or IV fluids through the IO. The usual dose is between 20 and 40 mg of lidocaine IO. In my practice, I have found that due to the emergency need for IO placement it is often not feasible to obtain and administer IO lidocaine in a timely fashion. The few times it has been obtained in time it did not seem to be very effective in eliminating pain upon medication administration via the IO.
Keep in mind that when an IO is being used to deliver medications or IV fluids, it cannot be used for drawing blood samples because the dilution of the sample by the medication or fluid will be significant enough to affect the accuracy of the test.
Flow rates of IV fluids without a pressure bag range from 1 to 5 liters per hour, and with a pressure bag may approach or exceed 10 liters per hour.
Any medication should be able to be administered via an IO device, including vasopressors, sedatives, and anticoagulants. Flushing the IO after each administration with 10 mL of normal saline is recommended so there is no risk of the medication remaining in the medullar cavity.
There is only a small amount of data looking at changes to medication pharmacokinetics with IO administration, but there does not seem to be any significant concerns in this area.
The extent of adoption of IO access when a peripheral IV cannot be obtained is likely to be institution-specific according to local training, practice and culture. A pharmacist on a rapid response or code blue team may be able to prompt the team to consider IO access when appropriate in order to increase the adoption of this potentially life-saving technique.
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