October 4, 2024

Welcome back to UH EMS-I’s Pharmacy Phriday. As we close out our series about medication routes, we focus on the Intraosseous (IO) route. IO access is fast, reliable access, has few complications, and can be accomplished rather easily in the pre-hospital setting. In one study, IO success rates were cited as being twice as high as intravenous line placement in critical trauma patients without a blood pressure.1

IO vascular access refers to the placement of a specialized needle through the cortex of a bone into the medullary space for infusion of fluids and medications. The IO route was once considered an alternative access only after two peripheral IV attempts had been made but is now often considered before other access for emergent situations.  

Protocols often consider the IO route when standard venous access would delay therapy or is not easily obtained. Within the UH protocol, the use of IO access as a primary site is acceptable in cases of a life-threatening illness or injury and traditional IV access has failed or is unlikely. Elsewhere in the protocol, it is also stated that the IO route can be considered in cases of decompensated shock and if immediate access is needed. 

Multiple IO devices are available from manufacturers. Within the UH system, the Arrow EZ-IO® device is most widely used. Multiple-sized needles are available and are often referred to as the pediatric, adult, and bariatric-sized needles. However, it is more appropriate to refer to them as their specific size, be it the 15 mm (pink), 25mm (blue), and 45mm (yellow) sizes.  

Consider that some pediatric patients may require a larger needle if they are obese, and all humeral head insertions require a 45mm needle. Remember that with any patient, it is vital that at least one of the black lines (referred to as the 5mm mark) should be seen after placing the needle tip to the bone. At least one 5 mm mark of the needle visible above the skin indicates the needle should penetrate the medullary space of the bone. If a mark is not observed, the provider should choose a longer needle or a site with less soft tissue covering the bone.  

There are multiple sites for the placement of an IO. Within the UH protocol, the sites approved include the humeral head and the proximal tibia. The humeral head site is the preferred site today. Being familiar with the landmarks of each is extremely important. 

IOs are contraindicated anytime there is the presence of infection at the site, a fracture, a previous IO attempt in the same extremity, or burns. Another contraindication is the inability to locate landmarks or if excessive tissue is present that prevents observation of the 5mm mark on the IO needle.  

The provider can confirm the proper placement of an IO by checking the stability of the needle, successfully flushing the IO line, and being able to flow fluids and medications with no signs of leakage or infiltration. There is mixed opinion and literature on aspirating marrow to confirm placement. Some suggest there is a risk of clogging the needle through the step. The UH protocol does not currently include aspiration. However, all sources stress that flushing the line is essential to displace marrow and allow proper flow. The use of a pressure infuser bag or BP cuff is recommended to maintain good access. 

In cases where the patient is conscious or has a pain response to the procedure, the injection of 2% intravenous lidocaine into the IO needle is suggested for relief. Per UH protocol, dosing for the lidocaine is 20-40 mg for the adult patient or 0.5 mg/kg for the pediatric patient (not to exceed 40 mg). The lidocaine should be administered as a slow push over 2 minutes and allowed to dwell for a minute or so before flushing the line.  

Stabilization of the IO, whether using a commercial stabilizer or bulky dressing, is important to prevent dislodging or bending of the needle. Consider immobilizing the extremity to prevent displacement. 

Complications of the IO procedure include infiltration and extravasation as mentioned above, in addition to including compartment syndrome, tendon damage if landmarks and insertion are improper (i.e., the bicep tendon when using the humeral head site), and in the pediatric population, damage to the growth plate of the bone.  

For additional information and online training relating to the Arrow EZ-IO® and IO access, visit www.Teleflex.com or click here to view educational videos from Teleflex. 

Until the next installment, stay safe! 

Sincerely, 

The UH EMS-I Team 

University Hospitals