Many patients require multiple attempts at vascular access, and thus the speed of completing this access becomes relevant. Studies of IV insertions have been published indicating that these insertions often take more than 10 minutes in some patients.(1) In children, IV access may not be possible at all in many cases.(2)
Intraosseous (IO) access appears to provide the rescuer a substantial saving of time in providing access to the vascular space, reducing the length of time that it takes to give medications and fluids.(3) Rapid IO access is now possible in all age groups. With the advent of the new American Heart Association guidelines, the administration of drugs down the endotracheal tube has been de-emphasized in favor of IV and/or IO access.(4) Thus, it appears readily apparent that the use of IO access should be stressed by EMS providers.
IO vascular access was initially described more than 80 years ago.(5) During World War II, IO access was commonly used when IV cannulation was unavailable.(6) IO access was less emphasized in the years following the war, mostly because IV cannulation became more widespread. IO access reappeared in the late 1980s as standard therapy for the AHA Pediatric Advanced Life Support (PALS) training.(7)
Generally speaking, EMS rescuers can get into the IO space in one of three ways: via a manually inserted needle, a spring-loaded "punch device", or a powered drill. Manual needles include the Cook device and the ubiquitous Jamshidi needles used in the tibia. Spring-loaded punch devices include the Pyng IO device in the sternum and the Bone Injection Gun in the tibia.
The powered drill device produced by VidaCare is a relative newcomer. This battery-operated device employs single-use, disposable needles that are seated by way of a smoothly drilled hole into the marrow space. The needles for the device are available in three sizes, ranging from the infant and child (the "PD IO"), to the normal-size adult, and to the obese adult.
Preparation and insertion for the Pyng approaches 50 seconds.(8) B.I.G. is reported to require about 17 seconds for preparation and insertion.(9) Preparation and insertion time for the EZ-IO is reported to be approximately 10 seconds.(10)
Although each device has reported strengths and limitations, the above IO devices all achieve rapid vascular access, and EMS agencies should examine all available equipment from both risk-benefit and economic considerations.
In the adult population, the proximal tibia has been, until recently, the most commonly used insertion site. Recently the FDA cleared the humeral head site for routine use of the EZ-IO. The proximal aspect of the tibia is the insertion site that has been researched most widely.(11)
Training & Considerations
Insertion of the IO does require aseptic technique. Manual devices require substantial strength in the adult and are sometimes difficult to steady during insertion in children (or in a moving vehicle). It's reasonable to use a local anesthetic during insertion in the conscious patient, and thus, the EMS medical director may want to consider whether paramedics may have an expansion of scope of practice that permits administering subcutaneous anesthetic for this purpose. Administration of sterile lidocaine (that which is used for treating cardiac emergencies, which does not contain preservative) into the marrow space prior to flushing the needle or administering IV fluids decreases pain during infusion.
Standard training for IO insertion has proved straightforward. This training usually requires only two hours, including both a lecture and hands-on training. (12,13)
Obese patients may present greater difficuly in achieving IO access due to the increased soft tissue depth before the needle meets the bone. Patients with surgical scars on the extremity suggesting the possibility of an orthopedic appliance being present should not receive the IO in that area of the extremity. Combative patients may make IO access difficult, although this access may provide a route for rapid chemical control of the condition. Infection in the intended insertion site and the presence of vascular compromise in that extremity are both contraindications to using that extremity for IO access. Ongoing CPR may suggest using the lower extremity for the IO site, and extremity trauma and amputations will suggest alternative IO sites.
IO flow rates are variable, especially affected by the age of the patient and the site of insertion, and are generally similar to the flow achieved through a 21-gauge catheter. Pressure pumps improve flow of the IO. Flushing of the IO needle after insertion seems to improve flow rates as well.(10) All medications and blood products that are approved for IV infusion can be give via an IO. An exception is in the use of hypertonic saline. It appears that more research must be done before using the IO route for this treatment.
Complications are rare, and they include infection and fractures.15 However, complication rates have been published as low as 0.6%.(16) A small study on the EZ-IO of 250 patients revealed virtually no complications with the use of this device.(10)
Because rapid IO access is now possible in all age groups and the 2005 AHA Guidelines favor IV and/or IO access over drug administration via the ET tube, the use of IO vascular access will almost certainly become widespread in EMS in the coming years. Progressive agencies would be wise to adopt this technique, keeping in mind the equipment options, training and quality assurance considerations, and budgeting concerns.
Raymond L. Fowler, MD, FACEP, is in his 28th year of emergency medicine practice and EMS medical direction. He is an associate professor of Emergency Medicine and Surgery at the University of Texas Southwestern School of Medicine in Dallas, attending faculty at Parkland Memorial Hospital Emergency Department, the deputy EMS medical director for the Dallas Area BioTel System, and the co-chief of the Section on EMS, Disaster Medicine, and Homeland Security at the University of Texas Southwestern. He served on the initial steering committee to form the National Association of EMS Physicians, later becoming its fourth president. His publications include his work as a founding author of the National EMS Medical Director Training Course and Practicum, the new course of which is now in revision. In addition, he is avidly involved in international EMS research, leading the EMS coordination in Dallas of more than a thousand paramedics in research in CPR, hemorrhagic shock, traumatic brain injury, and acute coronary syndromes.
Editor's note: For more information on the EZ-IO, download the JEMS supplement "Adult Intraosseous Infusion Arrives."