Intraosseous (IO) Device · What Is It, Risks and Benefits, and More

An intraosseous (IO) device is a life-saving tool used to provide rapid vascular access in emergency situations where intravenous (IV) access cannot be obtained or is likely to delay treatment. 

The IO device consists of a hollow-bore needle that is placed through the cortical bone and into the medullary canal with the aid of an assisting device. The medullary canal is the inner cavity of long bones that contains the bone marrow, which is the site of blood cell production. This area of the bone is filled with a rich network of capillaries that are connected to the venous circulation through the emissary and nutritious veins. Unlike blood vessels, the bone marrow does not collapse in states of cardiovascular shock, so it can be used for the infusion of medications and fluids during resuscitation.

According to the American Heart Association (AHA) and European Resuscitation Council (ERC) guidelines, the IO route is recommended as an alternative vascular access when, after 60 seconds, it has not been possible to place an intravenous line in either children or adults. Most commonly, the intraosseous route is used in emergency medicine situations, such as cardiac arrest, as well as in cases of severe shock, extensive burns, status epilepticus, multiple traumatic injuries, or an altered level of consciousness. 

This procedure is faster than central venous line placement and can be done without interrupting cardiopulmonary resuscitation (CPR). It is also easy to learn and has a high success rate on first attempts, making it extremely useful in prehospital emergency care. 

Generally, IO devices are placed at the proximal and distal ends of long bones where the cortical bone is thinner and there is more spongy bone present. 

In adults, the preferred sites of insertion include the proximal humerus, the proximal and distal tibia, the sternum, and the iliac crest. The proximal humerus is usually the first choice in adults because it offers higher infusion rates and less pain on insertion. The sternum provides a rapid access to the central venous circulation; however, its location interferes with CPR since cardiac massage cannot be performed.

Several devices may be used for obtaining IO access, and they are classified as manual or automatic insertion devices. 

The most common manual devices include the Cook Dieckmann needle and the First Access for Shock and Trauma (FAST-1) device, which is specifically designed for IO insertion on the manubrium of the sternum. Manual devices insert the needle into the chosen site by using manual pressure. Conversely, automatic insertion devices use either a gun (e.g., Bone Injection Gun, or BIG) or a battery-powered drill (e.g., EZ-IO device) to push the needle through the cortical bone. The bone injection gun is available in two sizes, one for newborns and children up to 12 years of age and another for older children and adults. The EZ-IO device comes with three different lengths of IO needles to be used based on the weight of the individual. 

In all cases, the needle is placed perpendicular to the bone ensuring the growth plate is avoided in children. The bone injection gun works by pressing a trigger mechanism that releases the needle, while the EZ-IO device requires positioning the drill on top of the cortical bone and then activating the device until there is a “pop” or loss of resistance and the needle locks into place. If using a manual needle, it should be twisted firmly by applying pressure until a loss of resistance is felt. At this point, the needle shouldn’t be advanced anymore due to the risk of being pushed too deeply into the bone. Once the needle is in the bone marrow cavity, it should stand upright without support and there should be a return of blood when aspirating with a syringe.

Because the medullary cavity offers some resistance to the infusion of medications and fluids, it is necessary to perform a wash with saline before administering any treatment. In individuals who are awake, intramedullary anesthesia with lidocaine is recommended to relieve the pain. Medications administered via the IO route should be followed by a 5 to 10 mL flush of saline, and fluids need to be infused under pressure (e.g., with an infusion pump or pressure infusion bag) as gravity is insufficient to drive fluids through an IO line.

If swelling is observed at any time, the device should be removed and placed in another location. To remove the IO line, the needle is held by grasping the shaft while pulling up gently with a twisting motion until it is removed. It is important to avoid rocking the needle side to side which may bend it and enlarge the access hole in the bone. 

The main benefit of using an IO device is that it provides rapid vascular access in emergency situations, which can usually be obtained in less than one minute by trained personnel. In addition, the anatomical landmarks used to guide insertion sites are easily recognizable, resulting in a high rate of success when performing the technique. Because it is a non-collapsible cavity, the bone marrow can be used to infuse medications, fluids, and blood products in situations of severe shock or cardiac arrest as well as to obtain blood samples for laboratory testing. 

On the other hand, it is important to note that the IO access is meant to be a temporary venous access, and IO lines should be removed as soon as another venous access is obtained or within a maximum of 24 hours of insertion due to an increased risk of infection. Contraindications for the use of an IO device include insertion at sites with previous IO attempts or fractures of the bone and infection of the bone or surrounding tissues. This procedure should also be avoided in individuals with osteoporosis or prosthetic joints near the insertion site.