February 4, 2020
by Bomee Kim
The two most common methods for administering systemic medications to dental patients is by enteral (PO) or intravenous (IV) routes. In an emergency, the PO route has a slow onset of action. The drug, administered PO, needs to be absorbed before being systemically available.1 The IV route will offer faster onset, but IV access can be difficult to achieve, even for practitioners experienced in the placement of intravenous lines.1 An alternate technique for the emergency delivery of systemic medications is the intraosseous (IO) route.2 The intraosseous route accesses the systemic circulation via the bone marrow.2 Bone marrow has a good vascular supply and allows for the administration of fluids and medications in long bones to quickly reach the systemic vascular supply.2 As dentists, especially for those who provide any form of sedation, having the tools and the knowledge to establish IO access can be valuable in a critical event, such as anaphylaxis or cardiac arrest.
IO access is indicated when it is difficult to establish a peripheral IV access.3 This is common in cardiovascular collapse, such as cardiac arrest or anaphylactic shock.3 The IO route is helpful because in cardiovascular collapse, the veins are also collapsed, which makes vessels difficult to visualize and entry to the vessel more complex.4
In the ambulatory setting, the availabilities of IO devices differ among provinces. There are two types of IO devices: manual and semi-automatic.3 Manual devices require the provider to hand-twist the device to puncture the skin, tissue, and bone in order to enter the bone marrow.3 Semi-automatic IO devices have different ways to access the bone marrow, such as spring-loaded devices or drill-assisted devices.3,5 Some brand names of semi-automatic devices include Arrow EZ-IO and Bone Injection Gun (BIG). Needle sizes, techniques, and the insertion sites may differ for each IO device, and it is important to review this information when purchasing the equipment.
Landmarking and Placement
There are several recommended potential sites for establishing an IO access. These are the proximal humerus, proximal tibia, and the distal tibia.3,5 The distal femur is another usable site, but only for pediatric patients.5 The proximal humerus is a convenient site for dentists, as the landmarks are easily identifiable with a few brief maneuvers. Using the proximal humerus is controversial in pediatrics, as there may be an increased risk of injury to the growth plate in a developing child.5 However, the proximal tibia which is commonly recommended in pediatrics may be more difficult to landmark for the non-physician, and may result in failed attempts.5 For this reason, if IO is indicated in a dental setting for a patient medical emergency, it is reasonable to access at the proximal humerus in a child.
To locate the proximal humerus site, the shoulder must first be internally rotated, which can be done by turning the thumb toward the body.3 The insertion site is the greater tubercle of the humerus, which is located anterior to the midline of the lateral shoulder, and distal to the axilla or the shoulder joint.5
The following instructions are specific to a drill-assisted technique:5
Some signs to confirm correct IO placement include decrease of resistance when entering the marrow space, stability of the needle, the ability to aspirate bone marrow or blood with a syringe, no tissue distention after administering saline, and minimal resistance while administering fluids or medications.3 After the IO access is established, it needs to be secured with tapes on the limb to avoid accidental dislodgement.3
The medication doses are the same as those used in IV administration.3 However, to ensure that the medication reaches the systemic circulation and does not linger in the marrow cavity, each medication should be flushed with 10mL of saline.3
There are several contraindications for utilizing IO access. Many have to do with a locally compromised insertion site, such as skin infection or cellulitis, prosthesis limb, fractured bone, prior surgery, and burns.3,5 Others have to do with the quality of the bone, such as osteoporosis, osteomyelitis, osteopetrosis, osteopenia, and osteogenesis imperfecta.3,5 One other important contraindication is a recent failed IO attempt in the same bone.3
Complications with IO are rarely serious and mainly have to do with inaccurate needle placement or dislodgement, such as failing to enter or remain in the bone marrow space, through-and-through penetration of bone, or injuries to the growth plate.3,5 Other complications include the extravasation of fluids or medications into surrounding tissue, which can potentially lead to compartment syndrome, infection at the insertion site, and fracture of the bone.3,5
This article reviewed intraosseous (IO) access. IO access is a reasonable alternative to the enteral (PO) or intravenous (IV) routes of drug administration in an emergency scenario. While there are many potential sites for establishing an IO access, the proximal humerus is a convenient site for dentists. To familiarize with the anatomy and IO access landmarking, there are ample resources on the World Wide Web, such as Google or YouTube, including with the keywords “intraosseous proximal humerus landmark” and “IO proximal humerus landmark”.
Oral Health welcomes this original article.
About the Author
Bomee Kim is in her second year of a Dental Anesthesia residency at the Faculty of Dentistry at the University of Toronto.
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