Intraosseous access has the advantage of cannulating a noncollapsible structure that connects to the central circulation. The intraosseous approach is particularly useful for children as a result of their high percentage of red bone marrow and relatively thin bony cortex.
Intraosseous access is indicated when there is an emergent need for vascular access and other sites are difficult, high risk, or excessively time-consuming. Mechanical intraosseous insertion devices have insertion times of only seconds with consistently >90% success rates.1,2,3,4,5,6 Insertion devices include simple hand-twist needles, hand-held power drills, and spring-loaded devices.
There are few contraindications to intraosseous placement (Table 112-1), and the rate of serious complications from intraosseous insertion is ≤1%. The most common complication is extravasation at the insertion site. By comparison, central venous catheters have complication rates of at least 3.4%.7,8
TABLE 112-1Contraindications to Intraosseous Placement ||Download (.pdf) TABLE 112-1 Contraindications to Intraosseous Placement
Structural bone disorders (e.g., osteogenesis imperfecta)
MEDICATIONS AND FLUIDS ADMINISTERED BY THE INTRAOSSEOUS ROUTE
Any medication or fluid that can be given through an IV can be administered by the intraosseous route. Paralytics, anticonvulsants, analgesics, benzodiazepines, and vasopressors such as epinephrine have comparable intraosseous and IV infusion rates. Blood and blood products can be given by the intraosseous route.9 Medications for rapid-sequence intubation can be administered by the intraosseous route, although the time to effect may be delayed.10 In a study of sheep given IV or intraosseous succinylcholine, the IV route induced respiratory arrest in a mean of 30.8 seconds, whereas the intraosseous route took 57.5 seconds.11
The principal limitation of intraosseous access is a relatively low maximum flow rate. Resistance to flow within the bone marrow cavity limits the flow rate of intraosseous needles, and flow rates per kilogram tend to be higher in young patients who have a greater percentage of low-resistance red marrow compared to adults. The speed of administration of intraosseous infusions can be improved with pressure devices.
LABORATORY TESTING OF BONE MARROW ASPIRATE
The comparison of marrow aspirate with peripheral blood has been explored in small trials of hematology and oncology patients undergoing routine marrow sampling (Table 112-2). Two of these human studies have shown a close correlation of marrow aspirate to venous blood in regard to hemoglobin, sodium, chloride, bilirubin, pH, bicarbonate, urea, and creatinine concentrations.12,13 In another study, bone marrow taken for medical diagnosis correlated with the peripheral blood for ABO, Rh typing, and leukocyte activity.14 Correlation between bone marrow and peripheral blood is less reliable for leukocytes, platelets, glucose, potassium, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, partial pressure of carbon dioxide, and partial pressure of oxygen; however, the degree of discrepancy likely has minimal clinical significance. Aspirates obtained from the marrow after prolonged CPR may be considerably different from serum levels.15
TABLE 112-2Intraosseous Laboratory Findings Compared with Phlebotomy ||Download (.pdf) TABLE 112-2 Intraosseous Laboratory Findings Compared with Phlebotomy
| ||Equivalent ||Use Caution in Interpretation |
|Hematologic ||Hemoglobin ||Leukocytes, hematocrit, platelets |
|Chemistries ||Sodium, chloride, glucose, bilirubin, bicarbonate, urea, and creatinine ||Potassium, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase |
|Venous gas ||pH ||PCO2, PO2 |
|Transfusion ||ABO, Rh typing, and leukocyte activity ||— |
INTRAOSSEOUS CANNULATION DEVICES
There are several devices available for intraosseous insertion. The two most common manual insertion devices include the Cook® intraosseous needle (Cook Medical, Bloomington, IN) and the Jamshidi® style intraosseous needles. Powered devices are also available for intraosseous needle insertion; two examples are the EZ-IO® (Vidacare Corp., San Antonio, TX) and the Bone Injection Gun (BIG®) (Waismed, Ltd., Hertzliya, Israel). There is one prospective randomized study comparing manual to powered insertion devices in pediatrics in the prehospital setting, which compared the Jamshidi needle to the BIG. There were only 22 children in the cohort, which was primarily comprised of adults. There were no significant differences in time to insertion, which was less than 1 minute for both devices, or success rate, which was approximately 80% for both devices.4 Several studies have demonstrated rapid insertion and high success rates (>90%) using the EZ-IO in children, even among providers with minimal training.4,16 Small randomized studies in adults comparing the EZ-IO to the BIG suggest faster time to insertion and a higher first-time insertion success rate for the EZ-IO.5,6 The EZ-IO is a battery-powered cordless drill with a specialized needle (Figure 112-1). The needle is chosen based on the patient's weight and the distance from the skin to the bone (Figure 112-2). This device is intended for use in the proximal tibia, distal tibia, or proximal humerus. The BIG is a spring-loaded device that can be used in the proximal tibia; the pediatric device allows adjustable depths of insertion based on the patient's age. The BIG has the potential to cause injury to patient or provider if fired at the wrong time.
EZ-IO® needle sizes. The pink needle set is 15 mm in length (EZ-IO PD). This size is used in most children. The blue needle set is adult sized at 25 mm in length (EZ-IO AD), and the yellow needle set is for larger adults and is 45 mm in length (EZ-IO LD). The length and color are the only differences between needle sets. [Reproduced with permission from Vidacare Corp., San Antonio, TX. For updates see http://www.vidacare.com/ez-io/index.html.]
PLACEMENT AND INSERTION OF INTRAOSSEOUS NEEDLE
The ideal location for intraosseous access is a large bone with easily palpable landmarks, a thin cortex, and limited proximity to vital structures. The proximal or distal tibia, distal femur, and sternum are the sites most commonly described. The flat surface of the anteromedial proximal tibia is easily accessible given the paucity of overlying tissue, making it the most commonly accessed site (Figure 112-3).16 Insert the needle 2 cm inferior (distal) to the tibial tuberosity to avoid the physeal plate in children (Figure 112-4). When accessing the distal tibia, enter just superior to the medial malleolus, avoiding the saphenous vein (Figure 112-5), which is located 2 cm anterior and 2 cm superior to the malleolus. In adults, the distal tibia has thinner cortex than that of the proximal tibia. The anterior distal femur is an alternate site for children when the proximal tibia cannot be used or has failed (Figure 112-6). Insert the needle two fingerbreadths superior (proximal) to the distal end of the femur in the midline.
Cadaver anatomy with emphasis on landmarks for placement of intraosseous needle. [Reproduced with permission from Vidacare Corp., San Antonio, TX. For updates, see http://www.vidacare.com/ez-io/index.html.]
Anatomy of the distal tibia site for intraosseous placement.
Distal femur. The distal femur is an alternative site for intraosseous access. The red circle represents the site of insertion of the intraosseous needle. [Reproduced with permission from Hoffman ME, Ma OJ: Intraosseous infusion, in Reichman E, Simon RR (eds): Emergency Medicine Procedures. Figure 44-4, http://www.accessemergencymedicine.com/content.aspx?aID=50506.]
Once the appropriate insertion site has been selected, place the intraosseous needle perpendicular to the bone against the skin. Manual needles are pushed into the bone using steady pressure and slow rotation of the needle back and forth. If using an intraosseous drill, depress the trigger while applying gentle pressure on the needle. The drill significantly reduces the amount of pressure needed to penetrate the bone. Keep the trigger depressed during insertion, as the skin can twist and cause significant pain if the drill is repeatedly started and stopped. Once the cortex is penetrated, there will be a sudden decrease in resistance. At that point, release the trigger and detach the drill from the needle, which, in the EZ-IO, is secured with a magnetic chuck. Unscrew the stylet from the needle and attach a 5- or 10-cc luer lock syringe to the intraosseous needle and aspirate. Return of blood or bone marrow confirms placement, but return does not always occur, even when the needle is properly placed. Flush the intraosseous needle with 5 to 10 cc of normal saline, which should flow easily and further confirm placement. If the intraosseous needle has penetrated the posterior cortex or if the tip is not in the medullary cavity for another reason, fluids will extravasate into the soft tissues. This could include spaces posterior to the bone being cannulated, such as the gastrocnemius in a proximal tibial attempt. Palpate the area carefully to ensure that no extravasation is present. If the needle is misplaced, remove it and select a different bone for subsequent attempts. Frequently, automated gravity-based infusions and even automated pumps may not provide adequate pressure for infusion, and pneumatic pressure bags may be required. Secure the needle with bulky gauze dressing, but leave the dressing loose enough to check the site for signs of extravasation as infusions continue.
COMPLICATIONS OF INTRAOSSEOUS PLACEMENT
The complication rate is low. The most common complication is pain during insertion and infusion. Discomfort during infusion is thought to be due to pressure within the marrow cavity and can be reduced with the administration of lidocaine. The manufacturer of the EZ-IO recommends giving a 0.5 milligram/kg dose of 2% lidocaine without epinephrine (20 to 40 milligrams in adults) followed by a 10-mL normal saline flush after the intraosseous route is established.
In a prospective cohort of 95 patients who had intraosseous placement in the field or in the ED, no complications were noted other than difficulty removing the needle.3 A retrospective series of 42 patients with intraosseous placement had one serious complication of tibial fracture in a 10-day-old.17 A case series of 58 insertions in pediatric critical care transport team noted a 12% complication rate, all of which were minor local tissue edema or infiltration.16 A population-based study found no serious complications in 281 intraosseous insertions using administrative data.18 Case reports have described serious complications including compartment syndrome, osteomyelitis, fat embolism, cerebral air embolism, and skin necrosis from extravasation of caustic medications.18 Soft tissue fluid accumulation may be more likely in the setting of multiple attempts at intraosseous placement in the same bone. As a result, no more than one attempt per bone is recommended.19 Growth plate injuries are possible if not inserted at the proper site.20 Tibial fracture is a rare complication that is more likely in children with underlying bone disorders. In general, radiographs are not needed following intraosseous removal unless there is suspicion of a complication.
Each device has specific instructions for removal. The EZ-IO is removed by attaching a luer lock syringe then applying traction while twisting in a clockwise direction. If the syringe is twisted counterclockwise, it will unscrew from the short hub, which can be difficult to grasp. Other needles can be removed with traction and a back-and-forth twisting motion. Remove intraosseous needles as soon as another stable route of vascular access is established.