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The intraosseous line is the vascular access of choice for both adults and children when emergent access is needed for resuscitation. Long bones have a bony matrix that supports veins that drain to the medullary sinus even in a patient in shock or cardiovascular collapse. Accessing this space through the bony cortex allows the provider the ability to deliver fluids, medications and conduct diagnostic studies even when vascular access is impossible to too time constricted to obtain.
Studies have shown that IO access is much quicker and more likely to be successful than emergency central venous access or venous cutdown. Nearly all resuscitation medications and fluids can be delivered through IO access and nearly all ages of patients may have an IO safely placed. In the past adults were less likely to have an IO placed, however, new literature suggests that IO placement is well tolerated, more successful and time saving in adult resuscitation.
At least one study has looked at the optimal site placement for the first attempt at IO (done in the setting of prehospital cardiac arrest). Proximal tibia placement was faster and less likely to be lost than proximal humerus. It is also acceptable in all age groups. If a patient has a severe wound over a potential IO site, the bond is fracture or bone has already had an attempt at cannulation, a different site will be preferred.
The manual needle technique has the advantage of allowing placement without any need for battery power. They are also inexpensive. However, manual needles require more expertise than other techniques and cannot be used in patients greater than 6 years as the cortical bone of the proximal tibia becomes too thick for easy cannulation of the bone marrow (distal tibia is an alternative). Manual needles are successful 76 to 100 percent of the time (50 to 67 percent greater than one year old). Their median time to insertion was 38 seconds.
Battery-powered drivers have needles that are available for all ages, easy to learn, have been shown to have shorter insertion times with greater success. Secondary to these findings this device has become the preferred technique in many hospitals and pre-hospital settings. Battery-powered devices are successful 87 to 97 percent of the time. Their median time to insertion was less than 10 seconds.
Bone injection guns are spring loaded devices that insert an IO needle to a predetermined depth with in bone. They can be used in patients older than one year of age. Bone injection devices are successful 45 to 91 percent of the time. Their median time to insertion was 49 seconds.
Once the IO has been placed the provider should confirm that the needle tip is within the bone marrow. This can be accomplished by aspirating bone marrow from the line. It should be noted that bone marrow may not always be aspirated even in a properly placed IO. If the IO needle will not stand on its own, it is unlikely that it is in the proper position. If infusion of fluids causes swelling or induration indicative of extravasation, then the needle is likely outside of the bone marrow space. In addition to these methods, fluoroscopy and ultrasound have been shown to identify properly placed IOs.
Most diagnostic studies (including type and screen) obtained from the bone marrow are accurate. However, there may be inaccuracies for WBC count, oxygenation, potassium, AST, ALT and ionized calcium. Once, medications are infused into the bone marrow, subsequent laboratory tests may be inaccurate.
IO lines should be viewed as temporary and venous access should be obtained as soon as possible and the IO removed. IOs in place longer than 24 hours have been associated with osteomyelitis. Fractures have been associated with IO placement as has compartment syndrome from infiltration. Fat and bone marrow emboli can occur with IO placement, but their consequence is poorly understood. Despite these risk, IO placement is very safe with complications occurring in less than 1 percent of patients.