Intraosseous lines (IO) make life easy. They are quicker to insert, have a higher success rate, and require less experience than a standard IV. And they can be used for pretty much any solution or drug that can be given through an IV.
But there are some limitations. They can’t be inserted into a fractured bone. The manufacturer cautions against multiple insertions into the same bone. A second insertion should not be performed in the same bone within 48 hours.
But, as with so many things in medicine, there is little in the way of proof for these assertions. They seem like good ideas for precautions, but that does not mean they are correct. No real research has been done in this area. Until now.
The concept of using two IO needles in one bone was explored in an animal model by researchers in Canada. They used a swine model (using the foreleg/humerus, to be exact), and tested several infusion setups.
Here are the factoids:
Infusing crystalloid using an infusion pump set to 999ml/hr took 30 minutes with a single IO, and 15 minutes with a “double-barrel” setup
Giving crystalloid using a pressure bag set at 300 mm/Hg took 24 minutes with a single IO, and 23 minutes with double the fun
The double-barrel setup also worked for a blood/drug combo. 250cc of blood and 1 gm of TXA in 100ml of saline infused via pump in 13 minutes.
Simultaneous anesthesia drugs (ketamine infusion in IO #1, fentanyl and rocuronium bolus in IO #2) without problems
Multiple fluid + drug infusion combinations were tested without incident
There were no needle dislodgements, soft tissue injuries, fractures, or macrohistologic damage to the bone or periosteum
Bottom line: Remember, these are pigs. Don’t do this in humans yet. However, this is pretty compelling evidence that the double-barrel IO concept will work in people. And it appears that infusion pumps must be used for effective, fast infusions. I recommend that prehospital agencies with inquiring minds set up a study in people to prove that this works in us, too.
Neurosurgeons tend to worry about aneurysms a lot. They can cause devastating and lasting neurologic dysfunction. The most common diagnostic finding, besides the classic “worst headache of my life” complaint, is subarachnoid hemorrhage (SAH). And one of the more common CT findings after head trauma is also SAH.
For that reason, CT angiography tends to get added on to the trauma workup from time to time. Trauma professionals are faced with the “chicken or the egg” question, trying to figure out if a leaking aneurysm caused the subarachnoid blood and then the fall/crash, or the fall/crash caused the blood.
A group at St. Luke’s Hospital in Bethlehem PA looked at this question using 5 years worth of retrospective data from their Level I trauma center. They noted a significant increase in the number of CT angiographic (CTA) studies being ordered in their head trauma patients and wanted to determine which patients would benefit most from this study.
Here are the factoids:
617 patients were identified with traumatic SAH during the study period, and 186 of them (30%) underwent CTA
13 patients (7%) who had CTA actually had an aneurysm
Of these 13 patients, 8 were believed to have presented with trauma caused by the aneurysm because they were found to be ruptured
All patients who had a ruptured aneurysm had a pattern of central subarachnoid hemorrhage on CTA
Of the patients who were “found down”, none had an aneurysm
Bottom line: Pre-existing aneurysms are not any more common in TBI patients than they are in the general population. However, they may be the cause of trauma on occasion. Contrary to what many think, they seem to be uncommon in cases of patients who are found down; it looks like the trauma usually comes first. However, a pattern of central subarachnoid hemorrhage is reasonably predictive of this uncommon yet dangerous problem, so addition of CT angiography of the head when it is seen on non-contrast CT appears to be warranted.