Seriously injured patients frequently develop coagulopathy, which makes resuscitation (and survival) more challenging. A few years ago, the CRASH-2 study lent support for using tranexamic acid (TXA) in select trauma patients to improve survival. This drug is cheap and has antifibrinolytic properties that may be beneficial if given for life-threatening bleeding within 3 hours of initial injury. It’s typically given as a rapid IV infusion, followed by a slower followup infusion. The US military has adopted its routine use at forward combat hospitals.
But what if you don’t have IV access? This can and does occur with military type injuries. Surgeons at Madigan Army Medical Center in Washington state tried using a common alternative access device, the intraosseous needle, to see if the results were equivalent. This study used an adult swine model with hemorrhage and aortic crossclamping to simulate military injury and resuscitation. Half of the animals then received IV TXA, the other half had it administered via IO. Only the bolus dose was given. Serum TXA levels were monitored, and serial ROTEM determinations were performed to evaluate coagulopathy.
Here are the factoids:
The serum TXA peak and taper curves were similar. The IV peak was higher than IO and approached statistical significance (0.053)
ROTEM showed that the animals were significantly hyperfibrinolytic after injury, but rapidly corrected after administration of TXA. Results were the same for both IV and IO groups.
Bottom line: This was a very simple and elegant study. The usual animal study issues come into play (small numbers, pigs are not people). But it would be nearly impossible to have such a study approved in humans. Even though the peak TXA concentration via IO is (nearly significantly) lower, this doesn’t appear to matter. The anti-fibrinolytic effect was very similar according to ROTEM analysis.
From a practical standpoint, I’m not recommending that we start giving TXA via IO in civilian practice. We don’t typically see military style injuries, and are usually able to establish some type of IV access within a reasonably short period of time. But for our military colleagues, this could be a very valuable tool!
Intraosseous (IO) lines are a godsend when we are faced with a patient who desperately needs access but has no veins. The tibia is generally easy to locate and the landmarks for insertion are straightforward. They are so easy to insert and use, we sometimes “set it and forget it”, in the words of infomercial guru Ron Popeil.
But complications are possible. The most common is an insertion “miss”, where the fluid then infuses into the knee joint or soft tissues of the leg. Problems can also arise when the tibia is fractured, leading to leakage into the soft tissues. Infection is extremely rare.
This photo shows the inferior vena cava of a patient with bilateral IO line insertions (black bubble at the top of the round IVC).
During transport, one line was inadvertently disconnected and probably entrained some air. There was no adverse clinical effect, but if the problem is not recognized and the line is not closed properly, there could be.
Bottom line: Treat an IO line as carefully as you would a regular IV. You can give anything through it that can be given via a regular IV: crystalloid, blood, drugs. And even air, so be careful!
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.
The intraosseous access device (IO) has been a lifesaver by providing vascular access in patients who are difficult IV sticks. In some cases, it is even difficult to draw blood in these patients by a direct venipuncture. So is it okay to send IO blood to the lab for analysis during a trauma resuscitation?
A study using 10 volunteers was published last year (imagine volunteering to have an IO needle placed)! All IO devices were inserted in the proximal humerus. Here is a summary of the results comparing IO and IV blood:
Hemoglobin / hematocrit – good correlation
White blood cell count – no correlation
Platelet count – no correlation
Sodium – no correlation but within 5% of IV value
Potassium – no correlation
Choloride – good correlation
Serum CO2 – no correlation
Calcium – no correlation but within 10% of IV value
Glucose – good correlation
BUN / Creatinine – good correlation
Bottom line: Intraosseous blood can be used if blood from arterial or venous puncture is not available. Discarding the first 2cc of marrow aspirated improves the accuracy of the lab results obtained. The important tests (hemoglobin/hematocrit, glucose) are reasonably accurate, as are Na, Cl, BUN, and creatinine. The use of IO blood for type and cross is not yet widely accepted by blood banks, but can be used until other blood is available. NOTE: your lab may try to refuse the specimen due to “other stuff” (marrow) in the specimen. Have them run it anyway!
The standard of care in vascular access in trauma patients is the intravenous route. Unfortunately, not all patients have veins that can be quickly accessed by prehospital providers. Introduction of the intraosseous device (IO) has made vascular access in the field much more achievable. And it appears that most fluids and medications can be administered via this route. But what about iodinated contrast agents via IO for CT scanning?
Physicians at Henry Ford Hospital in Detroit published a case report on the use of this route for contrast administration. They treated a pedestrian struck by a car with a lack of IV access sites by IO insertion in the proximal humerus, which took about 30 seconds. They then intubated using rapid sequence induction, with drugs injected through the IO device. They performed full CT scanning using contrast injected through the site using a power injector. Images were excellent, and ultimately the patient received an internal jugular catheter using ultrasound. The IO line was then discontinued.
This paper suggests that the IO line can be used as access for injection of CT contrast if no IV sites are available. Although it is a single human case, a fair amount of studies have been done on animals (goats?). The animal studies show that power injection works adequately with excellent flow rates.
The authors prefer using an IO placement site in the proximal humerus. This does seem to cause a bit more pain, and takes a little practice. A small xylocaine flush can be administered to reduce injection discomfort in awake patients. Additionally, the arm cannot be raised over the head for the torso portion of the scan.
Bottom line: CT contrast can be injected into an intraosseous line (IO) with excellent imaging results. Insert the IO in a site that you are comfortable with. I do not recommend power injection at this time. Although the marrow cavity can support it, the connecting tubing may not. Have your radiologist hand-inject and time the scan accordingly. And don’t be surprised if your radiology department doesn’t have a protocol for this!
Note: long term effects of iodinated contrast in the bone marrow are not known. For this reason, and because of smaller marrow cavities, this technique is not suitable for pediatric patients.