SilverIO does IOs
Patient is a 27 year-old man status post stab wound with sword to the abdomen. The patient is hypotensive and tachycardic, but oriented. The medics have not been able to get intravenous access yet. Once the patient arrives in the department, it is clear that he is still mentating. He has an open fracture to the left lower extremity and a very large stab wound to the abdomen. Nursing has been unable to obtain peripheral IV after two attempts. Your colleague is attempting a femoral central line but the patient has thready pulses. You decide to place an intraosseous line.
Where do you go?
There are several locations to place intraosseous lines, but the most common spot is in the proximal tibia, 2 fingerbreadths distal to and 1 fingerbreadth medial to the tibial tuberosity. Other locations include the lateral epicondyle of the distal femur, the medial malleolus of the distal tibia, and the humeral head. There are only 3 absolute contraindications to IO placement:
1) Previous IO placement in the same bone, as this can cause extravasation from the marrow into the surrounding soft tissue through the previous site and result in compartment syndrome.
2) Bony fracture, for the same reason as above.
3) Absence of limbs.
The patient is mentating and highly responsive to pain. What next?
Prime the tail of your IO line with 1-2% lidocaine. This will go in with your initial flush and help make the process more tolerable.
How fast can you give this patient (who likely has hemorrhagic shock) blood?
No more than 1 liter per hour (do not hook up to the level 1)
After 2 units of packed red blood cells, the patient becomes hemodynamically stable and a CT with contrast is ordered for operative planning.
Can you give contrast through your IO?
Although not ready for prime time yet, there have been studies of patients receiving contrast studies for evaluation of trauma through IO lines with appropriate contrast loading. It may be worth trying when the time comes--although if a patient is hemodynamically stable enough to get a CT scan, they can probably wait for definitive access prior to obtaining imaging.
Can you get labs?
You can obtain labs from bone marrow aspirate; you do have to discard the first 2cc of bone marrow that is aspirated and the labs are significantly limited. As you can seen in the picture, some of most important labs in a coding patient (potassium, HCO3) are not accurate in bone marrow aspirate. Most importantly, bone marrow aspirate can clog the rapid blood gas analysis machine so it is generally recommended to send the results to the formal lab, which will take at least 30 minutes to result. Sodium and calcium are within 5 and 10% (respectively) of their serum equivalents, but not precise.
In summary:
References:
Knuth TE, Paxton JH, Myers D. Intraosseous injection of iodinated computed tomography contrast agent in an adult blunt trauma patient. Annals Emerg Med 57(4):382-386, 2011.
Miller TJ et al. A new study of intraosseous blood for laboratory analysis. Arch Path Lab Med 134(9):1253-1260, 2010
