By Mary Haas, MD, PGY-II
Few things instill fear in the emergency physician more than caring for a crashing patient without a line. If you’ve got a patient with impending cardiorespiratory collapse and a lack of good IV access, know your IO!
Why do IOs work well in patients with shock/cardiac arrest?
- Can be performed quickly, often faster than peripheral lines in settings where there is peripheral vasoconstriction (bone marrow is a noncollapsible venous access route).
- Requires less skill and practice than central and umbilical line placement
- Fewer serious complications than central lines
Which medications can be given through an IO?
- Any medication that can be safely given through a peripheral vein can be given safely through an IO
- IO and IV doses are the same, however each medication administration via IO should be followed by 3-5 mL fluid flush
In which sites can you place IOs?
- Proximal tibia:
- Palpable landmarks (2 cm below patella, 2 cm medial to tibial tuberosity)
- Away from airway/chest during simultaneous resuscitative efforts
- Proximal humerus:
- Palpable landmarks (rest patient’s hand on their abdomen with elbow adducted, palpate directly up the humerus to the most prominent aspect of the greater tubercle, and use the yellow need if the pt is 40 kg)
- Better flow rates
- Less painful (preferred in awake patients)
- Less risk of compartment syndrome
- Distal tibia
- Distal femur (last resort)
How do you place an IO?
What sizes exist for IOs?
- For patients 3-39 kg: Pink (15 mm)
- For patients 40 kg and above: Blue (25 mm)
- For patients with excessive tissue/obesity: Yellow (45 mm)
What are the potential complications of IOs?
- Extravasation of fluid (most common): can lead to compartment syndrome or muscle necrosis
- Infection: osteomyelitis, cellulitis
- Local hematoma
- Growth plate injuries with incorrect placement
- Fat microemboli
How long can you keep an IO in?
- Ideally, remove within 3-4 hours, but IOs can remain in 72-96 hours (risk of infection increases with time that it remains in place)
- Remove once more definitive venous access is achieved
How do you know you’re in the right place?
- Needle will stand firmly upright when released
- Aspirate marrow upon entry
- Bolus 5-10 ccs of isotonic sodium chloride: High resistance to flow or visible extravasation means it’s likely in the wrong place. Can also use ultrasound in addition to physical exam to evaluate for extravasated fluid.
Which laboratory values from IOs correlate with peripheral venous levels?
- Some data on this comes from this small study.
Good correlation: Hemoglobin/hematocrit, chloride, glucose, BUN/Cr, albumin, total protein
Not as good of a correlation: CO2 (lower), platelet (lower), WBC (higher), Potassium (often hemolyzed), CO2, calcium
- Before obtaining/sending IO sample for labs, aspirate and discard the first 2 mL.
Sources & Additional Reading: