Intraosseous (IO) access is an alternative route for administering medications, fluids, and blood products when peripheral or central venous access is not readily available. A large bore needle is passed through the bone cortex into the intramedullary space. Fluids and medications delivered through the IO needle are rapidly absorbed in the intramedullary sinusoids and delivered centrally. IO access is indicated whenever resuscitation is deleted by unsuccessful or difficult peripheral IV access. It is especially useful in cardiac arrest, shock, severe dehydration, and extensive burns. Multiple anatomic sites can be used for IO placement, and decision will depend on factors such as patient age and accessibility of the site. The proximal tibia is the most commonly used site. IO needle insertion is most commonly achieved using a semiautomatic insertion system. IO access should not be established in a limb with a fracture, infection, burn, or chronic pathologic condition. Complications are rare but include IO extravasation and infection.
A needle that transverses the bone cortex, terminating in the intramedullary space of a bone
- Urgent need for patient resuscitation in the absence of other available or easily obtainable functioning venous access 
- In cardiac arrest, obtain IO access if peripheral IV access is unsuccessful after 2–3 attempts OR takes > 90 seconds to establish. 
For patients in severe shock or cardiac arrest, IO access is faster to establish (typically < 1 minute) than central venous access or difficult peripheral IV access that requires multiple attempts. 
Avoid in patients with any of the following, unless absolutely necessary: 
- Fracture or previous IO access attempt in the same bone
- Infection or burn at the intended insertion site
- Osteoporosis or osteogenesis imperfecta
- Prosthesis or hardware at insertion site
We list the most important contraindications. The selection is not exhaustive.
Access locations 
- Distal tibia: used for adults
- Proximal tibia: used for both adults and children < 6 years of age
- Other: proximal humerus, sternum
Needles and insertion devices 
Insertion devices are generally preferred over manual needle placement.
- Semiautomatic insertion devices: EZ-IO® system, Bone Injection Gun®, NIO®
- Manual needles: Jamshidi™ needle, Cook intraosseous infusion needle
- Sterile gloves and PPE
- Sterile drape
- Antiseptic solution (e.g., chlorhexidine)
- Local anesthetic solution (e.g., 1% or 2% lidocaine)
- Syringe and small gauge needle for local anesthetic
- 10 mL syringe
- IO insertion driver device (manual or semiautomatic)
- Associated appropriately-sized IO needle
- Associated primed extension set, if applicable
- Primed IV tubing
- Needle stabilizing device 
- Sterile dressing
- Support the leg in a comfortable position.
- Clean dirt and debris from the insertion site.
- Identify insertion landmarks.
- Distal tibia: flat surface of the bone 2 cm above the medial malleolus 
- Proximal tibia: flat surface of the bone 2 cm below and 1–2 cm medial to the tibial tuberosity 
- Choose the appropriate IO needle length. 
- 15 mm (pink): patient weight 3–39 kg
- 25 mm (blue): patient weight ≥ 40 kg
- 45 mm (yellow): significant overlying tissue
- Don PPE.
- Prep skin to create a sterile field.
- Apply a sterile drape.
IO insertion using semiautomatic system in adults 
Commonly used semiautomatic IO insertion systems include the EZ-IO® system.
- Administer single-point local anesthesia to the skin and periosteum in conscious patients.
- Attach an appropriately sized IO needle to the automated driver.
- Manually advance the needle (without using the trigger) at 90° through the skin until it touches bone.
- Activate the driver by pressing the trigger and push gently downward until a loss of resistance is felt.
- Grasp the needle and remove the driver.
- Remove the stylet with a counterclockwise motion.
- Attach the needle stabilizing device.
- If applicable, attach the associated extension set and aspirate.
- Slowly administer 2% lidocaine if the patient is in pain. 
- Flush the needle with 5–10 mL of saline.
- Apply a sterile dressing.
Remove the IO needle within 24 hours of insertion to minimize the risk of complications.
- Attach a Luer-Lok syringe to the needle.
- Pull it out straight while rotating it clockwise.
Do not rock the needle during removal.
Pitfalls and troubleshooting
Resistance to fluid flow 
- Penetration into the opposite cortex (most common mistake) : Withdraw the needle 1–2 mm and recheck fluid flow.
- Incomplete penetration of the cortex : Replace the stylet and advance the needle until bone marrow can be aspirated.
- Obstruction of the needle : Flush IO access frequently and after every medication administration with 3–5 mL of saline. 
IO extravasation or IO infiltration 
- Ensure the IO needle is in the correct position.
- Examine for cortical injury, e.g., fracture, previous IO access attempt, widening of IO access site.
- Ensure adequate local anesthesia prior to insertion.
- Administer intermittent IO lidocaine boluses. 
Easy bone marrow aspiration, minimal resistance to a fluid flush, stability of the needle in the bone, and no evidence of IO extravasation suggest correct IO access placement. 
- Correct placement verified
- Fluid flow evaluated
- IO extravasation ruled out
- Analgesia prescribed (e.g., lidocaine boluses)
- Removal planned within 24 hours
Complications are uncommon, especially if the needle is removed within 24 hours of insertion. 
- IO extravasation
- Compartment syndrome
- Skin or soft tissue necrosis
- Bone fracture or epiphyseal injury
- Fat emboli
We list the most important complications. The selection is not exhaustive.