Intraosseous Access

Indications

Cardiac arrest — first-line vascular access if IV access is not rapidly achievable, per Resuscitation Council UK guidance.
Peri-arrest / critically unwell patient where urgent drug or fluid delivery is needed and peripheral IV access has failed or would take too long.
Major trauma with difficult IV access, particularly in shock with collapsed peripheral veins.
Any emergency drug, fluid, or blood product can be given via IO; onset and levels are comparable to IV administration.

Contraindications

Absolute (at that site)

Fracture of the target bone, or a recent IO attempt in the same bone (typically within the last 24–48 hours).
Overlying infection, burn, or significant soft tissue injury at the insertion site.
Prosthetic joint or hardware at or near the site.

Relative

Bone disease that may increase fracture risk (severe osteoporosis, osteogenesis imperfecta).
Inability to locate landmarks (severe oedema, excessive tissue) — choose an alternative site.
Vascular injury proximal to the intended site with concern for extravasation into a compromised limb.

If one site fails or is contraindicated, move to an alternative bone rather than repeated attempts at the same site.

Sites

Adult

Proximal humerus — greater tubercle, arm adducted with hand on abdomen; fast flow rates, good for resuscitation drugs and fluids, but more painful on insertion and needs the arm held still.
Proximal tibia — 2 cm medial and 1–2 cm proximal to the tibial tuberosity, on the flat antero-medial surface; most familiar site, easy to identify landmarks.
Distal tibia — 3 cm proximal to the medial malleolus; alternative when proximal sites are unavailable.

Paediatric

Proximal tibia is first-line in children — flat, broad, and easily palpable landmark below the growth plate.
Distal femur is an additional paediatric site in smaller children.
Needle set selection is weight-based rather than by site alone — follow device-specific guidance.

Needle selection (EZ-IO)

15 mm (pink hub) — for smaller patients, roughly 3–39 kg.
25 mm (blue hub) — standard adult needle, ≥3 kg with average tissue at the site (commonly used for proximal tibia).
45 mm (yellow hub) — for patients ≥40 kg or where excess soft tissue overlies the insertion site (typically proximal humerus, or a tibia with significant soft tissue).
Before drilling, confirm needle length by placing the tip on bone through the skin — the 5 mm marking above the hub should still be visible; if it is not, select a longer needle.
Selection should always be individualised by palpated tissue depth over the chosen site, not by weight alone.

Landmark — proximal tibia

Step-by-step technique

Identify landmarks and confirm no contraindication
Palpate the chosen site; clean the skin with antiseptic.
Select and prepare the needle
Choose needle length by palpated tissue depth; attach to the driver. Local anaesthetic to skin and periosteum in the conscious patient reduces insertion discomfort where time allows.
LAST rescue — AAGBI algorithm ↗
Insert perpendicular to the bone
Position the needle tip against the bone at 90° to the surface, confirm the 5 mm mark is visible above the skin, then power the driver (or use manual pressure for a manual needle) until a sudden "give" or loss of resistance signals entry into the marrow cavity.
Confirm placement
The needle should stand firmly upright without support ("firm seat" in bone). Remove the stylet, attempt to aspirate marrow (not always possible, and its absence does not exclude correct placement), then flush with saline — free flow without significant swelling confirms placement; resistance or subcutaneous swelling suggests extravasation.
Manage pain of infusion in the conscious patient
In a conscious patient, the infusion of fluid through the IO is often more painful than the insertion itself. Give preservative-free 2% lidocaine slowly through the IO (typical adult dose around 40 mg, i.e. 2 mL of 2%, over 1–2 minutes), allow it to dwell for around a minute, then flush with 5–10 mL saline before starting infusion; a smaller supplementary dose can be repeated if pain recurs. Confirm local departmental dosing before use.
Secure and connect
Attach the stabiliser dressing supplied with the device, connect extension tubing, and label the line clearly as intraosseous.

Pressure or a pump is usually needed for anything beyond small drug boluses — gravity flow through an IO is slow; use a pressure bag or syringe push for fluids and blood.

Complications

Early

Extravasation — most often from failure to seat the needle fully or dislodgement; check for swelling and stop the infusion if suspected.
Pain, particularly with rapid infusion in a conscious patient.
Failed placement / needle bending against dense cortex.
Through-and-through penetration (posterior cortex) in a small bone.

Late (rare)

Compartment syndrome from unrecognised extravasation.
Osteomyelitis — rare, more likely with prolonged dwell time or repeated attempts.
Fat embolism (theoretical, rarely reported clinically).
Growth plate injury in children if landmarks are misjudged.

Aftercare & removal

Regularly check the site for swelling, which indicates extravasation and mandates stopping the infusion and removing the device.
IO access is a temporary bridge — establish definitive IV (or central) access as soon as safely possible and remove the IO device (device removal typically within 24 hours per manufacturer guidance).
Document: site, needle size, indication, number of attempts, drugs/fluids given, complications, and time of planned removal.

Pitfalls & pearls

Don't chase a second attempt at the same bone — move to a different site or bone.
Absence of marrow aspirate does not mean the IO has failed — a free-flowing flush without swelling is the more reliable sign.
Warn the conscious patient before flushing — unanaesthetised IO flush is genuinely painful, and lidocaine pre-treatment through the needle makes a real difference.
All standard resuscitation drugs and fluids can be given IO with equivalent effect to IV — do not delay drugs waiting for IV access once IO is in.

DOPS pointers

RCEM curriculum: Core Procedural Skill. What assessors look for at each entrustment level:

1	Observed only — can describe indications, sites and contraindications.
2a	Performs with supervisor present: correct landmark identification, needle selection, confirms placement.
2b	Performs with supervisor in the department: manages pain of infusion, secures the device, documents fully.
3	Indirect supervision: chooses between sites appropriately, troubleshoots extravasation and failed placement, knows when to abandon a site.
4	Independent; can teach and supervise others, including in the paediatric and peri-arrest setting.

References

Resuscitation Council UK. Adult Advanced Life Support Guidelines, 2021 — vascular access in cardiac arrest.
Teleflex. Arrow EZ-IO Intraosseous Vascular Access System — clinical reference and needle selection guidance.
IAEM. Clinical Guideline: Intraosseous Access in Adult Patients, Version 1.0.
RCEM Curriculum 2021 — Emergency Medicine Specialty Learning Outcomes: core procedural skills (DOPS).