A specialised IO needle (manual or powered drill device such as EZ-IO) is inserted through the cortex of a long bone into the marrow cavity. Common sites: proximal tibia (most common in adults), distal tibia, proximal humerus, or distal femur. In adults, a powered drill device is preferred. The needle is confirmed in position by aspiration of marrow (though absence does not exclude correct placement). Fluids and medications are then infused through the marrow cavity and enter the systemic circulation rapidly. The procedure takes 30–60 seconds.
IO access is indicated when peripheral intravenous access cannot be obtained within 60–90 seconds in a critically ill or injured patient — cardiac arrest, severe trauma, burns, dehydration, septic shock, or status epilepticus. It is a bridging measure until definitive IV or central venous access is established.
Peripheral intravenous access (first line), central venous access (femoral, internal jugular, subclavian — takes longer to establish), and surgical cut-down (rarely used now).
This is an emergency procedure performed without delay when IV access fails. No preparation beyond standard resuscitation is needed.
Rapid vascular access in under 60 seconds. All medications and fluids that can be given IV can be given IO — including blood products, vasopressors, antibiotics, anaesthetic agents, and crystalloids. Flow rates are adequate for resuscitation.
Pain on infusionExpected
Awake patients experience pain during fluid infusion through the IO. Lidocaine flush reduces this.
ExtravasationUncommon
Fluid may leak around the insertion site if the needle is not secure.
Local haematomaCommon
Bruising at the insertion site.
OsteomyelitisRare
Bone infection. Very rare with short-term use (under 24 hours).
Compartment syndromeRare
If fluid extravasates into the soft tissue compartment. Monitor calf circumference.
Fat embolismRare
Theoretical risk of marrow entering the bloodstream. Clinically very rare.
FractureRare
Through the insertion site, particularly in children with small bones.
Growth plate injuryRare
In children if the needle is placed too close to the physis.
No anaesthesia needed in cardiac arrest. In conscious patients, local anaesthetic is infiltrated at the insertion site and lidocaine (preservative-free) is flushed into the marrow cavity before infusion.
IO access is temporary — typically removed within 24 hours once definitive IV access is established. The insertion site is covered with a dressing. No specific rehabilitation needed.
IO needle removed within 24 hours. Site monitored for infection. No long-term follow-up needed.
Is this safe?
IO access is an established, life-saving emergency technique. Complications are rare and the procedure is recommended by all major resuscitation guidelines (ALS, ATLS, ERC) when IV access fails.
Does it hurt?
In conscious patients, insertion causes brief pain similar to an injection. Fluid infusion through the marrow can be painful — a flush of lidocaine into the marrow cavity before infusion significantly reduces this.