60 seconds, then the bone — intraosseous access

Structured clinical encounter — resuscitation leadership

This station tests whether the candidate leads a team to the right decision under time pressure, performs the procedure correctly, and prevents the complications. Marks reward the explicit decision rule, the correct landmark and needle, the physiological defence, and the safety net. [1] [3]

Stem

A two-year-old is brought to the emergency department cold, mottled, and barely rousable. He has had a fever and a rash for six hours. Heart rate 180, respiratory rate 40, capillary refill 6 seconds, blood pressure 60/35. Two peripheral cannulation attempts over the last 75 seconds have failed. The team looks to you. [1] [3]

Candidate tasks

1. Lead the access decision (2 minutes). State the rule aloud: failed intravenous access within 60 to 90 seconds in a child with shock mandates an intraosseous needle now. Name the operator, allocate roles, and run the clock. Do not allow a third cannulation attempt. [1] [3]
2. Direct or perform the insertion (4 minutes). Choose the proximal tibia — flat anteromedial surface, one to two centimetres below and medial to the tibial tuberosity. Select the EZ-IO 15 millimetre pink needle (3 to 39 kilograms). Drill perpendicular until the give of the cortex, stop, remove the stylet. [1] [9]
3. Confirm placement and begin resuscitation (3 minutes). Confirm the needle is firm, aspirate marrow if possible (recognise that failure to aspirate does not exclude a good line), and flush easily with no calf swelling. Begin fluid with a pressure bag at 300 millimetres of mercury (gravity flow is too slow), and give adrenaline at the intravenous dose if the child arrests, flushing after each drug. [1] [12]
4. Manage pain in the conscious child (1 minute). Give preservative-free, epinephrine-free lidocaine 0.5 milligram per kilogram (maximum 40 milligrams) slowly into the line, dwell 60 seconds, then flush. [1]
5. Prevent complications and plan removal (2 minutes). State the complications — extravasation and compartment syndrome, infection with dwell time, fracture and growth-plate injury, fat micro-embolism. Commit to removing the line as soon as definitive access is in and within 24 hours, and to observing the limb for swelling and infection. [3] [11]

Examiners' discussion points

• Why IO here and not a central line? Speed. A central line takes many minutes and interrupts resuscitation; an IO is placed in under a minute, does not interrupt compressions, and delivers drugs centrally in seconds. [1]
• Defend the physiology. The medullary sinusoids sit in a rigid cortex and do not collapse in shock; drugs reach the heart in seconds at intravenous doses. Gravity flow is slow because the cavity resists flow, hence the pressure bag. [9] [12]
• The calf becomes firm during the bolus. Extravasation until proved otherwise. Stop the infusion, remove the needle, apply firm pressure, choose another site, and assess for compartment syndrome. Continuing is the unsafe move. [3] [11]

Marking grid (out of 20)