This has come up at least three times now.  Question 8 from the first paper of 2000, Question 15.1 from the first paper of 2012,  again in Question 15 from the second paper of 2014 and as a part of Question 30 from the first paper of 2018. The typical style of question has been "What is this item ? (colour picture of typical-looking IO needle). Discuss the complications / indications / insertion sites / etc etc." Half the marks seem to be awarded for recognising the object.

Indications

  • Failure to gain IV access in a life-threatening situation where IV access is critically important

Contraindications

  • Underlying fracture
  • Underlying prosthesis
  • Severe osteoporosis
  • Osteogenesis imperfecta
  • Contaminated site
  • Inability to identify landmarks
  • Insertion at a site of recently attempted IO access
  • Unfamiliarity with the device (you might hurt yourself)

Age is no longer a contraindication.

Sites of insertion

  • Humerus
  • Just above the medial malleolus
  • Anterior tibia
  • Sternum

Confirmation of position

How do you know you are in the right spot?

  • Aspiration of bone marrow
  • Ability to flush fluid with no evidence of extravasation
  • Ultrasound- colour flow within the intraosseous space (though this is so far experimental)
  • Circumferential pressure around to the IO site: if the needle is extravasating into soft tissues, the gravity-fed fluid infusion rate will slow considerably when those soft tissues are compressed by a blood pressure cuff.

Complications of intraosseous vascular access

  • Osteomyelitis
  • Fracture
  • "through and through" penetration
  • Extravasation
  • Compartment syndrome due to extravasation
  • Injury to staff (slipped needle)
  • Damage to surrounding structures
  • Microscopic fat emboli

With sternal approach:

  • Mediastinal injury
  • Pneumothorax
  • Greater vessel injury

References

Probably the best single reference for this:

Day, Michael W. "Intraosseous devices for intravascular access in adult trauma patients." Critical care nurse 31.2 (2011): 76-90.

Dev, Shelly P., et al. "Insertion of an Intraosseous Needle in Adults." New England Journal of Medicine 370.24 (2014).

James Cheung, Warren, Hans Rosenberg, and Christian Vaillancourt. "Barriers and Facilitators to Intraosseous Access in Adult Resuscitations When Peripheral Intravenous Access Is Not Achievable." Academic Emergency Medicine 21.3 (2014): 250-256.

Luck, Raemma P., Christopher Haines, and Colette C. Mull. "Intraosseous access." The Journal of emergency medicine 39.4 (2010): 468-475.

Stone, Michael B., Nathan A. Teismann, and Ralph Wang. "Ultrasonographic confirmation of intraosseous needle placement in an adult unembalmed cadaver model." Annals of emergency medicine 49.4 (2007): 515-519.

STRAUSBAUGH, STEVEN D., et al. "Circumferential pressure as a rapid method to assess intraosseous needle placement." Pediatric emergency care11.5 (1995): 274-276.