IO access (intraosseous)
Last reviewed 01/2018
Intraosseous access is used in paediatric resuscitation where there is difficulty establishing venous access - usually defined as requiring more than two attempts, or taking more than 90 seconds to obtain venous access in an emergency.
The technique relies on the fact that in young children the marrow of the long bones remains vascular. After cleaning, a specially designed needle is driven into the tibia, approximately two centimetres down, and slightly medial to the tibial tuberosity; this position is to avoid the growth plate. As the needle passes through the cortex it is felt to give, and care must be taken not to use so much force that it passes completely through the bone; the hand holding the leg should not be directly behind the path of the needle.
Once in the marrow blood can be drawn - and indeed sent for blood sugar estimation, chemistry and even cross-match, although FBC is obviously not useful.
Fluids can be safely given in this way in large - resuscitation - volumes; it will, however, need to be run in under pressure; it will not run under gravity. Care should be taken to fix the needle since it protrudes from the bone and therefore is likely to get knocked in the confusion of advanced care for the child.
The needle can be removed once adequate venous access has been established, but there is no hurry and intraosseous needles can be left in for, in extreme circumstances, more than 24 hours.
It is possible to use intraosseous needles up to the 6th year of life, although the majority are used in children in their first year.
It is a painful technique and should not be considered in the conscious patient without analgesia.