Epidural Catherisation

A close up view of the L3-L4 Interspace. After successful localisation of the space with the Tuohy needle using a 'loss of resistance' technique, the epidural catheter is slowly advanced a few centimetres into the space.

After ensuring that neither blood nor spinal fluid can be aspirated through the catheter, an appropriate amount of analgesic solution is injected. The solution spreads through the space, enveloping the subarachnoid space and the emerging nerve roots.