Epidural blocks are used for relief of chronic pain, labour pain and postoperative pain as well as for surgical anaesthesia. Effect can be targeted at the insertion level which can be from cervical spine level all the way to the sacral hiatus in the case of a caudal epidural block. Catheter insertion means doses can be repeated and the effect maintained. This contrasts with the typical single-shot spinal/subarachnoid injection primarily used for surgical anaesthesia. Specifically avoiding dural puncture also contrasts with the spinal's simple endpoint of detecting CSF. Accurate epidural needle insertion is therefore technically more difficult. The variety of methods available to identify if the needle tip is in the epidural space highlights this much less certain endpoint. With epidural injections, drug solutions need to physically spread to access each intended nerve root. This makes epidurals less reliable than spinals, where simply depositing the solution in the CSF rapidly enables it to bathe all the nerve roots encountered. Serious risks such as direct damage to nerve tissue, infection and epidural haematoma are shared with spinal anaesthesia but may be more likely with epidural techniques. Epidural needles are wider bore and more likely to damage tissue and vessels. They are sometimes directed close to the spinal cord itself. In-dwelling catheters can move and traumatize vessels and act as a focus for infection. Despite these potential drawbacks, careful selection, skilled placement and management mean patients can safely derive the intended benefits and epidurals and caudal blocks continue to be popular.
- Anaesthetic technique
- regional anaesthesia