Neuraxial block provides excellent analgesia for obstetrics, many lower limb orthopaedic procedures and major open pelvic and abdominal surgeries. Thoracic epidurals are also used for thoracic surgery analgesia. Neuraxial block are sometimes used alone, or in conjunction with sedation or general anaesthesia. The advent of minimally invasive surgery has seen a decline in the use of some neuraxial block, particularly epidurals as they are not required.

Spinal anaesthesia is usually a ‘single shot’ technique lasting a few hours, whereas epidurals have an epidural catheter inserted and can thus be used for several days. Both techniques usually employ local anaesthetics and opioids. The former will block sensory, motor nerves and autonomic nerves (sympathetic nerves) which can cause weakness, hypotension and urinary retention. Opioids can cause respiratory depression and itchiness as well as urinary retention.

Both techniques require informed consent, vascular access and strict asepsis. They should not be undertaken with abnormal clotting, patient sepsis, significant cardiac disease or hypovolaemia. Complications include hypotension (often requiring fluids and vasopressors) post dural puncture headache, a ‘total spinal’ and permanent nerve injury from an epidural haematoma or abscess and meningitis. Great care is required to inject the correct does of the correct drug.