Regional anaesthesia involves the injection of local anaesthetic (LA) and sometimes other drugs (e.g. opioids) targeted at a specific nerve(s) or nerve plexus to numb the area that the nerve innervates, including the spinal cord and its nerve roots. Indications for a nerve block include:

• sole form of anaesthesia during an operation;
• combined with general anaesthesia or sedation;
• postoperative analgesia;
• chronic pain conditions.

Central (neuraxial) blockade

Central blockade is the introduction of drugs into the CSF within the subarachnoid space (spinal blockade; Figure 22.1) or the surrounding epidural space (epidural blockade). Anaesthesia is provided for surgery below the level of the umbilicus (T10).

Advantages of central blockade are:

• avoidance of GA in at-risk patients, e.g. severe respiratory disease, difficult intubation, diabetic, myopathies, pregnant, malignant hyperthermia;
• good postoperative analgesia;
• avoids sedation/nausea and vomiting, e.g. by morphine;
• reduction in pulmonary thromboembolism due to sympathetic block;
• reduced blood loss;
• reduced stress response to surgery.

Side effects of central blockade are:

• hypotension (sympathetic block);
• nausea and vomiting (hypotension, opiates);
• lower limb motor block;
• post dural puncture headache (more likely with large needle, non-pencil-point tip, inadvertent Tuohy needle puncture of dura, young age);
• high block can effect upper limb power and respiration (C3–5);
• loss of consciousness (total spinal);
• nerve damage (rare).

Contraindications to central blockade include patient refusal, no i.v. access, severe CVS disease, hypovolaemia, sepsis, LA allergy, coagulopathy (e.g. INR needs to be <1.5). Caution must be exercised if there has been previous major spinal surgery or ongoing CNS disease.