Anaesthesia: Regional anaesthesia
In the fourth and final part of our series on anaesthesia, Jonathan M Behar and colleagues discuss regional anaesthesia
General anaesthesia is the systemic administration of a central nervous system depressant, which leads to loss of consciousness and complete absence of sensation. The trauma associated with surgery activates nociceptors and the nerve fibres emerging from them. But these are not perceived under the influence of a general anaesthetic-the exact underlying mechanism, however, is unknown.
Regional anaesthesia, by contrast, is a method of providing local analgesia by infiltration of a local anaesthetic into tissues adjacent to regional nerves. Regional anaesthetics can be given to central structures, such as the spinal cord, or peripheral nerves, which emanate from the cord. This varies according to the purpose of the anaesthetic “block” and the area that needs to be anaesthetised.
Epidural anaesthesia is epidural or extradural and therefore the injection of agent is outside all three membranes encasing the spinal cord. Spinal and epidural anaesthesia can be used for abdominal, pelvic (caesarean section),