Regional anaesthesia, is anesthesia affecting only a large part of the boy, such as a limb. Regional anaesthetic techniques can be divided into central and peripheral techniques. The central techniques include so called neuroaxial blocks (epidural anaesthesia, spinal anaesthesia). The peripheral techniques can be further divided into plexus blocks such as brachial plexus blocks, and single nerve blocks. Regional anesthesia may be performed as a single shot or with a continuous catheter through which medication is given over a prolonged period of time, e.g continuous peripheral nerve block. Last but not least, regional anesthesia can be provided by injecting local anesthetics directly into the veins of an arm (provided the venous flow is impeded by a tourniquette.) This is called intravenous regional techniques (Bier block).