<Li> Epidural anesthesia is an LA injected into the epidural space, where it acts primarily on the spinal nerve roots; depending on the site of injection and the volume injected, the anesthetized area varies from limited areas of the abdomen or chest to large regions of the body . </Li> <Li> Spinal anesthesia is an LA injected into the cerebrospinal fluid, usually at the lumbar spine (in the lower back), where it acts on spinal nerve roots and part of the spinal cord; the resulting anesthesia usually extends from the legs to the abdomen or chest . </Li> <Li> Intravenous regional anesthesia (Bier's block) is when blood circulation of a limb is interrupted using a tourniquet (a device similar to a blood - pressure cuff), then a large volume of LA is injected into a peripheral vein . The drug fills the limb's venous system and diffuses into tissues, where peripheral nerves and nerve endings are anesthetized . The anesthetic effect is limited to the area that is excluded from blood circulation and resolves quickly once circulation is restored . </Li> <Li> Local anesthesia of body cavities includes intrapleural anesthesia and intra-articular anesthesia . </Li>

Name the type of vasoconstrictor typically used in local anesthetic to help