Anesthesia works by blocking off the nervous system in some way so that a person feels numb or stays unconscious during surgery. An additional purpose can also be to help the patient relax before the surgery and block memories of it afterwards. There are three main types of anesthesia, according to scope: local, general, and regional.
Local anesthesia, as the name suggests, affects only a specific part of the body, such as a patch of skin or a limb. The person stays awake during the surgery, but they may be given strong sedatives to help limit movement. This type lasts only up to a few hours and is used in out-patient surgery, meaning the patient can come in and leave on the same day. The effect usually lasts for a while after the surgery, helping to relieve post-operational discomfort. Dental surgery and stitching wounds are the most common examples.
Regional anesthesia works on a large area, but not the whole body. An example is the epidural given to women in labor. The drug is injected into a cluster of nerves that control a given region, such as the lower half of the body. Sometimes doctors just inject large doses of local anesthesia, although this is risky and should be done only under very controlled