You are put into a state of unconsciousness either by the injection of an anaesthetic medication into a vein or by breathing in a mixture of gases. You will be unaware of what is happening around you and you feel no pain from the surgery. You will be constantly monitored and the anaesthetic adjusted as necessary throughout the operation. A muscle relaxant may also be administered, which relaxes muscle and allows easier surgical access to the operation area.

Following local anaesthesia, you are awake but the part of your body being operated on is numb. Local anaesthesia is administered via an injection; it takes effect quickly and lasts a long time. During the surgery you will be aware of touch and pressure, but not pain. If this type of local is being used, it is common practice to be looked after only by the nursing staff and the surgeon, an anaesthetist does not need to be present. The surgeon will generally administer the local anaesthesia. This type of anaesthesia can also be given with a sedative through an IV line, which means you will just be drowsy and semi-alert. This type of procedure is called local anaesthetic with sedation. Nerve Block This type of local anaesthesia is achieved by injecting an anaesthetic that blocks nerve impulse transmission. It can involve one or more nerves that are associated with the area to be operated on. A nerve block is often done for hand surgery. Epidural Block An epidural block involves injection of local anaesthetic and pain medication into the epidural space, blocking the transmission of nerve impulses in the spinal cord. It usually involves insertion of a small tube (that stays in place in the back) that can allow regular small does of pain medication to be administered, depending on the amount of pain you are feeling. An epidural takes around 10-20 minutes to take effect and takes about the same amount of time to set up and be administered. Sensation is decreased or lost (dependent on the amount administered) below the level of the block (usually around the mid stomach region). This should take effect on both sides of the body, but sometimes can be varied. An epidural block may be used as the only anaesthetic given for an operation that is carried out below the level of the diaphragm, but a sedative can also be administered with it. An epidural is commonly used for pain relief during labour and also for caesarian section. Spinal Block This involves an injection of a local anaesthetic and pain relief. A spinal block is a one-off injection, unlike an epidural which is used for regular/continuous administration. The injection is given directly into the cerebrospinal fluid and takes effect very quickly. Patients have a risk of headache that may be related to a leakage of cerebrospinal fluid from the hole made by the injection.

Complications may include: the patient is allergic to the anaesthetic, the dose given may be too high, or the anaesthetic effect has taken effect faster than wanted. Most complications occur with general anaesthesia. Airway obstruction: Irritation to the breathing passages causing spasms and interfering with breathing. Nerve damage: Some local anaesthetics can cause long term nerve damage, while some general anaesthetics can inflict brain damage. Brain damage will also result from depressed blood circulation. Malignant hyperthermia: An uncommon severe reaction to a general anaesthetic that results in extremely high body temperatures, blood pressure and heart rate. This rare reaction has a tendency to run in families. Awareness: A much talked about, but in fact a very rare, occurrence. It means that the patient appears asleep, but is not fully unconscious. This only happens when muscle relaxants are given. The patient cannot talk, move or speak. Newer technology can help an anaesthetist to reliably monitor for signs that this is happening. Complications of Epidural and Spinal Blocks: decrease in blood pressure having to remain still for administration (very difficult when in labour) problems in bladder emptying backache more serious complications are rare, but include convulsions, infection and death.