What is anaesthesia?

The word anaesthesia means ‘loss of sensation’. It can involve a simple local anaesthetic injection which numbs a small part of the body, such as a finger or around a tooth. It can also involve using powerful drugs which cause unconsciousness.

These drugs also affect the function of the heart, the lungs and the circulation. As a result, general anaesthesia is only given under the close supervision of an anaesthetist, who is trained to consider the best way to give you an effective anaesthetic but also to keep you safe and well.

The drugs used in anaesthesia work by blocking the signals that pass along your nerves to your brain. When the drugs wear off, you start to feel normal sensation again.

Local anaesthesia

A local anaesthetic numbs a small part of the body. It is used when the nerves can be easily reached by drops, sprays, ointments or injections. You stay conscious, but free from pain. Common examples of surgery under local anaesthetic are having teeth removed and some common operations on the eye.

Regional anaesthesia

This is when local anaesthetic is injected near to the nerves which supply a larger or deeper area of the body. The area of the body affected becomes numb.

Spinal and epidural anaesthetics

These are the most common regional anaesthetics. These injections can be used for operations on the lower body, such as Caesarian section, bladder operations, or replacing a hip. You stay conscious, but free from pain.

Other types of regional anaesthetic

Other regional anaesthetics involve an injection placed near to a nerve or group of nerves, for example in the arm or leg. This is often called a ‘nerve block’. This can allow you to have the operation without a general anaesthetic.

Nerve blocks are also useful for pain relief after the operation, as the area will stay numb for a number of hours.

For more information, see the leaflet below on nerve blocks on shoulder, arm, hand: http://www.rcoa.ac.uk/patientinfo/leaflets-video-resources

Sedation

Sedation involves using small amounts of anaesthetic drugs to produce a ‘sleep-like’ state. It makes you physically and mentally relaxed, but not unconscious. Many people having a local or regional anaesthetic do not want to be awake for surgery. They choose to have sedation as well. If you have sedation, you may remember little or nothing about the operation or procedure. However, sedation does not guarantee that you will have no memory of the operation. Only a general anaesthetic can do that.

General anaesthesia

General anaesthesia is a state of controlled unconsciousness during which you feel nothing. You will have no memory of what happens while you are anaesthetised.

A general anaesthetic is essential for a very wide range of operations. This includes all major operations on the heart or lungs or in the abdomen, and most operations on the brain or the major arteries. It is also normally needed for laparoscopic (keyhole) operations on the abdomen.

Anaesthetic drugs are injected into a vein, or anaesthetic gases are given for the patient to breathe. These drugs stop the brain from responding to sensory messages travelling from nerves in the body.

Anaesthetic unconsciousness is different from a natural sleep. You cannot be woken from an anaesthetic until the drugs are stopped and their effects wear off. While you are unconscious, the team in theatre look after you with great care. Your anaesthetist stays near to you all the time.