Anaesthesia is used to stop patients from feeling pain or other sensations during operations, medical procedures, dentistry or medical tests.
A patient may be unconscious or 'out cold' with a general anaesthetic, or a certain part or parts of the body may be numbed.
Anaesthetics block pain and other signals from passing along nerves to the brain. It is given as gas to breathe in, injections, ointments, drops or sprays.
After a procedure, the anaesthetic wears off, and the patient will regain sensation, and may start to feel some pain from the procedure.
Types of anaesthetic
There are different types of anaesthesia which doctors, dentists and anaesthetists (specialists in anaesthesia) will use separately, or in combination, depending on the procedure a patient is to undergo:
Used for major operations and when a patient needs to be unconscious, also known as being anaesthetised.
Used for minor procedures such as skin surgery and tooth extractions. The person remains conscious (awake) but should not feel pain in the area being worked on. Some over-the-counter creams, ointments and gels contain small amounts of local anaesthetic to help numb pain.
Also known as regional block, these are similar to local anaesthetic, but covering a wider or deeper part of the body by targeting specific nerves.
This type of regional anaesthetic is delivered into the lower spine to numb the lower half of the body. It is given through a tube that is left in place, so can be topped up over a period of time if necessary. It is often used for childbirth and caesarean sections.
Like an epidural, this targets nerves in the spine and is given as a single injection used to numb the lower part of the body before surgery.
A patient may receive a regional anaesthetic along with a general anaesthetic to give pain relief after an operation. Sedation may be given with a local or regional anaesthetic so that the patient is relaxed and drowsy as well as numb.
This is not specifically an anaesthetic, but a means of relaxing the patient or making them feel relaxed and sleepy during a procedure or test. It often means that the person remembers little of the experience afterwards.
Premedication or pre-med is sometimes given before anaesthetics. These drugs may be used to reduce or relieve anxiety before surgery, to contribute to pain relief after the operation or to help prevent sickness after the operation.
Anaesthetic risks and side effects
Anaesthetic affects different people in different ways. Common anaesthetic side effects include:
In very rare cases, permanent nerve damage can occur or an allergic reaction can be experienced.
To minimise risks, the doctor, dentist or anaesthetist will first check a person's medical history for allergies, get details of any medication being taken (including herbs and supplements) and other risk factors. They will then discuss the anaesthetic to be used and any likely side effects.