Anaesthesia means ‘loss of sensation’. Medications that cause anaesthesia are called anaesthetics.
Anaesthetics are used during tests and surgical procedures to prevent pain and discomfort. Local anaesthetic and general anaesthetic are two commonly used types of anaesthetic.
A local anaesthetic is often used during minor procedures where a small area of the body is numbed and you remain fully conscious.
A general anaesthetic is often used for more serious operations where you will be totally unconscious and unable to feel anything.
How anaesthetics work
Anaesthetics work by blocking the signals that pass along your nerves to your brain. Nerves are bundles of tiny fibres that use chemical and electrical signals to pass information around your body.
For example, if you cut your finger, the pain signal travels from your finger through your nerves to your brain . When the signal reaches your brain, you realise that your finger hurts.
Anaesthetics stop the nerve signals from reaching your brain, allowing procedures to be carried out without you feeling anything. After the anaesthetic has worn off, the nerve signals will be able to reach your brain and your feelings will return.
Types of anaesthesia
As well as local and general anaesthetic, there are also a number of other types of anaesthesia. Unlike general anaesthetic, these do not make you unconscious; they stop you feeling pain in a particular area of your body. The different types of anaesthetic are described below.
- Regional anaesthetic - is used for larger or deeper operations where the nerves are more difficult to reach. Local anaesthetic is injected near the nerves to numb a larger area, but you remain conscious.
- Epidural anaesthetic - is a type of local anaesthetic that is usually used to numb the lower half of the body - for example, during labour and childbirth.
- Spinal anaesthetic - is a type of regional anaesthetic that is used to numb the nerves of your spine so that surgery can be carried out in this area.
- Sedation - is sometimes used for minor, painful or unpleasant procedures; a sedative is medication that makes you feel sleepy and relaxes you both physically and mentally.
Different types of anaesthesia can be used in combination. For example, a regional anaesthetic can be used with a general anaesthetic to relieve pain after an operation.
A sedative is also sometimes used with a regional anaesthetic to help you feel relaxed during an operation as well as pain free.
How anaesthesia is given
Anaesthesia can be given in a number of ways. It can be given in the form of:
- an ointment, spray, or drops that are rubbed onto your skin
- an injection into a vein
- a gas that you breathe in
Anaesthetists
Anaesthetists are doctors who have received specialist training in anaesthesia. They will give you your anaesthetic and be responsible for your safety and wellbeing during your procedure.
Before the procedure, your anaesthetist will discuss a number of things with you including:
- the types of anaesthetic that are appropriate for the procedure you are having
- any risks or side effects that are associated with different types of anaesthetic
- they will also plan your anaesthetic and pain control with you, taking into account any preferences that you have for a particular type of anaesthetic
You should ask your anaesthetist to clarify anything that you are unsure about, and and raise any queries that you have.
Your anaesthetist will carefully monitor you throughout your operation and will make sure that you wake up comfortably afterwards They may also help with any pain relief that you need following the procedure.
Side effects
Anaesthetics consist of a number of medications that can cause side effects in some people. Your anaesthetist will tell you about any side effects that you may experience after having a specific type of anaesthetic.
Some of the common side effects that can occur after having a general anaesthetic and some regional anaesthetics include:
- feeling sick or vomiting (about 1 in 3 people feel sick after an operation)
- sore throat
- aches and pains
- dizziness
- blurred vision
- headache
- itchiness
- bruising and soreness
The side effects of anaesthetic do not usually last very long and, if necessary, they can be treated with additional medication.
You should tell the healthcare professionals who are treating you if you experience any of the above side effects or if you are in pain after your procedure.
Risks and complications
In recent years, having anaesthesia has become much safer. Advances in equipment, medication and training mean that serious problems are uncommon.
However, as with any medical procedure, there is a potential risk of serious complications. Possible complications include:
- permanent nerve damage - that can cause numbness or paralysis (inability to move a part of the body)
- a serious allergic reaction to the anaesthetic (anaphylaxis), and very rarely
- death - there are approximately five deaths for every million anaesthetics that are given in the UK
Your risk of developing complications will depend on a number of factors including:
- your medical history - for example, whether you have any other conditions or illnesses
- personal factors - for example, whether you smoke or are overweight (if you smoke, giving up several weeks before your operation will reduce your risk of having breathing problems; likewise, losing weight will help reduce your risk)
- the type of procedure - for example, whether it is a planned procedure or an emergency procedure, or whether it is a major or minor procedure
- the type of anaesthetic - general anaesthetic can have more side effects and associated complications than local anaesthetic.
Before your procedure, your anaesthetist will explain your risk of developing possible complications.
In most cases, the benefit of being free from pain will outweigh the risks, but you should discuss any concerns that you have with your anaesthetist.
Further information:
To find out more about anaesthesia, including the associated risks and complications, you can visit the website of The Royal College of Anaesthetists.
You can also find out more about specific types of anaesthesia by reading the following NHS Choices Health A-Z topics: