Types of anaesthesia

Three types of anaesthesia

The type of anaesthesia used will depend on the nature and duration of the procedure, your general medical condition, and your preference and those of your anaesthetist and surgeon or other doctor performing the procedure.

The three types of anaesthesia are general, regional and local. All three involve the administration of drugs to produce a change in sensation and they are frequently used in combination.

Confusion sometimes arises, because the term “ local anaesthesia” is used to refer to what is properly called “ regional anaesthesia”, so that an operation “under local” may in fact be an operation using regional anaesthesia.

General anaesthesia

You are put into a state of unconsciousness for the duration of the operation. This is usually achieved by injecting drugs through a cannula placed in a vein and maintained with intravenous drugs or a mixture of gases which you will breathe. While you remain unaware of what is happening around you, the anaesthetist monitors your condition closely and constantly adjusts the level of anaesthesia. You will often be asked to breathe oxygen through a mask just before your anaesthesia starts.

Regional anaesthesia

A nerve block numbs the part of the body where the surgeon operates and this avoids the need for general anaesthesia. You may be awake or sedated (see below).
Examples of regional anaesthesia include epidurals for labour, spinal anaesthesia for caesarean section and ‘eye blocks’ for cataracts.

Local anaesthesia

A local anaesthetic drug is injected at the site of the surgery to cause numbness. You will be awake but feel no pain. An obvious example of local anaesthesia is numbing an area of skin before having a cut stitched.


The anaesthetist administers drugs to make you relaxed and drowsy. This is sometimes called ‘twilight sleep’ or ‘intravenous sedation’ and may be used for some eye surgery, some plastic surgery and for some gastroenterological procedures. Recall of events is possible with ‘sedation’. Most patients prefer to have little or no recall of events. Please discuss your preference with your anaesthetist.

Factors that influence the choice of anaesthetic include:

Do you have a choice?

No matter what operation, examination or other treatment you are to undergo, you may ask your anaesthetist if there is any choice in the anaesthetic method. You should also understand that some surgeons are more comfortable operating on patients who have received one form of anaesthetic rather than another. This most often means that the patient has a general anaesthetic.

The surgeon does not choose the type of anaesthetic you will receive, unless there is no anaesthetist involved in your care. However, the surgeon may discuss the choice with you and with your anaesthetist. In the same way, your anaesthetist does not choose what operation you will have or how it will be carried out. Again, your anaesthetist may discuss your operation with you and your surgeon, particularly if you have special anaesthetic problems.

Can you choose your anaesthetist?

It is sometimes possible to choose your anaesthetist, but there are factors which may make this difficult.

Nevertheless, you are entitled to ask if you may have a particular anaesthetist look after you.

You have every right to ask questions, to receive information, and to participate in choosing the care you will receive. Asking questions and receiving information are the basis of giving informed consent for any medical procedure, including anaesthesia.

Agreement or consent

What does ‘informed agreement/consent’ mean ?

In many countries, including Canada and Australia, your doctor is obliged to give you the opportunity to know about the risks of the anaesthetic (or operation) that are serious or  material risks. The discussion that you have with your anaesthetist should include the possibility of a choice of anaesthetic method (if appropriate) and the risks and benefits associated with the choices. Only then should you agree or consent to undergo examination or treatment.

Having agreed to have the examination or treatment, you are then required to sign a piece of paper which describes the examination or treatment. Your signature should be dated and witnessed. This is known as giving written consent. However, written consent is normally obtained only for the operation or procedure for which an anaesthetic must be given. In Australia, Canada and the United Kingdom, a separate written consent for anaesthesia is not routinely obtained. This means that written consent for the operation includes consent for the anaesthetic. Occasionally, you may be asked to give separate written informed consent for the anaesthetic. This might occur if you agreed to undergo a technique that is not routinely carried out or one that involves considerable or unusual risk.

In fact, the piece of paper that you (and all patients) sign is only that – a piece of paper—although it is a very important one in the hospital admission process. What is more important is the discussion which you have with the treating doctor before signing the form. This discussion enables you to give consent on the basis that you understand the treatment and implications to your satisfaction. The consent you give after this kind of discussion is called informed consent.


What if you don’t want to have the operation?

If you have second thoughts, even at the last minute, you should discuss them with your surgeon and your anaesthetist.

Ultimately, the decision as to whether or not to proceed with the operation is yours.