Anaesthetics Overview

This page will provide you with information about anaesthetics. For further details, you should speak to your consultant.

What are anaesthetics?

An anaesthetic is a mixture of drugs that combine to create a loss of sensation for the patient – either all over the body or in a specific area. Here is a run-down of the different options:

General anaesthetic – this form of anaesthetic sends the patient into a deep sleep so they are unable to feel anything. They will be oblivious to what is happening while they are asleep and will not know what has happened when the anaesthetic wears off.

Epidural/spinal anaesthetic – these types of anaesthetics are administered with an injection into the spinal cord. It causes numbness and a loss of sensation in specific areas of the body.

Local anaesthetic – this type of anaesthetic has a far more localised effect as it is administered near the specific area that is to be operated on. It can also be used to stop the feeling in an arm or leg – this is called a nerve block.

Your Consultant will provide you with a breakdown of the different anaesthetic options available to you and provide a professional recommendation as to which option to choose. It is, however, your choice as to what form of anaesthesia to have.

What are the benefits to anaesthetics?

The main reasons behind requiring an anaesthetic are:

  • Needing to have an operation or painful procedure. In order for the surgeon or doctor to be able to perform an operation or procedure safely and effectively you will need to be in a state where you do not move and the muscles are relaxed; anaesthetics can help with this and will also mean you feel nothing as the operation takes place.
  • If you have already had an operation or procedure, or suffer from an existing condition and are in pain, then anaesthetics can help alleviate this.

Who provides the anaesthetics?

For a general, spinal or epidural anaesthetic, an anaesthetist (specially trained consultant in the field of anaesthetics) will administer the drugs. Other healthcare professionals will also be present. Local anaesthetic, on the other hand, can be administered by either an anaesthetist or another healthcare professional, such as consultant or surgeon.

How are the general anaesthetics given?

They can either be administered as an injection or inhaled in gaseous form. If they are injected, it will be done with a drip injected into a vein; with gas, it will be inhaled with the use of a facemask. Both methods take 30 seconds to work quickly and will put the patient to sleep. To ensure you remain fully unconscious as the procedure or operation continues, small doses of anaesthetic may be injected or inhaled throughout. Once the operation or procedure has finished then the anaesthetic will be eased off and you will be slowly woken up. In some cases, patients will be given extra painkillers after the operation to help with any pain or nausea.

How are epidural and spinal anaesthetics given?

Epidural anaesthetics numb the nerves and this is what provides pain relief. A small tube known as a catheter will be inserted into the epidural space of the spinal cord.

An epidural catheter being inserted

  1. A needle is inserted into the back
  2. When the needle reaches the epidural space the position is checked
  3. A catheter is inserted into the epidural space and the needle removed

A vast majority of the body’s nerves pass in and out of this space, so when the local anaesthetic is injected here it provides an effective loss of sensation all over. An infusion may be used to provide continual pain relief – this is when a small amount is continually injected. Sometimes, a few different injections will be made for the same effect. For a spinal anaesthetic the drugs are injected only once, into the fluid bag that encompasses the spinal cord.


Figure 1

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How are local anaesthetics administered?

Local anaesthetics work in only one very specific area; they will be injected near the point where the operation or procedure is due to be performed. Whilst this can sting/burn initially, this sensation will soon pass as the area numbs. Nerve blocks are another form of local anaesthetic that can cause a loss of sensation in an arm or leg, for example. Anaesthetic is injected into the major nerves connected to the part of the body that is to be operated on. It is possible to have a few different forms of anaesthesia in order to make the operation/procedure as painless and comfortable as possible. Local anaesthetic is sometimes administered before a general anaesthetic.

How safe are anaesthetics?

For most people, having an anaesthetic and pain relief is safe. It is normal for a few routine tests to be performed before general anaesthetic is approved. These tests will allow the anaesthetist and healthcare team to ascertain the best course of action for each individual case. Sometimes you may be asked to work on your overall health prior to an operation; conditions that may need better monitoring include high blood pressure, diabetes, angina, anaemia and asthma.

How can I help make the operation successful?

Staying warm is very important as coldness can cause complications like heart difficulties and sometimes infection of the surgical site. Extra clothing like jumpers and a dressing gown should be brought to the hospital; during the operation the anaesthetist will keep you warm.Stopping smoking, keeping fit and losing excess weight can all help to improve the chances of a successful operation and also improve long-term health. Always seek advice from your consultant before beginning any exercise programme.

Are there any potential complications with this surgery?

Most surgical procedures carry some level of risk or possible complication. These will be discussed with you by your consultant or pre-assessment nurse prior to your procedure.


There are various forms of anaesthetics available to you and each will provide safe and effective pain relief for whichever operation or procedure needs to be performed.Some complications can arise from the use of anaesthetics but they are rare; understanding the risks will allow you to make an educated decision on which form of anaesthetic is best for you.

References: EIDO Healthcare Limited – The operation and treatment information on this website is produced using information from EIDO Healthcare Ltd and is licensed by Aspen Healthcare.

The information should not replace advice that your relevant health professional would give you.