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Anaesthesia (General)

This information was published by Bupa's Health Content Team and has been reviewed by appropriate medical or clinical professionals. To the best of their knowledge the information is current and based on reputable sources of medical evidence, however Bupa (Asia) Limited makes no representation or warranty as to the completeness or accuracy of the Content.

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When you have a general anaesthetic, you will be asleep before your operation begins and will wake up afterwards with no memory of the procedure.

Your anaesthetist is present throughout your time in the operating theatre and will give various drugs so that you are comfortably asleep during the operation and wake up promptly when it is over, feeling the minimum amount of pain.

The anaesthetist is also in charge of monitoring and controlling your breathing, heart beat and other vital body functions during the operation so that the surgeon can concentrate on the surgery. All anaesthetists are doctors and have additional specialist qualifications.

Your anaesthetist will visit you in your room before the operation starts. He or she will ask you about your health and about any previous experience you have had of operations or anaesthesia. Its particularly important that you tell the anaesthetist about any medicines, prescribed or over-the-counter, that you are taking. Also tell the anaesthetist about any caps, crowns or dentures you have so that extra care can be taken to protect these when masks and tubes are fitted.

You will be given specific advice about this from the hospital. In general, you should not eat for about six hours before surgery so that your stomach is empty. This reduces the chance of complications caused by being sick during the operation. Sipping clear fluids up to two hours before your operation is usually allowed.

To get ready for surgery, you may be asked to put on a surgical gown and some elastic stockings. These are worn from the knee down and help to maintain the circulation in the veins of your lower legs, so helping to prevent blood clots from forming.

Lastly, many people may be nervous before an operation and you may be offered a pre-medication. This is a drug given as tablets, liquid or by injection. It relieves anxiety and makes you feel relaxed. It can also make you feel quite sedated or even out of it.

Modern anaesthetics are so safe, rapidly acting and effective that most people do not need pre-medication, especially for procedures that do not require an overnight stay. You can discuss this with your anaesthetist.

The operating theatres are usually in a separate area of the hospital - the theatre suite or operating block. You will normally travel from your room to the theatre on a bed or trolley.

At the entrance to this area, you will be handed over to a theatre nurse or theatre technician. At this point in the journey you will be awake.

From the entrance to the theatre suite, you will be taken to the anaesthetic room. This connects with the operating theatre. A technician or a nurse will help the anaesthetist prepare you for the operation.

The anaesthetist will insert a narrow plastic tube - called a cannula - into a vein on the back of one of your hands. This is a sharp sensation, like an injection, that passes quickly. With the cannula in place, the anaesthetist can give the various drugs that put you to sleep and control pain and nausea, without repeated injections. For certain operations, you will also be given a water-based drip into another vein to help prevent you becoming dehydrated.

For most operations, the anaesthesia is started with a drug injected through the cannula. Within seconds of having this, you will fall asleep and wont wake up again until after the operation is complete.


When the operation is finished, you will be moved to the recovery room where a nurse provides one-to-one care. This is where you will wake up from the anaesthetic. The care includes constant monitoring of your heart rate, breathing, blood pressure and other vital body functions. Its routine to be given oxygen through a face mask.

Its normal to feel sleepy or disorientated in the first 15 minutes or so after you first come round. You may also have a sore throat caused by the tube that was placed there to keep your airway open. You may feel sick, although preventive medicines are now given routinely for many procedures. You should not experience serious pain.

Returning to your room

Once you have recovered from the anaesthetic, and the anaesthetist is happy with your progress, the connections to the monitoring equipment will be taken off. You will then be able to return to your room on the trolley or bed.

When you no longer need intravenous medicines or fluids, the cannula or drip will be removed.

After complex operations you may need further close monitoring. This takes place in a high dependency ward where one nurse looks after no more than two patients at a time. Attachment to the monitoring machines and connection to a drip will be continued.

Pain relief

This is also known as analgesia. Depending on the type of operation you have had, you may need pain relief medication which will be tailored to the expected amount of pain you may experience. This is often simple painkillers such as paracetamol, but for more severe pain, there are other drugs available.

Controlling pain after an operation is very important as pain can interfere with your recovery.

Patient-controlled analgesia (PCA)

PCA is used for some but not all procedures. It consists of a pump connected to a vein in your hand or arm that allows you to regulate how much medication you receive. Patients who are in control in this way tend to use a smaller amount of pain relief medicine than if its administered in set doses at regular intervals.

You will be shown how to use the pump, which is usually operated by a simple button. Its designed so that you cannot take a harmful amount of the painkiller.

Going home

If your operation has been planned as a day case, you will need to rest on your bed for a couple of hours or so before going home.

Modern anaesthetics are quickly flushed out of your system. However, you should follow the advice of the nurses about how much activity you should do and this will depend on the type of operation you have had.

Get someone to drive you home and avoid operating machinery or making important decisions in the 24 hours after your operation.

Once you get home, you can ring the hospital for information or advice at any time.

Anaesthesia has made surgery much safer. The routine use of high technology, such as equipment that constantly measures the amount of oxygen in the blood, has made it safer still.

However, there are still some risks. These can be divided into the risk of side-effects and the risk of complications.


These are unwanted but mostly temporary effects of successful treatment. You may feel tired for a day or so after a general anaesthetic, but this may also be part of the body's normal response to surgery. You may also find your memory and concentration are worse than usual for a while.


Serious complications, and death, as a result of anaesthesia do occur, but they are very rare. Older people in good health are not necessarily at higher risk than younger people. Your anaesthetist will be willing to discuss how these risks affect you.

The exact type of anaesthesia you are given depends on the procedure you are having. After you have been put off to sleep, general anaesthesia typically includes an inhaled gas that is a modern form of ether, plus a strong painkiller. Depending on the site of the operation you may also get a drug that relaxes your muscles.

Once you are asleep, a flexible tube may be put into your throat to allow oxygen and anaesthetic gas to flow freely into your lungs.

Throughout the procedure, the anaesthetist will use electronic monitoring equipment to constantly check the amount of oxygen reaching your bloodstream. The amounts of other gases in the air you breathe in and out, including the anaesthetic and carbon dioxide, are also measured.

Your blood pressure and pulse rate will be constantly supervised.

As well as the gas that keeps you asleep, the anaesthetist may give you a number of other drugs. These ensure that when you wake up any pain is controlled. Other drugs help avoid the nausea (feeling sick), or vomiting, that can be caused by some anaesthetics or surgery.

When the surgery is complete, the anaesthetist will start your wake up from anaesthesia. This is known as recovery and begins when the anaesthetic gases or drugs are stopped. You will also be given a drug to reverse the effects of any muscle relaxant. If you have a tube in your throat this will be taken out as you wake up and a mask will be put over your face to provide oxygen.


American Society of Anesthesiologists

The Association of Anaesthetists

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