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Published by Bupa's health information team, May 2009.
This factsheet is for people who are planning to have general anaesthesia, or who would like information about it.
General anaesthesia stops pain during surgery and other medical procedures by blocking pain signals from being carried by nerves to the brain. A person having general anaesthesia will be asleep during the procedure.
Your care will be adapted to meet your individual needs and may differ from what is described here. So it's important that you follow your anaesthetist's advice.
About general anaesthesia
The word 'anaesthesia' comes from a Greek word meaning absence or loss of sensation. Anaesthesia is one of the most significant developments of modern medicine because it allows once unbearable medical procedures to be performed while you're relaxed and/or asleep.
If you have a general anaesthetic, you will be asleep during the operation/procedure. When you have a general anaesthetic you won't feel or remember the operation. Anaesthetic medicines stop the messages from your nerves being recognised by your brain.
What are the alternatives to general anaesthesia?
General anaesthesia isn't suitable for everyone. There are other types available, such as regional anaesthesia. This completely numbs parts of your body but you stay awake or are lightly sedated. Your anaesthetist will discuss with you which type of anaesthesia is most suitable for you.
Preparing for your general anaesthesia
You will be asked about your health and about any previous hospital treatment you have had. It's important that you tell your anaesthetist about any allergies that you have and whether you have asthma, hay fever or eczema, and about any medicines that you're taking (whether prescribed, herbal or over-the-counter).
You should tell your anaesthetist if you have any dental crowns, bridges or loose teeth, as these could be damaged by the tube in your mouth while you're asleep. If you wear contact lenses, glasses, dentures or hearing aids you will need to remove them.
If you smoke you will be asked to stop, as smoking increases your risk of breathing problems during and after general anaesthesia. It's best to stop smoking at least two weeks prior to your operation to allow time for phlegm to be cleared from your lungs.
You will be asked to follow fasting instructions. Typically you must not eat for six hours before a general anaesthetic. Your anaesthetist will allow you to drink water and water-based drinks (not milk) until two hours beforehand. It's important to have an empty stomach when you have a general anaesthetic so that you're less likely to be sick. Vomiting while you're unconscious can be dangerous because you can't cough, so fluid from your stomach could get into your lungs.
Most people are anxious before an operation. Pre-medication drugs that help to relieve anxiety (sedatives) may be offered to you. You can discuss this with your anaesthetist beforehand.
At the hospital your nurse will explain how you will be cared for during your stay. Your nurse may check your heart rate and blood pressure, and test your urine.
Your surgeon will usually ask you to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.
You will be taken from your room to the operating room (theatre) where you will be met by a member of the theatre team.
He or she will insert a narrow plastic tube (called a cannula) into one of your veins, usually on the back of your hand or in your arm. This causes a sharp sensation, like an injection, which passes quickly.
With the cannula in place, this allows the anaesthetist to give you the drugs needed to put you to sleep and to control pain and sickness, without repeated injections. Your anaesthetist may also give you fluids through a drip into your cannula to keep you hydrated.
About your general anaesthesia
The exact type of anaesthetic you will be given depends on the procedure you're having. For most operations, your anaesthetic drug will be injected through the cannula in your hand or arm. Within seconds you will fall asleep and won't wake up again until after your operation is completed. Alternatively, your anaesthetist may ask you to breathe in anaesthetic gases and oxygen through a mask attached to your face, or which you can choose to hold. Your anaesthetist will stay with you during your operation.
To keep you asleep during your operation, your anaesthetist will either give you a mixture of oxygen and anaesthetic gases or a continuous infusion of anaesthetic through a drip.
To help control pain during and after surgery, your anaesthetist may give you strong painkillers. These can be injected through your cannula, or given as a suppository - a tablet inserted into your rectum (back passage).
Depending on your particular operation you may also be given a medicine to relax your muscles, so that the surgeon can operate more easily.
While under general anaesthesia, you will be connected to machines that monitor the activity of your heart and other body systems. Your anaesthetist will keep a close check on your heart rate, blood pressure and the amount of oxygen in your bloodstream.
What to expect afterwards
When the anaesthetic gases are stopped, you will usually begin to wake up or recover quite quickly. However, it may be necessary to keep you anaesthetised after your procedure, for example if you're being transferred to the intensive care unit (ICU). You will be given a medicine to reverse the effects of any muscle relaxant.
The theatre staff will move you to a recovery room where a nurse will take care of you. If you have a tube in your throat, this will be taken out as you wake up and you will be given oxygen to breathe through a face mask. Your nurse will continue to monitor your heart rate, blood pressure and other vital body functions.
You may feel sleepy or disorientated for 15 minutes or so and you may have a sore throat. You may also feel sick, but medicines are usually given to make this less likely.
Once your anaesthetist is happy with your progress, your nurse will disconnect the monitors and take you back to your room on a trolley or bed. When you no longer need them, your nurse will remove your cannula and drip.
Depending on the type of operation you have had, you may need pain relief to help with any discomfort as the anaesthetic wears off. Pain can interfere with your recovery, so it's important that you discuss any discomfort with your nurse or doctor. Before your operation, ask your anaesthetist what pain control options will be available to you.
Sometimes, local or regional anaesthesia is used to relieve pain, most commonly in the form of nerve blocks or epidurals. Patient-controlled analgesia (PCA) is another option. This is a pump connected to your cannula that allows you to control how much pain control medication you receive.
If your operation is planned as a day case, you will need to rest until the effects of the general anaesthetic have passed. You should follow the advice of your anaesthetist and nurse about how much activity you can do.
You will need to arrange for someone to drive you home. You should try to have a friend or relative stay with you for the first 24 hours.
Your nurse will give you some advice about caring for your healing wounds before you go home. You may be given a date for a follow-up appointment.
Recovering from general anaesthesia
General anaesthesia temporarily affects your coordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 48 hours afterwards. If you're in any doubt about driving, always follow your surgeon's advice and please contact your motor insurer so that you're aware of their recommendations.
What are the risks?
General anaesthesia is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.
Side-effects of general anaesthesia
These are the unwanted, but mostly mild and temporary effects of a successful anaesthesia.
feeling sick and vomiting after surgery
feeling tired and confused for a couple of days
Complications of general anaesthesia
This is when problems occur during or after the anaesthesia. Most people aren't affected.
Serious complications are extremely rare. They include:
damage to teeth, lips or tongue
The exact risks are specific to you and differ for every person, so we haven't included statistics here. Ask your anaesthetist to explain how these risks apply to you.
General anaesthesia Q&As
See our answers to common questions about general anaesthesia, including:
- Anaesthesia explained. Royal College of Anaesthetists. 2008. www.rcoa.ac.uk
- Brady M, Kinn S, Stuart P. Preoperative fasting for adults to prevent perioperative complications. Cochrane Database of Systematic Reviews 2003, Issue 4. Art. No: CD004423. DOI: 10.1002/14651858.CD004423. www.cochrane.org
- Gan TJ, Meyer T, Apfel CC, et al. Consensus guidelines for managing postoperative nausea and vomiting. Anesth Analg 2003; 97:62-71. www.anesthesia-analgesia.org
- De Witte J, Sessler DI. Perioperative shivering. Physiology and pharmacology. Anesthesiology 2002; 96:467-484. www.anesthesiology.org
- Higgins PP, Chung F, Mezei G. Postoperative sore throat after ambulatory surgery. Br J Anaesth 2002; 88:582-584. http://bja.oxfordjournals.org
- Bryson GL, Wyand A. Evidence-based clinical update: general anesthesia and the risk of delirium and postoperative cognitive dysfunction. Can J Anesth 2006; 53:669-677. www.cja-jca.org
- Selwood A, Orrell M. Long term cognitive dysfunction in older people after non-cardiac surgery. BMJ 2004; 328:120-121. www.bmj.com
- Cheney FW, Domino KB, Caplan RA, et al. Nerve injury associated with anesthesia: a closed claims analysis. Anesthesiology 1999; 90:1062-1069. www.anesthesiology.org
- Cucchiara RF, Black S. Corneal abrasion during anesthesia and surgery. Anesthesiology 1988; 69:978-979. www.anesthesiology.org
- Warner ME, Benenfeld SM, Warner MA, et al. Perianesthetic dental injuries: frequency, outcomes and risk factors. Anesthesiology 1999; 90:1302-1305. www.anesthesiology.org
- Personal communication, Dr Graeme Sanders, FRCA, Spire Alexandra Hospital, 22 January 2009
- Allman KG, Wilson IH. Oxford Handbook of Anaesthesia. 2nd ed. Oxford: Oxford University Press, 2006:8
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: May 2009