General anaesthesia

Published by Bupa’s Health Information Team, February 2011.

This factsheet is for people who are having general anaesthesia, or who would like information about it.

Anaesthesia describes a state or episode where there is a loss of feeling or sensation. General anaesthesia is a state of controlled sleep (unconsciousness).
You will meet the anaesthetist carrying out your procedure to discuss your care. It may differ from what is described here as it will be designed to meet your individual needs.

About general anaesthesia

The word ‘anaesthesia’ comes from a Greek word meaning absence or loss of sensation. Anaesthesia is one of the most important developments of modern medicine because it allows once unbearable medical procedures to be performed without discomfort.

An anaesthetic is the medicine used to produce the absence or loss of sensation.

For general anaesthesia, you will be given a combination of medicines to stop the messages from your nerves being recognised by your brain. This means when you’re under general anaesthesia you will be in a state of controlled sleep (unconsciousness).

You won’t respond to pain or remember what happened during your procedure.

What are the alternatives?

General anaesthesia isn’t suitable for everyone. Regional (local) anaesthesia with or without sedation may be used instead. This completely blocks pain from a large part of the body, such as below the waist and you will stay awake during the procedure. A sedative relieves anxiety and helps you to relax.

Your anaesthetist will discuss with you which type of anaesthesia is most suitable for you.

Preparing for your general anaesthesia

Your surgeon will explain how to prepare for your procedure. For example, if you smoke, you will be asked to stop as smoking increases your risk of getting a chest and wound infection, which can slow your recovery.

You will be asked to follow fasting instructions. This means not eating or drinking, typically for about six hours beforehand. However, it’s important to follow your anaesthetist’s advice.

You must 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.

Your surgeon or anaesthetist will ask you about your medical history. You should 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 he or she may need to put a tube in your throat to help you breathe while you’re under general anaesthesia. If you wear contact lenses, glasses, dentures or hearing aids, you will need to remove them.

Your surgeon or anaesthetist will discuss with you what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen, and you can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.

Your nurse will prepare you for theatre. You may be given pre-medication, although it is rarely used. The aim of pre-medication is to ensure you arrive at the theatre in a relaxed frame of mind. However, you will usually only be given pre-medication if you have severe anxiety.

You may be asked to wear compression stockings to help prevent blood clots forming in the veins in your legs. You may need to have injections or tablets of anti-clotting medicines as well as, or instead of, wearing compression stockings.

You will be taken from your room to a side-room next to the theatre. Your anaesthetist will insert a fine plastic tube (called a cannula) into one of your veins usually on the back of your hand. This causes a sharp sensation, like an injection, which passes quickly.

The cannula allows your anaesthetist to give you medicines and fluids without repeated injections.

What happens during general anaesthesia

Your anaesthetist will usually give you the anaesthetic through the cannula. Within a minute or so you will fall asleep and won’t wake up until after your procedure.

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 procedure.

While you’re under general anaesthesia, your anaesthetist may give you the following.

• A continuous infusion of anaesthetic through a drip or a mixture of oxygen and anaesthetic gases to keep you asleep during your procedure.
• Strong painkillers to prevent pain after the procedure.
• Medicines to relax your muscles, so that the surgeon can operate more easily.
• Antibiotics to prevent infection.
• Anti-sickness medicines to prevent sickness after the procedure.

While you’re 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. You may have a tube in your airway to help you breathe during the procedure.

What to expect afterwards

Immediately after your procedure you will be moved into a recovery room. As soon as the anaesthetic is stopped, you will begin to wake up. If you have a tube in your airway, this will be taken out as you wake up and you will be given oxygen to breathe through a facemask.

A nurse will 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 or ward.

You will need to rest until the effects of the anaesthetic have passed. You may need pain relief to help with any discomfort as the anaesthetic wears off.

The care you receive after this will depend on the type of procedure you have and your individual needs. If you have a day-case procedure, your nurse will remove the cannula and offer you something to eat or drink. You will usually be able to go home when you feel ready.

You will need to arrange for someone to drive you home. Try to have a friend or relative stay with you for the first 24 hours.

Recovering from general anaesthesia

General anaesthesia temporarily affects your co-ordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. If you’re in any doubt about driving, contact your motor insurer so that you’re aware of their recommendations, and always follow your doctor’s advice.

What are the risks?

There are some risks associated with having general anaesthesia. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your surgeon to explain how these risks apply to you.

Side-effects

Side-effects are the unwanted but mostly temporary effects you may get after having general anaesthesia. Side-effects of general anaesthesia may include:

• feeling sick and vomiting after surgery
• shivering
• sore throat
• headache
• feeling tired and confused

Complications

Complications are when problems occur during or after general anaesthesia. Specific complications of general anaesthesia are uncommon but can include the following.

• An allergic reaction. Signs of an allergic reaction include tingling lips, skin rash and difficulty in breathing. Medicines are available to help treat this.
• Difficulty in breathing. While you’re under general anaesthesia, your doctor will constantly monitor the amount of oxygen in your blood and you may be given extra oxygen if required.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.