General anaesthesia makes you both unconscious and unable to feel pain during medical procedures. General anaesthesia is commonly produced by a combination of intravenous drugs and inhaled gas (anaesthetics).

The "sleep" you experience under general anaesthesia is different from regular sleep. The anaesthetized brain doesn't respond to pain signals or surgical manipulations.

An anaesthetist is a specially trained doctor who specializes in all types of anaesthesia, including general anaesthesia. After you're asleep (unconscious), your body's vital functions are monitored and your breathing is assisted and controlled.

There are different methods to administering anaesthesia, such as:

In most cases, your anaesthetist delivers the anaesthesia medications through an intravenous line in your arm, but sometimes the anaesthesia may be given as a gas that you breathe from a mask. For example, children may prefer to go to sleep with a mask.

Once you're asleep, a tube may be inserted into your mouth and down your windpipe to ensure you get enough oxygen and to protect your lungs from blood or body secretions, such as from your stomach. You'll be given muscle relaxants before doctors insert the tube, to relax the muscles in your windpipe. In some cases this breathing tube isn't needed, which reduces your chance of a sore throat after surgery.

Your doctor may use other options, such as a laryngeal airway mask, to help manage your breathing during surgery.

A member of the anaesthesia care team monitors you continuously during your procedure, adjusting your medications, breathing, temperature, fluids and blood pressure as needed. Any abnormalities that occur during the surgery are corrected by administering additional medications, fluids and, sometimes, blood transfusions.

Blood transfusions may be necessary in some situations, such as complex surgeries. Anaesthetists and other members of the anaesthesia care team monitor your condition and deliver blood transfusions when necessary. However, blood transfusions may involve risks, particularly in people who are older, who have low blood red cell volume or who are undergoing complex heart surgeries.