Anaesthesia explained

Published: 02/08/2019

In the operating theatre

When your anaesthetist is satisfied that your condition is stable, the monitors will be briefly disconnected and you will be taken into the theatre. Your anaesthetist will stay with you and will constantly be checking that you are responding well to the anaesthetic.

Compulsory checks 

Before the operation begins, the whole team take a moment to make final checks on your care. The World Health Organization (WHO) recommends that these checks happen before every operation.

Why is there tape on the eyes? 

Most people do not close their eyes naturally when they have a general anaesthetic. This means there is a risk that something may brush against the open eye. Also, the cornea (clear surface of the eye) will dry out. Both these put you at risk of small grazes on the cornea. Tape or eye ointments prevent this.

More information about general anaesthesia  

These are some of the drugs that you may receive during a general anaesthetic.  

Anaesthetic drugs or gases 
  • Injected drugs are given into your cannula. The most commonly used is called propofol. It is a white liquid.
  • Anaesthetic gases. There are several of these – the commonest in the UK are sevoflurane and isoflurane. 

You will receive one of these continuously, to keep you unconscious as long as the operation lasts.

Pain relieving drugs 

These are given to reduce your body’s reaction to the surgery, as well as to provide pain relief afterwards. 

Muscle relaxants

These are needed for certain operations only. They relax the muscles completely and the anaesthetist uses a ventilator to do the breathing for you. At the end of the operation, you will not be woken up until the anaesthetist is sure they have worn off. 

Other drugs
  • Antibiotics to prevent infection.
  • Anti-sickness drugs.
  • Paracetamol to help with pain relief. 
  • Drugs to treat low blood pressure.

Other care you will receive 

Your anaesthetist shares responsibility with the surgeon and the theatre team for your overall wellbeing in the operating theatre.

Keeping you warm 

The team will take care to keep you as warm as possible. They will measure your temperature during the operation, and warming blankets are used if possible. For more information, please see our leaflet on shivering.

Protecting pressure points 

Your anaesthetist will also make sure that you are positioned as comfortably as possible. Bony parts such as your  heels and elbows will be cushioned.

Preventing blood clots 

As well as surgical stockings, the theatre team may also use wraps around your calves or feet which inflate every now and then to move the blood around in your legs.

Having a regional or local anaesthetic 

These anaesthetics are started in the anaesthetic room or in the operating theatre. There are many kinds of regional or local anaesthetic. Almost all types involve an injection. You will be awake for the injection unless you have asked to have sedation.

Spinal or epidural anaesthetic 

These are used for operations on the lower half of your body. They both involve an injection in the back. 

  • A spinal anaesthetic is a single injection which makes you numb for about two hours.
  • An epidural is when a needle is used to place a very fine tube (epidural catheter) in your back. ‘Top-up’ local anaesthetic is given for pain relief through the catheter, which can make the numbness last many hours or a few days. 
Starting a spinal anaesthetic

You will normally have the injection sitting or lying on the trolley or operating table. The anaesthetist and the team will explain what they want you to do. 

The injections are done in a very clean (sterile) way – just like an operation.

Local anaesthetic is given into the skin to reduce the pain of the injection. Your anaesthetist will ask you to stay as still as possible and to tell them if you feel any tingling or shock sensations. It can take more than one attempt to get the needle in the right place. If you find this difficult, tell your anaesthetist as there are things they can do to help,  including switching to a different kind of anaesthetic.

You may notice a warm tingling effect as the anaesthetic starts to take effect. The anaesthetist will not let the operation begin until they are satisfied that the area is numb. 

For more information, please see our patient information leaflets on Your spinal anaesthetic and Epidural pain relief after surgery.

Other types of regional anaesthetic 

Other regional anaesthetics involve an injection placed near to a nerve or group of nerves. This is often called a ‘nerve block’. This can allow you to have the operation without a general anaesthetic. Or, if you want a general anaesthetic, you can have a nerve block also, for longer-lasting pain relief.

A nerve block is useful for: 

  • operations on the arm or lower leg
  • operations on the artery in the neck, and
  • operations on the abdomen, where a nerve block can be used for extra pain relief, but a general anaesthetic will always be needed as well.

Ultrasound guidance 

Anaesthetists often use an ultrasound machine to identify the exact position of the nerves. 

Your anaesthetist will ask you to tell them if you feel any tingling or sharp pains during the injection. 

These injections can be done using a nerve stimulator instead of an ultrasound image. For more information see our leaflet on Nerve blocks for surgery on the shoulder, arm or hand.

In the operating theatre with a regional anaesthetic 

The operating theatre is often a busy place, with staff bustling about getting ready for your operation. Music may be playing. Staff will move you across onto the operating table. The monitoring equipment will be reconnected and ‘bleeps’ will start indicating your pulse. A blood-pressure cuff on your arm will take your blood pressure regularly. 

A cloth screen is used to shield the operating site, so you will not see the operation unless you want to. Your anaesthetist is always nearby and you can speak to them when you want to.

Recovering from a regional anaesthetic

It will take some hours for feeling to return to the area of your body that was numb. This ranges from one hour to about 18 hours depending on the type of nerve block you have had. 

During this time staff will make sure that the numb area is protected from injury. 

You can expect tingling as the feeling returns. This passes within the first hour, but then you will feel the pain of the operation. You should tell staff immediately so they can give you some pain relief medicine.