Anaesthesia explained

Published: 01/03/2021

In the operating theatre

When you are fully anaesthetised, the anaesthetic team will take you into the operating theatre.

Compulsory checks 

Before the operation begins, the NHS requires that the whole team has to make final checks on you, your care and the equipment for the procedure..

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.

For more information see our leaflet Damage to the eye during general anaesthesia.

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 through your cannula into your blood. The most commonly used is called propofol. It is a white liquid given in carefully controlled amounts.
  • Anaesthetic gases. There are several of these – the most common in the UK are sevoflurane and isoflurane.

You will receive one of these drugs continuously, to keep you unconscious as long as the operation lasts. The amount of anaesthetic you receive is closely monitored.

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 that the drugs have worn off.

Other drugs
  • Antibiotics to prevent infection.
  • Anti-sickness drugs.
  • Paracetamol and other drugs 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 your body temperature as close to normal as possible. They will measure your temperature during the operation, and will use warming mats or other equipment as needed.

For more information, please see our risk 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. Other parts will also be protected to reduce the risk of any damage to nerves.

For more information, please see our risk leaflet on Nerve damage associated with an operation under general anaesthetic.

Preventing blood clots 

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

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. All types involve an injection of local anaesthetic drug. You will be awake for the injection unless you have asked to have sedation. Regional anaesthesia provides pain relief on its own for operations such as caesarean section, hip or prostate surgery. Alternatively, you may have a regional as well as a general anaesthetic to help with pain relief after an operation. For example, this may be helpful in major bowel surgery.

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 up to two hours. Strong pain killers can be added to the local anaesthetic.
  • An epidural is a fine, flexible tube placed in the back near the nerves coming from the spinal cord, through which pain-killing drugs can be given to give pain relief.
  • ‘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 how to get into the right position.

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 several attempts to get the fine needle in the correct position. 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 before your legs and lower part of your body become numb. You will usually have little movement in your legs. The anaesthetist will only allow the surgery to begin when they are satisfied that the anaesthetic is working.

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

Other types of regional anaesthetic 

Other regional anaesthetics often involve an injection placed near to a nerve or group of nerves. This is called a ‘nerve block’. This can allow you to have the operation without a general anaesthetic. Or, you can have a nerve block as well as a general anaesthetic 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, alongside a general anaesthetic.

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 the leaflet 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 may need to move you from the trolley across to 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 regional anaesthetic you have had.

During this time, staff will explain to you how to 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 if you then feel the pain of the operation you should tell staff immediately so they can give you some pain-relief medicine.