Dr Bikash Agarwal
Consultant anaesthetist

What is anaesthesia?

 

‘Anaesthesia’ is derived from the Greek word meaning ‘without sensation’.

​

The term is applied to medications which can produce anaesthesia, as well as to the whole process that patients undergo when having surgical and other medical procedures. People often describe ‘anaesthesia’ as being ‘put to sleep’. This is not strictly true: in ‘general anaesthesia’, anaesthetists in fact place their patients into a state of carefully controlled unconsciousness so that they will be unaware and not feel pain.

​

Anaesthetic medications

​

Many people think that having an anaesthetic consists of just a needle, which the anaesthetist injects to make you ‘go to sleep’; after this the anaesthetist leaves you and you ‘wake up’ when the operation is over. In fact, as well as constantly looking after you during your anaesthetic, your anaesthetist gives you quite a few medications – usually somewhere between three and fifteen – all for different reasons.

​

There are four main types of medications used in anaesthetics:

• Induction medications - to produce unconsciousness

• Analgesics - to provide pain relief 

• Muscle relaxants - to induce muscle relaxation

• Inhalational anaesthetics - to keep you unconscious 

​

Other medications which are given include:

• medications that produce short-term memory loss or amnesia

• medications that minimise nausea and vomiting (anti-emetics)

• medications that counter-act the effect of other medications (antagonists)

• and medications that suppress certain nervous reflexes, such as slowing of the heart.

​​

Also, some patients may not have a general anaesthetic but may remain conscious, with part of their body made numb by the use of local anaesthetics.

​

Your anaesthetist may use other medications to decrease the chance of you remembering anything that happens in the Operating Room. Some medications may also be given to counteract the effects of other medications.  Medications can also be used to to control your heart rate and blood pressure.

​

Sedation - The anaesthetist administers drugs to make you relaxed and drowsy. This is sometimes called ‘twilight sleep’ or ‘intravenous sedation’ and may be used for some eye surgery, some plastic surgery and for some gastroenterological procedures. Recall of events is possible with ‘sedation’. Most patients prefer to have little or no recall of events. Please discuss your preference with your anaesthetist.

​

Three types of anaesthesia

​

The type of anaesthesia used will depend on the nature and duration of the procedure, your general medical condition, and your preference and those of your anaesthetist and surgeon or other doctor performing the procedure.

​

The three types of anaesthesia are general, regional and local. All three involve the administration of drugs to produce a change in sensation and they are frequently used in combination.

​

• General anaesthesia - You are put into a state of unconsciousness for the duration of the operation. This is usually achieved by injecting drugs through a cannula placed in a vein and maintained with intravenous drugs or a mixture of gases which you will breathe. While you remain unaware of what is happening around you, the anaesthetist monitors your condition closely and constantly adjusts the level of anaesthesia. You will often be asked to breathe oxygen through a mask just before your anaesthesia starts.

• Regional anaesthesia - A nerve block numbs the part of the body where the surgeon operates and this avoids the need for general anaesthesia. You may be awake or sedated (see below). Examples of regional anaesthesia include epidurals for labour, spinal anaesthesia for caesarean section and ‘eye blocks’ for cataracts.

• Local anaesthesia - A local anaesthetic drug is injected at the site of the surgery to cause numbness. You will be awake but feel no pain. An obvious example of local anaesthesia is numbing an area of skin before having a cut stitched.

 

​

​

​