All about anaesthesia

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Modern anaesthesia is very safe and modern surgery would not be possible without developments in anaesthesia.

Most people experience an anaesthetic at some time in their lives and some undergo anaesthesia many times.

It is normal for people to be uneasy about having an anaesthetic.

This section of our website explains what anaesthesia is, how anaesthetics are given, and how anaesthetists care for you.

You can also learn how anaesthetics affect you and how you can affect your anaesthetic.

‘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.

What is an anaesthetist?

Anaesthetists are medical doctors with at least five years of specialty training, in addition to medical school attendance followed by at least two years hospital training residency before commencing anaesthesia specialist training.

“A specialist anaesthetist is a fully qualified medical doctor who, after obtaining their medical degree, has spent at least two years working in the hospital system before completing a further five years of training in anaesthesia.” (The Australian and New Zealand College of Anaesthetists, ANZCA)

Clinical anaesthesia is built on the knowledge of physiology (how the body works) and pharmacology (how medications work in the body). Anaesthetists have an extensive knowledge of
medicine and surgery and understanding of the basic sciences. They know how the body responds to anaesthesia and surgery, and how a patient’s health affects these responses.

In Australia and New Zealand, anaesthesia training is supervised and accredited by the Australian and New Zealand College of Anaesthetists (ANZCA). The training to become a specialist anaesthetist is equal in length to that of other medical specialists, such as surgeons, and includes intensive assessments, both at the hospitals where trainees work, and by written and verbal examinations. Doctors in the training program are called registrars. When a registrar completes their training and passes all examinations, they are awarded a diploma of fellowship of ANZCA, become Fellows of the College and may use the initials FANZCA after their name. They can then practise as a specialist anaesthetist in Australia and New Zealand.

Anaesthetists are perioperative physicians trained in all forms of anaesthesia and are members of multidisciplinary teams providing healthcare to patients. They assess patients before their procedures and play an important role in caring for the patient before, during and after surgery. They also provide anaesthetic care for patients undergoing non-surgical procedures, particularly if the procedures are long, complex or painful.

Anaesthetists play a pivotal role in resuscitating acutely unwell patients, including trauma victims, and help to manage patients suffering from acute or chronic pain. They also provide pain relief for women during labour and delivery.

Throughout their practice, anaesthetists must continue to update their skills by regularly attending professional development sessions. Anaesthetists must participate in a continuing professional
development (CPD) program that complies with ANZCA’s CPD standard in order for them to practise.

Anaesthetists can choose to become members of the Australian Society of Anaesthetists. The ASA is a not-for-profit member-funded organisation dedicated to supporting, representing and educating anaesthetists to ensure the safest possible anaesthesia for the community. 

Each year in Australia, anaesthetists have a crucial involvement in almost four million operations.

Anaesthesia is a word derived from the Greek, meaning ‘without sensation’. Anaesthesia may be applied to the whole body, when it is known as general anaesthesia, or to part of the body, when it is known as regional or local anaesthesia. All of these techniques involve giving specific drugs that interfere with the transmission of nervous impulses so as to reduce sensation. ‘Anaesthetic’ is the term applied to some or all of the drugs used to produce anaesthesia and is also used to describe the whole process. For example, one might say, ‘Mary had a general anaesthetic.’

If you live in Australia, Canada, New Zealand, South Africa, or the United Kingdom, your anaesthetic will most likely be given by a specialist doctor. Depending on the country, this specialist is known as the anaesthetist or anaesthesiologist or anesthesiologist.

After graduating from medical school, these doctors have undertaken several years’ additional training in anaesthesia. Anaesthetic training is usually under the direction of a professional body, such as the Australian and New Zealand College of Anaesthetists, the Royal College of Physicians and Surgeons of Canada, or the Royal College of Anaesthetists in the United Kingdom. The training varies in content and length, depending on the country in which it is undertaken. In those countries mentioned above, the training is for a minimum of several years and equal in length to that of other specialists, including surgeons. The process to become a specialist anaesthetist includes intensive assessment and written and verbal examinations. If successful in passing the examinations, the anaesthetist becomes a Fellow of the national professional accrediting body, such as one of the Colleges mentioned above.

In Canada and the United States of America, specialist anaesthetists are known as anesthesiologists. American anesthesiologists have always been known by this term, to distinguish these doctors from Certified Registered Nurse Anaesthetists or CRNAs (see below). There are no nurse anaesthetists practising in Canada, Australia, New Zealand or the United Kingdom.

In the United States, at the completion of anaesthetic training, the doctor takes a written examination. The successful candidate must then pass an oral examination to become a Board Certified anesthesiologist. In Europe and many other countries, specialist anaesthetists are known as anaesthesiologists. This again denotes the distinction from ‘nurse anaesthetists’ who practise with specialists in many European countries.

After qualification, anaesthetists are strongly encouraged to continue their education throughout their professional lives. Most Colleges or other regulatory and licensing bodies now require some on-going evidence that the anaesthetist is keeping up to date. The degree of professional regulation depends on the country in which the anaesthetist practises.

In Canada, the Canadian Anesthesiologists’ Society is a professional organisation that has undertaken development of Guidelines to the Practice of Anaesthesia. These provide recommendations as to how anaesthetics are given – for example, which monitors should be used during an anaesthetic. The Royal College of Physicians and Surgeons of Canada (RCPSC), which regulates training and certification of anesthesiologists, plays no further specific role in the regulation of anaesthetic practice. However, the RCPSC does direct a system of continuing medical education, to enable specialists to continue learning and keep up to date.

By way of contrast, in Australia and New Zealand, the College of Anaesthetists (ANZCA) has developed guidelines for anaesthetic practice. In addition, the College directs a Continuing Professional Development (CPD) program in which any anaesthetist can participate.

In some countries, non-specialist doctors may also give anaesthetics, most often in rural areas. Smaller communities depend on non-specialist anaesthetists because the amount of work available is not sufficient to support a full-time specialist. These doctors have not usually had full specialty training, and tend to give anaesthetics for less complex operations; however, they also participate in programs aimed at maintaining skills and knowledge. Many non-specialist anaesthetists also continue to work as Family or General Practitioners.

Non-medical practitioners

In some countries, particularly in Europe, nurse anaesthetists give anaesthetics under the supervision of a specialist anaesthesiologist. Often they will work as a team, with one nurse anaesthetist and one anaesthesiologist for each patient. In other areas, nurse anaesthetists give anaesthetics under the direction of the surgeon, cardiologist or radiologist who may be operating or performing a procedure on a patient at the same time. In a few countries, nurse anaesthetists are legally allowed to practise without any supervision by a doctor.

Other assistants

In the Operating Room, your anaesthetist usually has the help of an assistant. This person could be a nurse, respiratory therapist or an anaesthetic technician. Ideally, the assistant has undergone formal training and examination, although this is not always the case. Anaesthetists value good assistants, who carry out many differing tasks. These tasks include preparing and checking drugs and equipment, and obtaining extra equipment from outside the Operating Room. The assistant may also attach various monitors to patients, such as an automatic blood pressure cuff, and then may record heart rate, blood pressure and other measurements on the anaesthetic record. In addition, the assistant hands drugs or equipment to your anaesthetist, and is generally available to help at all times, particularly at the beginning and end of the anaesthetic.

Depending on where you live and where your hospital is, a number of the people described above may be involved in providing your anaesthesia care. In addition, some hospitals also train other health care workers, such as ambulance attendants and paramedics, who may be present in the Operating Room and help with part of your anaesthetic..

Anaesthetists provide anaesthetic care for surgical operations, before the operation ( preoperative), during the operation ( intraoperative), and after the operation ( postoperative). They also provide anaesthetic care for patients undergoing non-surgical procedures, such a special heart examinations or X-ray treatment, particularly if these procedures are long, complex, or painful. Sometimes this care consists of providing sedation, either for a procedure such as an examination of the bowel ( endoscopy) or in addition to regional or local anaesthesia. (This is often called monitored anaesthesia care.)

Anaesthetists also provide relief of acute pain for women during labour and delivery, and to many patients after operations, as well as treatment of chronic pain for patients with long-term pain problems.

Many anaesthetists are involved in intensive care or in the provision of retrieval services and resuscitation. Retrieval services involve going to a small hospital by air or road ambulance, to fetch accident victims or patients who need specialised care in a major hospital.

Other anaesthetists spend part of their time doing research in diverse fields – studying how the body works, developing new drugs and equipment, and working out how to teach teams of medical workers to minimise human error and patient harm. Many anaesthetists also teach a wide range of health care workers, including medical and nursing students, interns, residents, specialists in training, and other specialists (surgeons, obstetricians, physicians, etc). Anaesthetists are also often asked to give talks of a general nature to interested groups, such as the Scouts, community organisations, and school classes. (If you would like to have an anaesthetist speak to your group, contact your local hospital Department of Anaesthesia or the College or Society.)

No matter which type of anaesthetic care they provide, the responsibilities of anaesthetists are similar. These responsibilities include evaluating the patient before the operation or procedure; forming a plan for the care of the patient during and after the anaesthetic; monitoring and supporting the patient during the procedure; and supervising care after the procedure.

Modern anaesthesia is safe, despite some of the stories you hear. To compare one hour of being anaesthetised with, say, one hour spent in traffic or a one-hour plane trip, the risk of dying is about one in ten thousand in traffic, about one in one million in an aircraft, and one in 100,000 – 500,000 during the anaesthetic. If you compare one hour of having an anaesthetic with an hour of air travel, then the risk of dying is about five to ten times higher during the anaesthetic. In contrast, an hour spent parachute-jumping carries a risk of death about 20 – 100 times that associated with anaesthesia. The safety of anaesthesia has increased over the years, even though much more complicated operations are being performed, for patients with more severe illnesses. For example, in Australia, the risk of death associated with anaesthesia has decreased to one-tenth of what it was thirty years ago. You can be confident that modern anaesthesia is very safe.

A number of factors have contributed to the overall safety of modern anaesthesia. These factors include your anaesthetist, the drugs and equipment used in the Operating Room, and overall medical care. For example, your anaesthetist is responsible for your overall health and safety from the start of your anaesthetic until you leave the recovery room after your operation. Your anaesthetist makes sure that all the anaesthetic equipment is working properly before you undergo anaesthesia. (This is just like the airline pilot who completes a pre-flight check of the aeroplane.) Your anaesthetist knows what to do if a problem occurs with any of the equipment during your anaesthetic. He or she will be with you throughout your operation, watching you and watching your surgeon. Your anaesthetist also continuously watches a number of monitors that measure many of the things happening to you while you are under the effects of the anaesthetic. Should there be any complications, either because of the anaesthetic drugs, or more likely because of the operation, your anaesthetist will respond quickly, having been fully trained in managing emergencies.

There have been major improvements in the drugs used for anaesthesia. Starting in 1846, the first anaesthetics were given with one drug, such as ether or chloroform. Inhaling these drugs was unpleasant, because of the smell and a sensation of choking. induction of anaesthesia was often slow and occasionally patients would struggle and have to be restrained. Because only one drug was used, patients needed heavy doses to make them very deeply anaesthetised. This was to ensure that the patients’ muscles were sufficiently relaxed for the surgeons to be able to operate. After the operation, patients often slept for long periods of time, as they breathed out the large amounts of drug that had been used. Vomiting and severe postoperative pain were very common.

Since the 1940s, anaesthetists have had the benefit of being able to use many new anaesthetic agents. All have contributed to the development of anaesthetic practice as it is today. The newer agents tend to be absorbed less by the body’s fat, which means that they have a shorter duration of action than the older agents. This allows anaesthetists to determine and control the depth of an anaesthetic more precisely for the requirements of each individual patient. However, the principle upon which the use of all of these drugs is based remains common to those of the original agents – ‘sufficient and safe’.

In addition to improvements in anaesthetic agents, there have been major changes in the equipment used to give the anaesthetic and to monitor its effects. As recently as the mid-1970s, anaesthetics were given in modern hospitals in Canada and Australia with only a blood pressure cuff and a stethoscope to monitor the patient. Since then, many new pieces of equipment have been introduced. As a result, anaesthetists are now better able to assess and evaluate what is happening to their patients.

The cost of anaesthetic care is in addition to the cost of surgical care. Fees charged by anaesthetists for their services vary in different countries, and depend on whether or not medical treatment is covered by a public health system. For patients receiving private medical care, the fee varies according to the length and complexity of the anaesthetic. In Australia, fees range from around $200 to $2000 or more. If you live in a country where anaesthetic fees are charged, you should ask your anaesthetist about the fees before the procedure.

Did you know?

There is no safer place in the world to undergo anaesthesia than in Australia.

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.

Type of medications

There are four main types of medication used in general anaesthesia

Induction medications

To produce unconsciousness



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.


Local anaesthetics

Injection of a local anaesthetic around a nerve or a group of nerves temporarily blocks the transmission of the electrical impulses in the nerve. The lack of transmission causes the area of the body supplied by the nerve to become numb. This is also known as a ‘sensory block’, which may progress to temporary muscle weakness, depending on the concentration and dose of the local anaesthetic used. 


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.

Confusion sometimes arises, because the term “ local anaesthesia” is used to refer to what is properly called “ regional anaesthesia”, so that an operation “under local” may in fact be an operation using regional anaesthesia.

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.

  • The procedure to be performed. Some procedures can only be performed under general anaesthesia. For example, a patient undergoing removal of the gallbladder, whether by means of a laparoscopic or key-hole technique or through a standard incision, needs a general anaesthetic. For other procedures it is reasonable to consider whether or not the operation should be carried out under local, regional or general anaesthesia, or if a combination of techniques should be used, such as combined regional and general anaesthesia. For example, a patient undergoing an examination of the knee using a special instrument called an arthroscope could be offered a choice of local, regional, or general anaesthesia. A patient undergoing an open-heart operation needs general anaesthesia, however some minimally invasive cardiac procedures can be performed with local anaesthesia and sedation.
  • The experience, expertise and preference of the anaesthetist can vary with different techniques.
  • Your own preference – whether or not you would prefer to be unconscious or wish to remain as conscious and in control as possible. Most patients prefer to be unconscious for major surgical procedures. For some procedures it is increasingly common for patients not to have a general anaesthetic—for example, caesarean section.
  • Age – It is common for children to have a general anaesthetic for procedures that might be done without any form of anaesthetic in an adult, for example, MRI (magnetic resonance imaging) scanning. This is because children may not understand the explanations or be able to lie still.

No matter what operation, examination or other treatment you are to undergo, you may ask your anaesthetist if there is any choice in the anaesthetic method. You should also understand that some surgeons are more comfortable operating on patients who have received one form of anaesthetic rather than another. This most often means that the patient has a general anaesthetic.

The surgeon does not choose the type of anaesthetic you will receive, unless there is no anaesthetist involved in your care. However, the surgeon may discuss the choice with you and with your anaesthetist. In the same way, your anaesthetist does not choose what operation you will have or how it will be carried out. Again, your anaesthetist may discuss your operation with you and your surgeon, particularly if you have special anaesthetic problems.

It is sometimes possible to choose your anaesthetist, but there are factors which may make this difficult.

  • The anaesthetist you want may not have hospital privileges, which means that the anaesthetist is not legally entitled to practice medicine in a particular institution. This does not imply any lack of skill but rather indicates that the anaesthetist does not normally practice at that institution. (This may apply to surgeons as well.)
  • Some anaesthetists and surgeons often work as a team and develop a close working relationship. A particular anaesthetist may therefore not work regularly with a particular surgeon.
  • Other anaesthetists may choose to practise anaesthesia only for certain types of operations – for example, cardiac anaesthetists may not look after women undergoing labour and delivery, and paediatric anaesthetists may not provide anaesthetic care for adults.
  • Although an anaesthetist may work with a particular surgeon or provide care for a patient undergoing a particular operation, the anaesthetist may not regularly use a particular type of anaesthetic – for example, regional anaesthesia.
  • The anaesthetist might not be available, having been on call the night before, on holiday, or otherwise engaged.

Nevertheless, you are entitled to ask if you may have a particular anaesthetist look after you.

You have every right to ask questions, to receive information, and to participate in choosing the care you will receive. Asking questions and receiving information are the basis of giving informed consent for any medical procedure, including anaesthesia.

What does ‘informed agreement/consent’ mean ?

In many countries, including Canada and Australia, your doctor is obliged to give you the opportunity to know about the risks of the anaesthetic (or operation) that are serious or  material risks. The discussion that you have with your anaesthetist should include the possibility of a choice of anaesthetic method (if appropriate) and the risks and benefits associated with the choices. Only then should you agree or consent to undergo examination or treatment.

Having agreed to have the examination or treatment, you are then required to sign a piece of paper which describes the examination or treatment. Your signature should be dated and witnessed. This is known as giving written consent. However, written consent is normally obtained only for the operation or procedure for which an anaesthetic must be given. In Australia, Canada and the United Kingdom, a separate written consent for anaesthesia is not routinely obtained. This means that written consent for the operation includes consent for the anaesthetic. Occasionally, you may be asked to give separate written informed consent for the anaesthetic. This might occur if you agreed to undergo a technique that is not routinely carried out or one that involves considerable or unusual risk.

In fact, the piece of paper that you (and all patients) sign is only that – a piece of paper—although it is a very important one in the hospital admission process. What is more important is the discussion which you have with the treating doctor before signing the form. This discussion enables you to give consent on the basis that you understand the treatment and implications to your satisfaction. The consent you give after this kind of discussion is called informed consent.

If you have second thoughts, even at the last minute, you should discuss them with your surgeon and your anaesthetist.

Ultimately, the decision as to whether or not to proceed with the operation is yours.

Find out more


Preparing for your anaesthetic



During your anaesthetic



After your anaesthetic