The core element of the specialty is the prevention and mitigation of pain and distress using various anesthetic agents, as well as the monitoring and maintenance of a patient's vital functions throughout the perioperative period.

[7] Since the 19th century, anesthesiology has developed from an experimental area with non-specialist practitioners using novel, untested drugs and techniques into what is now a highly refined, safe and effective field of medicine.

This comprises the use of various injected and inhaled medications to produce a loss of sensation in patients, making it possible to carry out procedures that would otherwise cause intolerable pain or be technically unfeasible.

[10] Safe anesthesia requires in-depth knowledge of various invasive and non-invasive organ support techniques that are used to control patients' vital functions while under the effects of anaesthetic drugs; these include advanced airway management, invasive and non-invasive hemodynamic monitors, and diagnostic techniques like ultrasonography and echocardiography.

The concept of intensive care medicine arose in the 1950s and 1960s, with anesthesiologists taking organ support techniques that had traditionally been used only for short periods during surgical procedures (such as positive pressure ventilation) and applying these therapies to patients with organ failure, who might require vital function support for extended periods until the effects of the illness could be reversed.

The first intensive care unit was opened by Bjørn Aage Ibsen in Copenhagen in 1953, prompted by a polio epidemic during which many patients required prolonged artificial ventilation.

This allows continuity of care when patients are admitted to the ICU after their surgery, and it also means that anesthesiologists can maintain their expertise at invasive procedures and vital function support in the controlled setting of the operating room, while then applying those skills in the more dangerous setting of the critically ill patient.

[15][16] Ambulance services employ units staffed by anesthesiologists that can be called out to provide advanced airway management, blood transfusion, thoracotomy, ECMO, and ultrasound capabilities outside the hospital.

[1][2] In these countries, the term anesthestist is used to refer to non-physician providers of anesthesia services such as certified registered nurse anesthetists (CRNAs) and anesthesiologist assistants (AAs).

[20] In other countries – such as United Kingdom, Australia, New Zealand, and South Africa – the medical specialty is referred to as anaesthesia or anaesthetics, with the "ae" diphthong.

[4][5] Throughout human history, efforts have been made by almost every civilization to mitigate pain associated with surgical procedures, ranging from techniques such as acupuncture or phlebotomy to administration of substances such as mandrake, opium, or alcohol.

[23][24][25] However, by the mid-nineteenth century the study and administration of anesthesia had become far more complex as physicians began experimenting with compounds such as chloroform and nitrous oxide, albeit with mixed results.

[23] Reportedly, following the quick procedure, operating surgeon John Warren affirmed to the audience that had gathered to watch the exhibition, "Gentlemen, this is no humbug!

[27] Over the next one hundred-plus years the specialty of anesthesiology developed rapidly as further scientific advancements meant that physicians' means of controlling peri-operative pain and monitoring patients' vital functions grew more sophisticated.

Then in the twentieth century neuromuscular blockade allowed the anesthesiologist to completely paralyze the patient pharmacologically and breathe for him or her via mechanical ventilation.

With these new tools, the anesthetist could intensively manage the patient's physiology, bringing about critical care medicine, which, in many countries, is intimately connected to anesthesiology.

[30] Anesthesiologists in training spend this time gaining experience in various different subspecialties of anesthesiology and undertake various advanced postgraduate examinations and skill assessments.

These lead to the award of a specialist qualification at the end of their training indicating that they are an expert in the field and may be licensed to practice independently.

[citation needed] In the final written examination, there are many questions of clinical scenarios (including interpretation of radiological exams, EKGs and other special investigations).

[40] On completion of training, the trainees are awarded the Diploma of Fellowship and are entitled to use the qualification of FANZCA – Fellow of the Australian and New Zealand College of Anaesthetists.

[43] In order to be an instructor of a residency program certified by the SBA, the anesthesiologists must have the superior title in anaesthesia, in which the specialist undergoes a multiple choice test followed by an oral examination conducted by a board assigned by the national society.

[30] Canada, like the United States, uses a competency-based curriculum along with an evaluation method called "Entrustable Professional Activities" or "EPA" in which a resident is assessed based on their ability to perform certain tasks that are specific to the field of anesthesiology.

[43] Upon completion of a residency program, the candidate is required to pass a comprehensive objective examination consisting of a written component (two three-hour papers: one featuring 'multiple choice' questions, and the other featuring 'short-answer' questions) and an oral component (a two-hour session relating to topics on the clinical aspects of anesthesiology).

[45] Upon completion of training, the anaesthesia graduate is then entitled to become a "Fellow of the Royal College of Physicians of Canada" and to use the post-nominal letters "FRCPC".

To be qualified as an anesthesiologist in Hong Kong, medical practitioners must undergo a minimum of six years of postgraduate training and pass three professional examinations.

[citation needed] Anesthesia training is overseen by the Italian Society of Anaesthesia, Analgesia, Resuscitation, and Intensive Care (SIAARTI).

The Swedish Board of Health and Welfare regulates specialization for medical doctors in the country and defines the speciality of anesthesiology and intensive care as being: "[…] characterized by a cross-professional approach and entailing A medical doctor can enter training as a resident in anesthesiology and intensive care after obtaining a license to practice medicine, following an 18–24 month internship.

Before the end of core training, all trainees must have passed the primary examination for the diploma of Fellowship of the Royal College of Anaesthetists (FRCA).

The curriculum focuses on a modular format, with trainees primarily working in one special area during one module, for example: cardiac anaesthesia, neuroanaesthesia, ENT, maxillofacial, pain medicine, intensive care, and trauma.