For a century after chloroform’s introduction, its inherent toxicity was debated, especially in relation to lightly anesthetised patients receiving noxious stimuli [5]. The landmark 1954 publication by Henry Beecher and Donald Todd supported the notion of the inherent toxicity of anaesthetic agents [33]. This report examined outcomes after 600,000 anaesthetics administered over five years in ten university hospitals, finding that the data “strongly suggests an inherent toxicity” for neuromuscular blocking drugs, particularly curare. A furore followed. Sixteen distinguished anaesthesiologists sought to refute the suggestion [34], and from a study of 33,000 cases, Dripps concluded that neuromuscular blockers did not increase risk [11]. It became clear that the use of curare without reversal by neostigmine placed patients at risk of fatal respiratory failure.

Halothane was introduced in the mid 1950s, and soon replaced all other potent inhaled anaesthetics. Although its hepatotoxicity was rare, it led to halothane’s replacement in the 1970s and 1980s by enflurane and isoflurane. In the 1960s and 1970s, volatile inhaled anaesthetics and succinylcholine were found to trigger malignant hyperthermia in susceptible individuals. In 1975, Harrison reported that dantrolene was an effective specific antidote and mortality fell from 80% to virtually nil [35]. It is now appreciated that the drugs used in anaesthesia today rarely contribute directly to mortality, provided they are used with adequate skill and care.

As Sykes noted, inadequate equipment was identified early as a major cause of mortality and morbidity (Table 41.1) [5]. Understanding equipment became fundamental to safety in anaesthesia, with contributions from many anaesthetists, notably Jerry and Susan Dorsch in the USA [36] and John Russell in Australia [37], whose books have become established as readily understandable references in this field. Equipment for anaesthesia has become more complicated, and the increasing incorporation of electronics and computers within anaesthesia devices creates new risks. There are particular challenges in providing equipment for low income regions of the world that is affordable, appropriate, and simple to maintain. Mike Dobson and Phoebe Mainland, working through the World Federation of Societies of Anaesthesiologists (WFSA), have advanced the case with the International Standards Organization (ISO), for standards that address these needs.

Early academic leaders recognized that an environment conducive to safe anaesthesia required proper training, infrastructure and support. Robert Macintosh forcibly expressed the importance of proper training in 1949 [38]. These points were articulated in the 1993 International Standards for a Safe Practice of Anaesthesia [39], and repeated when these standards were subsequently revised [40]. Greater understanding has developed about techniques for airway management, patient positioning, ventilatory support, cardiopulmonary bypass, and crisis management.

In a lengthy, fascinating, and at times vitriolic paper (already cited above), MacIntosh argued in 1949 that there should be no deaths due to anaesthetics, and that those that did occur were mostly (if not all) attributable to failures on the part of the anaesthetist, rather than any inherent dangers in the drugs used or any underlying pathology that the patients might have [38].

Debate about the legitimacy of “anaesthetic death” as a default diagnosis for all otherwise unexplained perioperative deaths continued through the 1950s, 1960s and 1970s. Longitudinal studies by Holland [15,16] and Harrison [22,23] considerably increased our understanding of why things go wrong. In 1979, Arthur Keats published an important paper in which he criticised Macintosh’s 1949 article. He accepted that a proportion of anaesthetic deaths are attributable to error but suggested that this proportion might be about 10%. He argued that many of the drugs and techniques used in anaesthesia are inherently hazardous (citing malignant hyperthermia and succinylcholine-induced hyperkalemia as examples) although he agreed that attribution of deaths to anaesthetic drugs was unacceptable, without demonstration of a cause-effect relationship [41]. In 1979, William Hamilton, a friend and hunting companion of Keats, followed with a very balanced editorial [42], accepting many of Keats’ points but suggesting that the proportion of deaths attributable to error might be closer to 90%. Clearly a better conceptual framework was needed to sort out the relative contributions of drugs, equipment, the “system”, patients, and anaesthetists themselves.

The earliest statement on the importance of critical incidents probably came from RH Todd, anaesthetist to the Prince Alfred Hospital in Sydney, who wrote the following in 1889: “An accident may be defined as any event in the course of the administration which interferes with the simple process of inducing and maintaining a state of surgical anaesthesia. Some of these accidents are of slight importance in themselves, but in as much as small accidents are often the forerunners of greater ones, successful results may depend on a readiness in anticipating, and failing this, a promptitude in remedying small accidents.” [43] He then went on to classify accidents as impediments to free respiration, and those in which cardiac failure occurs, with lists of causes.

In 1974, Jeffrey Cooper was a bioengineer at the Massachusetts General Hospital (MGH). Whilst helping carve a pumpkin at a Halloween party, he struck up a conversation which led to an invitation to speak on human factors in healthcare. The resulting lecture, ‘The anaesthesia machine: An accident waiting to happen’, led a listener to suggest that he use the critical incident technique pioneered by Flanagan in World War II. This led to the study which resulted in his landmark first paper on anaesthetist-reported incidents, demonstrating the multifactorial cause of most problems and the important contribution of human behaviour to things that go wrong [6].

In 1987, David Gaba introduced the concepts of “Normal Accident Theory” to the anaesthesia literature [44]. Gaba, Cooper [45], and then others, advanced the principles of a systems-based (rather than a person-based) response to error. At about the turn of the century, Alan Merry and Alexander McCall Smith (who was then Professor of Law in Edinburgh) extended these ideas into the debate about the most appropriate legal and regulatory response to human error [46].

Cooper’s seminal publication coincided with a medical indemnity crisis that had begun in the mid 1970s, characterised by increased litigation and steep rises in insurance premiums [47,48]. These factors and others led Cooper, with Ellison (Jeep) Pierce’(then President of the American Society of Anesthesiologists) and Dick Kitz (then Chairman of Anaesthesiology at Harvard), to organise the first meeting of the International Committee on Anaesthesia Mortality and Morbidity (ICPAMM) in Boston in 1984 [48,49]. This focused attention on how anaesthesia-related adverse events happened, and how they might be prevented. During the meeting, Pierce conceived the idea of the Anesthesia Patient Safety Foundation (APSF). With Cooper and others, Pierce formed the APSF in 1985 with the motto “to ensure that no patient should be harmed by anesthesia” [50]. The APSF became a potent advocate for preventing harm rather than cleaning up the mess after an (often tragic) event.

The Closed Claims Study also arose from the 1984 ICPAMM meeting, where preliminary findings were presented on “closed” malpractice claims [51]. Fred Cheney, then Chairman of the ASA Committee on Professional Liability, saw the value of such a study. He formed a team including Robert Caplan, Karen Posner and Karen Domino, and pursued the cooperation of medical indemnity organisations. Limitations notwithstanding [52], this approach produced an influential series of papers (from ICPAMM to the present) including a 1990 report showing that adverse respiratory events underlay the largest single class of injury (35% of the total), and an even larger percent of payouts [53]. It showed that better monitoring would prevent 75% of these injuries. Another landmark study showed the tendency of human beings to display “outcome bias”’the strong human tendency to find fault if there has been a bad outcome – even when there was no question of conciliation or compensation [54].

The ASA used the Closed Claims data to develop practice standards, guidelines and advisories which have increased safety. The Closed Claims Study now possesses the findings for 8,000 malpractice cases, from 34 insurance organisations that insure nearly 15,000 anesthesiologists.

A decrease in the cost of malpractice insurance for anaesthetists has been evident world wide. It is difficult to say how much of this is the direct result of the outcomes of Closed Claim Studies, or how much is due to improved training, newer and better monitoring, new drugs, crisis management algorithms etc.

John Lunn and Brendan Devlin launched NCEPOD in 1988, following a report on surgical and anaesthetic practice during 1985–86 in three UK regions. The report compared patients who had died in hospital within thirty days of a surgical procedure, with “index” (control) cases, using information from those who had cared for these patients [55]. Although frequencies could not be calculated, because of the voluntary nature of the data source and low response rates, NCEPOD reports led to substantial improvements in the availability of resources, supervision of junior staff, appropriateness of surgery and access to critical care facilities [55,56].

Inspired by developments in the US, William Runciman called a meeting in Australia of 65 influential anaesthetists in 1987. The group comprised department heads and academic leaders, together with past and current deans of the Faculty of Anaesthetists. Standards for anaesthesia monitoring were proposed, and the group decided to form the Australian Patient Safety Foundation (Aus.PSF) to promote patient safety in anaesthesia and, more ambitiously, throughout healthcare [57]. An early initiative developed a voluntary national incident reporting system for anaesthesia – the Australian Incident Monitoring System (AIMS). In 1993, 30 publications resulted from analysis of the first 2,000 incidents [58]. This, with the US Closed Claims Study, established the utility of oximetry and capnography in anaesthesia, and influenced the promulgation of the International Standards for a Safe Practice of Anaesthesia, which were endorsed by the General Assembly of the WFSA in 1994 [59].

Unexplained disparate results between retrospective medical record reviews by the Harvard Medical Practice study in 1991 [60], and by a similar Australian study in 1995 [61,62], prompted the development of a comprehensive classification of things that go wrong in health care. This showed that there were, effectively, no qualitative or quantitative differences between adverse events in Australia and the US, but also confirmed how safe anaesthesia had become. Anaesthesia-related adverse events contributed less than 2% of the total events, compared with nearly 50% for surgery [61]. Anaesthesia related events were also, on average, less severe. Following this study, Runciman developed a 12,000 category classification (the Generic Occurrence Classification), subsequently expanded into “the Generic Reference Model”, with 20,000 categories [63]. With input from 250 international experts, this formed the basis for the new International Classification for Patient Safety (ICPS) [64]. The Australian team led by Runciman, now has responsibility for populating the ICPS framework with concepts and preferred terms on behalf of the World Health Organisation (from 2006 onwards). This is being done in collaboration with the “Common Formats” project for reporting to Patient Safety organisations in the US. To this end, Runciman was a member of the National Quality Forum’the group in the US which oversaw this project.

Several other anaesthesia patient safety experts have promoted patient safety across all of healthcare [65]. For example, Cooper participated in the Institute of Medicine report “To err is human.…”; and was a key player in the formation of the National Patient Safety Foundation of the American Medical Association. In 2010, Alan Merry was appointed to chair the Board set up to establish the New Zealand Health Quality and Safety Commission.

If it is possible to eliminate a problem by design, then this should be done. In the post war years, problems with equipment, particularly equipment used to deliver gases and vapours, were common [67–69]. In 1940, two patients died because carbon dioxide cylinders were substituted for oxygen cylinders, having had their green colour painted over with black [69]. The introduction of PIN indexing for gas cylinders in 1954 [69] is a classic example of an engineering solution to remove a latent factor [70] in the system that sets people up to make mistakes. Other examples include breathing circuits that can only be assembled in the correct manner [71,72], and modifications to gas flowmeter systems of anaesthesia machines that prevent the administration of hypoxic gas mixtures.

By the mid 1980s, it became evident that some problems could not easily be “designed out” (inadvertent oesophageal intubation, breathing circuit disconnections, and adverse reactions to drugs or surgical stimuli), but more effective management was possible if they could be rapidly detected. Equipment monitors (the Ritchie Whistle was an early example of an alarm to warn of oxygen supply failure [73]) and highly effective patient monitors set the scene for the widespread promulgation of standards of care. These included pulse oximeters providing beat-to-beat measurements of arterial blood saturation (invented in 1972 by a bioengineer, Takuo Aoyagi and first used on patients by a surgeon, Susumu Nakajima, in1975 [74,75]) and capnographs providing breath-by-breath measurements of carbon dioxide concentrations (the modern infrared capnograph was developed in 1937 by Karl Luft [76]) In 1986, the nine Harvard hospitals initiated the Harvard Monitoring Standards as a standard of care, thereby beginning a wider adoption of monitoring; John Eichhorn and Jeff Cooper played major roles in this process [77]. Monitoring devices became de facto standards across the US and prompted the setting of standards in Australia, UK, and the rest of the world. Eichhorn was the organiser of the International Task Force of Anaesthesia Safety that led to the original 1993 international standards for safe practice of anaesthesia [39], and a major contributor to the revision of these standards in 2008 [40]. Anaesthesia safety standards were proposed for Australia during the 1987 meeting that gave birth to the Australian Patient Safety Foundation [58]. The 1980s Closed Claims Study and the 1990s AIMS, indicated that half of all incidents could be detected by monitors, and that up to 90% of these would be detected by capnography and oximetery [53,59]. These monitors have become the standard of care in high income regions of the world, but many operating rooms internationally are without them. In 2008, the revised International Standards for a Safe Practice of Anaesthesia [40] effectively elevated the use of pulse oximetry to a mandatory requirement for elective anaesthesia, in concert with the aims of the Global Oximetry project [32] (see below). National anaesthesia societies and the WFSA have endorsed these initiatives to enhance the safety of anaesthesia

It had long been recognised in the aviation industry, that if a cockpit crisis occurred, it was not managed effectively if dealt with through deductive reasoning. By the time a solution was found in increasingly complex aircraft control systems, it was invariably too late. Instead, pre-compiled responses, the basic steps of which could be learned by rote, were instituted. These algorithms enabled pilots to respond to crises in an ordered manner, and were designed to reach a management solution, with or without determining an immediate cause. In the early 1990s in the US, David Gaba spearheaded advances in the use of pre-compiled algorithms for the management of crises during anaesthesia [78]. This was followed in Australia by the development of a specific set of crisis management algorithms for anaesthesia, tested against 4,000 incidents [27]. The development of courses to pioneer the systematic management of crises in anaesthesia (including the use of algorithms when appropriate) was pioneered in the US, Australia and New Zealand [79].

The need to monitor things that might go wrong will persist. Each new initiative or technological advance contains new ways of making mistakes. An early example might be the introduction of the laryngoscope, that facilitated safe insertion of an endotracheal tube, but potentially damaged the patient’s teeth. Unintended consequences, or “revenge effects”, can have major implications [80].

In responding to accidents in healthcare, the focus has shifted from one on individual culpability, through one in which no blame is attributed, except in egregious circumstances, to a current view which emphasises a just culture [46]. There are times when “whistle blowing” is called for. Steve Bolsin exemplifies the importance of speaking up when things persistently go wrong. He is famous as the “whistle blower” whose actions changed the mortality of paediatric surgery at the Bristol Royal Infirmary from 30 to 5%. He conducted the Cardiothoracic Anaesthesia Audit in the UK from 1990, when he came to realise the high mortality rate in his own unit. When his efforts to address this were blocked, he took his concerns to the media with the result that a major enquiry ensued. Many lessons were learned [81] and changes followed both at Bristol and in the United Kingdom generally [82]. His actions also had the less salutary effect of leading to his unemployment in Britain. This proved to be a watershed in the patient safety movement in the UK [83].

In 1991, Gaba convened a conference on Human Error in Anaesthesia. Sponsored by the APSF and the United States Food and Drug Administration, the meeting brought together 30 experts in the field of human factors in patient safety, including James Reason and Jens Rasmussen. Reason, a psychologist from Manchester, had just published his classic book, Human Error [70], in which he advanced the view of accident causation that has subsequently became famous as the “Swiss Cheese Model.” [84] He distinguished the role of active and latent failures in producing an accident, emphasising that latent failures lie dormant in a complex system, until by confluence of one or more additional failures, often triggered by an active failure, an accident occurs. The meeting launched important developments in the understanding of the role of human error in anaesthesia, and in the organisational theory of safety in healthcare, in particular the idea of learning from high-risk environments like aviation and nuclear power [7,85]. The meeting accelerated the uptake of simulation as a tool for teaching and research in anesthesia [86–89].