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  1. E C Pierce, Jr2
  1. 2770 Boylston St # 10C, Boston, MA 02199, USA; epierce500{at}

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    In 1978 Cooper and colleagues published their landmark paper1 on the application of the critical incident technique,2 adapted from uses in aviation and other fields, to examine the causes—and later prevention strategies—for adverse anesthesia outcomes. Following on 20 years of rudimentary anesthesia mortality studies, this was a brilliant approach that gave anesthesia clinicians new insights on which we could act. As the report told us: “. . . factors associated with anesthetists and/or that may have predisposed anesthetists to err have, with a few exceptions, not been previously analyzed. Furthermore, no study has focused on the process of error—its causes, the circumstances that surround it, or its association with specific procedures, devices, etc—regardless of final outcome.” Data from the study at one hospital and from an extension to four hospitals 6 years later3 provided two widely cited tables listing “the most frequent incidents” and “summary of associated factors cited”. This innovative examination of critical events provided the first useful mirror for clinicians to reflect on their practice. In that mirror we were able to see how our imperfections could lead to errors and patient injury.

    In my view this study was one of a few pivotal events responsible for the dramatic success in promoting anesthesia patient safety, starting with Beecher and Todd's paper on the rate of anesthesia mortality based on a large sample of operative cases.4 Later, in part catalysed by the reports from the critical incident studies, the Committee on Patient Safety and Risk Management in the American Society of Anesthesiologists (ASA) was created in 1984, the Anesthesia Patient Safety Foundation was founded in 1985, and the Closed Claim Analysis project was initiated by the ASA beginning in the mid 1980s.5

    Anesthesiology is the one domain in which patient safety was identified as a problem long before the Institute of Medicine's 1999 wake up call to the healthcare community.6 Not only was the problem identified in the late 1970s, but anesthesiologists faced the issues, taking actions to effect changes that would reduce errors, adverse outcomes, and injuries. While it is often difficult to trace the historical path of change, there is reason to believe that the anesthesia critical incident studies planted seeds of ideas for others, either directly or subliminally. The studies demonstrated the power of qualitative research (although that term was not used at the time). They catalysed change in anesthesia. In combination with the influences noted above, they fostered the strong culture of safety for which anesthesiology is recognised.

    The first peer reviewed publication of the critical incident studies “Preventable anesthesia mishaps: a study of human factors”1 is reproduced in this issue of QSHC. Several other papers appeared over the next few years, the most widely cited of which is the 1984 study entitled “An analysis of major errors and equipment failures in anesthesia management: considerations for prevention and detection” which also appeared in Anesthesiology.3 These papers describe a then almost unknown methodology for medicine, although it had been applied in two prior studies, one of hospital medication error (in 1960)7 and the other to the beneficial and detrimental performance of physicians from several specialties (in 1970).8 Yet, neither of those studies inspired the kind of action of the reports in Anesthesiology. Perhaps it was the way the method was used to examine the underlying mechanisms of error or just a matter of timing that gave the anesthesia studies their enormous impact. For whatever reasons, anesthesia clinicians gained the insights needed to effect change in their basic attitudes and practices toward dealing with errors.

    The critical incident technique is now used more often, but still not as often as it might be in this new era of interest in errors and system failures. As applied by Cooper et al, the approach was employed to capture first hand reports of human errors and equipment failures that had actual or potential negative consequences. The definition they crafted for a critical incident has been revised in many ways over the years in studies of adverse events, but the main wording of it is still generally applicable: “A mishap was labeled a critical incident when it was clearly an occurrence that could have led (if not discovered and corrected in time) or did lead to an undesirable outcome, ranging from increased length of hospital stay to death or permanent disability”.

    Using an inductive approach with well specified definitions, the investigators analysed the events in search of the underlying causes of error and what we would now call “failure to recover” from error. Later, deeper analysis identified practical understandable strategies that would prevent or trap most errors. Today the thinking about human error and systems failures is more sophisticated and the methodologies to study errors are more rigorous (most would seek inter-rater reliability rather than a consensus approach to rating incidents). Yet, for the study of critical events, both positive and negative, the critical incident approach is still attractive. Now aided by then unimaginable computer power and web access and by qualitative analysis software, it is a method that many can apply to explore patient safety questions in all medical fields. On the other hand, such studies have become more difficult to undertake because of the barriers created by mandatory reporting requirements for errors reported even in research studies.

    These original studies were emulated by anesthesiologists in several countries, most notably by Williamson et al in Australia.9 That paper was itself the catalyst for one of the earliest and most informative national incident reporting systems, the Australian Incident Monitoring System (AIMS).10 Other investigations using the critical incident technique had an impact in their native countries, contributing greatly to the development of standards of practice which are now essentially universal.

    The critical incident studies were elegant in their simplicity. While primitive in some respects, the findings are still relevant today. With the benefit of time it may seem obvious that such research and methodology were needed to expose a hidden truth that had been kept by health care for many years. But, recall that there was little before to prompt this kind of research. Thus, by their pioneering innovative approach to examine a previously unidentified problem, tactful and eloquent word crafting, and sensitivity to what clinicians needed to know about themselves, Cooper and his colleagues have made an immeasurable contribution to anesthesia. By the road they paved, that contribution has been applied to all of health care.