Safety in the operating theatre - Part 2: human error and organisational failure.

Over the past decade, anaesthetists and human factors specialists have worked together to find ways of minimising the human contribution to anaesthetic mishaps. As in the functionally similar fields of aviation, process control and military operations, it is found that errors are not confined to those at the "sharp end". In common with other complex and well defended technologies, anaesthetic accidents usually result from the often unforeseeable combination of human and organisational failures in the presence of some weakness or gap in the system's many barriers and safeguards. Psychological factors such as inattention, distraction and forgetfulness are the last and often the least manageable aspects of the accident sequence. Whereas individual unsafe acts are hard to predict and control, the organisational and contextual factors that give rise to them are present before the occurrence of an incident or accident. As such, they are prime candidates for treatment. Errors at the sharp end are symptomatic of both human fallibility and underlying organisational failings. Fallibility is here to stay. Organisational and local problems, in contrast, are both diagnosable and manageable.

Human factors and cardiac surgery: a multicenter study.

OBJECTIVE: To study the role of human factors on surgical outcomes, with a series of 243 arterial switch operations performed by 21 surgeons taken as a model. METHODS: The following data were collected: patient-specific and procedural variables, self-assessment questionnaires, and a written report from a human factors researcher who observed the operation. The relationship of patient-specific variables to outcomes (death and death and/or near miss) was used to develop a multivariable baseline model to analyze the role of human factors after adjustment for these variables. RESULTS: The overall mortality was 6.6% with 24.3% of cases resulting in death and death and/or near misses. The self-assessment questionnaires were found to be unhelpful. Major and minor human failures were extracted from the written report. Major negative events were potentially life-threatening failures, whereas minor events were failures that, in isolation, were not expected to have serious consequences. Major events were closely related to death (P <.001) and death and/or near misses (P <.001). Appropriate compensation, however, sharply reduced the risk of death (P =.003). The total number of minor events was also closely related to both death and death and/or near misses (P <.001). CONCLUSION: The study highlights the role of human factors in negative surgical outcomes. Even in the most eventful circumstances, however, appropriate human factors defense mechanisms can lead to a successful outcome.

Intravenous iron-dextran: studies on unsaturated iron-binding capacity.

A method is described for measuring the plasma unsaturated iron-binding capacity in the presence of very high concentrations of iron as iron-dextran. The procedure utilizes (59)Fe to label the apotransferrin with subsequent separation of ionic iron from transferrin-bound iron on an ion exchange or Sephadex G.25 column. The unsaturated iron-binding capacity has been measured in rabbits and dogs after intravenous injection of iron-dextran and in human subjects after total dose infusion of iron-dextran. No evidence of saturation of the unsaturated iron-binding capacity was found even when the plasma iron values were greater than 40,000 mug Fe/100 ml.

The human factor in cardiac surgery: errors and near misses in a high technology medical domain.

In this review, we discuss human factors research in cardiac surgery and other medical domains. We describe a systems approach to understanding human factors in cardiac surgery and summarize the lessons that have been learned about critical incident and near-miss reporting in other high technology industries that are pertinent to this field.

Beyond the organisational accident: the need for "error wisdom" on the frontline.

Complex, well defended, high technology systems are subject to rare but usually catastrophic organisational accidents in which a variety of contributing factors combine to breach the many barriers and safeguards. To the extent that healthcare institutions share these properties, they too are subject to organisational accidents. A detailed case study of such an accident is described. However, it is important to recognise that health care possesses a number of characteristics that set it apart from other hazardous domains. These include the diversity of activity and equipment, a high degree of uncertainty, the vulnerability of patients, and a one to one or few to one mode of delivery. Those in direct contact with patients, particularly nurses and junior doctors, often have little opportunity to reform the system's defences. It is argued that some organisational accident sequences could be thwarted at the last minute if those on the frontline had acquired some degree of error wisdom. Some mental skills are outlined that could alert junior doctors and nurses to situations likely to promote damaging errors.

Combating omission errors through task analysis and good reminders.

Leaving out necessary task steps is the single most common human error type. Certain task steps possess characteristics that are more likely to provoke omissions than others, and can be identified in advance. The paper reports two studies. The first, involving a simple photocopier, established that failing to remove the last page of the original is the commonest omission. This step possesses four distinct error-provoking features that combine their effects in an additive fashion. The second study examined the degree to which everyday memory aids satisfy five features of a good reminder: conspicuity, contiguity, content, context, and countability. A close correspondence was found between the percentage use of strategies and the degree to which they satisfied these five criteria. A three stage omission management programme was outlined: task analysis (identifying discrete task steps) of some safety critical activity; assessing the omission likelihood of each step; and the choice and application of a suitable reminder. Such a programme is applicable to a variety of healthcare procedures.

A visually-driven postural after-effect.

Viewing a large-scale moving scene typically causes a free standing observer to lean in the direction of the seen motion. It was also noted that when the visual motion ceases, the observer drifts back toward the upright position, but instead of this body movement stopping at the vertical, it tends to continue so that the observer remains leaning in the opposite direction for several seconds before finally returning to the upright. The two experiments reported here were designed to investigate the determinants of this postural after-effect in relation to a pitch vection stimulus. Our findings clearly showed that the after-effect was dependent upon (1) the establishment of a prior visually-induced body lean, and (2) sight of the static display on the cessation of motion. The notion of an internalised representation of body position was invoked to account for these results.

Determinants of intention to commit driving violations.

Ajzen's theory of planned behaviour was used to measure the attitudes and intentions of a large stratified sample of drivers (N = 881) towards four driving violations. Measures were taken of respondents' attitudes to four imaginary scenarios depicting their commission of the four violations concerned. Demographic subgroups of drivers within the sample were differentiated on the basis of their beliefs about and evaluations of their commission of the violations. We were able to identify attitude items differentiating the younger, statistically more "accident liable" drivers in the sample from their older, and statistically safer counterparts. The implications of using this approach to inform future road safety campaigns are discussed.

Absent-mindedness in shops: its incidence, correlates and consequences.

This paper describes a questionnaire study of absent- mindedness in shops, and an analysis of 166 letters written by 67 individuals who felt themselves to be wrongly accused of shoplifting . A total of 150 men and women were asked how often they had experienced each of 24 varieties of mental lapse while shopping. If they had not actually suffered a particular lapse, they were asked to judge its likelihood of occurrence. Approximately half of the sample also completed the Cognitive Failures Questionnaire ( CFQ ). Lapses carrying the risk of shop-lifting accusations were reported as occurring far less frequently, and were judged as less likely, than either ' embarrassing ' or 'nuisance' lapses. However, an examination of the circumstances leading up to accusations of shoplifting indicated that high risk lapses can occur when ill health, extreme preoccupation and distraction are combined with unwise supermarket practices. A positive and significant correlation was found between the CFQ and the Absent- Mindedness in Shops Questionnaire ( AMSQ ). A factor analysis of the AMSQ revealed a very pervasive general factor, together with a risk appreciation factor. The findings supported the view that responses to both the CFQ and the AMSQ reflected characteristic differences in the management of some superordinate attentional control resource.

Understanding adverse events: human factors.

(1) Human rather than technical failures now represent the greatest threat to complex and potentially hazardous systems. This includes healthcare systems. (2) Managing the human risks will never be 100% effective. Human fallibility can be moderated, but it cannot be eliminated. (3) Different error types have different underlying mechanisms, occur in different parts of the organisation, and require different methods of risk management. The basic distinctions are between: Slips, lapses, trips, and fumbles (execution failures) and mistakes (planning or problem solving failures). Mistakes are divided into rule based mistakes and knowledge based mistakes. Errors (information-handling problems) and violations (motivational problems) Active versus latent failures. Active failures are committed by those in direct contact with the patient, latent failures arise in organisational and managerial spheres and their adverse effects may take a long time to become evident. (4) Safety significant errors occur at all levels of the system, not just at the sharp end. Decisions made in the upper echelons of the organisation create the conditions in the workplace that subsequently promote individual errors and violations. Latent failures are present long before an accident and are hence prime candidates for principled risk management. (5) Measures that involve sanctions and exhortations (that is, moralistic measures directed to those at the sharp end) have only very limited effectiveness, especially so in the case of highly trained professionals. (6) Human factors problems are a product of a chain of causes in which the individual psychological factors (that is, momentary inattention, forgetting, etc) are the last and least manageable links. Attentional "capture" (preoccupation or distraction) is a necessary condition for the commission of slips and lapses. Yet, its occurrence is almost impossible to predict or control effectively. The same is true of the factors associated with forgetting. States of mind contributing to error are thus extremely difficult to manage; they can happen to the best of people at any time. (7) People do not act in isolation. Their behaviour is shaped by circumstances. The same is true for errors and violations. The likelihood of an unsafe act being committed is heavily influenced by the nature of the task and by the local workplace conditions. These, in turn, are the product of "upstream" organisational factors. Great gains in safety can ve achieved through relatively small modifications of equipment and workplaces. (8) Automation and increasing advanced equipment do not cure human factors problems, they merely relocate them. In contrast, training people to work effectively in teams costs little, but has achieved significant enhancements of human performance in aviation. (9) Effective risk management depends critically on a confidential and preferable anonymous incident monitoring system that records the individual, task, situational, and organisational factors associated with incidents and near misses. (10) Effective risk management means the simultaneous and targeted deployment of limited remedial resources at different levels of the system: the individual or team, the task, the situation, and the organisation as a whole.

Diagnosing "vulnerable system syndrome": an essential prerequisite to effective risk management.

Investigations of accidents in a number of hazardous domains suggest that a cluster of organisational pathologies-the "vulnerable system syndrome" (VSS)-render some systems more liable to adverse events. This syndrome has three interacting and self-perpetuating elements: blaming front line individuals, denying the existence of systemic error provoking weaknesses, and the blinkered pursuit of productive and financial indicators. VSS is present to some degree in all organisations, and the ability to recognise its symptoms is an essential skill in the progress towards improved patient safety. Two kinds of organisational learning are discussed: "single loop" learning that fuels and sustains VSS and "double loop" learning that is necessary to start breaking free from it.

Voluntary movement control and adaptation to cross-coupled stimulation.

The rates at which protective adaptation was acquired to an incremental cross-coupled stimulus were compared under three conditions of movement control: 1) a passive condition in which the 45 degree lateral tilts of the subject's chair were controlled entirely by the experimenter (N = 12); 2) an active condition in which the same movements were achieved directly through the subject's own muscular effort (N = 12); and 3) an active-passive condition in which control was exercised indirectly through microswitches located on the chair arms (N = 12). Adaptation was measured by the rate of neutralization of the oculogyral illusion, as estimated from the apparent motion of a small, dimly illuminated target. The results supported the prediction that the passive condition would be the least effective mode for acquiring adaptation. An unexpected finding was that the active-passive condition proved to be the most efficient for the development of adaptation.

Motion sickness: Some theoretical and practical considerations.

This paper reviews some of the more important theoretical and practical considerations relating to the widespread problem of motion sickness. A brief outline is given of the sensory rearrangement theory which seeks to define the essential nature of the nauseogenic stimulus. A wide range of provocative situations is classified as involving either a visual-inertial conflict, or a canal-otolith conflict or both. A number of behavioural measures by which the passenger can minimise the risk of motion sickness are described. Also considered are quantitative studies of vertical oscillatory motion, factors influencing motion sickness susceptibility (sex, age, exposure-history, receptivity and adpatability and personality characteristics), and the paper concludes with recommendations regarding the most effective use of anti-motion sickness drugs.