**2. The 'Swiss cheese' model of health care and hospital setting adverse events**

James Reason in his book 'Managing the Risks of Organizational Accidents' states that organisational accidents, as opposed to individual accidents, are predictable events [42]. An individual accident is one in which a person or a group of people makes an individual slip, lapse or error of judgement with the net result being an adverse outcome either to the person or the people who erred, or to the person or people in the immediate vicinity. As such, there is usually a relatively tight, simple explanation for cause and effect in an individual accident. On the other hand, organisational accidents have 'multiple causes involving many people at different levels of an organization' [42]. These events, whilst usually infrequent, are often catastrophic. Analyses of such organisational accidents often reveal that the defences an organisation has to prevent such catastrophes are breached by a unique series of sequential hazards that play out in an environment of latent conditions, the so-called 'Swiss Cheese'. It follows that one can decrease the incidence of these organisational accidents by increasing the number of defences (more cheese slices) and/or by shrinking the size of the holes in each of the defences (**Figure 1**).

The 'Swiss Cheese' model does explain well some types of hospital adverse events, in particular patient falls, wrong-side surgery and medication errors. In the case of medication errors, the root cause analysis of these events often highlights holes in the 'Swiss Cheese', such as poor transcription of medication prescriptions and failure to do appropriate checks [47]. In the case of patient falls, there is failure to identify the 'at risk' patient and put appropriate preventative strategies in place. Fixing the holes or at least reducing the size of them can reduce the incidence of patient falls and medication errors. This can be done by and large with topdown policy and procedure and ensuring implementation of such [47]. The best example of this has been the reduction in the incidence of wrong-side surgery, with the implementation of time-out, with completion of a check list before surgery [48]. The Reason 'Swiss Cheese' model gives good explanation of the adverse event when there is a relatively tight temporal relationship, between the adverse event and the preventative strategies. The adverse event in these circumstances is itself evidence that a mistake or error was made. There is usually a series of clear errors with the 'Swiss Cheese' model that can be identified. This model then allows for preventative strategies to be implemented, and with the increasing move back to professional responsibility for compliance, in theory, at least the Holy Grail of the perfectly

Adverse Events in Hospitals: "Swiss Cheese" Versus the "Hierarchal Referral Model of Care and…

http://dx.doi.org/10.5772/intechopen.75380

39

However, most adverse events in hospital, particularly the more serious ones, often do not have such clear errors with a tight temporal relationship with the adverse event and the contributing errors. When the temporal relationship between the adverse event and the preventative strategies is not so tight, hospital cultural factors start to be more significant, and the potential for policy and procedure to help is much less so, simply because it can be and often is ignored.

There are three fundamental problems with the application of the 'Swiss Cheese' model to adverse events in hospitals. First, in the hospital, the distinction between individual and organisational accidents is not clear. The entire premise of the 'Swiss Cheese' model was the investigation of causation factors of large industrial accidents as opposed to individual accidents. In the hospital, we do not have large-scale accidents but, instead, multiple little accidents or adverse events daily, if not hourly, and in almost every setting. The study on the causation of adverse events in hospitals overwhelmingly points to failures at the sharp end of care delivery to the patient by frontline staff. Analysis of the causative factors associated with the adverse events in The Quality in Australian Health Care Study found that cognitive failure was a factor in 57% of these adverse events [49]. In this analysis, cognitive failure included such errors as failure to synthesise, decide and act on available information; failure to request or arrange an investigation, procedure or consultation; lack of care or attention; failure to attend; misapplication of, or failure to apply, a rule, or use of a bad or inadequate rule [49]. In a two-hospital study from the United Kingdom that looked at 100 sequential admissions to the intensive care unit (ICU) from ward areas, it was found that 54 had sub-optimal care on the ward prior to transfer [50]. This group of patients had a mortality rate of 56%. Some of the

**3. Problems with the 'Swiss cheese' model: why are hospitals** 

safe hospital should be attainable.

**different from other industries?**

In 2008, Palmieri et al. published their 'Health Care Error Proliferation Model' of adverse health-care events [45]. This model takes the 'Swiss Cheese Model' and specifically adapts the various factors that exist in health care. Most notably, they place clinician vigilance as a key defence at the sharp end of the actual adverse event, in the form of clinical improvisation and localised workarounds. This clinician vigilance repairs gaps produced by actions, changes and adjustments that are made at the blunt end of the health-care organisation with its administrative and therefore higher level, layers of defence. A good example of this is the use of high-definition mobile telephone devices in rural and regional settings that allow almost an immediate transfer of clinical information to an appropriate clinician at a referral centre. However, this clinical workaround and improvisation is clearly at odds with most organisations' patient privacy policies that have been developed at the blunt administrative end of the organisation.

Having for the most part accepted the Reason 'Swiss Cheese' model of adverse events and adapted variations, most hospitals' response to adverse events has been to increase defences at the blunt end of the health-care organisation's administration [46]. These defences, in the hospital, take the form of dedicated quality and safety units and committees, electronic eventreporting systems and the development of appropriate standards linked to hospital accreditation [46]. The aim of each of these blunt end defence layers is to continually decrease the size of the holes in each defence layer, by more audits, meetings and root cause analysis projects combined with the use of the quality improvement cycle. Inevitably, what are generated are recommendations, guidelines and more policy and procedure.

**Figure 1.** The reason 'Swiss cheese' model [37] (with kind permission from Ashgate Publishing).

The 'Swiss Cheese' model does explain well some types of hospital adverse events, in particular patient falls, wrong-side surgery and medication errors. In the case of medication errors, the root cause analysis of these events often highlights holes in the 'Swiss Cheese', such as poor transcription of medication prescriptions and failure to do appropriate checks [47]. In the case of patient falls, there is failure to identify the 'at risk' patient and put appropriate preventative strategies in place. Fixing the holes or at least reducing the size of them can reduce the incidence of patient falls and medication errors. This can be done by and large with topdown policy and procedure and ensuring implementation of such [47]. The best example of this has been the reduction in the incidence of wrong-side surgery, with the implementation of time-out, with completion of a check list before surgery [48]. The Reason 'Swiss Cheese' model gives good explanation of the adverse event when there is a relatively tight temporal relationship, between the adverse event and the preventative strategies. The adverse event in these circumstances is itself evidence that a mistake or error was made. There is usually a series of clear errors with the 'Swiss Cheese' model that can be identified. This model then allows for preventative strategies to be implemented, and with the increasing move back to professional responsibility for compliance, in theory, at least the Holy Grail of the perfectly safe hospital should be attainable.

organisation has to prevent such catastrophes are breached by a unique series of sequential hazards that play out in an environment of latent conditions, the so-called 'Swiss Cheese'. It follows that one can decrease the incidence of these organisational accidents by increasing the number of defences (more cheese slices) and/or by shrinking the size of the holes in each

In 2008, Palmieri et al. published their 'Health Care Error Proliferation Model' of adverse health-care events [45]. This model takes the 'Swiss Cheese Model' and specifically adapts the various factors that exist in health care. Most notably, they place clinician vigilance as a key defence at the sharp end of the actual adverse event, in the form of clinical improvisation and localised workarounds. This clinician vigilance repairs gaps produced by actions, changes and adjustments that are made at the blunt end of the health-care organisation with its administrative and therefore higher level, layers of defence. A good example of this is the use of high-definition mobile telephone devices in rural and regional settings that allow almost an immediate transfer of clinical information to an appropriate clinician at a referral centre. However, this clinical workaround and improvisation is clearly at odds with most organisations' patient privacy policies that have been developed at the blunt administrative

Having for the most part accepted the Reason 'Swiss Cheese' model of adverse events and adapted variations, most hospitals' response to adverse events has been to increase defences at the blunt end of the health-care organisation's administration [46]. These defences, in the hospital, take the form of dedicated quality and safety units and committees, electronic eventreporting systems and the development of appropriate standards linked to hospital accreditation [46]. The aim of each of these blunt end defence layers is to continually decrease the size of the holes in each defence layer, by more audits, meetings and root cause analysis projects combined with the use of the quality improvement cycle. Inevitably, what are generated are

recommendations, guidelines and more policy and procedure.

**Figure 1.** The reason 'Swiss cheese' model [37] (with kind permission from Ashgate Publishing).

of the defences (**Figure 1**).

38 Vignettes in Patient Safety - Volume 3

end of the organisation.

However, most adverse events in hospital, particularly the more serious ones, often do not have such clear errors with a tight temporal relationship with the adverse event and the contributing errors. When the temporal relationship between the adverse event and the preventative strategies is not so tight, hospital cultural factors start to be more significant, and the potential for policy and procedure to help is much less so, simply because it can be and often is ignored.
