Chapter 5 - Contextualising the Conceptual Model
5.3 Applying the model
In applying the SWE (v3) to the empirical research it is necessary to clarify the
constructs being used. It is argued that the SWE (v3) has the following five constructs:
• ‘boundaries’ – depicts the constraints within which the system is designed to work
• ‘operating point’ – depicts the performance of the system in relation to the boundaries
• ‘gradients’ – depict the competing pressures on the OP
• ‘structure’ of the system and the relationships between the parts
• dynamic ‘feedback’ between the parts that contribute to the stability of the whole system
The term ‘constructs’ is defined in this thesis as ‘an abstract form of concept which cannot be observed directly or indirectly but can be inferred by observable events’
(Meredith, 1993). This approach is in line with the pragmatic critical realist position adopted in this research. The five constructs derived from the four boundary SWE (v3) are explored empirically through the case studies. The investigation gathers data about the construct dimensions which were identified from the literature in Chapter 3. The aim of using this SWE (v3) model is to gain insights into the characteristics of the hospitals studied and how they influence patient safety. The five constructs are grouped into three sets which interact which create emergent system behaviour (Figure 5.9).
These are examined in detail in Chapters 6 – 8.
Figure 5.9: Combination and interaction of construct sets depicted by the SWE model
The SWE model is used in healthcare (Cook and Rasmussen, 2005) to consider the consequences for a hospital ‘going solid’ due to a bed crisis. The change in dynamics that occurs when a system becomes tightly coupled, for example, due to lack of bed capacity, is explored in this research through the application of the model. Cook and Rasmussen (2005) have not undertaken an empirical inquiry using the SWE in hospitals. The operations management literature on NHS hospitals and policy
documents suggests a number of actions to both reduce and cope with peaks in demand in order to avoid a bed crisis (Klassen and Rohleder, 2001, Armitage and Raza, 2002,
System behaviour
(Operating Point)
Pressures
(Gradients)
Ch 7 Constraints
(Boundaries)
Ch 6 System
Dynamics
(Structure and Feedback)
Ch 8
Ham et al., 2003, Proudlove et al., 2003, Proudlove et al., 2007, Department of Health, 2005b, Department of Health, 2010c). However, the link between the operations management of patient demand and patient safety is not usually made.
It is argued that the SWE (v3) can be used to explore a number of concepts derived from the patient safety and accident theory literature that apply to systems. Using the safety theory concepts assists in explaining the influence that the system characteristics have on patient safety. The eight accident theory concepts, identified from the literature, are explicitly linked to the model in the following way:
• the tension between production verses safety – through the boundaries and gradients;
• blunt / sharp end – through the pressures generated by the gradients on sharp end staff and system performance depicted by the movement of the OP;
• latent or hidden conditions – through the ‘conditions’ created by the competing pressures on the OP;
• safety as a dynamic non-event – through the idea of compensating actions holding the OP within the envelope;
• redundancy / buffer capacity – through de-compensation of capacity to hold the OP within the envelope;
• normalisation – through staff accepting the shift in the position of a boundary or the OP;
• practical drift – through the gradual movement of the OP or small movements of a marginal zone boundary;
• trade-offs – through making the boundaries and the location of the OP explicit to decision makers.
The boundary construct is explored in Chapter 6 through analysis of data from the three case studies. The gradients and OP are examined in Chapter 7 using thick description of three events in case studies 1 and 2. The design and implication of the ‘structure’ and
‘feedback’ is presented in Chapter 8. The analysis seeks to conceptualise the findings in terms of both the model constructs and the safety concepts. This is done by indentifying the different SWE construct dimensions and how they incorporate the accident theory concepts.
5.4 Summary
In this chapter the interactive three boundary SWE model (Rasmussen, 1997) is first extended using concepts from SD. Secondly the model is contextualised and developed with the additional boundary of ‘target failure’. This is included as a result of the hermeneutical and content analysis of the NHS ‘Operating Framework’ documents.
Both experience and the analysis indicate a high level of attention to finance and targets and substantially less to staff workload and patient safety. The SWE (v3) depicts the context for NHS hospitals in terms of the failure boundaries and gradients that create dynamic influences on the OP. The safety concepts derived from the accident theory literature can be taken into account when using the SWE model.
The five constructs of the SWE (v3) provide a conceptual basis on which to examine the system characteristics of hospital systems. The following three chapters combine the constructs of the SWE with the concepts derived from the safety literature to analyse empirical case data collected during periods of high demand for inpatient beds.