What is Lean?
Lean can be defined as ‘a management practice based on the philosophy of continuously improving processes by either increasing customer value or reducing non-value adding activities (Muda), process variation (Mura), and poor work conditions (Muri).’ (Radnor and Holweg, 2010).
The implementation of lean in a healthcare setting, particularly a hospital, should remove duplicate processes and unnecessary procedures such as: recording patient details in multiple formats and places; patients being moved to wards before beds are available; patients being moved from one ward to another; excessive waiting for doctors and consultants; and uncoordinated, variable discharge processes resulting in a longer length of stay than necessary (NHSI, 2007).
What is Simulation?
Simulation is ‘the imitation of the operation of a real-world process or system over time.’ (Banks et al. 2005, p.3).
Discrete Event Simulation (DES) is a specific approach to simulating processes and systems in which the state of a system changes instantaneously at points in time, for instance, a customer arrives or a service activity is completed. This approach is particularly suited to modelling queuing systems (Pidd, 2004). Of course, many healthcare processes can be conceived as queuing systems in which it is primarily patients who wait.
Robinson (2004) discusses the key reason for using DES as the need to model processes that are subject to variability and that are interconnected, which leads to complexity. Variability can be thought of in terms of predictable variability (e.g. shift changeovers) and unpredictable variability (e.g. patient arrival patterns and consultation times). Given that most processes are subject to a range of sources of variability, which are interconnected (e.g. arrival profiles, to triage time, to initial consultation time, etc.), the process becomes complex. As a result, the performance of the process is difficult to predict; hence the need for simulation. Complexity arises not just from the scale of the process under investigation, but also through the dynamic interaction and feedback between elements of the process. Meanwhile, queues emerge between process steps as a result of the complex interaction of individual processes which are subject to variability. Hence the key assumptions of DES are that processes are subject to variability, they are interconnected and complex; queues emerge within the process and process performance (process flow) is difficult, or indeed impossible, to predict without a simulation.
DES is primarily used as a means for testing whether a proposed process performs as expected and to look for means of improving a process. According to Hollocks (1992) the common benefits of using DES in a manufacturing context are risk reduction, greater understanding, operating cost reduction, lead time reduction, faster plant changes, capital cost reduction and improved customer service. These benefits can easily be translated to other contexts such as services and healthcare.
What is SimLean?
Based on our understanding of DES and lean, and previous research (Robinson et al. 2012), we are able to identify three key roles for DES with lean:
SimLean Educate
DES can play an educational role in teaching key lean principles. It provides a powerful means for demonstrating and understanding the dynamics of healthcare processes. This enables key lessons to be learnt in terms of reducing waste (muda), unevenness (mura) and excessive strain (muri). DES also provides an environment in which ideas can be tried out rapidly, giving much faster turnaround than can be achieved through manual simulation exercises such as Lego-brick games. The idea is to have one or more prebuilt standard DES models that can be used for delivering key lean lessons. These models could be used as part of general lean training (before a lean event starts) or during a lean event, at the start and/or part way into the event if a specific lesson would prove useful at this point (e.g. for myth busting).
SimLean Facilitate
Most lean events that concentrate on process flow involve the drawing of a process map. There is a clear interest in using DES to create a dynamic version of this map. This could be achieved during an event through the rapid development of a simple process map DES model which could then be used to better understand the dynamics of the as-is process, engaging the participants, and to facilitate the exploration of alternative ideas for the to-be process during the event.
SimLean Evaluate
This involves the development of detailed DES models of to-be processes which would be used to experiment with alternative options and to evaluate their effectiveness. This is very much a traditional use of DES which typically requires days to weeks of modelling, detailed data, thorough model validation and statistically sound experimentation. By its very nature this would have to take place after a lean event as a 14 means for testing the ideas generated from the event and creating new suggestions where necessary. Such models could also be used in the longer-term to aid implementation and as the basis for continuous improvement.
Combining Simulation and Lean
Simulation and lean are approaches that are rarely discussed together, particularly in the healthcare context. This is surprising given that they have a similar motivation: improvement of processes and service delivery.
This Project
Exploiting the SimLean approach using stakeholder and user workshops, this study will investigate how emergency hospital admissions can be reduced.
References:
Banks, J., Carson, J.S., Nelson, B.L. and Nicol, D.M. (2005). Discrete-Event System Simulation, 4th ed. Prentice Hall, Upper Saddle River, NJ.
Hollocks, B. (1992). A Well-kept Secret? Simulation in Manufacturing Industry Reviewed. OR Insight, 5 (4), pp. 12-17.
NHSI (2007). Going Lean in the NHS.http://www.institute.nhs.uk/option,com_joomcart/Itemid,26/main_page,document_product_info/products_id,231.html (Accessed January 2011).
Pidd, M. (2004). Computer Simulation in Management Science, 5th ed. Wiley, Chichester, UK.
Radnor, Z.J. and Holweg, M., (2010). From Tools to Systems: A Critical Appraisal of Lean Healthcare Implementations. European Operations Management Association Conference.Sousa R. Porto.
Robinson, S. (2014). Simulation: The Practice of Model Development and Use. 2nd Edition. Palgave,London, UK.