###### Abstract
Since then, multiple publications have appeared in the scientific community [9], addressing several applications of different Lean tools in healthcare services, such as the application of SMED techniques to reduce the setup time of an operating room [12], the application of performance indicators such as the overall equipment effectiveness of operating rooms [13], or the application of the methodology 55 in a hospital establishment [14]. Research in lean healthcare has been growing almost exponentially; however, according to [PERSON] et at. [15] and [PERSON] et al. [16], lean healthcare is still in an early stage of development, with countless opportunities yet to be explored [9]. Although the lean approach was initially inspired for the automotive segment, some of its associated tools can be applied to all sectors. From these tools are analysis techniques, and against current prejudice, the simulation of discrete events is one of the techniques that stands out. The constant technological advancement has enhanced the development of simulation software that is increasingly robust and capable of numerically translating a real scenario. This fact made it possible to test changes to existing processes without the need to implement them on a real scale [17; 18]. Despite representing a theme that has been cherished in academia since 1950, its use as a tool to analyse issues related to production only proliferated from 1986 onwards [19]. Since then, the adoption of simulation as an analysis technique has gained notoriety, with a multitude of studies published in sharp detail in different contexts to date [20]. Just as lean has expanded to different sectors, so has simulation. The application of this technique as a problem analysis technique and support to the decision-making process quickly spread in the health sector, highlighting the adoption of themes such as the study of surgical procedures, intensive care unit design, among others [21]. Both the discrete event simulation technique and the lean healthcare principles share the objective of improving the analysed process. An example of integration between these two concepts was proposed in 2012 by [PERSON] [22]. Thus, testing the various scenarios resulting from the adoption of measures based on lean healthcare concepts became possible with the use of discrete event simulation [23; 24]. Based on the succinct historical framework presented, it can be easily understood that both the application of the lean philosophy to the health sector, as well as the use of the simulation technique as an aid to the improvement of hospital services, represent a remarkably recent theme in the scientific community. Thus, in terms of scientific research, answering the question if is possible to achieve an improved design in healthcare services by using innovative simulation techniques was the foundation for the study presented here. In this context, the authors' willingness to answer the question with the need for improvement of a hospital emergency department located in the north region of Portugal culminated in the research plan presented. The main goal was to develop a new operation parameterization for the hospital's emergency department, through the association of simulation techniques with the lean healthcare philosophy. In this way, several variant scenarios, optimized according to a lean healthcare philosophy, can be studied without the need for scale tests.