A hybrid simulation approach to analyse patient boarding in emergency departments

This paper deals with the problem of patient boarding in Emergency Department (ED) due to the lack of availability of stay beds in inpatient hospital wards. The boarding of emergent patients is a major reason of ED overcrowding, which in turn creates long waiting times in ED, as well as patient and staff dissatisfaction. In this paper a hybrid simulation framework is proposed to describe how emergent and elective patients flows interact each other inside the hospital. The framework combines System Dynamics (SD) and Discrete Event Simulation (DES). Flows are generated at macro level by the SD model, while in DES model they are disentangled into single entities following a detailed process-oriented pathway. The hybrid model has been then applied and validated to data from a medium-size public hospital located in Genova (Italy). Furthermore, some metrics (such as waiting times to be admitted in hospital, number of trolleys in ED, inpatient bed occupancy rates and elective patients delayed) are proposed as key indicators to assess the system performance.