  Emergency Departments (EDs) overcrowding is a well recognized worldwide
phenomenon. The consequences range from long waiting times for visits and
treatment of patients up to life-threatening health conditions. The
international community is devoting greater and greater efforts to analyze this
phenomenon aiming at reducing waiting times, improving the quality of the
service. Within this framework, we propose a Discrete Event Simulation (DES)
model to study the patient flows through a medium-size ED located in a region
of Central Italy recently hit by a severe earthquake. In particular, our aim is
to simulate unusual ED conditions, corresponding to critical events (like a
natural disaster) that cause a sudden spike in the number of patient arrivals.
The availability of detailed data concerning the ED processes enabled to build
an accurate DES model and to perform extensive scenario analyses. The model
provides a valid decision support system for the ED managers also in defining
specific emergency plans to be activated in case of mass casualty disasters.
