  Most of the studies dealing with the increasing and well-known problem of
Emergency Department (ED) overcrowding usually mainly focus on modeling the
patient flow within a single ED, without considering the possibilities offered
by the cooperation among EDs. Instead, it is important to analyze the
overcrowding phenomenon considering an ED network rather than a single ED. In
this paper, the Simulation-Based Optimization approach is adopted for studying
an ED network under different conditions, by means of Discrete Event Simulation
models. In particular we consider the so called Ambulance Diversion problem,
analyzing different diversion policies. Such models are carried out from real
data collected from six big EDs in the Lazio region of Italy. The aim is to
optimize the performances of the entire network, in order to provide the best
service to the patients without sustaining too high costs. The obtained
experimental results show which are the best diversion policies both in terms
of patient waiting time and costs for the service providers.
