Proceedings of the 2011 Industrial Engineering Research Conference T. Doolen and E. Van Aken, eds. Analysis of Single-Threshold Ambulance Diversion Policies with Simple Destination Rules Adrian Ramirez-Nafarrate, John W. Fowler and Teresa Wu School of Computing, Informatics and Decision Systems Engineering Arizona State University Tempe AZ, 85287, USA Abstract Ambulance Diversion (AD) has been the subject of numerous discussions and analyses recently. It has been criticized because of the significant impact from the potential delay in the transportation of an emergent patient. However, there is not sufficient evidence to suggest that AD is, in general, a poor choice to improve the performance of a regional emergency care delivery system. This paper shows a simulation-based analysis of single- threshold AD policies with simple patient destination rules in the context of a multi-hospital system. The objective is to determine the effect of a small set of combinations of AD policies and destination rules on the activities with non- value added time through Pareto analysis of the performance of multiple hospitals. The non-value added time is a metric that includes the transportation time, waiting time in the emergency department and boarding time. The findings of the analysis suggest that AD policies and an effective destination rule may reduce the delay that a patient spends to receive appropriate treatment at different stages of care. Keywords Ambulance Diversion, Discrete-Event Simulation, Non-Value Added Time. 1. Introduction Ambulance diversion (AD) is the name of the status in Emergency Departments (EDs) that indicates significant overcrowding. During AD, the hospitals request ambulances to bypass their facilities. Concern regarding long periods on AD has been highlighted in various reports and journals. For instance, the General Accounting Office submitted a report to the US Senate in 2003 showing that nearly 70% of the EDs that took part in the study went on diversion status at some point during fiscal year 2001 and about 10% of them were on diversion at least 20% of the time [1]. In addition, the Centers for Disease Control and Prevention through their Advance Data from Vital and Health Statistics (now called the National Health Statistics Report) reveals that in 2003-04 the mean annual hours on diversion, among the EDs that reported any period of AD, was 403.9 hours [2]. Empirical studies have focused on the objective of minimizing AD instances under the belief that it may deteriorate the health condition of the patient because of longer transportation; therefore, much of the medical community suggests avoiding AD [3]. Furthermore, some regulations have prohibited AD in some cities around the United States; however, these policies may put strain on the operations of EDs if no other actions are taken to reduce congestion [4]. The underlying hypothesis of this research is that a smart flow control of ambulances in a regional emergency care delivery system (RECDS) can reduce the time that patients spend waiting for the appropriate level of treatment. Thus, a patient diverted from an ED may spend more time in transportation, but he/she may be treated sooner in a farther away facility than in a close overcrowded one. The flow control of ambulances proposed on this paper is achieved through ambulance diversion policies and ambulance destination rules. The remaining parts of this paper are as follows. Section 2 summarizes the findings in the literature regarding ambulance diversion followed by the results of a previous study made on AD in Section 3. A simulation model of a RECDS is described in Section 4. In Section 5 the logic of ambulance flow control is presented along with the