Operations Research Tools for Addressing Current Challenges in Emergency Medical Services

Emergency Medical Service (EMS) providers face a host of significant challenges, including traffic congestion, increasing call volumes, hospital diversion (i.e., emergency departments at hospitals not allowing ambulances to deliver patients to them), and increasing transfer times at emergency departments. Many of these challenges can be attacked through an application of operations research techniques in conjunction with EMS expertise. The purpose of this article is to outline some of the key challenges and potential operations research based remedies, and to discuss in detail one such remedy that has various names including “system-status management” and “move up.” The job of an Emergency Medical Service (EMS) provider is to respond to calls for assistance, render urgent medical care at the scene of a call and then, if necessary, transport the patient to an appropriate hospital. An EMS provider must coordinate the actions of many ambulances, the staff in which may have different levels of training, to address calls of many different types. Call volumes vary significantly according to cyclical patterns on a daily, weekly and annual basis, and calls are certainly not evenly spread over geographic regions. EMS problems are similar to those faced by other emergency services including fire and police, although there are important differences. For a superb overview of work in these various fields to the early 1990s see [40], and for some recent commentary see [23]. The survey [20] is a valuable reference for both operations research specialists and EMS professionals, although it is written primarily for EMS professionals. EMS problems also have some similarities with the taxi and courier industries, although the latter industries can benefit from a-priori scheduling of a nontrivial fraction of their calls. The focus in this article is on operational issues rather than clinical issues. Clinical issues are those issues that are essentially medical in nature, such as the difference that prompt intubation can make to patient survival rates. The clinical side is extremely active. See, for example, the Annals of Emergency Medicine, the Journal of Emergency Medical Services, or Academic Emergency Medicine. These journals also publish occasional articles that focus on operational aspects. Operations research tools have been used to assist in decision making in EMS at least since the 1960s, e.g., [38]. Typical applications include the siting of new bases and staff scheduling. But there are still a host of challenges faced by EMS providers, some of which are variants of these well-known problems, while others have arisen only recently. The goal of this article is to describe some of these challenges and suggest possible avenues of (operations) research that might help address them. I will particularly emphasize system-status management as a tool for addressing several problems at once. The article is not meant to be a state of the art survey, but rather a “call to arms.” To absorb the entire article the reader should have a background in the tools of operations research, say at the undergraduate or masters level, but much of the discussion should be accessible without this background.