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Priority dispatching strategies for EMS systems

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Journal of the Operational Research Society

Abstract

Emergency medical service (EMS) systems provide urgent medical care and transport. In this study we implement dispatching policies for EMS systems that incorporate the severity of the call in order to increase the survival probability of patients. A simulation model is developed to evaluate the performance of EMS systems. Performance is measured in terms of patients’ survival probability, since survival probability more directly mirrors patient outcomes. Different response strategies are evaluated utilizing several examples to study the nature of the optimal dispatching policy. The results show that dispatching the closest vehicle is not always optimal and dispatching vehicles considering priority of the call leads to an increase in the average survival probability of patients. A heuristic algorithm, that is easy to implement, is developed to dispatch ambulances for large-scale EMS systems. Computational examples show that the dispatching algorithm is valuable in increasing the patients’ survival probability.

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Notes

  1. OptQuest uses metaheuristic methods by taking the output of the simulation model as input to the optimization procedure that performs a special ‘non-monotonic search,’ where the generated inputs produce varying evaluations, not all of them improving, but which over time provide a highly efficient path to the best solutions. The process continues until it reaches some termination criterion.

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Acknowledgements

It is our pleasure to acknowledge Chief Fred C. Crosby, II, Battalion Chief Henri Moore, Jr., Mr. Lawrence Roakes of Hanover County Fire and EMS Department in Hanover County, Virginia, for the data they provided to support this research.

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Authors and Affiliations

  1. Clemson University, Clemson, SC, USA

    Damitha Bandara

  2. North Carolina State University, Raleigh, NC, USA

    Maria E Mayorga

  3. University of Wisconsin-Madison, Madison, WI, USA

    Laura A McLay

Authors
  1. Damitha Bandara
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  2. Maria E Mayorga
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  3. Laura A McLay
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Corresponding author

Correspondence to Maria E Mayorga.

Appendix

Appendix

In Table A1, under Response Times (μ1, σ) implies that response times are distributed lognormally with mean of μ1 and standard deviation of σ. Table A2 provides Turn-Around Times with respect to call priority and proportion of Priority 1 calls by demand zones. In Table A2, turn-around time (μ2) implies that turn-around times are exponentially distributed with mean of μ2.

Table A1 Response times and proportion of calls for 12 × 5 case
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Table A2 Turn-around times for 12 × 5 case
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Bandara, D., Mayorga, M. & McLay, L. Priority dispatching strategies for EMS systems. J Oper Res Soc 65, 572–587 (2014). https://doi.org/10.1057/jors.2013.95

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