Response time is a very important factor in determining the quality of
prehospital EMS. Our objective was to model the response by Israeli
ambulances and to offer model-derived strategies for improved deploy-
ment of ambulances to reduce response time. Using a geographic infor-
mation system (GIS), a retrospective review of computerized ambulance
call and dispatch logs was performed in two different regional districts,
one large and urban and the other rural. All calls that were pinpointed
geographically by the GIS were included, and their data were stratified by
weekday and by daily shifts. Geographic areas (polygons) of, at most, 8
minutes response time were simulated for each of these subgroups to
maximize the timely response of calls. Before using the GIS model, mean
response times in the Carmel and Lachish districts were 12.3 and 9.2
minutes, respectively, with 34% and 62% of calls responded within 8
minutes. When ambulances were positioned within the modeled poly-
gons, more than 94% of calls met the 8-minute criterion. The GIS simu-
lation model presented in this study suggests that EMS could be more
effective if a dynamic load-responsive ambulance deployment is
adopted, potentially resulting in increased survival and cost-effective-
ness. (Am J Emerg Med 2004;22:164-170. © 2004 Elsevier Inc. All rights
reserved.)