Simulation and evaluation of emergency medical services systems resource allocation and performance

Objectives: The research attempts to assess alternatives of the number and locations of ambulances in order to improve emergency medical services systems performance. Methods: From January to October 2004 ambulances responded to 13,871 calls in Tainan City, Taiwan. According to the spatial distribution of calls of every shift, we used K-means, point pattern spatial analysis, to redeploy the ambulances. A simulation model based on the empirical data was developed to analyze response times and utilization ratios to evaluate the performance of each alternative. Results: Based on the simulation analysis, alternative #1 (14 ambulances) performs best on overall response time, while alternative #2 has the highest utilization ratio among those alternatives whose response times are acceptable. In comprehensive evaluation of the two indicators, alternative #6 (number of ambulances that varies with shifts) is superior. Conclusions: There is a trade-off relation between response time and utilization ratio. Our research shows that redeploying ambulances according to arrival frequency and spatial distribution of calls can improve not only the performance of their response time but also their utilization ratio. (Taiwan J Public Health. 2007;26(3): 184-195).