Abstract: In order to accurately evaluate the performance of urban emergency medical system(120 emergency), the ambulance state is defined as idle or busy considering the urban ambulance rescue dispatching process, and the state space of the ambulance fleet is established. Based on the multiplication rule of conditional probability and detailed balance equations of birth and death process, approximate linear equations and its iterative solving algorithm are constructed to solve the work intensity of each ambulance (the proportion of the time that the ambulance is in the busy state). The mathematical procedures of performances, including the fraction of the inter-district dispatches and the response time, are given. To verify the proposed model, the performances of the ambulance system in Suzhou are evaluated, and the improvement schemes of the ambulance system deployment are proposed to equalize the work intensity and minimize the response time. The result shows that the proposed model can handle a large number of ambulances (more than 15) that the previous models cannot. The dispatch priority of ambulance in each zone, set by the rescue distances, enables ambulances to share, and balances each ambulance work intensity and the fractions of inter-district dispatches. The schemes of ambulance deployment and emergency zone partitions based on rescue performances can effectively minimize response time under a fixed number of ambulances.

Key words: service science, medical emergency service, ambulance deployment, ambulance dispatch priority

摘要： 为了准确评估城市医疗急救(120急救)系统的救援绩效,面向救护车救援调度过程,通过将救护车状态定义为空闲或繁忙建立救护车队的救援状态空间,基于条件概率的乘法规则以及生灭过程平衡方程,构造求解各救护车工作强度(救护车处在繁忙状态的时间占比)的近似线性方程组及其迭代求解算法,由此提出了救护车工作强度近似模型。基于救护车工作强度,给出了救护车跨区救援比例、响应时间等救援绩效计算方法。为了验证上述模型,评价了苏州市区120急救系统的绩效指标,据此改善了救护车救援系统配置方案。研究表明,救护车工作强度近似模型克服了以往救护车数量较多时(大于20辆)难以求解的困难;根据救援距离设置救护车指派优先级能够实现救护车共享、平衡各救护车工作强度以及跨区救援比例;在不增加救护车总数的情况下,基于救援绩效能够改善救护车分布以及急救辖区划分从而有效缩短医疗急救响应时间。

关键词: 服务科学, 医疗急救服务, 救护车配置, 救护车优先级