Emergency medical service: response time achievability and number of call-outs

This paper focuses on Emergency Medical Service (EMS), one of the basic units of the Integrated Rescue System of the Czech Republic. The study analyzes EMS response times and call-out frequencies using records from 2009 provided by the Regional Offices of the Olomouc and Ústí nad Labem Regions, together with road network data. The distribution of EMS response times was statistically analyzed, and accessibility zones and travel-time maps were constructed. Comparisons among EMS stations were performed to identify factors affecting response times. The results showed that response times were similar across calendar days, months, and times of day. The main influencing factor was the geographical location of EMS stations, determined primarily by elevation and the quality and density of road networks. Because EMS capacity may also affect response times, call-out frequencies were subsequently analyzed. The number of EMS operations was modeled using a finite mixture of three circular von Mises distributions, with parameters estimated by the expectation-maximization algorithm. Artificial intelligence methods were used to determine model parameters by minimizing the chi-square statistic. The resulting density model identified peak call-out times over 24 hours and enabled seasonal comparison of these peaks. The proposed methods provide useful tools for EMS planning, prognosis, and evaluation.