Route selection of an ambulance considering the disease or injury of a patient

Abstract

To improve patient safety in ambulance transport service, this paper proposes a new method for finding an optimal route of an ambulance depending on the disease or injury of a patient. Three transport cases are considered in this paper: Heart disease (HD), hemorrhagic cerebrovascular accident (HCVA) and fracture/dislocation (Fx/dx). The route optimality is measured with three evaluation functions. The first function evaluates an elapsed time from the scene of an emergency to a hospital. The second evaluates a blood pressure variation induced by the acceleration/deceleration motion of an ambulance. The third evaluates a compression load acting on the back of a patient due to the centrifugal force. They are calculated by applying the traveling model of an ambulance to the three-dimensional road network. The optimal route is selected in two stages. First, the candidate routes are found by solving the multiobjective optimization problem of minimizing the three evaluation functions. If the completely optimal solution (route), which minimizes the three functions simultaneously, is found, the selection process is finished. Otherwise, obtain the Pareto solutions to go to the second stage, in which a preference solution is selected from the Pareto solutions depending on the disease or injury of a patient. In the numerical example, the route selection is shown for HD, HCVA and Fx/dx. For the reference sake, the real routes of the ambulance recorded in Hiroshima City and the shortest routes obtained by Google Maps Navigation are also presented and compared to each other.

Keywords

• route optimization
• path search
• ambulance
• multiobjective optimization
• genetic algorithm