Quantify and visualize disparities in accessibility of physician response vehicles and helicopter emergency medical services: Use of the geographic information system

Background: Physician Response Vehicles (PRV) and Helicopter Emergency Medical Services (HEMS) provide faster physician access to patients in critical condition. While both are resource-intensive, few studies have investigated effective resource utilization for PRVs and HEMS given the disparity in patient needs and access to emergency units (EU). We aimed to quantify and visualize the needs and availability of PRVs and HEMS for severe trauma patients.

Methods: We estimated the number of severe trauma patients in Kyushu, a major Japanese island with 7 prefectures, a total area of 35,640 km², and a population of 13,352,928, using EMS transportation records and the population for each mesh block (1 km²). Transportation time from each mesh to EUs and distance from each mesh to heliports were calculated using MapInfo. Mesh categorization included: 1) Ambulance covered (within 30 minutes from dispatch to arrival), 2) PRV covered (within 30 minutes from PRV-equipped EU), 3) HEMS covered (within 50 km from heliport), or 4) Non-covered. We assumed that EUs only cover patients injured within the prefecture, with no disaster-prevention helicopter available. Patients were mapped into each group to visualize disparities in access to PRVs or HEMS.

Results: Annual mean number of severe trauma patients was 26.8 per population 100,000. In Kyushu, 644.2 (20.2%) of 3,191.1 patients were estimated to require EMS in ‘Non-covered' mesh blocks. If EUs cover patients outside the prefecture and utilize disaster-prevention helicopters, additional 67.4 patients (2.1%) could be coverd. Our approach will be useful for examining effective resource utilization for PRVs and HEMS.