2025/10/23 by Tatsuru Kikuchi, Kikuchi, Tatsuru
Business, Management and Accounting · Medicine · #Facility Location and Emergency Management #Trauma and Emergency Care Studies #Emergency and Acute Care Studies
paper · pdf · doi:10.48550/arxiv.2510.26810
Emergency medical services (EMS) response times are critical determinants of patient survival, yet existing approaches to spatial coverage analysis rely on discrete distance buffers or ad-hoc geographic information system (GIS) isochrones without theoretical foundation. This paper derives continuous spatial boundaries for emergency response from first principles using fluid dynamics (Navier-Stokes equations), demonstrating that response effectiveness decays exponentially with time: τ(t) = τ0 exp(-κt), where τ0 is baseline effectiveness and κ is the temporal decay rate. Using 10,000 simulated emergency incidents from the National Emergency Medical Services Information System (NEMSIS), I estimate decay parameters and calculate critical boundaries d^* where response effectiveness falls below policy-relevant thresholds. The framework reveals substantial demographic heterogeneity: elderly populations (85+) experience 8.40-minute average response times versus 7.83 minutes for younger adults (18-44), with 33.6% of poor-access incidents affecting elderly populations despite representing 5.2% of the sample. Non-parametric kernel regression validation confirms exponential decay is appropriate (mean squared error 8-12 times smaller than parametric), while traditional difference-in-differences analysis validates treatment effect existence (DiD coefficient = -1.35 minutes, p < 0.001). The analysis identifies vulnerable populations--elderly, rural, and low-income communities--facing systematically longer response times, informing optimal EMS station placement and resource allocation to reduce health disparities.