Modelled Response Times for Police and Fire Brigade Co-Dispatch to Out-of-Hospital Cardiac Arrest: A Geospatial Simulation Study in Vorarlberg, Austria

Background/Objectives: Survival after out-of-hospital cardiac arrest (OHCA) depends on the interval between collapse and the start of chest compressions. We estimated how co-dispatching police and volunteer fire brigades alongside emergency medical services (EMS) would change the modelled time from dispatch to arrival of the first unit in Vorarlberg, Austria. Methods: In a geospatial simulation, 500 OHCA locations were drawn from a 100 m population raster, weighted by residential population. Driving times from all 18 EMS, 28 police and 121 volunteer fire stations were routed on the road network, and turnout times of 2 min (EMS), 0 min (police) and 5 min (fire brigade) were added; all units were modelled as continuously available at fixed stations. Four configurations (EMS alone, EMS plus police, EMS plus fire brigade, triple dispatch) were compared by paired time gains and 10 min coverage with bootstrap confidence intervals (CIs); uncertainty from sampling, turnout times, unit availability and routing was assessed separately. Results: Of 500 missions, 499 were analysable. Median response time was 9.81 min with EMS alone, 5.45 min with EMS plus police, 7.36 min with EMS plus fire brigade and 5.41 min with triple dispatch; the paired median time gain of triple dispatch over EMS alone was 4.34 min (95% CI 3.80–4.67). Locations reached within 10 min rose from 51.1% to 87.4%, 87.0% and 94.6%, and the resident population inside the 10 min isochrones rose from 55.6% to 90.9%, 91.9% and 95.5%. Conclusions: Under fixed station locations, continuous unit availability and assumed agency-specific turnout times, police and fire brigade co-dispatch increased modelled ten-minute coverage compared with EMS alone. Police arrived earlier at most locations, whereas the denser fire station network contributed most in rural areas; their combination reached the most locations. Operational validation is required before these estimates can inform regional implementation.