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Defining a mission-based method to determine a HEMS unit's actual service area
Jukka Pappinen1,2, Anna Olkinuora3, Päivi Laukkanen-Nevala3
1FinnHEMS Research and Development Unit, Lentäjäntie 3, FI-01530, Vantaa, Finland. jukka.pappinen@finnhems.fi.
Summary
Administrative boundaries do not accurately reflect helicopter emergency medical service (HEMS) operational areas. A new GIS-based method using mission data defines actual HEMS service areas for better statistical analysis and quality measurement.
Area of Science:
- Emergency Medical Services (EMS)
- Geographical Information Systems (GIS)
- Spatial Analysis
Background:
- Administrative boundaries often inaccurately represent actual Emergency Medical Service (EMS) geographical service areas.
- This discrepancy can lead to biased indicators like population or mission density, hindering accurate comparisons between different EMS units.
- A standardized method is needed to define the true operational service area for Helicopter Emergency Medical Service (HEMS) units.
Purpose of the Study:
- To introduce a univocal, repeatable, and adaptable method for determining the actual service area of HEMS units.
- To enable accurate statistical analysis, quality measurement, and research using geographical information and statistical tools.
- To address the inaccuracies caused by using administrative areas as service indicators.
Main Methods:
- Utilized historical mission data (2017) from the Tampere HEMS unit, extracting mission locations.
- Calculated distances from the HEMS base to each mission, determining 95th and 99th percentiles of mission distances.
- Generated convex hulls encompassing 95% and 100% of missions to define the actual service area, then repeated for all Finnish HEMS bases.
Main Results:
- Approximately 90% of Tampere HEMS missions occurred within 100 km of the base; 10.9% were outside the administrative area.
- The 95% convex hull area for Tampere HEMS covered 76.5% of the administrative population and 89.8% of its area.
- Applying the method to all Finnish HEMS revealed overlapping service areas and areas outside any HEMS coverage.
Conclusions:
- Administrative areas are inadequate for defining HEMS operational service areas.
- A convex hull method based on historical mission data provides a standardized approach to delineate actual HEMS service areas.
- This method facilitates more accurate statistical comparisons, quality assessments, and system development for HEMS.
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