How to improve automated external defibrillator placement for out-of-hospital cardiac arrests: A case study

Introduction In out-of-hospital cardiac arrests (OHCAs), the use of an automatic external defibrillator (AED) by a bystander remains low, as AEDs may be misplaced with respect to the locations of OHCAs. As the distribution of historical OHCAs is potentially predictive of future OHCA locations, the purpose of this study is to assess AED positioning with regard to past locations of OHCAs, in order to improve the efficiency of public access defibrillation programs. Methods This is a retrospective observational study from 2014 to 2018. The locations of historical OHCAs and AEDs were loaded into a geodata processing tool. Median distances between AEDs were collected, as well as the number and rates of OHCAs covered (distance of <100 meters from the nearest AED). Areas with high densities of uncovered OHCAs (hotspots) were identified in order to propose the placement of additional AEDs. Areas over-covered by AEDs (overlays) were also identified in order to propose the relocation of overlapping AEDs. Results There were 2,971 OHCA, 79.3% of which occurred at home, and 633 AEDs included in the study. The global coverage rate was 7.5%. OHCAs occurring at home had a coverage rate of 4.5%. Forty hotspots were identified, requiring the same number of additional AEDs. The addition of these would increase the coverage from 7.5% to 17.6%. Regarding AED overlays, 17 AEDs were found to be relocatable without reducing the AED coverage of historical OHCAs. Discussion This study confirms that geodata tools can assess AED locations and increase the efficiency of their placement. Historical hotspots and AED overlays should be considered, with the aim of efficiently relocating or adding AEDs. At-home OHCAs should become a priority target for future public access defibrillation programs as they represent the majority of OHCAs but have the lowest AED coverage rates.

Strategic Mapping and Optimised Allocation of Automated External Defibrillators in Urban Areas

<p><strong>Background</strong>: Out-of-hospital cardiac arrest (OHCA) is a leading cause of death and is regarded as a significant public health issue. Immediate treatment with an automated external defibrillator (AED) increases OHCA patient survival potential. For AEDs to be used and fulfil their lifesaving potential, they need to be in close proximity to the victim and accessible at the time of a cardiac arrest. The current paper sheds light upon an optimized location-allocation method achieving full coverage with immediate accessibility in an urban context given a limited number of available AEDs for deployment using GIS. The case study is the Region of Western Macedonia (RWM) in Greece for a pilot AED placement program for the Governance of RWM. The focus of the current study is the capital city of RWM, Kozani. The initial number of the defibrillators (120) that are needed to be distributed is very small and cannot cover the needs for every major city or rural area in the region. Out of the 120 AEDs, the challenge is to find the minimum required number of AEDs to allocate in the city providing full coverage and accessibility. This paper focuses only on one city, however, the same methodology was applied to allocate AEDs in the other selected cities of the region. The rural dimension and methodology are not in the scope of this paper. <br> <strong>Methods</strong>: Road network data, spatio-temporal analysis of accessibility network, digital elevation model, land uses, population density, seasonal fluctuations and socio-demographic variables were used. GIS algorithms such as spatial analysis, kernel density, hot spot analysis, maximal covering location problem (MCLP) tests, proximity algorithms, buffer zoning, were a few of the tests made in order to find the most efficient positions and maximize coverage keeping in mind that access to an AED until defibrillation time must not exceed the time range of five minutes. <br> <strong>Results</strong>: optimised sites and allocated AEDs in urban areas we managed to achieve full city coverage with 17 AEDs. In every part of the city, people can have access to a nearby AED with its critical radius of less than or equal to 250m achieving defibrillation in the critical period of 5 minutes. The results are promising for the establishment and expansion of optimised AED deployment in cities. <br> <strong>Conclusions</strong>: The progress of the project must be monitored and there are still unresolved problems that need to be tackled to provide a robust allocation of future defibrillators. Further research to enhance our understanding on public access defibrillation and optimize the accessibility and functionality of the medical health care services is needed. A network of engaged and informed citizens ready to act is required for a successful public access defibrillation program.</p>