New model predicts best distribution of AEDs to treat heart failure
in public places
8 September 2014
A new method to predict the optimal number and location of
automated external defibrillators (AEDs) has been developed by a
group of academic and clinical centres in Paris.
The study is the result of close collaboration between the Paris
Sudden Death Expertise Center (SDEC), the National Institute of
Medical Research (Inserm), the Paris Descartes University and the
Assistance Publique-Hôpitaux de Paris (APHP).
The researchers conducted a systematic analysis of all out of
hospital cardiac arrest (OHCA) locations during 2000-2010. They then
simulated different scenarios to evaluate how useful AEDs would have
been to the OHCA cases such as comparing the effect of distance
between AEDs, from 200 metres to 2000 metres.
The researchers also tested the scenario of having AEDs in all
well known public areas including subway stations, post offices,
pharmacies and bike-sharing stations. Using road network information
and a geographic information system (GIS), they calculated the
median distance (in metres) between OHCAs and potential AED
locations. The plot distribution was modelled using a non-linear
According to this model, Paris needs 350 AEDs located in public
places for optimal prevention of out of hospital cardiac arrest
Researcher Dr Benjamin Dahan said, “Out of hospital cardiac
arrest is a major public health issue with an annual incidence
ranging between 50 and 100 per 100 000 in the general population in
Europe and North America. Because the vast majority of OHCA starts
with ventricular fibrillation, early defibrillation and
cardiopulmonary resuscitation are the only way to save the victim.
Every minute of delay prior to defibrillation, decreases survival by
“Except for a few recent encouraging reports, survival after OHCA
remains poor at 7 to 8%. Survival has not improved over time despite
decades of research and major financial investments in
resuscitation. In the last two decades, public access defibrillation
has been developed with a large deployment of AEDs for lay
Dr Dahan continued, “However, although the benefits of AEDs are
undeniable, public utilisation rates remain very low, and thus the
effectiveness of such programmes could be dramatically improved. One
of the key issues is the disparity between the location of AEDs and
OHCAs. To optimise AED deployment, policy makers have to consider
many scientific, geographic, societal and political issues.
Systematic scientific approaches are needed to improve the
cost-effectiveness of public access to defibrillation programmes.
“Geographic optimisation modelling could be used for many urban
areas, taking into account population density, population movements,
urbanisation and other demographic data. This approach brings
scientific rigour to the process of determining the optimal number
of AEDs required in different urban areas.
“The expense of deploying AEDs is an important issue, with
each device costing approximately €1000, plus maintenance. AEDs are
underused because lay rescuers do not know where they are. Our
approach to modelling the number and location of AEDs should
dramatically improve cost-effectiveness by avoiding an excess number
and ensuring they are accessible. Previous research has shown that
efficient public access defibrillation programmes may improve the
number of OHCA survivors by 100%.
He concluded: “In the current financial climate it is essential
to avoid wasting resources. Our modelling ensures that the ideal
number of AEDs can be deployed at the optimal location. This could
be the change needed to improve the survival rates of
out-of-hospital cardiac arrest.”
Hallstrom AP et al. Public Access Defibrillation Trial
Investigators. Public-access defibrillation and survival after
out-of-hospital cardiac arrest. N Engl J Med. 2004;351(7):637-646.