AED Registries Need Readiness Accountability, Not Device Counts Alone
Public-access automated external defibrillator (AED) programs are often summarized by device counts or map coverage, but those measures do not prove that a device can be found, reached, used, or restored during an out-of-hospital cardiac arrest. This conceptual synthesis reviewed AlexandrAI graph search results, FDA device guidance, Healthy People/CARES surveillance definitions, CDC policy synthesis, AHA systems guidance, ILCOR public-access defibrillation recommendations, randomized and observational AED studies, registry accessibility studies, a 2026 international consensus study, and registry implementation examples. The evidence supports public-access defibrillation as part of an integrated response system, yet also shows persistent gaps: low bystander AED use, off-hour inaccessibility, proximity without application, maintenance needs, and inconsistent registry integration. The paper contributes an AED readiness-accountability chain that separates inventory, validated location, public access, device readiness, emergency integration, retrieval, application, outcome, maintenance feedback, and quality improvement. AED registries should report stage-specific readiness rather than treating installed devices as emergency-ready assets.
Introduction
Public-access automated external defibrillators (AEDs) are often counted as if each installed device were a unit of emergency readiness. That is a convenient metric for grant programs, legislation, building owners, and public maps, but it is a weak public-health claim. A device can be installed, mapped, and even nearby while remaining unreachable after hours, hidden inside a large building, missing usable pads, absent from the emergency dispatcher workflow, unknown to bystanders, too far to retrieve without delaying cardiopulmonary resuscitation (CPR), or unreported after use.
The stakes are high because defibrillation can matter greatly when the surrounding system works. The 2004 Public Access Defibrillation trial found 30 survivors among 128 treated arrests in CPR-plus-AED community units, compared with 15 survivors among 107 in CPR-only units [[cite:hallstromPad2004]]. The Resuscitation Outcomes Consortium cohort found survival to discharge of 24 percent when an AED was applied before emergency medical services (EMS) arrival, compared with 9 percent among patients with bystander CPR but no AED application [[cite:weisfeldtRoc2010]]. Japan population studies likewise connect public-access AED dissemination to earlier shocks and better neurologic outcomes in selected witnessed shockable arrests [[cite:kitamuraJapan2010,kitamuraJapan2016]].
Yet the same literature shows that AED availability is not self-executing. The International Liaison Committee on Resuscitation (ILCOR) scientific statement notes that public-access defibrillator programs have been associated with improved outcomes, but devices are used in less than 3 percent of all out-of-hospital cardiac arrest (OHCA) episodes [[cite:ilcorPad2022]]. Healthy People 2030, using CARES data, set a public-location bystander AED-use baseline of 9.0 percent in 2020 and a target of 12.0 percent [[cite:hp2030Prep02]]. This paper asks how AED registries should represent success when device counts do not prove readiness.
Methods
This paper is a conceptual synthesis. I searched AlexandrAI for prior AED, public-access defibrillation, defibrillator-registry, OHCA, and emergency-response papers; no duplicate AED-readiness paper was found. I then searched official sources, guidelines, PubMed-indexed studies, implementation reports, and public registry examples on 2026-06-27. The evidence base includes FDA device guidance, Healthy People/CARES surveillance definitions, CDC PAD law synthesis, AHA systems guidance, the ILCOR scientific statement, randomized and observational PAD studies, registry accessibility studies, a 2026 international consensus study, and a public AED registry example [[cite:fdaAed,hp2030Prep02,cdcPadLaws,ahaSystems2020,ilcorPad2022,thiesConsensus2026]].
Sources were included when they helped answer one of four questions: whether AED use can improve outcomes under structured conditions; where device count, proximity, or mapping fails as a readiness proxy; which operational fields make an AED findable, reachable, and functional; and how emergency systems should connect registry data to dispatch, event use, outcomes, and maintenance. The synthesis is not a new survival meta-analysis and does not provide individual medical advice. Its contribution is a registry accountability model that keeps program claims proportional to operational evidence.
The analytic rule was stage discipline: a registry should not claim a later stage unless it records the signals required by earlier stages. A device-count dashboard can claim inventory. A validated map can claim findability. A 24/7-access field can claim time-conditioned reachability. A readiness field can claim likely device function. Event linkage can claim retrieval, application, shock, and outcome. Table 1 summarizes the sources most directly shaping this rule.
Evidence Boundary: PAD Works as a System
The most defensible positive claim is not "AEDs on walls save lives." It is narrower and stronger: early defibrillation can improve outcomes when a shockable arrest is recognized quickly, bystanders or trained responders act, the device is reachable, and the emergency-care chain continues. AHA systems guidance describes cardiac-arrest survival as an integrated system of people, training, equipment, and organizations, with OHCA recommendations spanning recognition, CPR, public-access defibrillation, mobile phone technologies, telecommunicators, debriefing, and performance measurement [[cite:ahaSystems2020]].
The PAD trial illustrates this system dependency. The intervention was not only device placement; it was a structured and monitored emergency-response system with lay volunteers trained in CPR and AED use. Survival to discharge was higher in CPR-plus-AED units, and no inappropriate shocks were delivered [[cite:hallstromPad2004]]. The trial also reported only two survivors in residential complexes, a caution against transferring public-setting evidence to every location type without considering event visibility, responder availability, and retrieval time.
Population evidence extends but does not erase those constraints. In the ROC cohort, only 2.1 percent of OHCAs had an AED applied before EMS arrival, yet survival was higher when AEDs were applied or delivered a shock [[cite:weisfeldtRoc2010]]. In Japan, increasing public-access AED density was associated with shorter mean time to shock and more survivors with minimal neurologic impairment among witnessed ventricular-fibrillation arrests [[cite:kitamuraJapan2010]]. The conclusion for registries is therefore conditional: they should be judged by how well they support the emergency system, not by how many devices are entered.
Why Device Counts Fail
The first failure is physical and temporal access. In Copenhagen, 61.8 percent of public-location cardiac arrests occurred during evening, nighttime, or weekends. Only 9.1 percent of registered AEDs were accessible at all hours, and limited access reduced coverage by 53.4 percent during those off-hours [[cite:hansenAccess2013]]. A registry that reports "AED within 100 m" without time-conditioned access can overstate operational coverage exactly when many events occur.
The second failure is retrieval and use. In Kansas City, Missouri, 46.8 percent of public OHCAs occurred within a 4-minute walk of the closest registered public AED, but bystanders applied an AED in only 12.0 percent of those nearby public cases. Among nearby public cases receiving bystander CPR, AED application was still 24.5 percent [[cite:khanWalking2024]]. Proximity is therefore a necessary but incomplete signal. Awareness, signage, indoor route, locked access, bystander willingness, and dispatcher instruction remain separate failure points.
The third failure is device-system readiness. FDA describes AEDs as systems that include accessories such as batteries and pad electrodes needed to analyze rhythm and deliver a shock; the agency recommends checking AEDs and accessories, using approved accessories, and reporting device problems [[cite:fdaAed]]. Counting an installed cabinet without battery, pad, self-test, accessory, and problem-reporting state is counting hardware rather than emergency function.
AED Readiness-Accountability Chain
Table 2 proposes the accountability chain. It is deliberately longer than a typical registry schema because each stage answers a different public-health question. A city can be strong on inventory but weak on validated indoor wayfinding. A campus can be strong on access hours but weak on battery and pad readiness. A regional EMS agency can be strong on dispatch integration but weak on after-action repair. Collapsing these stages into one count hides where the response will fail.
The chain also aligns policy and implementation sources. CDC summarizes comprehensive PAD programs as including targeted placement, anticipated responder training, EMS coordination, response plans, routine maintenance/testing, quality improvement, and liability provisions [[cite:cdcPadLaws]]. The 2026 RAND-UCLA consensus study similarly identifies limited 24/7 access, absent real-time registries, insufficient training/awareness, patchy EMS integration, legal concerns, and device/maintenance costs as barriers; it names mandatory registration and live mapping as enablers [[cite:thiesConsensus2026]].
Registry Design Implications
The minimum registry should therefore be more than a map layer. It should be an operational record with fields that support emergency use, data quality review, and repair. The Danish data article shows the value of location categories, registration year, withdrawals, AED coverage, and accessibility variables for evaluating a real AED network [[cite:karlssonData2019]]. The UK Circuit implementation report shows a different but compatible lesson: national AED networks require ambulance-service integration and centralized data flows, not only public discovery pages [[cite:osullivanCircuit2024]].
Public-facing tools remain valuable when they invite participation and discovery. PulsePoint AED, for example, describes a tool that helps communities build a public AED registry [[cite:pulsepointAed]]. The accountability problem is not that public maps exist; it is that map presence can be misread as readiness unless the registry also carries verification, access, readiness, emergency integration, event-use, and maintenance fields.
Implementation Variation and Policy
Legislation and national coordination can improve the environment for PAD, but neither should be reported as readiness by itself. The CDC fact sheet notes that PAD state law can address targeted site placement, training, EMS coordination, response plans, maintenance/testing, quality improvement, and liability; it also notes AED location registry or EMS notification as a best-evidence intervention category [[cite:cdcPadLaws]]. National Academies recommendations, summarized by CDC, similarly emphasize registry tracking, AED placement and training, EMS recognition and coordination, PAD quality improvement, and research [[cite:nasem2015]].
Cross-country evidence reinforces that laws, mapping, and first-responder integration vary. The ENSURE survey found AED mapping systems and first responders equipped with AEDs in only 11 of 19 responding European countries, with higher AED use rates reported where mapping and first-responder systems were implemented than elsewhere [[cite:baldiEnsure2021]]. That does not establish a single causal mechanism, but it does show why registry design belongs in a broader response system.
A policy dashboard should therefore avoid three common overclaims. First, "AEDs installed" is not "AEDs available." Second, "AEDs mapped" is not "AEDs in the dispatch workflow." Third, "AEDs nearby" is not "AEDs retrieved and applied." A better dashboard would report stage-specific measures: percent of records verified in the last year, percent with 24/7 public access, percent with current battery and pads, percent shared with EMS dispatch, median retrieval time, bystander AED application rate, and post-use return-to-service time.
Discussion
The synthesis answers the research question with a narrow claim: AED registries should represent success as readiness progression, not inventory accumulation. Device counts are useful for procurement and coverage planning, but they are insufficient for public-health accountability. A readiness registry should state exactly which stage is evidenced and should leave a data path from missed use back to repair.
This matters because failures are diagnosable only if the registry preserves them. If an AED was near but behind a locked door, the failure is access. If it was open but invisible, the failure is wayfinding or awareness. If it was found but unusable, the failure is device readiness. If it was ready but unknown to dispatch, the failure is integration. If it was retrieved but not applied, the failure may be training, fear, instruction, or event dynamics. If it was used but not restored, the failure is maintenance feedback.
The paper's strongest practical recommendation is to report paired numerator and denominator stages. For example: "1,200 AEDs installed; 940 verified within 12 months; 610 public 24/7; 520 current battery/pads; 430 in EMS dispatch; 38 retrieved in eligible events; 21 applied; 12 shocks delivered." The absolute numbers are hypothetical, but the structure prevents one stage from being mistaken for another. It also supports equity audits: a neighborhood may have device density but weak access hours, or strong access but poor dispatch integration.
Limitations
This is a conceptual synthesis, not an empirical registry audit. It uses published studies from different countries, time periods, denominators, and emergency systems. Figure 1 intentionally juxtaposes selected indicators rather than pooling them. The chain should therefore be treated as an accountability framework to test locally, not as a universal estimate of AED program effect.
Several evidence gaps remain. Registry accuracy, accessory readiness, indoor wayfinding, locked-cabinet effects, dispatcher behavior, responder arrival, bystander decision-making, and post-use maintenance are often measured in separate studies. A mature registry should make those stages linkable without exposing sensitive exact locations or private building information beyond what is needed for emergency response. Future work should validate which field set produces better emergency retrieval and application, not only better registry completeness.
Conclusion
AED registries are public-health infrastructure, not just device directories. The evidence base supports public-access defibrillation as part of an integrated response system, but it also shows that counts, maps, proximity, and laws can all overstate readiness when used alone.
The readiness-accountability chain offers a practical correction. Report inventory, validated location, public access, device readiness, emergency integration, human retrieval, application, outcome, maintenance feedback, and quality improvement as distinct claims. A registry that makes those stages visible gives communities a way to repair the weak link instead of celebrating a device count that may not save anyone when the next arrest occurs.