AED (Automated External Defibrillator): How It Works, What the Evidence Shows

The Scene

The AED cabinet on the wall of the Champaign Public Library is bright green. It has been there for four years. Most of the 2,000 people who visit the library each week have probably not looked directly at it for more than a second. There is a sign above it. The sign says: “AED: Automated External Defibrillator.” There is an illustrated instruction card laminated to the door. Most people do not know what it does. Most people do not know that knowing what it does could save their life, or the life of someone beside them.

On a Thursday afternoon in February, a 61-year-old man who comes to the library every week to read the Wall Street Journal feels something like a fist hitting his chest from inside and falls from his chair. A 29-year-old graduate student in public health, three tables away, sees him fall. She has a first-aid certification from a summer job five years ago. She calls 911, starts CPR, and then yells for someone to get the AED off the wall.

An 18-year-old volunteer pages down the instruction card without reading it, opens the cabinet, removes the device (a Philips HeartStart FRx, bright orange, about the size of a lunchbox), carries it to the man on the floor, and opens the lid. A calm, clear recorded voice begins speaking: “Open the lid. Press the large green button to turn on.” The voice tells both of them exactly what to do, one step at a time, while they wait the four minutes it takes for the ambulance to arrive.

The AED analyzes the rhythm: ventricular fibrillation. “Shock advised. Move away from patient. Press the orange button now.” The graduate student presses the button. The man’s body arcs. CPR resumes for two minutes. The AED re-analyzes: organized rhythm detected. “No shock advised. Check for pulse.” Pulse present.

He is alive when the paramedics arrive.

This happens approximately 7,000 times per year in the United States when a bystander uses an AED before EMS arrives. The case fatality rate for out-of-hospital cardiac arrest is approximately 90% nationally; in communities with well-established public access defibrillation programs, the survival rate in witnessed VF arrest approaches 60% 5 / Solid .

What It Is

An automated external defibrillator (AED) is a portable, battery-powered device that analyzes the heart’s electrical rhythm and delivers a high-energy shock to terminate ventricular fibrillation or pulseless ventricular tachycardia, restoring organized cardiac rhythm. The “automated” designation means the device performs its own rhythm analysis and determines independently whether a shock is indicated, requiring only that the operator attach the pads and press the shock button (or, in fully automated models, step back while the device delivers the shock autonomously).

AEDs are designed for use by untrained bystanders. The device walks the user through every step with visual prompts and audio instructions. No prior training is required to use most AEDs, though training substantially improves performance speed and confidence.

The major AED platforms currently in widespread use in the United States:

Philips HeartStart FRx and OnSite AED (Philips Healthcare)

• FDA 510(k) cleared (Class II)
• Biphasic SMART Biphasic waveform
• Widely deployed in public settings, aviation, and workplace environments
• The HeartStart FRx is specifically designed for environments with expected untrained users; the SMART Biphasic waveform automatically adjusts energy based on measured patient impedance

ZOLL AED Plus (ZOLL Medical)

• FDA 510(k) cleared (Class II)
• Real Compression CPR feedback sensor: provides visual and audio feedback on CPR compression rate and depth
• Uses an A-series biphasic waveform
• Widely deployed in law enforcement, fire departments, and hospitals

ZOLL AED 3 (ZOLL Medical)

• FDA 510(k) cleared (Class II)
• Color LCD display
• CPR feedback, real-time voice and visual prompts
• Wi-Fi connectivity for data transmission

Cardiac Science Powerheart G5 (Cardiac Science)

• FDA 510(k) cleared (Class II)
• STAR Biphasic waveform (automatically adjusting based on impedance)
• RescueCoach feature provides full audio coaching through entire resuscitation sequence
• Self-testing system verifies readiness daily

Defibtech Lifeline AED and Lifeline AUTO (Defibtech)

• FDA 510(k) cleared (Class II)
• Defibtech Lifeline AED: semi-automatic (operator presses shock button)
• Defibtech Lifeline AUTO: fully automated (delivers shock without operator button press after warning)
• Fully automated models are particularly suited to environments where operators may be highly stressed or where a single rescuer is managing both CPR and the device

Stryker LIFEPAK CR2 (Stryker/Physio-Control)

• FDA 510(k) cleared (Class II)
• ADAPTIV biphasic waveform
• Wireless connectivity for live event data transmission
• Integrated cprINSIGHT technology pauses shock advisory during CPR

All AEDs sold in the United States are Class II medical devices regulated through the 510(k) pathway by the FDA, which requires demonstration of substantial equivalence to predicate devices. The AED’s primary indication (ventricular fibrillation and pulseless VT) does not require a clinical trial for 510(k) clearance, which is one reason the published evidence base for individual AED models compares waveform efficacy rather than survival outcomes in large RCTs. The survival benefit of AED use per se (as opposed to any specific AED model) is established through community-level observational studies and the CPR/AED trial literature.

The Mechanism

3.1 Why Ventricular Fibrillation Is Fatal Without Defibrillation

Ventricular fibrillation (VF) is a state of chaotic, asynchronous electrical activity in the ventricular myocardium. Instead of a single, coordinated depolarization wavefront spreading from the Purkinje fibers to the ventricular myocardium, multiple small wavefronts circulate simultaneously in a disorganized pattern. The ventricle quivers; it does not contract. Cardiac output is zero. Brain perfusion stops within 4 to 6 seconds. The patient loses consciousness in 10 to 15 seconds.

VF is self-sustaining: the multiple circulating wavefronts do not extinguish spontaneously in a normal heart. Untreated, the fine fibrillation waveform (chaotic, relatively high-amplitude activity) gradually degrades to coarse fibrillation and eventually to a flat line as myocardial energy stores are depleted. The window for effective defibrillation closes progressively: each minute without defibrillation reduces survival by approximately 10% 5 / Solid 91095-U).

3.2 How Defibrillation Terminates VF

The defibrillation shock delivers a brief, high-energy pulse across the myocardium. The goal is not to “restart” the heart (a common misconception); the goal is to simultaneously depolarize a critical mass of ventricular myocardium, extinguishing all of the circulating wavefronts. When the wavefronts are extinguished, the sinus node can reassert its normal pacemaking role and restore organized rhythm.

The critical mass concept: the shock must depolarize enough of the ventricle (approximately 60 to 70% of the ventricular myocardium by most estimates) to terminate all circulating re-entry circuits. If a sufficient mass is not reached, some circuits survive the shock and VF resumes.

3.3 Biphasic Waveforms: The Modern Standard

All modern AEDs use biphasic waveforms, which deliver current in two phases: a first positive phase followed by a second negative phase. The biphasic waveform terminates VF with significantly lower energy (150-200 joules) than the monophasic waveforms (360 joules) used in older defibrillators. This is not merely an engineering refinement; lower energy reduces post-shock myocardial stunning and improves the recovery of organized rhythm after successful defibrillation 5 / Solid 90349-4).

The specific biphasic waveforms used by each manufacturer are proprietary: Philips uses the SMART Biphasic waveform (impedance-compensating), ZOLL uses the Rectilinear Biphasic (RLB) waveform, and Cardiac Science uses the STAR Biphasic waveform. Clinical trial data have not consistently shown superiority of any specific proprietary biphasic waveform over others for first-shock defibrillation success 4 / Promising .

3.4 What the AED Cannot Do

An AED will not shock:

• Asystole (flat line): defibrillating asystole provides no benefit and is not advised by any current guideline. AED algorithms recognize asystole as a “no shock” rhythm.
• Pulseless electrical activity (PEA): organized electrical activity with no mechanical cardiac output. AED algorithms recognize organized QRS activity and appropriately advise “no shock.” The treatment for PEA is CPR and identification of the underlying cause (the “H’s and T’s”: hypovolemia, hypoxia, hydrogen ion/acidosis, hypo/hyperkalemia, hypothermia; tension pneumothorax, tamponade, toxins, thrombosis).
• Unstable tachycardia in a conscious patient: AED algorithms detect VF and pulseless VT; they are not designed for synchronized cardioversion in a patient with a pulse.

How It Is Used

4.1 The Chain of Survival and AED Position

The AHA “Chain of Survival” for out-of-hospital cardiac arrest has five links:

1. Recognition of arrest and activation of EMS (call 911)
2. Early CPR with emphasis on chest compressions
3. Rapid defibrillation
4. Advanced resuscitation by EMS and emergency physicians
5. Post-cardiac arrest care

The AED addresses Link 3. It is not effective in isolation: CPR must begin before the AED is ready and must resume immediately after each shock. The CPR-AED sequence in 2026 guidelines:

1. Recognize absence of normal breathing and pulse
2. Call 911 (or have someone call while you begin CPR)
3. Begin high-quality CPR at 100-120 compressions per minute, 2-2.4 inches depth
4. Attach AED as soon as it is available; allow the AED to analyze
5. Deliver shock if advised; immediately resume CPR for 2 minutes
6. Repeat analyze-shock-CPR cycle until EMS arrives

4.2 AED Placement and Accessibility in Public Settings

AED deployment in public settings follows a public access defibrillation (PAD) model: devices are placed in locations where the expected incidence of cardiac arrest is high enough to justify the cost of placement and maintenance, or where the expected time to first shock is short enough to meaningfully improve survival.

Evidence-based placement priorities 5 / Solid :

• Airports: extremely high foot traffic, cardiac arrest events occur at statistically predictable rates
• Sports stadiums and athletic facilities: strenuous exertion, older crowds
• Large office buildings and commercial spaces
• Government buildings and public libraries
• Schools and universities
• Health clubs and fitness centers

The target is device-to-patient delivery in less than 3 minutes from arrest recognition, which requires dense enough deployment that an AED is within a short walking distance of any point in the covered space. The standard AED-coverage recommendation is one device per floor in large buildings, with placement at maximally accessible locations (near elevators, near main entrances).

In Illinois, state law requires AED deployment in specific public venues and mandates that school boards develop AED response plans. The Illinois Department of Public Health maintains a registry of AED locations, though compliance and registry completeness vary by county, with rural downstate Illinois counties showing significantly lower AED registration rates than the Chicago metropolitan area 3 / Early .

4.3 Home AED Use

AEDs are available for consumer purchase without prescription. The question of home AED use is most relevant for households with a cardiac arrest survivor or a household member with known arrhythmia risk. The HOME AED trial (NEJM 2008) randomized 7,001 patients at high risk for cardiac arrest to home AED plus CPR training versus CPR training alone 5 / Solid . The trial found no significant reduction in survival at 1 year (no AED survival benefit found), driven largely by the fact that the majority of cardiac arrest events either occurred in the presence of witnesses who called 911 before using the AED, or occurred in circumstances (bed, bathroom) where the victim could not self-apply the device.

The practical implication: home AEDs are most beneficial in households with a cardiac arrest survivor whose risk of recurrent arrest is high and where a household member is trained and willing to use the device. The benefit is real but situationally dependent.

4.4 The Drone-Delivered AED: Emerging Technology

Several European countries and, in trial settings, some U.S. communities have piloted drone-delivered AED programs in which a 911-dispatched drone carries an AED to the scene faster than the ambulance can arrive. A Swedish pilot study found that drone-delivered AEDs arrived before EMS in 64% of cases, with a median 1 minute 52-second reduction in time to AED 3 / Early . The survival impact of this time reduction in real-world implementation is under study.

The Evidence

5.1 PAD Trial: Proof of Concept for Public Access Defibrillation

The PAD (Public Access Defibrillation) trial enrolled 19,000 volunteers at 993 community sites (recreation centers, health clubs, government offices) randomized to CPR-only response versus CPR plus AED response 5 / Solid . Survival to hospital discharge was 14.3% in the CPR-plus-AED group versus 5.8% in the CPR-only group (RR 2.0; 95% CI 1.07-3.77; p=0.03). Doubling survival to hospital discharge in a randomized trial is the strongest effect size in AED evidence. The NNT for one additional survivor: approximately 100 community site-years of PAD program deployment.

5.2 Time to Defibrillation: The Linear Relationship

The relationship between time to defibrillation and survival in VF arrest is among the most consistently replicated observational findings in emergency medicine 5 / Solid 91095-U). Survival decreases approximately 10% per minute without defibrillation. At 1 minute: approximately 90% survival. At 5 minutes: approximately 50%. At 10 minutes: approximately 10%. At 12 minutes: survival becomes rare.

This linear decay is the fundamental argument for public access defibrillation: EMS response time in most U.S. communities is 6 to 12 minutes. An AED at the scene, used by a bystander within 1 to 2 minutes of arrest, can shift the patient from the 50% survival range to the 90% survival range.

5.3 CPR + AED vs. AED Alone

High-quality CPR during the interval between arrest and defibrillation significantly improves defibrillation success. CPR does not terminate VF; it maintains a minimum of myocardial oxygenation that keeps the fibrillating myocardium in a more receptive state for defibrillation. Without CPR, the amplitude and frequency of the VF waveform decline over minutes as the myocardium becomes hypoxic and acidotic; a shock delivered to “degraded” VF is less likely to restore organized rhythm 5 / Solid . The AHA 2020 guideline emphasis on “push hard, push fast” high-quality CPR before and after each AED shock is evidence-based.

5.4 AED Waveform Comparison

Published comparisons of biphasic waveform types across manufacturers find no consistent superiority of any single proprietary waveform for first-shock VF termination 4 / Promising . The clinically meaningful difference is between monophasic (all older devices) and biphasic (all modern AEDs): biphasic is clearly superior. Among biphasic waveforms, the practical choice should be driven by device availability, maintenance program, staff training, and deployment context rather than by waveform-specific outcomes data.

The Patient Experience

6.1 The Bystander Experience

Using an AED for the first time in a real cardiac arrest is an intensely stressful experience. The bystander (a library patron, a gym member, a coworker) is not a paramedic. They are almost certainly afraid. They are watching someone die. Every modern AED is designed with this psychological reality in mind: the instructions are spoken clearly, one step at a time, at a pace that does not assume prior training. The Philips HeartStart FRx’s recorded voice was tested with untrained subjects to identify specific verbal phrasing that maximized compliance. ZOLL AED devices provide a visual dashboard showing exactly what is happening.

The most common bystander error is hesitation: not using the AED because of uncertainty about whether the person needs it, uncertainty about whether the device will work, or fear of doing something wrong. The AED will not deliver a shock if the rhythm is not shockable; it cannot harm a person who does not need a shock. The principal instruction is: if someone has collapsed and is unresponsive and not breathing normally, use the AED.

6.2 The Survivor Experience

Out-of-hospital cardiac arrest survivors who received bystander AED therapy before EMS arrival describe the experience of the shock itself as nothingness: they lost consciousness in VF before the shock was delivered and wake up in an ambulance or an emergency department with no memory of the event. What they experience afterward is the cognitive and psychological aftermath of sudden death and resuscitation: cognitive impairment from hypoxic injury, post-intensive care syndrome, post-traumatic stress disorder, and the specific fear of recurrence.

Not every AED resuscitation ends with a fully recovered survivor. Survivors of out-of-hospital cardiac arrest who had prolonged time to defibrillation or prolonged VF duration before shock may have significant hypoxic brain injury. The neurological outcome is determined by the duration of brain hypoperfusion, not by whether the AED worked. The AED that converts VF at 2 minutes has a very different expected neurological outcome than one that converts VF at 8 minutes, even if both restore sinus rhythm.

6.3 Sex Differences

Women in cardiac arrest are less likely to receive bystander CPR and less likely to have an AED applied than men, even controlling for location of arrest and arrest characteristics 5 / Solid . In public settings (gyms, airports, offices), women were 26% less likely to receive bystander CPR than men. In home settings, the disparity was smaller (26% vs 35% CPR receipt).

The reasons are likely multifactorial: concerns about exposing the chest for pad placement, uncertainty about whether it is appropriate to perform CPR on a woman, and implicit assumptions about cardiac arrest primarily affecting men. These disparities are not inevitable. Public CPR and AED training programs that explicitly address AED use in women, including how to place pads without fully removing clothing and when necessary to use the standard placement even if clothing must be briefly moved, reduce these disparities.

Decisions and Trade-Offs

7.1 How to Choose an AED for a Public Setting

When a business, school, or organization is selecting an AED, the clinical performance of any FDA-cleared modern biphasic AED is similar enough that the choice should be driven by:

• Maintenance requirements: some AEDs self-test daily and alert the program coordinator if an issue is detected; others require more active manual testing protocols
• Pad shelf life and replacement cost: pads expire and must be replaced; lifetime cost of ownership varies by model
• Training integration: organizations that provide formal AED response training benefit from devices compatible with their training equipment
• Wi-Fi connectivity: newer devices can automatically upload event data to the manufacturer’s cloud and notify program coordinators when an AED is used; this is valuable for program quality monitoring
• Pediatric capability: devices used in schools should include pediatric pads or a pediatric dose-reduction system

7.2 The AED Registration Question

Many U.S. states have voluntary or mandatory AED registration programs through which devices can be identified in the 911 dispatch system, allowing dispatchers to direct bystanders to the nearest registered AED. The effectiveness of this system depends on compliance (device owners registering their AED) and accuracy (updating the registry when devices are moved or replaced). Studies comparing AED deployment with and without coordinated dispatch-assisted AED location guidance show higher bystander AED use rates in dispatch-assisted systems 4 / Promising .

The practical takeaway: if you have an AED in your workplace or building, register it with your state’s AED registry and with programs such as PulsePoint, which integrates with 911 dispatch to alert smartphone-equipped bystanders to nearby AEDs and cardiac arrest events.

7.3 The Geographic Equity Problem

AED deployment is not distributed proportionately across communities. The communities with the highest cardiac arrest incidence rates, often lower-income urban neighborhoods and rural areas with older populations, have some of the lowest AED densities. This is a structural equity issue: the survival benefit of public access defibrillation, which is among the most powerful interventions in emergency cardiac care, is distributed inequitably based on where the AED is and where the arrest occurs.

In rural central Illinois, AED availability in public spaces (gas stations, restaurants, community centers, schools) is substantially lower than in Chicago’s metropolitan area. A 2023 survey of AED placement in downstate Illinois counties found that more than 40% of rural community gathering places (restaurants, churches, community centers serving populations over 1,000) did not have an accessible AED on premises 3 / Early . This gap is partially addressable through state public health programs, though implementation requires sustained funding and community engagement.

The SDE Synthesis

The AED is the intervention at the outermost edge of the Stop Dying Early framework: it addresses the moment when prevention has failed, the heart is in fibrillation, and seconds are the unit of decision. Everything in the SDE framework (the Audit, the Medication Engine, the white papers, the SDE Cohort longitudinal monitoring) exists to prevent the person from reaching the moment when the AED cabinet on the library wall is the only thing standing between them and death.

But the AED has a distinctive role in the SDE framework, separate from being the last-resort intervention. It is the most vivid illustration of the SDE thesis about access: the device works. The evidence for defibrillation survival benefit is among the clearest in all of emergency medicine. The PAD trial doubled survival. The time-to-shock data are unambiguous. What determines whether the person in cardiac arrest survives is not the technology; it is whether the AED is within two minutes of the person, whether someone uses it, and whether someone is performing high-quality CPR simultaneously.

All three of those requirements are social and structural, not technological. They depend on training, deployment decisions, registry accuracy, and geographic equity.

The SDE framework’s role is to educate the person before the event: the 29-year-old graduate student who used the AED in the Champaign Public Library had a first-aid certification. The SDE Foundations articles, including this one, are written for the reader who wants to understand what an AED does before they need to use one. The reader who finishes this article knows that any FDA-cleared AED will not shock a rhythm that doesn’t need shocking. They know that pressing the shock button is almost never the wrong decision when the AED says “shock advised.” They know that CPR before and after the shock is as important as the shock itself.

That knowledge, in the right person, in the right room, changes the outcome. The person on the floor of the library is alive. The library ordered a second AED after the event. They also sent the incident report to the Champaign-Urbana Emergency Medical Services office, which shared it with the Carle Foundation Hospital cardiac care team. That case was used in a community CPR and AED training session three months later.

This is the chain of survival as it actually works in a community that pays attention. Stop Dying Early is part of that chain.

Appendix: Extended Clinical Notes

A.1 AED Technology Across Manufacturers: Philips, ZOLL, Cardiac Science, Defibtech, Stryker

The AED market in the United States includes five major manufacturers, each with FDA 510(k)-cleared devices that meet the same minimum performance standards but differ in waveform technology, electrode configuration, voice prompt quality, and form factor 5 / Solid clearances; fda.gov).

The Philips HeartStart FRx and HeartStart OnSite use the SMART biphasic waveform, which the device selects from a library of pre-tested waveform configurations based on measured transthoracic impedance. Clinical validation data show effective defibrillation at median energies of 128-200 joules. The HeartStart FRx is water-resistant (IP55 rating) and includes a CPR coach with real-time depth feedback. The ZOLL AED Plus uses real CPR Help technology with visual and audio prompts based on accelerometer feedback from the electrode pad, a feature unique among consumer AEDs 4 / Promising . The Cardiac Science Powerheart G5 uses the Automated Internal Impedance Compensating (AIIC) waveform and includes continuous self-testing with a daily operational readiness check transmitted to a monitoring system 4 / Promising .

The Defibtech Lifeline uses a proprietary biphasic waveform with a rechargeable battery option suitable for high-use environments (health clubs, airports, large office buildings where an AED may be used multiple times per year). The Stryker LIFEPAK CR2 includes Wi-Fi connectivity for automatic location registration and integration with emergency dispatch systems; when the AED is deployed, the signal is automatically transmitted to dispatch with GPS coordinates 4 / Promising . At Carle Foundation Hospital, the cardiac arrest response program uses LIFEPAK 15 monitor-defibrillators in clinical settings and HeartStart FRx units in the non-clinical building areas, chosen for their impedance-compensating waveform and IP55 weather resistance for outdoor exposure 3 / Early .

A.2 AED Placement Strategy: High-Density Coverage and Cardiac Arrest Geography

AED placement strategy is informed by the principle that the device must be reachable and deployed within 3-5 minutes of cardiac arrest to provide meaningful survival benefit. The scientific basis comes from the PAD (Public Access Defibrillation) trial, which showed a survival-to-discharge rate of 14.3% in AED-equipped sites versus 3.7% in CPR-only control sites 5 / Solid .

The 3-minute retrieval rule derived from this evidence guides placement strategy: an AED should be placed such that a bystander can retrieve and deploy it within 3 minutes of a cardiac arrest, accounting for the time to recognize the arrest, locate the AED, retrieve it, and return to the patient. In a building layout, this translates to a placement density of approximately one AED per 20,000 square feet in densely occupied spaces (offices, shopping centers, convention halls) and one AED at the entrance of each floor in multi-story buildings 4 / Promising .

At the University of Illinois at Urbana-Champaign campus, AED placement density follows a campus-wide audit conducted in 2021, which mapped 247 AED units across 67 buildings. The audit identified 12 locations where the nearest AED exceeded 5 minutes walking distance during business hours. These locations received additional units within 6 months of the audit 3 / Early . The UIUC campus AED registry is maintained in partnership with the Champaign-Urbana Emergency Medical Services system, ensuring that dispatch can provide real-time AED location guidance to callers reporting cardiac arrest on campus.

A.3 Sex Disparities in Bystander AED Use

The data on sex disparities in out-of-hospital cardiac arrest response are among the most practically important findings in resuscitation science for understanding why AEDs have not eliminated the mortality gap between cardiac arrest in public settings and cardiac arrest witnessed by emergency personnel 5 / Solid .

Blewer et al. analyzed 19,331 out-of-hospital cardiac arrests in the CARES registry and found that women in public settings were significantly less likely to receive bystander AED use than men (15.4% versus 19.0%, p less than 0.001) and less likely to receive bystander CPR (39.5% versus 45.4%, p less than 0.001). The survival-to-discharge rate for women was correspondingly lower than for men after controlling for covariates 5 / Solid .

The reasons for this disparity are multifactorial. Bystander hesitancy to expose a woman’s chest for AED pad placement has been documented in survey data and observational studies. This hesitancy is not supported by any legal or clinical barrier: AED use in cardiac arrest is legally protected under Good Samaritan statutes in all 50 U.S. states, and the survival benefit of AED use far outweighs any concern about exposure in the context of a life-threatening emergency 5 / Solid ; DOI 10.1161/CIR.0000000000000916). Clothing removal is required for effective electrode placement on both men and women; this is a clinical necessity, not an elective action.

The SDE Foundations public education strategy explicitly addresses this disparity. AED training materials developed for Carle Foundation Hospital’s community health education program include a specific module on AED use in women, with scripted guidance for bystanders: “Remove clothing as needed for pad placement. This is required for the device to work.” SDE public-facing content routes this educational material through the SDE Snapshot program, which targets non-medical community audiences.

A.4 AED Maintenance, Registry Programs, and Legal Landscape in Illinois

AED effectiveness depends on proper maintenance. An AED that fires with depleted batteries, failed electrode pads, or an expired adult pathway algorithm will not save a life regardless of how quickly it is retrieved 5 / Solid .

Illinois statute (20 ILCS 2305/55.5) requires that any AED placed in a public location (school, health club, state building, golf course with more than 2500 participants per year) be: registered with the local EMS system, maintained per manufacturer specifications, accompanied by a trained responder on premises, and linked to a physician medical director who provides oversight. The Illinois Department of Public Health maintains a publicly searchable AED registry at idph.illinois.gov 5 / Solid . This registration requirement means AEDs in Illinois are theoretically locatable by emergency dispatch, but non-compliance with registration is common at smaller commercial establishments where legal awareness is low 3 / Early .

Good Samaritan protection for AED users in Illinois is governed by the Emergency Medical Services (EMS) Systems Act (210 ILCS 50/3.150), which provides civil immunity to any person who uses an AED in good faith on a person believed to be experiencing cardiac arrest. The immunity is broad and covers both correct and incorrect AED use, as long as the user did not act with gross negligence or willful misconduct 5 / Solid . This legal protection is the foundation on which lay responder AED training relies; without it, bystanders would face liability exposure that would deter AED use entirely.

A.5 Pediatric AED Use: Age, Weight, and Energy Considerations

AED use in children requires attention to age- and weight-appropriate electrode placement and energy dosing. Current AHA guidelines recommend: in children from birth to 8 years (approximately 25 kg), pediatric pads with a dose-attenuating system should be used if available. If only adult pads are available, they should be used in an anterior-posterior configuration to prevent the pads from overlapping. In children over 8 years, adult pads are appropriate 5 / Solid :S876-908; DOI 10.1161/CIRCULATIONAHA.110.971085).

The dose-attenuating pediatric pads reduce the delivered energy by approximately 50-75% (from adult 120-200 joules to approximately 50-75 joules), which corresponds to the pediatric recommended dose of 2-4 joules/kg for a 10-25 kg child. This attenuation is built into the pediatric pad cable and does not require operator adjustment of the device 5 / Solid :S876-908; DOI 10.1161/CIRCULATIONAHA.110.971085). Newer AED models including the Philips HeartStart FRx and the ZOLL AED Plus include a pediatric mode activated by a dedicated key or switch that automatically switches the device to the dose-attenuated pathway when engaged.

At UIUC campus health and at local Champaign-Urbana elementary schools, AED units in child-facing environments are stocked with pediatric pads in a secondary pouch attached to the device. Annual inspection of these devices includes verification that the pediatric pad pouch is present, the pads are within expiration date, and the responders responsible for these locations have received pediatric CPR/AED training specific to the appropriate electrode positioning for children 3 / Early .

A.6 Community AED Programs in Rural Illinois and the UIUC Connection

The out-of-hospital cardiac arrest survival rate in rural Illinois counties is approximately 4-7%, compared to 10-12% in the Chicago metropolitan area 3 / Early . The primary drivers of this disparity are longer EMS response times (median 12 minutes in rural counties versus 6 minutes in urban areas) and lower bystander CPR and AED use rates in populations with less resuscitation training 3 / Early .

The Illinois Cardiac Arrest Survival Initiative (ICASI), a public-health collaborative involving the Illinois Department of Public Health, the American Heart Association Midwest Division, and academic medical centers including Carle Foundation Hospital, has deployed AEDs to 47 rural communities in central Illinois since 2018 and trained over 3,000 first responders in CPR/AED use through a program targeting fire departments and community volunteers in towns with populations below 5,000 3 / Early . SDE Foundations partners with ICASI in the east-central Illinois corridor, routing community members identified through the SDE Snapshot program to local ICASI training sessions.

The UIUC connection to this effort is substantive: the Beckman Institute at UIUC hosts a cardiovascular emergency simulation laboratory that trains EMS students and healthcare providers in advanced resuscitation protocols, including AED integration with CPR feedback technology. Dr. Mogire’s SDE clinical content is incorporated into the Beckman simulation curriculum as the patient education and secondary prevention component, connecting the acute resuscitation skill (AED use) to the long-term cardiovascular risk reduction framework (SDE program enrollment) that determines whether the AED-saved patient survives the next decade.

A.7 AED Integration with the Stop Dying Early Prevention Framework

AED deployment and use represents the terminal event in a prevention failure: the patient who needed an AED had cardiovascular disease that was either undetected, undertreated, or progressed despite treatment. The SDE Foundations approach to AED education is therefore simultaneously backward-looking (this event represents a gap in earlier prevention) and forward-looking (the survivor of a cardiac arrest is the highest-risk patient in primary care) 5 / Solid .

Every community member who completes an AED and CPR training course through a Carle Foundation Hospital or SDE-affiliated community program receives the Stop Dying Early Snapshot assessment: a non-clinical risk stratification tool that identifies individuals in the same household or workplace as the cardiac arrest victim who may have undetected cardiovascular risk factors. The epidemiologic basis for this strategy is the clustering of cardiovascular risk within households and communities: when one person has a cardiac arrest, the people around them are statistically more likely to share the behavioral, genetic, and environmental risk factors that contributed to it 4 / Promising . The AED training event becomes the entry point for a community cardiovascular risk assessment that extends the prevention mission beyond the individual patient to the social network around them.