We have only about 10 percent (perhaps less) of the total number of AEDs required if rapid defibrillation is going to be available to most people experiencing SCA.

A New Model for Increasing Cardiac Arrest Survival Requires We Fix the National AED Shortage, Too

The obvious reason for the AED shortage is the fact these life-saving devices are, with a few exceptions, not legally required at most locations. But voluntary deployments are clearly not getting the job done on their own.

This is the second in a series of articles on the state of affairs in public access automated external defibrillators (AEDs) and the challenges and opportunities we face in deploying them for optimum community preparedness. For the first, see "Squad Goals: Moving the Needle on Sudden Cardiac Arrest Requires a New Model." (October 2018 OH&S).

In the previous article in this series, we discussed that sudden cardiac arrest (SCA) is the third-leading cause of death in the United States and one of the most challenging public health issues to address. Sadly, less than 6 percent of SCA victims survive, despite 30 years of effort to combat this scary statistic. We know that CPR and the use of an AED soon after SCA occurs are the keys to saving more lives. Yet, today, only one in four people who experience SCA get bystander CPR, and fewer than four in 100 benefit from bystander use of an AED.

So, while device makers innovate the AED technology and community leaders increase SCA awareness, why haven't we made more progress? The biggest reason is the scarcity of these life-saving devices in public places throughout the country. As AEDs have become more commonplace, many believe they can be found "everywhere." But the truth is, because of an AED shortage in the United States, most SCA victims experience their life-or-death emergency where no AED can be found. The solution? We must have a clearer understanding of the magnitude of the problem and then concerted public policy action by policymakers, thought leaders, national advocacy organizations, SCA survivors, victims’ families, and others who care to effect positive change.

Quantifying the AED Shortage
The AED shortage can best be understood as a math problem. Using the key variables explained below, we can calculate how many AEDs are needed to cover a given area. Comparing this number to the number of AEDs currently available helps shed light on the critical gap.

AED Response Time: Time is the most critical factor to survival. In fact, the time it takes to deliver the first AED shock has a direct effect on the chances an SCA victim will survive at all. Longer times to defibrillation equal lower survival rates. In non-medical settings such as health clubs, shopping malls, retail stores, government and office buildings, schools, and similar locations, it is reasonable to expect that AEDs should be used within four to five minutes from the time SCA is first recognized. This concept of "AED response time" refers to the time it takes someone to recognize SCA (not an easy thing for volunteer bystanders), start CPR (which requires bystanders to be willing and at least minimally trained), tell people nearby to call 911 and retrieve an AED (assuming other people and an AED are available), and apply and use an AED.


Beware the AED Response Time Trap: Many wrongly suggest that public access AED programs should enable lay responders to retrieve and use AEDs within three minutes of recognizing SCA. The fact is, most bystander AED programs cannot consistently meet this three-minute response time target (actually, neither can most professional medical environments). We shouldn't put AED owners in legal jeopardy by imposing an unreasonable and mostly unachievable AED response time objective. Rather, a four to five minute organizational response time policy properly balances the benefits of early defibrillation with the need to rationally manage the legal accountability risks of owning AEDs. You can read more about this in How to Avoid the 3-Minute AED Response Time Trap. (http://www.readisys.com/avoid-the-3-minute-aed-response-time-trap/)


AED Retrieval Time: Because of time considerations, AEDs can cover only a limited geographic area. Given the known time constraints associated with treating SCA, we can calculate the area a single AED can cover within a four to five minute AED response time goal. Factors impacting an AED's coverage area include time, distance, and obstacles. Generally, two minutes of the AED response time are allocated to AED retrieval. On average, adults walking rapidly can travel approximately 300 feet per minute. At 300 feet per minute, it will take up to one minute to reach the AED and another minute to return to the person having SCA. So we use a 300-foot radius to calculate the maximum potential AED coverage area that will allow an AED retrieval time of up to two minutes.

AED Coverage Area: Going back to high school math, we use the formula Pi*r2, where r is a radius of 300 feet, to calculate that the maximum theoretical area an AED can cover is 283,000 square feet (equal to about five football fields). But because AEDs are most often not placed in open areas, we must also account for obstacles such as people, doors, hallways, stairs, elevators, escalators, physical barriers and obstructions, AED storage methods, and similar constraints that reduce the effective area an AED can cover within the two-minute AED retrieval time. Let's assume that obstacles reduce the coverage area radius by half to 150 feet. This means, on average, an AED can cover about 70,650 square feet.

Calculating the AED Shortage: The factors described above serve as the foundation for quantifying the AED shortage. To calculate the breadth of this shortage, I also make the following assumptions:

  • It takes 395 AEDs to cover one square mile (27.9 million square feet per mile/70,650 square feet of AED coverage area).
  • There are an estimated 88,000 non-residential, urbanized square miles in the United States.
  • AEDs must provide coverage horizontally and vertically (e.g., in multi-story buildings).
  • AEDs are often placed in locations that limit their effective range or add to response time (e.g., where AEDs are not permitted to be removed from the AED owner's location even if an SCA event is nearby at a different location, or the worst case, AEDs are placed in a locked cabinet).

Putting all this together, we can now estimate our need to be more than 30 million AEDs to cover the 70 percent of the population found in the non-residential, urbanized areas of the United States. We’ll need at least 10 million more to cover the non-urbanized areas and remaining 30 percent of the population. (For those who care to dig into the math, take a look at The AED Shortage post for more, http://www.readisys.com/the-aed-shortage/.)

An estimated 4.5 million AEDs have been sold in the United States since the 1990s (though not all remain in service, of course). This means we have only about 10 percent (perhaps less) of the total number of AEDs required if rapid defibrillation is going to be available to most people experiencing SCA. So you can see how this AED shortage may help explain why, in public settings, AEDs are used by bystanders a minuscule 2.1 percent to 3.7 percent of the time.

How to Fix the AED Shortage
The obvious reason for the AED shortage is the fact these life-saving devices are, with a few exceptions, not legally required at most locations. As a result, the vast majority of publicly accessible AEDs in the United States are there only because organizations voluntarily chose to place them—decisions that should certainly be commended. But voluntary deployments, along with well-meaning fundraisers and charitable donations, are clearly not getting the job done on their own.

Only two states (Oregon and Rhode Island) broadly require AEDs at many places. Some states have targeted mandates for places such as health clubs, schools, government buildings, and the like. But these limited mandates lead to only a small increase in the number of AEDs in a community, cover very small response areas, and protect a fraction of a community's population. Broad mandates, in contrast, have the power to increase the number of AEDs in a community more rapidly, cover larger response areas, and protect a much larger percentage of a community’s population.

So how do we solve the AED shortage? The answer is clear: state legislative mandates requiring AEDs at most public locations. Large-scale mandates, coupled with true Good Samaritan legal protections, will lead to a rapid increase in the number of AEDs and will improve the odds of survival for thousands more people experiencing sudden cardiac arrest. And for those who push back with arguments over SCA prevalence in any given location, we need only look at the broad mandates for fire extinguishers—whereas fires occur with much lower frequency—as an example that blows any such objection out of the water.

To make things easy for would-be public policy advocates willing to take on the challenge of pushing for this new approach, we should look to the Model AED Law below. This law, if enacted in every state, would require lots of AEDs, provide meaningful legal protections to AED owners and users, and rid us of the silly and unhelpful regulatory requirements found in most state AED laws today.

We've already discussed the importance of a new "SCA response squad" model with the goal of a 50 percent rate of bystander CPR, 50 percent rate of public access AED use, and enough AEDs so that defibrillation can be delivered within five minutes for most SCA victims. If we pair this new model with effective legislative action that helps bridge the gap left by the national AED shortage, we may very well be on our way to seeing meaningful change in SCA survival.

An act to repeal [insert statutory references] and enact new provisions relating to the placement and use of automated external defibrillators (AEDs).

Section 1. Repeal and replacement of existing AED laws:

[Insert statutory references] are hereby repealed and replaced with the following:

Section 2: Definitions:

(a) "Automated external defibrillator" or "AED" means an automated external defibrillator approved for sale by the U.S. Food and Drug Administration.

(b) "Person" means an individual, corporation, partnership, limited liability company, association, trust, unincorporated organization, or other legal entity or organization, or a government or governmental body.

(c) "Public place" means an enclosed indoor or outdoor area capable of holding one hundred (100) or more people and to which the public is invited or in which the public is permitted but does not include a private residence.

Section 3. Good Samaritan legal protections:

(a) The following persons are not subject to civil liability for damages arising out of any acts or omissions relating to the placement and availability of automated external defibrillators absent gross negligence or willful or wanton misconduct:

(i) Any person that acquires an AED;

(ii) Any person that owns, operates, manages or is otherwise responsible for the location where an AED is placed;

(iii) Any person who retrieves or fails to retrieve an AED;

(iv) Any person who uses, attempts to use or fails to use an AED;

(v) Any person who was present at a location where an AED was used or not used;

(vi) Any physician or other authorized healthcare provider or person who issues a prescription for the purchase of an AED or provides medical oversight services to a location where an AED is placed;

(vii) Any person that is involved with or responsible for the design, management or operation of an AED program; and

(viii) Any person or entity that provides instruction in the use of an AED.

(b) The immunity described in paragraph (a) of this section applies regardless of where an AED is retrieved from or used.

Section 4: Automated external defibrillators required; persons authorized to retrieve and use automated external defibrillators:

(a) A person who owns, operates or manages a public place shall place functional AEDs in sufficient quantities to ensure reasonable availability for use during perceived sudden cardiac arrest emergencies.

(b) Any person is permitted to retrieve or use an AED.

This article originally appeared in the January/February 2019 issue of Occupational Health & Safety.

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