Determining AED Needs
Identifying factors for acquisition and placement of Life-saving technology.
Background: Being prepared for an emergency medical response is paramount to achieving the best casualty outcome. This not only applies to organized EMS response organizations, but to almost every level or location of emergency assistance including at the workplace or in public areas. There is a wealth of evidence indicating this is particularly true when dealing with Sudden Cardiac Arrest (SCA), the medical term for the sudden malfunction of the heart which results in the immediate cessation of the heart’s pumping action. Over 80% of SCA arise because of the abrupt development of abnormal electrical signals in the heart (arrhythmias). These arrhythmias cause the heart to quiver and unable to circulate blood and oxygen to the major organs. Portable computerized shock boxes called AEDs have been proven effective in correcting this electrical emergency. Implementing CPR skills and providing immediate access to this device is a major factor(s) or link in the Chain of Survival, which contributes to the successful resuscitation of the collapsed casualty.Fortunately, with the changes in medical philosophy over the last decade and advancing technology with more user-friendly and safe AED devices, we can now utilize the minimally trained responder to provide these lifesaving interventions.
Multiple factors including available trained responders, effective communication, and immediate access to the required equipment all facilitate a timely emergency response. Although I will comment on the key elements of establishing an AED program or the essential components, this article is not meant to be a comprehensive guide to establishing an AED program. Determining the adequacy of supply and the strategic location of the needed equipment, specifically AEDs and related resources is the target of this article.
Determining the Need for and AED program:
Almost any location is at risk to be the next site of a SCA. The predictability of SCA location and timing is poor. Consequently, unless it is for safety reasons, no company, organization or individual should be denied the opportunity to have an onsite AED program. However, many studies have identified the type of locations that seem to have a higher incidence of sudden cardiac arrest. These include but are not limited to: airports, golf courses, business office settings, correctional facilities, “Gaming” establishments, large industrial or work sites, retirement homes, shopping malls, sports complexes, “Urgent Care” centers, trains and ferries.
If fiscal considerations influence the decision to implement an AED program, then the following factors will help provide insight into the actual “need”: People Volume: The number of people using or visiting the facility, shopping centre, school, exercise facility (baseball diamond, soccer field, hockey rink etc.),
EMS Response time: How long will it take for EMS services to actually “reach the casualty”?
Other factors that influence the “need” decision because they may affect the response time of the either the onsite rescuers or the local EMS include:
- Presence of enhanced 911 coverage allowing emergency dispatchers to locate cell phone callers, (wireless callers make roughly one-third of all 911 calls)
- Ability of 911 dispatchers to give CPR and AED instructions over the phone?
- Percentage of people with CPR training
- The survival rate for SCA in your area?
- Presence of community AEDs nearby and time delay for arrival to the casualty
- Presence of high risk population.
- Higher-risk location
Formula to determine if a site is a high risk location:
The jury is still out on the ideal placement of AEDs in community settings. This fundamental topic is being addressed by a multi-site clinical trial called the Public Access to Defibrillation (PAD) study. It may be helpful to consider the formula used in the PAD study to identify higher-risk locations. A high risk location is an area which has a likelihood of having an event more frequently than every five years.
The formula is as follows:
- Take the number of individuals at a particular location
- Multiply this number by the percentage of individuals age 50 or over
- Multiply this number by the average number of hours spent at the location each day
- Multiply this number by:
a. 350 if the location is residential (or a 7 day commercial site)
b. 250 if the location is non-residential (or 5 day business site).
This number equals the number of exposure hours. If the number exceeds 500,000 there is a statistical probability of one SCA per 5 years at that site.
Key elements of establishing AED programs:
AED programs should be established under the direction of a physician (or EMS authority) familiar with the necessary components and capable of providing input. The individual should be aware of the existing onsite emergency response plan and familiar with the community’s EMS response time and ability. Designating an on-site contact or coordinator to facilitate equipment checks or coordinate and schedule training is essential and is part of the overall AED program quality assurance. Other parameters including the logistics of AED data download should be predetermined.
Once a corporation or facility has determined their interest and commitment to implementing an AED (Public Access Defibrillation) program, other common concerns include choosing the type and number of AEDs, determining the location of equipment, estimating the number of required AED trainees and establishing a training program endorsed by the Medical Director.
Choosing an Automatic External Defibrillator (AED):
Making the correct choice of AED type or style can be challenging since there are many good AEDs on the market. It can be advantageous to choose an AED unit that is manufactured by one of the larger AED manufacturers that also provides defibrillators for the EMS market. There have been AED failures and recalls, and if the technology is not backed by a sizeable company, there may be no solutions made available to upgrade the AED or compensate the purchaser, should a technical issue evolve. Choose an AED that can be easily upgraded to new guidelines or configurable by the program director utilizing simple software solutions.
Many Medical Directors still prefer AEDs that will not automatically deliver the shock without the user pushing a shock button. An AED with a LED screen usually provides the rescuer with text prompts (in addition to the audible prompts), and a visible time and shock count. The method of data downloads should be simplistic and most AEDs offer an infrared port download option or a card readable on a PC. AEDs that have preattached electrodes displaying easily visible expiry dates without removing the cover are preferable and choosing an AED with electrodes that have a long shelf life can reduce maintenance requirements.
Some AEDs offer pads with up to a 5 year expiry date. Likewise, AEDs with non-rechargeable battery solutions that last for up to 5 years should help reduce the risk of battery failure because of poor maintenance. AEDs that can accommodate pediatric defibrillation may be an important consideration for some applications. Some units incorporate newer technology that utilizes different algorithms for pediatric analysis and actually does a pediatric ECG interpretation to determine the need for a shock. Rhythm analysis and electrode pad technology have advanced significantly in recent years.
For most public access defibrillation sites, especially those that do not utilize trained medical responders, it can be advantageous to consider AEDs with pad systems that measure the depth of compressions, that provide the rescuer with feedback about the adequacy and pace of CPR, and prompt the rescuer to continue CPR if ceased prematurely. The new 2005 guidelines reinforce the importance of delivering good CPR, which most casualties of SCA require for at least some interval. Choosing an AED with a clearly marked “ON” button and with a visible status indicator that is easily checked externally and clearly indicates AED readiness is imperative. All AEDs should have some form of rescue kit (with personal protective equipment enclosed) that can be attached or enclosed in the AED. Depending on the intended location, choosing an AED that has a high ingress against dust and water (IP55) can be important for pool areas, marine or industrial sites.
It should be a rare concern to select an AED that complements the local EMS defibrillators. Various adapters can be acquired if this is a concern. It is more important to select a user friendly AED with visible prompts and audible cues that will guide and coach the infrequent rescuer through all steps of the rescue. Biphasic technology is the current standard for AEDs, and there may no longer be a reason to choose high energy AEDs, since with the newer waveforms, AEDs that deliver 120-200 joules have been shown to be just as effective or more effective in the high impedance victim. AEDs vary in price from under $2000 to over $5000, but it is important to select a quality AED suitable for the required application and that will complement the skill level of the rescuer.
AED Site Assessment
The goal of an AED site assessment is to provide a rational process for determining the optimal quantity and location of AED placement. It is essential to utilize the available resources and provide a timely response to a sudden cardiac arrest.
Deciding on location:
Ascertain if there is area with a more frequent employee or customer density, e.g. conference room, reception areas, clubhouse, banquet hall, main corridors, etc.. If there are higher risk areas (like exercise areas, hazardous areas, e.g. electrical or chemical) or high-stress areas, this may impact the ideal location. Areas that present an access problem like secure work areas, multiple doors, etc. may need their own AED. High visibility areas like reception areas or next to existing emergency equipment usually are good locations. Establish whether the desired location can be tied into the communications system, either by an open AED cabinet automatically triggering a call to security or the proximity of a telephone. Assess if there a better area where the AED can be mounted to be less vulnerable to tampering, theft or damage if an alarmed cabinet is not being used?
The site should be accessible during all shifts or hours of operation, or a specific fail-safe plan should be in place if the AED gets moved during shifts. If you are utilizing a targeted responder type response like security personnel as members of the response team, internal policies must address whether security personnel will have a unit at their checkpoints and if they can leave their post to respond to medical emergencies. If these alternative strategies are not feasible, then make sure that time measurements include the worst case delay the rescuer might encounter when required to pass through a potentially difficult access point, i.e., accessing a golf cart, passing a security check-point.
Determining Number of AEDs required: Time is the single most important consideration when determining the number of AEDs for a location. For every minute delay in response, there is a 10 percent reduction in the chance of survival. The number and placement of the AEDs directly impacts response times. The American Heart Association and Heart & Stroke Foundation recommend defibrillation within 3 to 5 minutes – ideally in less than three minutes. To achieve this response time, there must be enough AEDs in the right places, a clear communications pipeline, and enough people trained to respond quickly. Even if the event is witnessed, other factors delay a response and include, recognizing and communicating the event as a cardiac emergency, activating the internal responders, retrieving the AED, responding to the casualty’s location, and attaching the AED and delivering the shock. Sites using a “targeted responder” approach (where there are delegated responders like security personal responding initially) should still have AEDs distributed throughout the site and in addition equip the targeted responder.
To meet a goal of 3-4 minutes from “drop to shock” leaves 2-3 minutes to reach a casualty of SCA with an AED (to leave the casualty’s side, go to the AED and get back to the casualty) and one minute to assess the casualty and attach the electrodes. Walking at a brisk pace, a person can cover about 300 feet per minute, but this assumes no barriers in the route. Horizontal barriers that may delay the response need to be considered and include doorways, crowded hallways and security coded access doors, etc. Vertical barriers include elevators and stairways and can significantly impede the time to respond. AEDS should never be placed in a locked inaccessible area. In performing this assessment, you may need to consider other modes of transport and conditions that might delay AED arrival. For outside environments or industrial areas, clarify if you need to utilize other modes of transport like a snowmobile, golf cart, boat, all-terrain vehicle, tractor, or motorcycle.
To determine the optimal number of AEDs required using the recommended criteria, determine a visible location that would logistically be ideal to mount the AED. Then use a stopwatch and briskly walk the area to be covered, and establish whether all the desired points can be reached within 60 seconds (90 seconds if your response time goal is 4 minutes). The farthest point that can be reached in your desired response time is the “outlying” point. If your outlying point can be reached by changing but not compromising the location of the AED, then reconsider the placement location and re-verify the placement can accomplish your goal. Ideally, in facilities with multiple floors, each floor should have an AED. At a minimum, every second floor should be equipped.
Remember the First responder’s response time is only one component of the response. It is still important to notify EMS. AEDs are ideally stored in a monitored wall cabinet that automatically notifies both EMS and the building security or other designated responders when the cabinet is opened. While performing a site assessment, be alert to potential wiring connections for these monitored wall cabinets if there are plans to incorporate it into the security alarm system. Attempt to place AEDs in the proximity of electric smoke detectors or fire alarm devices, to facilitate visibility and an electrical source if required.
You must also consider what type of wall cabinet will be used in the recommended placement locations. Recessed cabinets are not appropriate for many wall surfaces such as marble, stone, or steel. A wall mounted AED cabinet that fastens to the wall utilizing several fasteners without interfering significantly with the wall integrity may be preferable. Architectural restrictions or policies within the facility may also influence what type of storage cabinets is most appropriate.
Secured areas can present special problems in terms of response time. Consider locating units within unsecured areas unless the likely responders can easily transcend security checkpoints, or the high risk area is inside the secure area.
Choosing which responders to train:
The immediate availability of trained personnel greatly impacts the effectiveness of an AED program. If possible, the primary source of responders should be security, safety, fire, and medical personnel. Other “natural” responders include “hall monitors”, “floor captains”, supervisors, golf pros or other personnel designated to assist or respond to various medical and non-medical emergencies. CPR training should be a prerequisite to AED training and it may be acceptable to have more people trained in CPR than AED trained. Training should be congruent with Heart & Stroke guidelines. Finally, any volunteer responders should be offered training. Increasing the number of trained personnel in a given facility increases the likelihood of a more timely and effective response. The goal of an AED program is to have multiple responders and at least one AED arriving at the scene within 2-3 minutes of the collapse!
In summary, minimizing the time to the first shock/CPR for the SCA casualty will increase survival rates for out of hospital life threatening cardiovascular emergencies. This can be achieved by establishing a complete AED “program” supported by strategic AED placement, rescuer training and ongoing quality assurance.
Optional Information: Once an AED program is established and the AED location is selected, notify all employees, clients or customers about AED location. Provide information about how it integrates with any existing emergency plan and how they can activate your emergency plan.
The existence of an AED program can be promoted by:
- Placing large easily visible signs or symbols on the AED cabinet;
- Posting well designed notifications about the AED program on bulletin boards;
- Circulating literature about your program or device with each pay stub;
- Clearly indicating to all employees the physical location of the AED device;
- Educating the staff about the contents in the AED cabinet, including the alarm system.
AED Needs Analysis by Dr. David Henstridge is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.5 Canada License.