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Automated External Defibrillators (AEDs)

Quick Tips #271

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Introduction

Each year nearly 500,000 people die from sudden cardiac arrest. Preventing death caused by sudden cardiac arrest requires fast action and a critical sequence of events including: early activation of the EMS system (calling 9-1-1), early CPR, early defibrillation and early advanced care at a medical facility. Administering CPR techniques and dialing 9-1-1 have been the way to respond to a cardiac arrest for years, but the use of automated external defibrillators (AEDs) is relatively new.

In the past, only highly-trained individuals in hospitals or EMS personnel had access to manual defibrillators. But technology has now made it possible for non-medical personnel to perform defibrillation in non-medical settings. AEDs equipped with an internal computer can interpret the heart rhythm to determine if a victim is in ventricular fibrillation (V-fib), a potentially fatal heart rhythm. If V-fib is indeed occurring, the unit instructs the user to press an activation button which causes defibrillation.

Operation

In a healthy heart, a natural "pacemaker" delivers organized electrical impulses that generate a steady repeating rhythm. When the heart goes into cardiac arrest, random electrical impulses come from many locations within the heart, simultaneously causing an uneven heart rhythm. This uneven rhythm does not allow the chambers of the heart to fill and pump blood properly through the body. To restore a normal heart-beat, a defibrillator delivers a shock to the heart—momentarily stopping it—which interrupts the electrical chaos and helps restore a normal heartbeat.

Various AEDs operate in a similar manner. A pair of electrode pads are connected to the unit and the unit is activated. After a brief automatic internal check, the user can place the pads on the victim's bare chest. The AED's diagnostics determine whether defibrillation is required. If defibrillation is required, the unit instructs the user to clear the area around the victim and press an activation button. The unit will then instruct the user to immediately begin CPR. After two minutes the unit will perform another analysis to see if defibrillation is needed again.

Audible and/or visual prompts guide the user through the entire process so the possibility of error is very small. Studies of the units indicate that AEDs are capable of accurately detecting V-fib and recommending a shock 90% of the time, and recommending no shock 99% of the time when not required. With this accuracy, an AED has a greater ability to diagnose V-fib than does an emergency response team.

An automated external defibrillator delivers approximately a 3000-volt charge in less than 1/1000 of a second. That is enough electricity to light a 100-watt bulb for 23 seconds. In cases when the heart is in full cardiac arrest with no sign of V-fib, only medications can restore heart movement.

CPR is also required since an AED only restores a hearts normal beating pattern to a heart in V-fib. Rescue breathing and chest compressions are needed to supply oxygen to the victim if breathing and heart-beats are not occurring. After the prescribed sets of breaths/compressions, the unit will analyze the motionless victim and determine if a shock is necessary.

During treatment, the AED records the data it detects on the patient's condition. Some models can also record a live audio of the incident. This data can be transferred to the physician treating the patient when he/she arrives at the hospital.

Training

Manufacturers of automated external defibrillators recommend users undergo training which normally takes several hours. The defibrillators are so easy to use that most untrained users will be able to attach the pads, allowing the unit to analyze and provide shocks. However, users must still be taught when to use the AED, how to respond if a shock is not required and how to operate an AED safely.

Company Risk Factors

Before the advent of automated external defibrillators, 95% of sudden cardiac arrest victims died even with first aid, rescue breathing and cardio-pulmonary resuscitation. In contrast, defibrillation delivered within the first minutes saves the lives of up to 75% of cardiac arrest victims. Many large facilities such as airports, sports stadiums and large workplaces are installing AEDs to increase the chance of saving lives.

In order to evaluate whether your facility would benefit from an AED, consider the following: How many people are at your site? Large numbers of people increase the likelihood that an AED would need to be used. What is the response time of the local emergency response service to get to the furthest place on your site? Traffic conditions, elevators, stairs, gates all can cost valuable time to negotiate. What type of workforce or visitor demographics does your facility encounter? Consider the health, age, fitness and stress levels of the people. Are workplace hazards present such as electrical or confined spaces? Electrical shock or asphyxiation could induce heart fibrillation. Is the facility in a remote area? Can an emergency response team reach these areas in time? Does your facility have an emergency response team already in place? If these teams are needed, it's a good bet an AED would be of use someday.

Automated External Defibrillator Programs

An AED program is a natural extension of an existing first aid program. After purchasing a unit, you should contact your local hospital emergency dept. and consult with a physician. The physician is responsible for establishing appropriate policies and procedures for the use of the device. Specific requirements do vary from state to state so it's important to discuss details with your AED supplier, physician or local American Heart Association/American Red Cross chapter. Generally, programs contain the following topics:

  • Periodic training and evaluation of the user on AED use, first aid and CPR
  • Notifying the local EMS service of its presence and meeting their requirements
  • Maintenance and regular testing of the AED according to manufacturer guidelines
  • When emergency care is rendered to activate the EMS system
  • Bloodborne pathogen training may also be required
AED Resources

American Heart Association
American Red Cross
Public Access Defibrillation League
American Association of Occupational Health Nurses
American College of Emergency Physicians
International Medical Consulting

Commonly Asked Questions
Q.   Is liability a concern with AED use?
A.   The majority of states have "Good Samaritan" laws that protect persons rendering good faith emergency treatment with an AED from civil liability. Check with your states regulations to see about your protection.
 
Q.   Are there specific regulations regarding AEDs?
A.   While there are some laws and regulations concerning AEDs at the federal level (e.g., FDA, Congress, etc.), most of the regulatory activity in the past few years centers on the state and local level, where a greater availability of AEDs is encouraged. Most states allow a "Good Samaritan" exemption from liability for any individual who gives emergency treatment with a defibrillator. The following is a comprehensive discussion on State Laws on Cardiac Arrest & Defibrillators.

Q.   What is Sudden Cardiac Arrest?
A.   Sudden Cardiac Arrest occurs when the heart unexpectedly and suddenly stops beating normally. It is caused by abnormalities in the heart's electrical system which causes the heart to twitch quickly and chaotically. While twitching, the heart is unable to pump blood to the brain and body. It is commonly called ventricular fibrillation.
 
Q.   Is Sudden Cardiac Arrest the same as a heart attack?
A.   No. A heart attack is caused by blood flow blockage to the tissue of the heart, causing the tissue to die. Persons having heart attacks often feel pain in the chest, upper abdomen and arms. Others signs include nausea and sweating. During a heart attack, the heart does continue to beat and pump blood. During Cardiac Arrest, the heart stops beating and pumping blood.
 
Q.   What is the average useful life of an AED?
A.   Typically, the useful life of AED's would be 5-10+ years. Every 5 years or so, the American Heart Association (AHA) and European Resuscitation Council (ERC) issue new or refined guidelines for resuscitation and upgrades may be needed in the AEDs or the software, in order to meet the new guidelines.

Q.   Is maintenance required?
A.   There is some maintenance required. Obvious maintenance would be replacing the non-rechargeable battery (LiO2), which is waranted for 4 years from the date of installation, and pad replacement (2 yr. shelf life). These units self test on a daily, weekly, monthly and annual basis. There is some maintenance associated with these self tests, especially if the test indicates a failure in some mode. Usually, one would check to see if the unit passed the self test. There are also visual and audible alarms. It is suggested that the voice prompts be checked monthly. The procedure for the annual test is a bit more extensive, opening the unit, unplugging the pads, etc. The protocols are given in the instructions.
 
Sources

Automatic External Defibrillators: Do You Need an AED?, Lesley Young, Occupational Health and Safety Canada, March 2000, pp.62-66.

AEDs: Starting a Company Program, Karen Sarkis, Occupational Hazards, April 2000, pp.61-64.

American Heart Association

(Rev. 6/2014)


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