AEDs - The Truth and the Fiction

AEDs - The Truth and the Fiction

AEDs - The Truth and the Fiction

Few innovations have had such immediate and sweeping popularity as Automatic External Defibrillators (AEDs). However, there is no centralized registry to collect data on the use and effectiveness of AEDs.

   
AEDs - The Truth and the Fiction
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About a million people die every year from heart disease, four hundred thousand from sudden cardiac death which is usually due to ventricular fibrillation (V-Fib), an ineffective twitching of the heart, or ventricular tachycardia (V-Tach), a too-fast racing of the heart that degenerates into V-Fib.

The survival rate, living to be discharged from the hospital, of cardiac arrest is between 2 to 20 percent. Most initial rhythms are treatable ones; V-fib and V-tach. If help gets there before five minutes pass, survivability increases. Every subsequent minute that passes leads to decreasing survivability, about 15% less per minute. Basic life support people who deliver CPR increase your chance to survive, paramedics, with sophisticated airway management techniques and drugs make a difference. Another key element at this step is the arrival of electricity in the form of some sort of defibrillator to convert your rhythm.1

Seventy five percent of cardiac arrests occur at home. The rest happen in public places: Fitness centers and golf courses, and restaurants are quite common. Best chance of surviving is to be in public except, for some reason, office buildings and hotels. People deemed at increased risk for sudden death, like those with a history of V-Fib are much better off with an implanted automatic defibrillator, a much different device and not the subject of this article.

There is still controversy about AEDs and the final verdict isn’t in.

For being so ubiquitous and commonly used, there is a surprising variance of opinion about their ability to save lives. Since the AED was first developed and marketed by R. Lee Heath in the late seventies, over a million have been purchased and distributed. Its proponents claim it has saved thousands of lives, is safe, effective and needs to be deployed so that one is in every home of high risk patients and readily available in those areas which are not close to paramedic stations. To help acheive this goal, in 2005 the U.S. Federal Drug Administration decided to make them available without a prescription.

The American Heart Association says they could save fifty thousand lives a year but a study out of Johns Hopkins University claims no more than five hundred. But what's even more shocking is there is no centralized registry monitoring AEDs use and effectiveness. There are only registries that document AED locations. However, The AED Use in Sports organization is a good start.2-6

But, is there validity to their value or are we part of what the social psychologists call a “Moral Delusion”, a sort of group-think process motivated by an imperative to do something.

Where’s the truth, what’s the fiction?

I’m going to tell a story about something that happened to me at a lecture I attended during the course of my Master’s of Health Care Administration program at La Verne University in California. It concerns a fact I don’t think a lot of people know. The lecturer was a prestigious management consultant from nearby Claremont University who, among other things, had been a consultant to the nation of Japan during the 1950s, was known as the Father of Modern Management, and had advised President Eisenhower to get a single-payer National Health Program going before hospitals became too expensive to build.

But the night of my lecture he spoke about other things, like his uncle Willem. He would often visit his Uncle Willem, a cardiologist, in his Netherlands home, and watch him tinker with a strange machine, a 600 pound monstrosity that took up an entire room.

My gosh, in a moment of sudden insight I determined that Uncle Willem was Willem Einthoven. He standardized the EKG with the use of vector analysis and made it possible to compare EKGs of different patients. Eventually, Uncle Willem was able to record the first vector cardiogram and he received the Noble prize for it in 1929. The study of the heart, its normal and diseased states, and its dysrhythmias had begun. Thanks to Uncle Willem medicine was able to determine how a heart’s rhythm changes and causes sudden cardiac arrest.

In 1775, Dr. Albigaard, in the Netherlands, was able to cause V-Fib in hens with a crude direct current battery. He also noticed that the twitching could be terminated by the application of a second shock. The first defibrillation.

In 1887, Dr. Thompson, in England, recorded the first tracing of the hearts electrical activity and Uncle Willem devised the Vector Cardiogram in 1903, which showed the electrical activity from standardized electrical lead placement. All health care people should be familiar with Einthoven’s triangle which gives us different “looks” at the electrical current flow in the heart.

This standardized tool for assessing heart activity lead to the development of experimental drugs and defibrillation equipment that were introduced in the 1940s. By the 1950s a patient diagnosed with myocardial infarction or heart attack would be observed, usually by an intern who had the patient hooked up to an EKG machine, drugs and a crude defibrillator at the ready. There were no alarms or sophisticated monitors so the most critical element in the treatment plan was the intern’s ability to stay awake. The primordial Intensive Care Unit.

The first defibrillation on a human was done by Dr. Claude Beck in 1947, at the University of Cleveland. He had been experimenting in his spare time with the use of electricity to stop V-Fib. During a routine surgery on a 14 year-old boy, his patient went into fibrillation and in desperation Dr. Beck had his machine brought to the operating room where he used it to restore a normal rhythm. It took two shocks. The news made national headlines and gradually commercially available defibrillators, most in wooden cabinets with spatula-shaped contact pads, found their way into hospitals. Lidocaine, the first-line drug used on ventricular fast rhythms, was developed in the 1940s in post-war Germany.

Researchers recognized early that time-to-treatment of V-Fib was a critical factor. We know now that for every minute delay in treatment survivability decreased by 15 percent. So the first models for pre-hospital care were developed in the attempt to get effective treatment to the patient sooner. In 1969, in Belfast Ireland, physicians were sent to homes of heart attack victims with their drugs and defibrillators. It worked, according to most, and the next year St. Vincent’s hospital in New York had our country’s first physician-staffed mobile unit.

To have a bunch of doctors assigned to ambulances and sitting around most of the time was quickly deemed inefficient so the concept of the paramedic physician-extender was developed in the U.S. and the UK including Glasgow, Los Angeles, King County Washington, Miami and New York.

Motivated to save even more lives, the AED made its debut and has been extensively deployed and widely touted as a success.

They’ve been given to policemen, ambulance drivers, teachers, casinos, airports, airline attendants. They’re are all over, even the hospital waiting room, WalMart and other department stores, the golf course. They’re ubiquitous. And thanks to the 2005 Federal Drug Administration (FDA) ruling that allowed the sale of AEDs without a prescription, there are many home units.

AEDs have been placed in the waiting areas of hospitals, even hospitals with emergency departments. And when there were in-house code blues (person down) and both “civilians” and ER people both responded guess who got there first. The visitors, by twice as fast and more people survived. 

15 percent of workplace deaths, 400 nationwide yearly, are cardiac arrests, the Occupational Safety and Health Administration (OSHA) estimates if all places of work were equipped 130 lives would be saved. Sudden death at schools is a different story. Less than 20% of deaths are cardiac related and occur during athletic activity, usually with a history of preexisting heart disease. A position paper from the American College of Emergency Physicians falls just short of recommending AEDs for schools but they could well save some of these sudden deaths. Standard AEDs can be used in anyone over 8 years of age. Special paddles are now available for any child over 1 year of age.

AEDs have never seriously harmed a patient or rescuer. Studies have clearly shown they are easy to use. Paramedics who like to use AEDs will point out that the units are lightweight and more portable than the heavy, bulky manual defibrillators they use. Many “events” were operator-dependant like a cable wasn’t hooked up or a battery was put in improperly. There have been some misinterpretations on the part of AEDs, rhythms that should have been shocked that weren’t, others that shouldn’t have and were. Subsequent study has shown these tracings were difficult for cardiologists to determine also.7

All types of defibrillators are generally safe. The only incidents of serious harm have been in the older manual units, not AEDs, where healthcare people, accidentally or sometimes on purpose, shocked themselves. This would be an argument to use the AEDs exclusively in the hospital. They are safer. AEDs use a biphasic discharge a different waveform that uses less voltage, and will not discharge unless they sense they are hooked up to a patient.

If you are going to be near an AED unit, it’s advised you learn how to use it. The deployment and initial shock are done more quickly with a trained user. Although untrained users are usually able to operate the unit also. Children can learn, they even measured old people to see if they could learn. Anybody can learn how to use it.

Basically there are several units on the market now. They all have the basic protocol for shocking V-Fib and V-Tach with a heart rate over 180. Instructions advise you to check for pulse and to deploy the AED only if you feel no pulse. Three shocks are administered with 10 to 15 second analyzing intervals in between; either the machine will shock the patient after warning you, or it will instruct you to push the “shock” button. If the shocks fail to change the rhythm AEDs will even coach you in how to do CPR, if all the shocks fail, and can sense whether your technique is adequate or not; it senses through the chest pads, and tells you what to do differently.

But, surviving cardiac arrest is dependent on multiple factors, not just AEDs

This is best understood using the concept of Chain of Survival, the idea that a series of related events including arrival times must dovetail into each other for a person to have the best chance of surviving a potentially lethal cardiac event.

The American College of Emergency Physicians recommends AEDs be part of an integrated prehospital care system, under physician control, so that the Chain of Survival and all its components can be coordinated, including maintenance checks and training programs.

To appreciate the importance of arrival times of the ambulance units and their care givers, one need only look at the Seattle experience. The city with the most survivors-to-hospital-discharge following cardiac arrest. An honor bestowed yearly for some time now. And guess what their 911 call to paramedic arrival times are. Always around five minutes or less. This is all part of the Chain of Survival.

So, are AEDs making an positive impact on improving the dismal survival rate from sudden cardiac arrest?

Honestly, we are not so sure. Although there are organizations that 'map' AED locations such as My HeartMap and The Atrus National AED Registry, as of 2012 there is still no true centralized registry to collect ongoing data on the use and effectiveness of AEDs. However, there is at least a registry for AED use in sports and it appears that Spain may be taking the lead in establishing on going data on the use and effectiveness of AEDs.8-11

The Johns Hopkins study showed 500 lives a year could be saved with a policy of PAD using AEDs, other, sometimes industry sponsored, opinions put the figure at thousands. Unfortunately, virtually all the studies on effectiveness are more concerned with the performance of the AED unit as opposed to its cost effectiveness and impact on the overall problem of sudden cardiac death. Recent studies have attempted to do this including a study in Denmark and California, as well as the Johns Hopkins study. More will surely follow.12-14

Careful review of all the studies, given their strengths and weaknesses, tends to show what we’ve known all along, for many years, actually: If electrical defibrillation is applied in less than five minutes, survival will be markedly increased.

For instance, in one of the best studies done in Italy, a Public Access to Defibrillation (PAD) program was implemented using hundreds of public locations and private homes. Survivability of the people receiving AED shocks was almost double, 25% versus 15% in those who had to wait for paramedics. The authors say PADs will increase survival and should be implemented.15

They may be right, but the real lesson to be learned from this study comes from looking at their data. The survivors had shorter time intervals to their first shock, by about a minute and a half. AED advocates recommend no location, be it home, business, or recreational areas, should be more than a minute and a half walk from an AED, others say 3 minutes, presumed to be at a fast pace or running. One of the strangest recommendations for placement of AEDs is locations where they would “be used at least once every five years. This seems to require the use of psychics.

Furthermore, most of the AED studies exhibit a major flaw...the majority did not have any control groups. If a study is going to be called “scientific” it needs to have, among other things, control groups. For instance, the Charlotte study showed no improvement in survival rates in both AED equipped and unequipped groups of rescue personnel. This brings into doubt all the studies that did not have a control group.

Of interest this study that seemed at first to show no value for AEDs was done in Charlotte, North Carolina where some ambulances were given AEDs and others weren’t. The results, as measured by percent of people surviving to be discharged from the hospital showed no difference. Closer inspection of the data showed that since the recent introduction of the city’s Computerized Dispatch System times for the call-to-arrival intervals had increased an average of two minutes, so that rescue units were arriving more than 6 minutes after the call. Once again, any interval over five minutes will result in poor survivability.16

So, are AEDs worth it?

Undoubtedly, much of the benefit AEDs provide may be related to the Halo Effect. Every study has, to one extent or another, what’s known as a halo effect; just the fact that someone or something is being studied changes the results. An example of which can be seen by taking note of the American Heart Association's profound effect on the incidence of heart disease and sudden cardiac death.

After introduction of its CPR programs in the late 60s, gradual, consistent decreases in the incidence and severity of heart disease was noted and at first everyone thought it was because people were learning CPR. To a certain extent it was, but closer analysis showed that the major factors for the decrease were increasing public knowledge of the importance of modifying life styles, paying attention to the risk factors for heart disease, and other things, like calling 911 early.

So by advocating use of AEDs and PADs one may draw attention to all the elements of the Chain of Survival. More people will be trained in CPR and know to call 911 first, and prehospital planners will try to get their arrival times to less than 5 minutes.17-19

The Bottom Line

It’s safe to say AEDs are here to stay. It's evident that getting electricity to a failed heart in under 5 minutes is essential in making a significant impact on increasing survival rates. And it appears that the AED PAD movement is a major step in the right direction. However, we may never know the true effectiveness of AEDs until a central registry tracks its utilization as opposed to only receiving anecdotal media accounts of the successes and not the failures.

It had to happen. I was having dinner with a family member who leaned over and asked “We’re thinking about buying an AED for the church. What do you think, 'Is it worth it?” Life isn’t priceless, each of us has an economic value. But if it’s your family member or loved one, or the chairman of your church’s foundation who raises money for you, it’s a different story. I told my family member to buy the AED, as soon as she could.

But, don’t forget to call for paramedics, train your people, the Italian study trained those who would be using the units, and teach your community CPR, especially when to call 911.

Published December 11, 2008, updated June 08, 2012

Photo By:  halfrain


References:

  1. Kumar V, Fighting cardiac arrest: Automated external defibrillation, Indian J Crit Care Med 2003;7:242-9
  2. Cummins RO et al, Improving survival from sudden cardiac arrest: the "chain of survival" concept. A statement for health professionals from the Advanced Cardiac Life Support Subcommittee and the Emergency Cardiac Care Committee, American Heart Association, Circulation. 1991;83:1832-47
  3. Lives Are Saved When Defibrillators Are Placed In Public Spaces, ScienceDaily, November 7, 2007
  4. Levins H, The Automated External Defibrillator: Medical Marvel But Measurement Mystery, LDI Health Economist, PENN
  5. AED Locator, UK
  6. The National Registry for AED Use in Sports
  7. The Public Access Defibrillation Trial Investigators, Public-Access Defibrillation and Survival after Out-of-Hospital Cardiac Arrest, N Engl J Med 2004; 351:637-646
  8. MyHeartMap,
  9. The Atrus National AED Registry
  10. Myers JB, Lack of integration of automated external defibrillators with EMS response may reduce lifesaving potential of public-access defibrillation, Prehosp Emerg Care. 2005 Jul-Sep;9(3):339-43
  11. AEDs in Spain, Cardiac Science, Mon, Apr 4, 2011
  12. Weisfeldt M, Survival After Application of Automatic External Defibrillators Before Arrival of the Emergency Medical System, J Am Coll Cardiol, 2010; 55:1713-1720
  13. Folke F, Strategic Placement of Automated External Defibrillators in Public Locations, Circulation. 2009; 120: 510-517
  14. Winkle RA, The effectiveness and cost effectiveness of public-access defibrillation, Clin Cardiol. 2010 Jul;33(7):396-9
  15. Capucci A, Out-of-hospital early defibrillation successfully challenges sudden cardiac arrest: the Piacenza Progetto Vita project, Ital Heart J. 2002 Dec;3(12):721-5
  16. Sweeney TA, EMT defibrillation does not increase survival from sudden cardiac death in a two-tiered urban-suburban EMS system, Ann Emerg Med. 1998 Feb;31(2):234-40
  17. Capucci A, Tripling survival from sudden cardiac arrest via early defibrillation, Circulation. 2002 Aug 27;106(9):1065-70
  18. PUBLIC ACCESS TO AUTOMATED EXTERNAL DEFIBRILLATORS (AEDs), Heart and Stroke Foundation of Canada Position Statement, Last updated October 2008
  19. Reinberg S, Widespread Use of Defibrillators in Public Places Saves Lives, HealthDay, January 26, 2011

J. Linder Jones MD MHA practiced emergency medicine for over two decades in Southern California and now writes on occasion for HealthWorldNet.

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