By Erica Heilman
It's hard to imagine an episode of ER without at least one really bad cardiac arrest. The EKG goes haywire, a nurse presses the electro-charged paddles to the victim's chest, screams, "Clear!" and voila, a heartbeat.
In the real world, however, 95% of cardiac arrest victims do not make it to the ER in time for resuscitation. According to the American Heart Association, approximately 250,000 people die annually from sudden cardiac arrest suffered outside the hospital, the equivalent of a full 747 plane crashing with no survivors every day.
Survival often depends on the amount of time between the onset of sudden cardiac arrest and defibrillation, which is an electrical stimulation, or "jump start" of the heart. Traditionally, defibrillation begins only when an emergency rescue team can reach the victim or when the victim can be delivered to an emergency room. Thanks to a portable device called an automated external defibrillator (AED), ordinary people at the scene of a cardiac arrest may be able to provide defibrillation, saving precious minutes and potentially many lives.
Below, Dr.Vinay Nadkarni, Chairman of the American Heart Association Emergency Cardiovascular Care Committee, talks about how AEDs work, and the role that ordinary people may one day play in reducing the number of cardiac-arrest-related deaths.
What percentage of people who have sudden cardiac arrest survive?
It varies. Survival can be as low as 2%—two survivors out of a hundred—and as high as 25%, in victims who arrest outside the hospital.
What causes sudden cardiac arrest?
There are many, many causes of sudden cardiac arrest. The most common cause is an abnormal heart rhythm, usually called ventricular fibrillation or a quivering of the heart, and the most common cause of this is heart disease. There are many other causes, which can include respiratory compromise or arrest, drowning, and trauma. The risk factors depend on the age and activity level of the individual.
Where does it most often happen?
The most common location for adults to have sudden cardiac arrest is in the home. In most studies, between 60 and 70% of sudden cardiac arrest occur in or around the home—the remainder mostly occurring in public places or venues.
What is an automated external defibrillator?
Automated external defibrillators, or AEDs, are extremely simple little machines that deliver life-saving shocks to the heart. They're about the size of a telephone. Basically they are little minicomputers that, when you attach the pad to the victim's chest and turn on the machine, it automatically analyzes the heart rhythm. If the rhythm is analyzed to be one that would benefit from a shock, the machine gives you a voice prompt to push a button that delivers the shock. It's very simple.
So essentially, the person administering the shock doesn't have to make any medical decisions?
Right. They simply have to follow the instructions once they place the pads on the chest.
Who is qualified to use these machines?
There is no credential required. Anyone who completes a course that teaches them how to do it—the American Heart Association offers courses—is qualified to use the AED. All of the AHA courses currently that are geared towards CPR include a section on automated external defibrillators.
Is there any way to actually harm somebody with one of these machines?
There's a theoretical risk. But there's good data that the machines are extremely accurate at identifying shockable rhythms, and there have been no reported adverse events from the use of the AEDs.
Now, remember, most of the information that we have is coming from the use of AEDs by trained providers—like policemen, security guards, flight attendants, doctors, nurses, or respiratory therapists. But there are additional studies and developing information suggesting that even without training, there is the potential to save a life. But at this early stage, there is not enough data to recommend that AEDs be used by people who are not yet trained in their use.
Do you find that people are generally concerned that the machine could be used inappropriately?
Yes. And it's an important and valid concern. As with any technology that enters a home or public arena, there is potential for misuse. And on this count, one of the most important instructions with an AED is to not even place the pads on a victim unless they appear lifeless. In other words, they're not breathing, moving, or showing any signs of circulation or life. That's the first rule. And most people are really pretty good at determining that. Once the pads are placed on the chest, the machine has a number of checks and double-checks, and it checks the heart rhythm a number of times before it gives the advice to shock. And it does not deliver a shock unless everything is connected appropriately and it's advising a shock. It does not charge—or build up the energy for a shock—unless it reads a shockable heart rhythm. So there is an element of safety built in.
Where are these machines currently available?
AEDs are currently available in many public areas. They are beginning to appear in hospitals themselves, particularly in locations that are not currently patient areas, but are public areas. They are in many airports and on airplanes, because as you can imagine, these are higher-risk, high-stress, high-traffic areas, where there are lots of older people who are under stress. And they are environments where there is not rapid access to emergency medical service. So an intervention by a flight attendant or by a security officer, baggage handler, etc., might be a life-saving intervention.
Where do you think AEDs should be readily available?
Right now there are a couple important studies underway to help determine just that. One is called the Public Access Defibrillation trial, or the PAD trial. It is taking multiple public locations that are willing to train and develop an AED program compared to those that are not, and looking at the survival rates from sudden cardiac arrest in those communities across the country. The second study involves high-risk patients who are being discharged from the hospital. This study is trying to determine if AEDs would be appropriate in the home.
Might these machines be useful in schools?
Well, the rates of cardiac arrest are extremely low in school-age children. Ventricular fibrillation or sudden cardiac death is much, much less common as a presentation. Children much more commonly have a respiratory cause of arrest. The incidence of ventricular fibrillation goes up with strenuous activity. Usually if there is sudden ventricular fibrillation, it is because they either have a congenital heart condition, or they have a condition that predisposes them to that arrhythmia, like some athletes can have an abnormality of the heart valve or an abnormality of the heart rhythm that is brought out during exercise and can lead to this ventricular fibrillation.
Another cause of cardiac arrest in children is commotio cordis, which is a sudden blow to the chest. There are very small numbers, but there are children who have sustained a very sharp blow to the chest and dropped dead.
So even though the rates of cardiac arrest are extremely low in children, there is an impact of even one child being lost prematurely with a curable, treatable condition.
Do you think that AEDs should be required in public places?
Whether or not they should be required in schools and other public places is a matter of controversy. Every public place, every school is unique. What the American Heart Association advocates is that each public venue assess their risk for sudden cardiac arrest and their response to sudden cardiac arrest, and develop a program of recognition, access of EMS, AED response and CPR training that addresses their most likely causes of emergencies.
What about in the home?
Most cardiac arrests happen in the home. So a second question is whether AEDs should be available over-the-counter for use in the home. Currently they require a doctor's prescription and a training program. But are AEDs so simple, and are they becoming inexpensive enough that they could be made available over-the-counter and used at the public's discretion? And if it were used in that manner, would it improve outcome? These are important questions that still have not been fully answered.
RELATED PROGRAMS
