Portable Defibrillators Save Lives

I’m down with a cold so here’s a Technocopia article I wrote back in 1999.

Easy enough for a child to use, defibrillators may become as common as fire extinguishers.

With only seven per cent of people who suffer sudden cardiac arrest outside of hospitals surviving, the American Heart Association is championing the use of portable automatic external defibrillators (AED). There is only a ten-minute window in which a cardiac victim’s heart can be restarted usually by using a defibrillator. After that, if the person can be revived, he or she will sustain brain damage.

The statistics are frightening. Heart disease is the number one killer, and cardiac arrest is at the top. About 250,000 (some reports say 350,000) people in the U.S., and 80,000 in Canada, die of cardiac arrest every year. Eighty per cent of those happen at home (Los Angeles Times 7/16/98). In only ten per cent of cardiac arrest cases do ambulance attendants arrive in time to save a patient.

Health professionals, first responders (police, ambulances) and lay people are lobbying for automatic defibrillators to be made more accessible. They argue that more lives than seven per cent would be saved if a defibrillator were available in time.

An automatic external defibrillator is a heart-starting device that can be carried by one person. By placing electrodes on the patient’s chest it monitors, then instructs the person to deliver an electrical shock to the patient’s heart. This shock starts the heart pumping again in a regular rhythm. Sometimes additional shocks are needed to start the heart. Chances of survival decrease seven to ten per cent for each minute that passes before the hearts resumes pumping.

Cardiac arrest differs from heart attack (or stroke). A stroke is caused by blood deprivation and arterial blockage. The person remains conscious and usually has warning symptoms leading up to the stroke. Sudden cardiac arrest (SCA) can happen at any time to someone with no previous history of heart disease. The most common SCA is ventricular fibrillation, when the heart begins to contract chaotically. The person stops breathing and loses consciousness because the heart cannot pump oxygenated blood to parts of the body, especially the brain.

The American Heart Association states that there are four factors that contribute to ventricular tachycardia, or sudden cardiac arrest.

· Pre-diagnosed heart disease.
· Degeneration of the heart muscle.
· Enlargement of the heart due to high blood pressure.
· Hardening of the arteries.

SurvivaLink Corporation, Minneapolis, Physio-Control Corp., Redmond, and Heartstream, Inc. Seattle (division of Hewlett-Packard) designed the AEDs for use by paramedics and for situations when a plane is in-flight. These companies widened the scope, making these devices accessible to the public. The Food and Drug Administration approves AEDs for home use. They are easy to understand and use, perform self-checkups and have protective failsafes.

The company websites give instructions on what to do if someone suddenly passes out and stops breathing.

· Have someone call 911 or local emergency access number.
· Check airway.
· Check breathing.
· Check pulse.

Only at this point would you use the portable, lightweight defibrillator the size of a laptop computer, and weighing between four to seven pounds. When open, there are clear readable instructions with icons as to where to place the two electrodes. A voice command guides the user.

Though each AED is slightly different, the process is similar for all. Once the responder places the two electrodes on the patient’s chest the AED uses an electrocardiogram (displayed on some models) to check for pulse. If there is a pulse the person may be suffering a stroke or from some other health problem and it will not advise a shock. (It is unclear at this point if the shock button would work if someone pressed it inadvertently.) If it detects no pulse it instructs the responder to stand clear of the victim and to push the button. The AED releases a charge into the patient’s chest. If there is still no pulse the AED will charge and repeat the shock with verbal instructions each time.

Researchers found that the cause of failure for many of the larger older defibrillators was improper testing and maintenance of batteries. The new defibrillators come in their own sturdy plastic cases, some with spaces for spare batteries. The lithium batteries hold a charge longer than other types of batteries. The AED performs a daily self-test checking the charge and if the batteries are low it indicates the need for replacement. In most AEDs, even when the batteries are low, there is usually enough energy to deliver five to nine shocks.

The self-checking program requires smart technology that consists of a memory chip. As well, the AEDs use biphasic wave technology though monophasic is available in some brands. Biphasic technology is the use of optimal current each time a shock is discharged. The electrical wave reverses direction part way through and delivers the right charge. There is an impedance variable caused by the difference in size and weight of people. This impedance is checked and analyzed by the two-way current. Results with the biphasic wave technology (as in Physio-Control’s LifePak 500) showed a 100% success rate on the first shock.

An AED on Every Corner

A nearly foolproof, portable defibrillator makes it easy for anybody to use one. Researcher Dr. Gust H. Bardy, at the University of Seattle, and his team instructed fifteen sixth-graders for about one minute on using the defibrillators. “On average, the researchers found, the children completed defibrillation in 90 seconds, compared with the professionals’ (paramedics) time of 67 seconds. Furthermore, all of the children properly placed the device’s pads on the chest and remained ‘clear’ of the mannequin as the shock was delivered…” (Circulation: Journal of the American Heart Association 10/18/99) The American Heart Association recommends that everyone should first be trained on how to use a defibrillator.

Already many airlines have been carrying the AEDs, as well as resorts, casinos, and cruise ships. Advocates of the AED hope that it will be as accessible as fire extinguishers, available in gyms, shopping malls, sports arenas, theaters, seniors’ homes, restaurants and even in the homes of people diagnosed with heart disease. The defibrillators run between $2500-$4000 USD and still require a doctor’s signature to own, yet people as well as companies like FORD are buying them.

Some critics believe it is dangerous to put an AED into the hands of an untrained person who may forego calling a trained paramedic after the shock is administered. Others see it as infringing on the duties of police or firemen who already have other responsibilities. Yet, in many states police cars have been issued AEDs. In Rochester, Maine “survival after cardiac arrest jumped to 50 percent from 20 percent” after squad cars were issued AEDs (New York Times 04/15/99) Yet early studies (from 1998) in other states showed a negligible increase in survival.

Initially there was reluctance by police, airline attendants or even employees of large companies to use the portable defibrillators. Concern over machine malfunction or using an AED correctly led ultimately to concerns of who would be found liable. Some insurance agencies would not cover liability for such devices, and some airlines and companies did not want to carry them.

Thirty-one states have now passed limited Good Samaritan clauses for use of AEDs by laypersons. Airlines such as Lufthansa and United have been sued for not supplying timely medical care to victims of sudden cardiac arrest. “Two weeks after it was sued, United announced plans to place defibrillators on its planes. Other airlines followed suit.” (Gannett News Service 03/10/98). American Airlines has instituted the Golden Heart Club for those people whose lives have been saved on the airline, and those attendants and people who have used the devices to help them. (The Dallas Morning News 07/24/99)

Further lobbying continues for use of the portable automatic defibrillator. There are those that argue that to place so many portable defibrillators in every public access facility would be cost prohibitive. Many AEDs would never be used. Yet, fire extinguishers and sprinkler systems are required and fires do not happen in every building. Because an AED can also monitor heart signals and determine that a person is not having a cardiac arrest, they have saved money for airlines that are required to divert their paths when a cardiac arrest occurs.

When a portable defibrillator saves lives it will go beyond the naming of a price. Attitudes are changing with the ease of using an AED. It is now possible for even a child to be able to save someone from cardiac arrest: the number one killer of North Americans.

Automatic External Defibrillators: Medtronic Physio-Control LifePak 500 (there me other ones now and they are more common but you’ll need to Google to find them)

For more information:
Physio-Control http://www.physiocontrol.com
American Heart Association: Sudden Cardiac Death
http://www.amhrt.org/presenter.jhtml?identifier=3053

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