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By Lesley Young

Most of us consider it the ultimate in high-tech, hospital medicine, but new technology has brought on-the-spot cardiac defibrillation within reach of every first aider.

Your odds of surviving sudden cardiac arrest at the blackjack table in a Las Vegas casino are better than they would be almost anywhere else in North America. Vegas, city of perpetual day, is also a city of AEDs, or automatic external defibrillators. Every hotel and casino is equipped with a least one of these portable, book-sized electrical devices that can make the difference between life and death for a victim of sudden cardiac arrest.

Hotel and casino security guards are trained and authorized to use AEDs. With a response time of 90 seconds or less, they can reach a cardiac arrest patient, begin cardiopulmonary resuscitation (CPR), and, if needed, use their AEDs to deliver the electrical shock that provides the best hope of snapping a fibrillating heart back into a normal pumping rhythm. In fact, the city’s hotels and casinos are better equipped to treat cardiac arrests than many ambulances in major North American cities.

Technological improvements in AEDs have made the defibrillators as simple to use as a microwave oven. True, it’s not nearly as dramatic or high-tech as on television medical dramas. Users don’t need to diagnose a rhythm, or decide how big a jolt to deliver. There is no "flat line", there are no paddles and, no, the patient doesn’t jump three feet off the ground.

In parts of Canada, public access to early defibrillation is taking shape involving emergency medical departments, independent paramedic associations and the Canadian Heart and Stroke Foundation. Called "Public Access Defibrillation" or PAD, the idea is to have trained people ready to use AEDs everywhere -- from golf courses to the workplace.

To be sure, PAD is happening. AEDs can already be found in the Skydome in Toronto, in public places in Calgary and in BC Place in Vancouver; it’s on many commercial aircraft, in large industrial complexes and in small dentist’s offices. Those in the PAD community contend that thousands of lives could be saved if AEDs were made more available to the public. There’s little doubt that, if you’ve got a first aid program in your workplace, you will eventually have to consider purchasing a device.

RACING THE CLOCK

Early defibrillation is the most important link in a chain of survival for sufferers of sudden cardiac arrest (SCA). Nearly 90 per cent of SCAs occur outside the hospital setting -- many of them in the workplace or in large, public gathering places. CPR started within minutes of an arrest can maintain minimal oxygen levels and keep the brain alive; but the Canadian Heart and Stroke Foundation (CHSF) estimates that for every minute defibrillation is not delivered, chances of survival from SCA decrease 10 per cent.

In most cases, defibrillators arrive on the scene with the advanced life support team on an ambulance. But emergency response time in most major cities can be anywhere from seven to 10 minutes -- and that survival clock is ticking down at 10 per cent a minute. Newer AED technologies, making devices more affordable and practical, have allowed for widespread access to the public. It is now possible for trained first aiders to apply defibrillation to a victim of SCA in the critical minutes before the ambulance crew arrives.

Not all victims of heart problems can be saved through defibrillation. A heart attack is caused by a blockage of the coronary arteries, which decreases blood supply to the heart. Usually there is some advance warning, such as pain and shortness of breath. The sufferer often remains conscious and the heart keeps beating, even though it is damaged. Many heart attack victims have a history of heart problems. Many carry medication and know what to do. Most have time to get to the necessary care.

Sudden cardiac arrest, however, is the result of an electrical malfunction of the heart that strikes with little or no warning and can lead to sudden unconsciousness and collapse. Instead of beating in a normal rhythm and pumping blood, the heart starts to twitch or flutter rapidly -- that’s what "fibrillation" means. It stops pumping blood, breathing stops, and there is no pulse. The oxygen supply to the brain is cut off and, without CPR, clinical death is perhaps four to seven minutes away.

It is these people whom early defibrillation can save, and they make up more than two-thirds of all SCA victims. Defibrillation -- think of it as rebooting a "frozen" computer -- eliminates fibrillation and allows a coordinated heart rhythm to resume.

Early defibrillation won’t work for the less than 20 per cent of cases of SCA where there isn’t a type of fibrillation. For instance, where there is a complete absence of electrical activity in the heart (the famous "flat line" so popular on TV), defibrillation is useless. CPR must be continued until advanced help arrives.

But the first aiders on the scene don’t have to worry about diagnosing which condition they’re dealing with or about getting it wrong: The new AEDs are capable of diagnosing a "shockable" heart rhythm, and will not deliver shocks unless it detects them.

CPR remains an integral life-saving operation in cases of SCA. CPR is a "holding" operation: it maintains blood flow to the brain and heart. But without defibrillation within 10 minutes, it is like blowing on smoldering cinders that will never re-ignite.

THE CHAIN OF SURVIVAL

Everyone in the PAD community, including the American Heart Association and the CHSF consider early defibrillation the most important link in the internationally recognized "chain of survival", a term describing the four steps vital to survival from sudden cardiac arrest:

* early access to emergency medical care (calling 911 or other designated emergency phone number);

* early administration of cardiopulmonary resuscitation (CPR);

* early defibrillation; and

* early institution of advanced cardiac life support (when the EMS arrive to provide oxygen and drug therapy for stabilization).

An AED program in the workplace needs to make provision for each component in the chain of survival.

Mike Ichelson, a paramedic and medical director of an AED training company called "Code 8 Inc." in Toronto, Ontario, contends that AEDs need to be available in every workplace. Code 8 has trained several in Ontario already. "They need to know this is the only type of training that can saves lives. CPR will only work for a couple of minutes. But it’s not the whole thing," he says. "A defibrillator has got to be nearby."

The suddenness with which a SCA can strike can be disarming for family, witnesses and co-workers. In the summer of 1996, a 35-year-old worker died suddenly at the Harmac Pacific Inc. plant in Nanaimo, British Columbia, after suffering a sudden cardiac arrest. He was a member of the plant’s on-site security and first aid department. He also ran a private first aid training business. "We did everything we could. We called the ambulance. It got here as fast as it could," says Ian Maxwell, plant protection assistant at Harmac.

Five months later, another employee, 45 years old, woke one winter morning and shoveled his driveway. After coming into work, "he sat down to put on his coveralls and keeled over," says Maxwell. It was another SCA.

Maxwell says the two deaths in five months stunned the 700 employees, most of whom are in their forties to late fifties, many with poor physical fitness levels. "We had people signing up at our fitness centre after the incident, trading diet recipes. These deaths really shocked our work force."

"It stirred up a lot of feeling. We realized we did all we could. Still people asked, ‘But isn’t there something more?’"

There was. More than two years later, after long and arduous negotiations with government health agencies, justice officials and the workers’ compensation board, after consultations with doctors, lawyers, and other workplaces, Harmac has its first AED. Select staff members are currently being trained. Maxwell says that he believes Harmac is the first private workplace in the province to have an AED.

Harmac’s struggle for an AED was unique; it had to set the groundwork. In some provinces, the progress of PAD initiatives has made it easier for workplaces to get an AED. But often, removing pre-conceived notions and fears of defibrillation from managers, owners and legislators is difficult.

FOOLPROOF TECHNOLOGY

AEDs weigh less than four pounds, and are about the size a hardcover book. Each unit should come with back-up supplies including replacement defibrillator electrodes (the pads placed on a patient’s chest) and a replacement battery.

Most units have voice-prompt commands as well as visual commands on a screen, which may include the following: attach electrodes, press to analyze, stand clear, press to shock, or consider CPR. Lithium battery technology eliminates frequent recharging and reduces some of the maintenance requirements. New AEDs also incorporate self-test and status indicator features that monitor the batteries and internal electronics, and alert the owner if service is required. An AED used to cost between $5,000 and $10,000. Now they are available for around $3,000 to $5,000.

During an incident, an AED will record the data it senses regarding a patient’s condition. Some AEDs will also record a live audio of the situation. Units save the data in memory, which can then be transferred via modem to hospital or onto disks, compatible with PC software. The AEDs are entirely in charge of diagnosing a victim, and determining how much energy will applied and when . A first responder can’t make a mistake.

When defibrillating a patient, the AED sends out specifically calibrated energy loads. There is AED technology that will actually determine the size and weight of a patient, and tailor the shocks to the appropriate energy level (see box). Users only have to follow the commands. And it is impossible to shock someone who does not have a "shockable" rhythm.

The common wave form delivered by AED is "monophasic", meaning that the current travels in only one direction, from the positive pad, through the heart, to the negative pad. In the "biphasic" wave form, however, current is delivered in one direction, stops, and is then reversed to travel in the opposite direction across the heart again.

"The biphasic wave form crosses the heart twice in an incredibly short space if time," says Mike Ichelson, of Code 8 Inc., in Toronto, Ontario. "So it uses the same amount of electrical current to help the heart using less energy. It means it is a smaller machine, lighter and uses up the battery less. And less energy also means less cell damage."

Newer AEDs also deliver an individualized amount of energy. External defibrillator electricity must first travel trough muscle, bone, organs and other tissues before reaching the heart. The energy level used should take into account the electrical resistance of the chest, which varies significantly from person to person. Sometimes people with high chest resistance will not receive sufficient energy with initial shocks, while people with low chest impedance receive substantially more energy than may be needed.

HP-Heartstream’s ForeRunner, a biphasic defibrillator, uses a method of instantaneously measuring chest resistance and automatically optimizing the shape of the wave form for each person. The process is called "impedance-controlled defibrillation", and results in a cheaper, lighter-weight and more reliable machine. The biphasic wave form will likely become the standard in all AEDs in the future.

ONE LINK IN THE CHAIN

First responders sometimes panic when confronted with applying their own CPR skills; add a high-tech electronic device and the doubts can immobilize them. And, of course, things can go wrong. An electrode pad may come loose from the cord to the unit. The battery may suddenly fail. Add those possibilities into the time equation -- the need to shave a hairy chest, possibly move the victim off a conductive or wet surface, and general pandemonium in an emergency -- and there is some cause for resistance to public access defibrillation.

Ichelson says that the right kind of training can remove those fears. "Students have fears. They think it is scary at first. But once they are shown how it works, they’re okay."

"An AED is first aid for the dead" says Ichelson. We train people to observe that death has occurred. If the machine fails, it’s terrible, but it’s not like you’re responsible for their death."

Ichelson says that Code 8 training includes a grab-bag of everything-that-can-go-wrong scenarios. "We go through it if the battery fails. The person may vomit ... that during CPR you may break some ribs ... electrodes may be faulty ... the cord may be loose ... the battery may be low. Or the electrodes may come off the chest." "We throw [everything] at them in training. Even things that will never likely happen."

Still, some emergency medical workers and classic first responders, such as firefighters and police, have concerns over full public access to AEDs. "Most workplaces have trouble maintaining their first aid boxes," says Andre Aumont, a firefighter and certified defibrillator trainer with the Ottawa airport. An AED requires daily maintenance checks, and that information has to be sent monthly to a medical director or a training company.

"They have to be checked all the time," says Aumont. He is concerned that shift rotation at a workplace may make it difficult to ensure that designated, knowledgeable staff apply standard maintenance.

MAKING IT WORK

A workplace AED program should be incorporated into an existing first aid program. There are many factors to consider, such as employee demographics, before deciding to get an AED. (See "What You Need to Do" box, page XX.)

Lawson Mardon Flexible, a packaging company in Toronto, Ont. has had 11 certified AED responders and two units, one at each work site, since May, 1998. Cindy Paget, occupational health nurse heading the AED project, hasn’t encountered a maintenance problem. And they haven’t had to use either of their AEDs yet, either.

On a rotating schedule, each person on Lawson’s defibrillator team runs through a daily maintenance check on the AEDs -- including battery check, and back-up battery check -- which takes about five minutes. "The equipment does its own self-test and will start to beep if there is a problem," Paget says.

Lawson’s designated first responders took an eight-hour course in defibrillation in addition to a refresher in the standard CPR and first aid training. (A trainee must have first aid and CPR certification to take AED training.) The training company also helped with purchasing an AED and provided physician authorization.

Not all training providers are "all-inclusive". The Canadian Red Cross AED training program has a liability waiver that indicates its program does not permit someone to use the AED skills: a participant must obtain his or her own authorization from a medical director. St. John Ambulance will have a course ready for the new year. Also, most manufacturers will provide a basic run-though course with the purchase of a device.

Lawson’s AEDs are hooked up such that, if they are lifted off the charging unit, an alarm is triggered that patches through to a monitoring station which then calls the paramedics. There should always be a direct liaison with local EMS whenever an AED program is set up. Also, in an emergency, the ambulance crew arriving should be informed that an AED is being used.

NOTHING TO LOSE

In Canada, defibrillation is a "delegated medical act". This means a physician, or medical director, is responsible for ensuring a user is properly trained and prepared at all times to use an AED. A medical director must also establish or approve protocols of a program. According to Mike Ichelson of Code 8, protocols should all follow the American Heart Association’s international standards. By obtaining "physician authorization" the physician is taking responsible for the actions of the AED users. This can be given directly to a trainee, or in a three-tier manner: from the physician down to the training provider, who may then authorize a trainee on the physician’s behalf.

Are most physicians willing to risk their jobs for PAD? When asked about liability, Canadian doctors responsible for PAD programs and those conducting studies into PAD are quite forthright. The consensus: "What can go wrong? The person is already dead."

Yet, one of the biggest fears of public access to AEDs, expressed by private and public companies, is fear of liability, according to Doug Odney, public education officer with the City of Calgary EMS Department. Odney, a chief proponent of PAD, helped to create Calgary’s AED committee over three years ago. Promoting the concept of a "heart safe city", Calgary is ahead of most other North American cities in strengthening the chain of survival -- and in the number of public locations where AEDs are available.

Already, close to 20 large-scale public venues in Calgary have AEDs and trained staff, including the city’s zoo, city hall, golf courses, parks, colleges and several workplaces. The EMS department provides free training to companies that acquire AEDs, and a medical director for authorization.

The word is that AEDs are slowly becoming what is considered a necessary "standard of care" -- much like a first aid program in a workplace. Odney explains: Let’s says a park has an AED. Someone in the park suffers sudden cardiac arrest and the AED is used successfully. Now, a fitness centre across the street does not have an AED. Someone suffers sudden cardiac arrest and they die. It’s easy to show how the fitness centre has not provided a "standard of care", he contends.

"Could I be sued successfully?" asks Dr. Michael Shuster, emergency physician with Mineral Springs Hospital in Banff, Alberta. "I highly doubt it." Shuster ran an AED program in late 1980s, and trained ambulance workers and firefighters in Hamilton, Ontario, out of a base hospital program. This, at a time when first responders and AEDs were an unconventional combination. This year, he will be training ski patrollers and hotel staff in Banff to use AEDs.

"Theoretically, I suppose my license is on the line. But you start out with a dead person. Defibrillation can’t make them more dead. You may fail to resuscitate someone, but only a percentage are ever resuscitated," Shuster says. "In 1988 I was training firefighters. I was taking a chance. But who would go after me? Someone died, but they got a chance they might not have had otherwise."

Full public access to defibrillation will take many years. Part of the problem is that there is no "standard system across Canada, no number-one agency with authorization to delegate or allow AED use," explains Shuster. Also, before full-fledged PAD, traditional first responders, such as firefighters and policeman, and even some ambulance crews need to be trained and have access to AEDs.

The Canadian Heart and Stroke Foundation and the American Heart Association have position statements fully supporting PAD. Also, in Alberta, the CHSF chapter of Alberta and the Northwest Territories has presented an argument for legislative changes to promote PAD to the Standing Policy Committee on Health Planning, Public Health Department. In the United States, a bill, the Cardiac Arrest Survival Act, has been introduced to the House and Senate. The bill would facilitate widespread deployment of AEDs.

And do AEDs work? Yes. Does public access to defibrillation make sense? It may be hard to convince the skeptics when there is little empirical evidence regarding lay responders and AEDs. Few studies have been conducted on the efficiency and cost-effectiveness of AEDs by the emergency medical services. But there is always the Las Vegas experience to turn to.

In 1995, Clark County, Nevada, firefighters discovered that 64 per cent of the more than 700 sudden cardiac arrests which occurred per year in the county happened in hotel or casino environments. A plan was devised with specialists from the University of Arizona, in which over 1,500 security guards in more than 30 hotels and casinos were trained in AED use. A close look at the Vegas phenomena has since shown an astonishing 75 per cent survival rate from SCA victims. Without early defibrillation, the rate can be a low as five per cent.

The Calgary AED Committee promotes the idea that AEDs should be "as common as a fire extinguisher on a wall". It’s a good analogy. A fire put out in the first few minutes can save lives -- but you still call in the professional firefighters. And, as the Las Vegas experience has shown, using an AED in the first few minutes of a sudden cardiac arrest can radically change the odds of survival in your favour.

Lesley Young is assistant editor of OHS CANADA.

AED IN ACTION

In an ideal situation, there will be two first responders equipped with an AED at the scene of a sudden cardiac arrest, one to apply CPR, and the other to prepare the AED. The following is based on the Canadian Red Cross AED training program guide.

Upon arrival at the scene of what appears to be SCA, a rescuer should first verify unresponsiveness and the absence of a pulse.

1. Rescuers equipped with an AED initiated CPR immediately upon their arrival at the scene.

2. One rescuer then applies two large electrodes, which are connected to the AED by wire leads, to the patient’s chest.

3. Once electrodes are in place, CPR is stopped, the analysis mode on the AED is activated, and the patient’s ECG (electrocardiogram) will be automatically analyzed by the AED.

4. If the ECG shows that the patient should receive a shock for defibrillation, the AED identifies it as such and prepares to deliver an electrical shock.

The lead rescuer must ensure that no one is in contact either directly or indirectly with the patient when defibrillating (some machines will say "stand clear").

5. The AED then prompts the rescuer to give the shock (some devices do so automatically). If standard, the shock will consist of 200-Joules.

6. The rescuer’s next actions depend on the results of defibrillation.

7. After the first shock, the analysis mode is reactivated. If another shock is indicated, a second shock of 200 to 300 Joules is delivered (this depends on local protocol).

8. If required, a third shock is delivered at 360 Joules.

9. After the third shock, the patient’s pulse is checked. If there is no pulse, CPR is performed for one minute, after which the pulse is rechecked.

10. If there is no pulse, steps five through nine are repeated, but the amount of energy increases.

If at any time the analysis results in a "no shock indicated" message, the patient’s pulse should be checked, and if it is absent, one minute of CPR performed. The pulse should then be rechecked and patient re-analyzed with the AED. If still no shock is indicated, the cycle of AED analysis and one minute of CPR is continued until the patient has a pulse, a shock is indicated or EMTs arrive to take charge.

DO YOU NEED AN AED?

Does your company need an AED? A workplace that already has a medical clinic or section that is staffed by a nurse, emergency medical technician or physician is in a prime position to adopt an AED program. A workplace should also determine how long emergency response takes to arrive at the facility. If it is more than several minutes, it is a good idea to consider getting an AED. Keep in mind that incorporating an AED program is a lot of work, at first. It will likely involve a review of current emergency response policy and procedures.

The American Association of Occupational Health Nurses has compiled a number of factors for consideration before and after choosing to purchase an AED.

* Examine employee demographics. In addition the age and numbers of employees, look at risk factors of heart disease, as well as personal and family health histories of heart disease.

* Is there an emergency response team already in place, or would this AED program be the impetus for starting a comprehensive program at the work site? Identify individuals who are or will be involved in the response. What level of life-support training do these individuals already possess, and what additional training do they need?

* Contact the local EMS department. Who plays the role of first responder in the community (police, firefighters), and what is their average response time? Are the community first responders trained to use AEDs and do they carry them as standard equipment in their vehicles?

* Cost must also be considered. The number of AEDs needed to cover a site, however, will vary with the number of employees, layout and location. Cost of training materials, personnel coordination and implementation of a quality improvement program must be included.

* Assess the workplace for risk factors that may cause SCA. SCA can be an occupational hazard. Electrical hazards and exposure to chemical asphyxiates are examples. Preventive measures should be a priority, but, depending on the situation and accident history, there may be a need for an on-site cardiac intervention program.

The following factors should be incorporate when planning and implementing an AED program.

* Designate a coordinator for the program. A health nurse, or the person responsible for the first aid program, can provide effective coordination of the program and communication with key players, such as the ambulance service.

* Establish a working relationship with the local ambulance service and a medical consultant with occupational, cardiac or emergency medical expertise. Practice protocols for using and training in the AED should be developed in communication with the medical consultant and in keeping with provincial regulations.

* Establish training. Early access (calling 911) and early CPR must be included in a comprehensive emergency response training program that includes defibrillation.

* Carry out drills. Cardiac arrest drills provide hands-on practice for responders as well as an opportunity for evaluation of company procedures. Mock victims should receive defibrillator intervention within four minutes of initial call. Training on debriefing in the case of a cardiac incident should also be considered.

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