Critical Care Plus: Shockingly Good Idea?

Some experts want increased AED availability

Two studies on automated external defibrillators (AEDs) indicate that casinos and airlines may have a better shot at saving lives in cardiac arrest cases than many hospitals do.1,2 Yet even though the American Heart Association and others have supported AED use by nonmedical personnel, some say the devices should be under physician control.

Mickey S. Eisenberg, MD, PhD, director of emergency services at the University of Washington/Seattle, says AEDs should be an over-the-counter item available to any consumer. "The argument has to do with the safety and simplicity of the device," Eisenberg says. "Anyone can learn how to use it, literally in a matter of minutes." Eisenberg adds that the device coaches the user by providing prompts on what to do next. "We know that about 75% of all cardiac arrests happen at home," Eisenberg says. "The logical way to save more lives is to turn AEDs into a consumer item."

Eisenberg is certainly no stranger to out-of-hospital AED use. In 1980, along with several colleagues, he demonstrated that patients who were defibrillated by EMTs enjoyed significantly higher rates of survival to hospital discharge than patients who only got CPR and rapid transport to a hospital.

Survival rate figures from the casino and airline studies referenced above appear to further support making AEDs as a consumer item.

When AEDs were used at a casino, 56 of 105 patients whose initial cardiac rhythm was ventricular fibrillation survived to discharge from the hospital. The survival rate was 74% for those who received their first defibrillation no later than three minutes after a witnessed collapse and 49% for those who received their first defibrillation after more than three minutes. For 86% of the 90 patients whose collapse was witnessed, the clinically relevant time intervals were a mean (± SD) of 3.5 ± 2.9 minutes from collapse to attachment of the defibrillator, 4.4 ± 2.9 minutes from collapse to the delivery of the first defibrillation shock, and 9.8 ± 4.3 minutes from collapse to the arrival of the paramedics.1

Flight attendants for a major US airline were trained on AEDs in 1997. They used devices when passengers lost consciousness, pulse, or stopped breathing. The AED was also used as a monitor for other medical emergencies, usually at the direction of a physician passenger. Two arrhythmia specialists analyzed electrocardiograms obtained during AED use between June 1, 1997, and July 15, 1999, found the survival-to-discharge from the hospital rate following AED shock was 40%. No complications arose from use of the automated external defibrillator as a monitor in conscious passengers. Researchers concluded that complications are unlikely AEDs are used as a monitor in the absence of ventricular fibrillation.2

New AED May Eliminate Some ICU Stays

Thomas Mattioni, MD, director of electrophysiology at Arizona Heart Institute in Phoenix, says his hospital uses an AED called Powerheart. Unlike paddle-activated hospital-administered AEDs, PowerHeart devices are actually worn by patients. Powerhearts use wires that run from adhesive pads placed on chest where paddles would go with in-hospital defibrillation to the defibrillator. Powerheart AEDs, also used extensively at Boston’s Maimonides Hospital, detect signals through the pads, takes EKG’s and continuously monitors patients, delivering shocks during arrhythmias that return the heart rate to normal. "It’s like the implantable device in that once it’s attached it’s fully automatic, monitors the patient, detects when something has gone wrong and deliver the appropriate therapy without human intervention," Mattioni says, "Except that the adhesive pads need to be changed every 24 hours."

Mattioni says Powerheart is the only device that allows for fully automatic therapy. Mattioni says his facility has 20 PowerHeart AED devices and 58 beds. Half of the patients attached to the Powerheart survived. Only 20% of those not attached to the devices survived. "We can’t make any valid statements about the efficacy of the Powerheart based on those small numbers, but I think there’s certainly a trend there," Mattioni says.

Mattioni points out that the faster you can shock a patient following cardiac arrest, the faster they get back to normal. Powerhearts ensure that the patient will receive a shock at a pre-programmed time—typically after 30-60 seconds of arrhythmia—thus beating the usual hospitals response times of 4-5 minutes by a wide margin. "We don’t do as good a job of resuscitating people following cardiac arrest as some casinos do," Mattioni says, observing that casino response times for the majority of patients fell within three minutes. "That’s the whole key to this technology, decreasing the amount of time the patient is in ventricular arrhythmias and thus decreasing long-term neurological or cardiac damage associated with that arrest," Mattioni says. "Our goal is to bring the survival to the highest rate we can."

Mattioni observes that a patient in a telemetry unit who suffers arrest is shocked and resuscitated. A patient who survives is intubated, hooked up to a ventilator, and taken to the intensive care unit. Those patients are frequently given implantable defibrillators.

Mattioni says that with Powerheart AEDs, patients don’t need to be intubated, have their chest compressed or take special medications. "If you shock them very close to the time they lose consciousness, the patient not only doesn’t remember getting the shock but don’t have any long term brain damage, either, Mattioni says. "If properly applied, Powerheart stands to potentially eliminate post-resuscitation ICU stay."

Possible Access Drawbacks Cited

Not everyone thinks universal AED access is a great idea. Arthur Kellerman, MD, of the Department of Emergency Medicine at Emory University School of Medicine in Atlanta, says that "with rare exceptions, it is not even clear where public access AEDs should be placed because few locations are settings for more than 1 cardiac arrest per year.4

Kellerman acknowledges that AEDs are clearly efficacious for terminating ventricular fibrillation or ventricular tachycardia when swiftly applied. But he argues that alone does not justify making AEDs readily available before they are shown to be a cost-effective strategy for reducing mortality from out-of-hospital cardiac arrest.4 Kellerman also points out that prices quoted for AEDs rarely include initial and refresher training costs, or costs for electrodes, extra batteries, maintenance, and eventual replacement.

Kellerman writes that "the fact that some people can afford to purchase a medical device that delivers a powerful shock does not absolve physicians of the responsibility to control access to it. More important, there is no evidence that placing an AED in the home of a patient with heart disease is better than teaching family members to immediately call 911 and begin CPR. While there is little doubt that authorizing over-the-counter sales of AEDs would produce a financial windfall for the manufacturers of these devices, it is less clear that the public would benefit. Given the choice of spending between $250 and $1500 to purchase an AED for the home or spending a comparable amount of money on a bicycle, a smoking cessation program, a health club membership, or treatment of hypertension, most people would be better served by choosing one of the latter options for themselves or a loved one."

References

1. Valenzuela T, Roe D, et al. Outcomes of rapid defibrillation by security officers after cardiac arrest in casinos. N Engl J Med. 2000;343:1206-1209.

2. Page, R, Joglar, J, et al. Use of automated external defibrillators by a U.S. airline. N Engl J Med. 2000; 343:1210-1216.

3. Eisenberg, Mickey S. Is it time for over-the-counter defibrillators? JAMA. 2000;284:1435.

4. Brown, J, Kellerman, A. The shocking truth about automated external defibrillators. JAMA. 2000;284: 1438.

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