In hospitals, automated defibrillators may not work so well

November 14, 2011

Just over a decade ago, hospitals around the country began spending millions of dollars to buy automated defibrillators to save the lives of patients who go into sudden cardiac arrest. The purchases were spurred by a recommendation from an American Heart Association committee, which concluded that the equipment would bring patients speedier help.

But research done since the switch suggests that the more costly gear, which is now found in nearly all hospitals, saves fewer lives than old, lower-tech defibrillators. One recent study suggests that nearly 1,000 Americans die in hospitals every year because it can take longer to assess patients with the new devices and because nurses aren’t adequately trained on the equipment.

All told, some doctors now believe that the AHA recommendation came too soon, without investigating whether the new device is as effective in hospital settings as the old gear.

“I think they jumped the gun,” said Steven Nissen, chair of cardiovascular medicine at the Cleveland Clinic.

According to members of the AHA committee, concern about slow response times for treating hospital patients in cardiac arrest prompted the switch. The idea was that automated equipment would be so easy to use that almost any medical staffer nearby could operate them and quickly start helping a patient whose heart had stopped.

The new technology “was demonstrated to be effective in saving lives,” said Robert A. Berg, a committee member and the critical care division chief at Children’s Hospital of Philadelphia.

“We just assumed that we were going to make a difference,” added Roger D. White, who was on an AHA subcommittee that studied automated defibrillators and who currently is an anesthesiologist at the Mayo Clinic in Rochester, Minn. But, he said, “what we thought would work hasn’t worked so far.”

AHA officials said the new research is unlikely on its own to force reconsideration of the guidelines when they are eligible for a five-year review in 2015. “Guidelines are based on the entire body of evidence,” said a spokesman for the association.

AED sales soar

Defibrillators use an electrical current to shock hearts back into normal rhythm. Since the 1990s, automated equipment providing step-by-step audio instructions has been in widespread use at public buildings, including some hospitals. But the AHA panel’s 2000 guidelines pushed for far greater use by hospitals, saying this would reduce in-hospital preventable deaths.

Committee members said in interviews that studies had shown that the basic model of the new devices — often known as automated external defibrillators, or AEDs — saved lives in non-hospital settings such as airports.

Data was accumulating that lay-rescuer AED programs could shorten time from collapse to shock delivery and result in very high rates of survival,” said Mary Fran Hazinski, an AHA science editor and nurse who was a member of the committee.

Among the 11 committee members, three have acknowledged receiving research funding from manufacturers of the devices. (In one case, that funding was disclosed in the committee’s report.) When contacted, they said this funding was not a factor in their decision to approve the guidelines; rather, they were convinced that the automated equipment would save lives.

Purchases of the devices zoomed after the 2000 guidelines were released. U.S. hospitals bought close to 100,000 of the basic automated models between 2000 and 2010, according to the consulting firm Frost & Sullivan. The firm projects that sales of the AEDs to hospitals will keep rising over the next few years.

The cost of switching hospitals to the newer equipment was modest, by hospital equipment standards. The widely used basic models, which walk someone through the process after pads are attached to a person’s chest, begin at around $1,600.

Yet even as their use was increasing in hospitals, an analysis published this summer raised concerns about the automated devices.

Flaws lead to recalls

Based on reports sent to the Food and Drug Administration from 1993 through 2008, researchers found that the equipment sometimes failed to work properly. For example, the devices failed to turn on, turned off unexpectedly or failed to deliver the recommended shock. The analysis associated more than 1,000 cardiac-arrest deaths with equipment failures in a variety of settings.

The FDA said manufacturers have recalled tens of thousands of the devices.

The Advanced Medical Technology Association, which represents the medical device industry, said that companies are working with the FDA to improve the devices. It added that the FDA “continues to advocate the use of external defibrillators and is not recommending any change to current use practices for these devices.”

A separate study raised broader questions about the value of AEDs for hospitalized patients.

Published last year in the Journal of the American Medical Association, the study tracked 11,695 patients in 204 hospitals who suffered cardiac arrest between 2000 and 2008.

“AED use was associated with a lower rate of survival after in-hospital cardiac arrest compared with no AED use,” the study found. The main reasons were that patients who suffer cardiac arrest tend to be sicker than the average victim and may have complex medical problems that make them more apt to suffer “non-shockable” cardiac arrest — episodes that can’t be fixed by a defibrillator.

The study indicated that the use of an automated defibrillator might interfere with other life-saving techniques in some cases.

In those cases, a defibrillator may be needed to provide readings on how a patient is responding to cardiopulmonary resuscitation, or CPR. Ordinarily, CPR is applied and then periodically interrupted so that the defibrillators can provide those crucial readings. A big drawback to the automated machines is that they require longer interruptions to make those readings, and the lost seconds of CPR can be fatal.

Adequacy of training

The study also suggested that the new defibrillators have failed to achieve one of the major goals behind the AHA recommendation: getting patients in cardiac arrest shocked more quickly. It suggested that was not happening because many nurses had not been adequately trained to use the new devices.

All told, the study calculated that cardiac arrest patients treated at hospitals with automated defibrillators survived only 16.3 percent of the time. By comparison, the survival rate was 19.3 percent at hospitals that used manual equipment to shock patients.

Based on estimates that AEDs are used in one in six of the approximately 200,000 annual cases of cardiac arrest in hospitals, the lower survival rate would translate into about “965 fewer patients potentially who may be alive” every year in the United States, according to the study’s lead author, Paul S. Chan, a cardiologist at Saint Luke’s Health System in Missouri.

Manufacturers and some doctors counter that research shows that patients at certain hospitals, particularly those with a shortage of staffers trained to use manual defibrillators, benefit from the automated devices.

Richard O. Cummins, an emergency medicine professor at the University of Washington and one of three members of the AHA committee who said he received some funding from AED makers, said he stands by the committee’s original reasoning, emphasizing that financial considerations were never a part of his thinking. “I still endorse the idea” of the AEDs, he said.

Dana Edelson, a board member of the nonprofit Sudden Cardiac Arrest Foundation and an assistant professor at University of Chicago Medical Center who was not on the committee, agreed that the devices are needed despite the problems found in the studies.

“I think it would be a mistake to throw out a blanket statement [that] hospitals shouldn’t be using an AED,” she said. “It depends who is there in the middle of the night.”

This article was produced by FairWarning, a nonprofit investigative news organization focused on public-health and safety issues. A longer version can be read at www.fairwarning.org .

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