Bystander Defibrillation May Double Cardiac Arrest Survival

Marlene Busko

March 02, 2018

People who had a cardiac arrest in a public place and received an automated external defibrillator (AED) shock by a bystander were more likely to make a full neurologic recovery compared with those receiving defibrillation by a first responder, in a new study.

Specifically, 57% of people with a shockable cardiac arrest who received a bystander-delivered AED shock survived and were discharged from the hospital with no neurologic disability compared with 33% of people who received defibrillation from an emergency medical service (EMS) responder, a statistically significant difference.  

These findings from the US and Canadian Resuscitation Outcomes Consortium (ROC), by Ross A Pollack, BS, Johns Hopkins University School of Medicine, Baltimore, and colleagues were published February 26 in Circulation.

Almost 20% of the people received a bystander-delivered AED shock, which is "a pretty good number," senior author, Myron Weisfeldt, MD, Johns Hopkins University School of Medicine, told | Medscape Cardiology.

Even when EMS responders can arrive within about 5.3 minutes, as in this study, "if a bystander can find a defibrillator, put it on and use it, they can double the chance of survival," he noted.

"This study shows you really can save useful lives by having publicly available defibrillators, and obviously you need to train bystanders and encourage bystanders to use them. "

"The bottom line is this study provides additional strong evidence of the importance of public use of AEDs," Circulation guest editor for this article, Christopher B Granger, MD, Duke University Medical Center, Durham, North Carolina, told | Medscape Cardiology.

The next step is to increase the use of AEDs throughout the United States, he said. "In Denmark, for example, they've doubled or tripled the used of AEDs by the public in cardiac arrest, so we have good demonstration that it can be done."

Bystander AED use is better in some parts of the United States than in other areas, so "we need to focus on this as a public health opportunity," Granger said.

Time to Defibrillation Is Critical  

A person with shockable cardiac arrest, ventricular tachycardia and ventricular fibrillation, has much better survival odds than someone with cardiac arrest without a shockable rhythm, Pollack and colleagues note.

Three recent studies suggested that bystander AED use before the arrival of a first responder could improve the odds of surviving a shockable cardiac arrest, with excellent neurologic functional status.

The researchers aimed to compare functional outcomes after bystander AED use vs EMS shock in people with shockable out-of-hospital cardiac arrest in the nine ROC mid-sized cities (Seattle/King County, Washington; Dallas/Fort Worth, Texas; Pittsburgh, Pennsylvania; Milwaukee, Wisconsin; Birmingham, Alabama; Portland, Oregon; Toronto, Ontario; Ottawa, Ontario; and Vancouver, British Columbia), from 2011 to 2015.

Of 49,555 cardiac arrests that were treated by EMS personnel, 4115 (8.3%) occurred in a public setting and were witnessed by bystanders.

Of these, 2589 (63%) cardiac arrests had a shockable rhythm; 89 cardiac arrest cases were excluded from the current analysis because of missing data, "do not resuscitate" instructions, death on arrival at hospital, or not receiving an EMS-delivered shock.

Of the remaining people with shockable cardiac arrest, 469 (19%) received a bystander-delivered AED shock and 2031 people did not.

After adjustment for multiple variables, people with cardiac arrest who received a bystander AED shock vs those who received an initial shock from EMS personnel had 2.7-fold higher odds of surviving until they were discharged from the hospital with excellent neurologic function (modified Rankin Scale score ≤ 2; P < .001).

The odds of surviving to hospital discharge with excellent neurologic function with bystander defibrillation as opposed to EMS defibrillation were 1.86-fold higher if the EMS responder arrived within 4 minutes and 6.54-fold higher if the EMS responder arrived within 12 minutes.

"The longer it takes the EMS [responders] to get there, the more valuable the bystander defibrillation," Weisfeldt noted.

Moreover, these were medium-sized cities. Larger cities with more traffic congestion, or cases of cardiac arrest occurring on the 100th floor of an office tower, necessitating a long elevator ride, would make bystander AED use even more critical.

Place AEDs Near Fire Extinguishers

To improve survival after public cardiac arrests, Granger said, we will need "more deliberate placement of AEDs in the public places where cardiac arrests are more likely to occur and training the public to use AEDs and integrating AED location information with the dispatch center."  

When 911 responders know where the nearest defibrillator is, they can "direct bystanders to the nearest AED and get it used."

"AEDs are designed to be easy to use and it should be self-explanatory," he added, "but all too often in the United States, if you look at an AED on the wall, even at Duke Hospital, for example, half the time on the AED it says Only to be used by trained personnel,' which is totally false."

"The data advocates strongly for the idea of a uniform presence of a defibrillator in large public buildings in a uniform place," Weisfeldt said. "We do better than [this] for fire, which is far less of a threat."

A statement issued by the American Heart Association (AHA) notes that in a witnessed, out-of-hospital cardiac arrest, the first step is to call 911 and immediately start cardiopulmonary resuscitation (CPR), and then follow the directions on the AED.

For every minute without CPR, the chance of death increases by 10%.

One of the study's limitations is that it only examined bystander AED use without considering the combined impact of calling 911 and starting immediate CPR.

A 2017 AHA survey found that most US employees lack training in CPR and first aid, and half could not locate the AED at their workplace.

"First aid, CPR, and AED training need to become part of a larger culture of safety within workplaces," said Michael Kurz, MD, chair of AHA's Systems of Care Subcommittee and associate professor at the University of Alabama School of Medicine in the Department of Emergency Medicine.

"We are certainly seeing higher public interest in this training, and our campaign calls upon decision makers in workplaces and popular public spaces, such as arenas, fitness centers, hotels, and churches, to place AEDs in the same locations as a fire extinguisher."

ROC is funded by the National Heart, Lung, and Blood Institute in partnership with the National Institute of Neurological Disorders and Stroke; US Army Medical Research & Material Command; the Canadian Institutes of Health Research (CIHR)– Institute of Circulatory and Respiratory Health, Defense Research and Development Canada; the Heart, Stroke Foundation of Canada; and the American Heart Association. Pollack and Weisfeldt have no relevant financial disclosures, and the financial disclosures of the other authors are listed with the article.

Circulation. Published online February 26, 2018. Abstract

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