'Off Hours' Limit Access to AEDs in Cardiac Arrest

September 18, 2013

GENTOFTE, DENMARK — Despite widespread placement of automated external defibrillators (AEDs) in one European city, more than half of all cardiac arrests occurred during hours when access to the lifesaving devices is not possible, according to the results of a new study[1].

In Denmark, Copenhagen, nearly every individual who collapsed from cardiac arrest during working weekday hours did so in a location that was within 100 m of a publicly accessible AED, whereas just 53.4% of cardiac arrests that occurred within proximity to an AED in the evening, at night, or on the weekend were "covered" by the devices. The cardiac arrests during these "off hours" occurred in proximity to AEDs located in banks, offices, and private medical/dental practices where there is no accessibility to the life-saving devices in the evening, at night, or on weekends.

"These findings underline that not only strategic placement but also uninterrupted AED accessibility warrants attention if public-access defibrillation is to improve survival after out-of-hospital cardiac arrest," conclude lead investigator Dr Carolina Malta Hansen (University of Copenhagen, Denmark) and colleagues.

The results of the study are published online September 13, 2013 in Circulation.

One AED Every 10 Square Miles

Copenhagen is a city of approximately 600 000 people and covers an area of 97 sq km (60 sq mi). There are 5.7 AEDs per sq km (9.2 per sq mi) in the city. Since 1997, all AEDs available for public access have been registered with the Danish AED network. From the network, information about the AED location, type of establishment, and exact days and hours of accessibility is available to emergency dispatch centers. Of the 552 AEDs registered in the area, 49.8% are placed in government or municipal buildings and just 9.1% of the AEDs are available 24 hours per day, seven days per week.

From 1994 to 2011, there were 1864 cardiac arrests in public locations. Of these cardiac arrests, 62% occurred on weekends, in the evening, or during the night.

Regardless of the accessibility of AEDs, nearly 30% of all cardiac arrests occurred within 100 m of a public defibrillator. Similarly, 30.5% of cardiac arrests during workday hours occurred within 100 m of an AED, as did 27.8% of all cardiac arrests occurring in the evening, during the night, and on weekends. "Thus, assuming all AEDs were accessible 24 hours per day, seven days a week, nearly 30% of all cardiac arrests in public locations could be reached by an AED within a few minutes on weekdays and weekends," report the investigators.

However, of the 537 cardiac arrests that occurred within 100 m of an AED, there was no access to the device in 180 cases. During workday hours, the limited accessibility to the AEDs decreased coverage of the cardiac arrests by 4.1%. During the evening, nighttime, and weekend hours, limited accessibility to the devices reduced coverage of the cardiac arrests by 53.4%.

National Preparedness

Commenting on the results of the study for heartwire , Dr Benjamin Abella (University of Pennsylvania, Philadelphia), a spokesperson for the American Heart Association, said the issue of access to AEDs remains a challenge, although it is just one of many when it comes to cardiac arrest and sudden cardiac death.

"Many areas in the US are not well covered," said Abella. "There are many public buildings, an area of common use, that don't have AEDs. Another major challenge in the US is that we don't have a good system for registering AEDs and finding out where they are located. In Denmark, they have a system in place where they know where all the AEDs are, which helps their research, but which is also tremendously helpful clinically. We have multiple challenges to a good AED program, and this shows how complex the problem really is."

He said that cardiac arrest is a daunting problem because it occurs "anytime, anywhere, with little warning, and it has a high mortality rate." The US health community, he added, is only coming to terms with how challenging care for cardiac arrest can be. He stressed, however, that cardiac arrest occurs frequently in the home, so one of the best policies for national preparedness is to get people to learn cardiopulmonary resuscitation (CPR).

"In the US, it's the private residence issue that looms large," said Abella. "If somebody has a cardiac arrest at home, which is where the majority of events take place, if nobody in the house knows CPR, the only thing to do is wait for an ambulance, which can take precious minutes. One of the important things to keep in mind is that AEDs are not going to be a perfect solution and they're not going to save everyone, so [it's important] for the public to learn CPR. CPR should be the immediate response to a cardiac-arrest event--anywhere and anytime it occurs. If an AED is available, that's important, but we can't rely on it."

The authors and Abella have no conflicts of interest.


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