STOCKHOLM: The use of onsite automated external defibrillators (AED), increasingly found in places like airports and sports stadiums, is raising the chances of surviving a cardiac arrest, suggests a recent study from Europe.
Between 2008 and 2013 in regions of Denmark, the Netherlands, and Sweden, the proportion of patients experiencing cardiac arrest outside of a hospital who had a dose of electric current delivered to the heart by emergency medical services dropped by half, researchers found. At the same time, the proportion that received this treatment, known as defibrillation, from bystanders or first responders such as firefighters or police more than doubled.
On average, patients got shocks to restore their heart rhythm sooner than was typical in the past and there was an overall increase in survival over the study period, from 13% to 15%.
“An automated external defibrillator (AED) is a portable electronic device that automatically diagnoses life-threatening cardiac arrhythmias and is able to treat them through defibrillation,” senior author Dr Jacob Hollenberg, a cardiologist at the Karolinska Institute in Stockholm, told Reuters Health in an email.
“The application of electricity stops the arrhythmia, allowing the heart to reestablish an effective rhythm,” Hollenberg said. “An AED is simple to use, and you cannot do harm. With simple audio and visual commands, they are designed to be simple to use for the laypersons.”
Continued AED training programs for first responders and the general public are essential, the study team writes in the journal, Heart.
Altogether the researchers identified 22,453 patients whose survival status was known. Of these, 2,957 were alive 30 days after their cardiac arrest and 2,289 of them had received defibrillation before reaching a hospital.
Over time, the proportion of survivors defibrillated by first-responder AEDs rose from 13% in 2008 to 26% in 2013. Similarly, the proportion of survivors who received their first defibrillation from an onsite AED rose from 14% in 2008 to 30% in 2013.
Survivors of out-of-hospital cardiac arrest are increasingly defibrillated by non-EMS AEDs and these treatments are associated with increased survival, Hollenberg said.
New studies are needed, especially aiming to increase survival for the two-thirds of the cardiac arrests that occur at home, Hollenberg noted. “Here, I am convinced that further studies of dispatch of lay responders are the most promising solution for the future.”
The results substantially confirm what has also been seen in the US, said Dr Myron Westfeldt, a researcher at Johns Hopkins University School of Medicine in Baltimore who wasn’t involved in the study.
“There is no doubt anymore that bystanders can use the defibrillators that are now being manufactured,” Westfeldt said in a phone interview. “They’re easy to use, they’re self-instructional, and they really do save lives, tremendously save lives.”
Many previous studies have estimated that every minute waiting for defibrillation results in a loss of about 10% of potential survivors, Westfeldt noted.
“If a bystander does CPR and chest compression, it’s a little bit better than if nobody does anything, but the really important thing is how long it takes to defibrillate. And clearly, the benefit of the bystander defibrillating is going to be greater the longer it takes EMS to get there,” he said.
Citizen volunteers, drones, and even car services such as Uber could help increase access to AEDs, he added.
He also cited American Heart Association efforts in every US state over a two or three-year period to include defibrillation under Good Samaritan statutes.
“So, people who were consciously using the defibrillator in the best way they knew how could not be sued for . . . as long as they were a real bystander using it in an appropriate way,” he said.