Drones carrying AEDs to the rescue

A drone carrying an AED on its way to the site of an emergency call reporting a sudden cardiac arrest, which was timed as part of the study. — Assoc Prof ANDREAS CLAESSON

When a person suffers sudden cardiac arrest, which includes heart attacks, every minute counts.

Currently, as few as one in 10 people survives an out-of-hospital cardiac arrest.

However, with early CPR (cardiopulmonary resuscitation) and a shock from an automated external defibrillator (AED), the chances of survival could reach 50-70%.

To get there, help needs to arrive faster.

Reports from the emergency medical services of out-of-hospital cardiac arrests in Sweden show that in 2019, the median response time from alert to ambulance arrival in cases of cardiac arrest was 11 minutes.

In an effort to reach out-of-hospital cardiac arrest victims earlier, researchers at Karolinska Institutet, together with the Swedish national emergency operator SOS Alarm, Region Västra Götaland and drone operator Everdrone AB, explored using drones to quickly dispatch AEDs in parallel with ambulances.

The study, which was carried out in the summer of 2020 in the cities of Gothenburg and Kungälv in western Sweden, describes an integrated method where emergency operators, drone pilots and air traffic control worked together to facilitate the dual response.

During the four-month study period, the drones took off in response to 12 out of 53 alerts of suspected cardiac arrest.

They successfully delivered an AED to the site in 11 of those cases (92%).

In seven cases (64%), the drones arrived before the ambulance, with a median time gap of one minute and 52 seconds.

The drones travelled a median distance of 3.1km without causing any disturbances or damage to the surrounding area.

No drone-delivered AEDs were attached to the patients before the ambulance arrived.

“Even if none of the AEDs were used this time, our study shows that it is possible to use drones to transport defibrillators in a safe way and with target precision during real-life emergencies,” says first author and Karolinska Institutet PhD student Sofia Schierbeck.

“A precondition for their future use is that the dispatcher takes initiative and instructs people on site to quickly collect and attach the AED in order to help the person with cardiac arrest.”

Lead researcher and Karolinska Institutet Department of Clinical Science and Education Center for Resuscitation Science associate professor Andreas Claesson points out that: “This is the first time in the world that a research group can report results from a study where drones flew defibrillators to the location of real-life alerts of suspected cardiac arrest.”

The researchers note that further improvements are needed to increase dispatch rate and time benefits.

For instance, in 2020, the drones could not fly when it was dark, rainy or had winds of 8m per second or more.

The software system was also pre-set to avoid routes above densely-populated areas, which meant that some alerts were geographically out of range.

“Since this study was completed, we have identified several areas of improvement,” Assoc Prof Claesson says.

“In April, we began a follow-up study with a more optimised system.

“In that study, we want to test if we can use the drones in more alerts and reduce the response time further, and thereby increase the time benefit as compared to the ambulance.

“Every minute without treatment in the early stages reduces the chance of survival by around 10%, and that is why we believe this new method of delivery has the potential to save lives.”

The study was published in the European Heart Journal and presented at the European Society of Cardiology congress on Aug 24 (2021).

It was financed with grants from the Swedish Heart and Lung Foundation.