Are drones a fast way to deliver emergency defibrillators?

Drones may be able to rush emergency defibrillators to patients in cardiac arrest faster than traditional emergency medical services (EMS), potentially improving survival odds, a small Swedish experiment suggests.

Researchers ran 18 simulations comparing how long it took a drone and traditional EMS to reach various locations within a 10-kilometer (6.2 mile) radius of a fire station north of Stockholm. The drone consistently beat typical EMS response times, by almost 17 minutes in half of the cases.

“With drones carrying automated external defibrillators (AEDs) we may increase chances of survival significantly (by) delivering an AED within the very first minutes,” said lead study author Andreas Claesson of the Karolinska Institute in Stockholm.

In cardiac arrest, the heart stops abruptly, often due to irregular heart rhythms. Cardiac arrest may occur with no warning and is often fatal unless the heart can be restarted quickly.

Only about one in 10 patients typically survive a cardiac arrest when it happens outside a hospital, and reducing the time it takes to shock the heart back into a normal rhythm with a defibrillator is the biggest factor influencing survival odds, the researchers note in JAMA.

Automated external defibrillators are already common in public places like restaurants and airports. These devices typically have electrodes that attach to the chest with sticky pads and deliver shocks based on what a computer in the defibrillator determines the person needs.

Someday, emergency dispatchers might be able to respond to cardiac arrests by sending out drones with defibrillators that bystanders at the scene could use on cardiac arrest patients until EMS arrived. This shift might be especially helpful for improving survival odds in remote rural areas and resort communities that swell in population during the summer months, Claesson said by email.

The drone used in the study was equipped with a global positioning system (GPS), a high-definition camera and an autopilot software system. Even though it could use GPS to fly on autopilot, a pilot was present at the landing locations and the dispatcher could take over the drone for descent if necessary.

For the study, researchers pitted the drone’s performance in test flights conducted over 72 hours in October 2016 to the actual dispatch and arrival times for EMS in real cardiac arrest cases that occurred from 2006 to 2014.

Half of the emergencies in the simulations were at least 3.2 kilometers (2 miles) away from the fire station. In half of the cases, the drone took no more than three seconds to take off after the emergency calls came in, compared with three minutes for EMS.

With the drone, the time from dispatch to arrival at the scene of the emergency was only about five minutes in half of the cases, compared with 22 minutes for EMS.

Limitations of the study include the small number of test flights, which were all done in good weather, the authors note.

The drones also had some advantages in this experiment that they might not have in real life, said Dr Peter Pons, a professor emeritus of emergency medicine at the University of Colorado School of Medicine in Denver who wasn’t involved in the study.

Drones, for example, might not work well in bad weather and might have a limited flight range, Pons said by email.

At the same time, an ambulance involves several steps, including getting the necessary information on the location and the patient, notifying and assembling an EMS crew, and then getting the ambulance underway, Pons said.

For the same cost it might require to build a drone network just to deliver defibrillators to cardiac arrest patients, it might be possible to instead expand EMS services to speed response times in all types of emergencies, Pons said.

Still, he thinks drones could make a big difference in cardiac arrest survival odds.

“The time savings reported in this letter would clearly provide a meaningful improvement in the outcome of victims of cardiac arrest,” Pons said. “We know that for each minute that CPR and defibrillation are delayed, survival from cardiac arrest decreases.”