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It’s a modern guardian angel. Drones aren’t just good for getting your shopping in an instant – by carrying defibrillators they could prove to be life-saving if your heart stops beating.

Only around one in ten people survives a cardiac arrest outside hospital. Having a bystander perform chest compressions improves your chances, but a shock from a defibrillator must be applied quickly to restart the heart.

Every minute without CPR and defibrillation reduces someone’s chance of survival by 10 per cent. Defibrillators are designed to give spoken instructions so that anyone can use them, and many are available in public places.

Jacob Hollenberg at the Karolinska Institute in Sweden and colleagues wondered if drones could be used to get a defibrillator to the emergency scene more quickly than an ambulance. They attached a defibrillator to a drone stationed at a fire station in Norrtälje, a rural location near Stockholm, and dispatched it to locations within 10 kilometres where actual cardiac arrests had taken place in the past eight years.

Over 18 flights, the median time from the drone’s dispatch to its arrival at the emergency location was 5 minutes 21 seconds. During the real emergencies, the median dispatch time for the ambulance was 22 minutes.

“If we can decrease the time in cardiac arrest from collapse to defibrillation by a few minutes, hundreds of lives would be saved each year,” says Hollenberg.

His team is working with emergency services, preparing to dispatch the drone in real emergencies and test whether it improve outcomes. “Hopefully we will be up and running within a year or two,” he says.

Adrian Boyle of the Royal College of Emergency Medicine, London, says the approach is interesting, but making sure more people can do CPR would probably have more benefit. “One of the things we are bad at in the UK is teaching bystanders CPR, which would arguably be a much lower tech, more useful intervention than this.”

Stockholm, London and other cities have trialled mobile apps that alert CPR-trained people if someone has a cardiac arrest nearby.

Hollenberg’s team has also tested using drones to search for people who are drowning. “I’m convinced that the possibility of using drones in medical emergencies is enormous,” he says.

NHS England is planning to use drones to assist hazardous area response teams, who deal with medical emergencies involving chemical, biological or nuclear materials. It is also looking at the possibility of using drone technologies to deliver blood and organs for transplant, says Christian Cooper of the National Ambulance Resilience Unit.

Read more: App tries to fetch medical help before cardiac arrest kills you; NHS to use drones to help chemical, bio and nuke response teams